First crack at `terminal-modes' in SSH. PuTTY now sends ERASE by default,

[u/mdw/putty] / terminal.c

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>

#include <time.h>
#include <assert.h>
#include "putty.h"
#include "terminal.h"

#define poslt(p1,p2) ( (p1).y < (p2).y || ( (p1).y == (p2).y && (p1).x < (p2).x ) )
#define posle(p1,p2) ( (p1).y < (p2).y || ( (p1).y == (p2).y && (p1).x <= (p2).x ) )
#define poseq(p1,p2) ( (p1).y == (p2).y && (p1).x == (p2).x )
#define posdiff(p1,p2) ( ((p1).y - (p2).y) * (term->cols+1) + (p1).x - (p2).x )

/* Product-order comparisons for rectangular block selection. */
#define posPlt(p1,p2) ( (p1).y <= (p2).y && (p1).x < (p2).x )
#define posPle(p1,p2) ( (p1).y <= (p2).y && (p1).x <= (p2).x )

#define incpos(p) ( (p).x == term->cols ? ((p).x = 0, (p).y++, 1) : ((p).x++, 0) )
#define decpos(p) ( (p).x == 0 ? ((p).x = term->cols, (p).y--, 1) : ((p).x--, 0) )

#define VT52_PLUS

#define CL_ANSIMIN      0x0001         /* Codes in all ANSI like terminals. */
#define CL_VT100        0x0002         /* VT100 */
#define CL_VT100AVO     0x0004         /* VT100 +AVO; 132x24 (not 132x14) & attrs */
#define CL_VT102        0x0008         /* VT102 */
#define CL_VT220        0x0010         /* VT220 */
#define CL_VT320        0x0020         /* VT320 */
#define CL_VT420        0x0040         /* VT420 */
#define CL_VT510        0x0080         /* VT510, NB VT510 includes ANSI */
#define CL_VT340TEXT    0x0100         /* VT340 extensions that appear in the VT420 */
#define CL_SCOANSI      0x1000         /* SCOANSI not in ANSIMIN. */
#define CL_ANSI         0x2000         /* ANSI ECMA-48 not in the VT100..VT420 */
#define CL_OTHER        0x4000         /* Others, Xterm, linux, putty, dunno, etc */

#define TM_VT100        (CL_ANSIMIN|CL_VT100)
#define TM_VT100AVO     (TM_VT100|CL_VT100AVO)
#define TM_VT102        (TM_VT100AVO|CL_VT102)
#define TM_VT220        (TM_VT102|CL_VT220)
#define TM_VTXXX        (TM_VT220|CL_VT340TEXT|CL_VT510|CL_VT420|CL_VT320)
#define TM_SCOANSI      (CL_ANSIMIN|CL_SCOANSI)

#define TM_PUTTY        (0xFFFF)

#define UPDATE_DELAY    ((TICKSPERSEC+49)/50)/* ticks to defer window update */
#define TBLINK_DELAY    ((TICKSPERSEC*9+19)/20)/* ticks between text blinks*/
#define CBLINK_DELAY    (CURSORBLINK) /* ticks between cursor blinks */
#define VBELL_DELAY     (VBELL_TIMEOUT) /* visual bell timeout in ticks */

#define compatibility(x) \
    if ( ((CL_##x)&term->compatibility_level) == 0 ) {  \
       term->termstate=TOPLEVEL;                        \
       break;                                           \
    }
#define compatibility2(x,y) \
    if ( ((CL_##x|CL_##y)&term->compatibility_level) == 0 ) { \
       term->termstate=TOPLEVEL;                        \
       break;                                           \
    }

#define has_compat(x) ( ((CL_##x)&term->compatibility_level) != 0 )

const char sco2ansicolour[] = { 0, 4, 2, 6, 1, 5, 3, 7 };

#define sel_nl_sz  (sizeof(sel_nl)/sizeof(wchar_t))
const wchar_t sel_nl[] = SEL_NL;

/*
 * Fetch the character at a particular position in a line array,
 * for purposes of `wordtype'. The reason this isn't just a simple
 * array reference is that if the character we find is UCSWIDE,
 * then we must look one space further to the left.
 */
#define UCSGET(a, x) \
    ( (x)>0 && (a)[(x)].chr == UCSWIDE ? (a)[(x)-1].chr : (a)[(x)].chr )

/*
 * Detect the various aliases of U+0020 SPACE.
 */
#define IS_SPACE_CHR(chr) \
        ((chr) == 0x20 || (DIRECT_CHAR(chr) && ((chr) & 0xFF) == 0x20))

/*
 * Spot magic CSETs.
 */
#define CSET_OF(chr) (DIRECT_CHAR(chr)||DIRECT_FONT(chr) ? (chr)&CSET_MASK : 0)

/*
 * Internal prototypes.
 */
static void resizeline(Terminal *, termline *, int);
static termline *lineptr(Terminal *, int, int, int);
static void unlineptr(termline *);
static void do_paint(Terminal *, Context, int);
static void erase_lots(Terminal *, int, int, int);
static void swap_screen(Terminal *, int, int, int);
static void update_sbar(Terminal *);
static void deselect(Terminal *);
static void term_print_finish(Terminal *);
#ifdef OPTIMISE_SCROLL
static void scroll_display(Terminal *, int, int, int);
#endif /* OPTIMISE_SCROLL */

static termline *newline(Terminal *term, int cols, int bce)
{
    termline *line;
    int j;

    line = snew(termline);
    line->chars = snewn(cols, termchar);
    for (j = 0; j < cols; j++)
        line->chars[j] = (bce ? term->erase_char : term->basic_erase_char);
    line->cols = line->size = cols;
    line->lattr = LATTR_NORM;
    line->temporary = FALSE;
    line->cc_free = 0;

    return line;
}

static void freeline(termline *line)
{
    if (line) {
        sfree(line->chars);
        sfree(line);
    }
}

static void unlineptr(termline *line)
{
    if (line->temporary)
        freeline(line);
}

#ifdef TERM_CC_DIAGS
/*
 * Diagnostic function: verify that a termline has a correct
 * combining character structure.
 * 
 * This is a performance-intensive check, so it's no longer enabled
 * by default.
 */
static void cc_check(termline *line)
{
    unsigned char *flags;
    int i, j;

    assert(line->size >= line->cols);

    flags = snewn(line->size, unsigned char);

    for (i = 0; i < line->size; i++)
        flags[i] = (i < line->cols);

    for (i = 0; i < line->cols; i++) {
        j = i;
        while (line->chars[j].cc_next) {
            j += line->chars[j].cc_next;
            assert(j >= line->cols && j < line->size);
            assert(!flags[j]);
            flags[j] = TRUE;
        }
    }

    j = line->cc_free;
    if (j) {
        while (1) {
            assert(j >= line->cols && j < line->size);
            assert(!flags[j]);
            flags[j] = TRUE;
            if (line->chars[j].cc_next)
                j += line->chars[j].cc_next;
            else
                break;
        }
    }

    j = 0;
    for (i = 0; i < line->size; i++)
        j += (flags[i] != 0);

    assert(j == line->size);

    sfree(flags);
}
#endif

/*
 * Add a combining character to a character cell.
 */
static void add_cc(termline *line, int col, unsigned long chr)
{
    int newcc;

    assert(col >= 0 && col < line->cols);

    /*
     * Start by extending the cols array if the free list is empty.
     */
    if (!line->cc_free) {
        int n = line->size;
        line->size += 16 + (line->size - line->cols) / 2;
        line->chars = sresize(line->chars, line->size, termchar);
        line->cc_free = n;
        while (n < line->size) {
            if (n+1 < line->size)
                line->chars[n].cc_next = 1;
            else
                line->chars[n].cc_next = 0;
            n++;
        }
    }

    /*
     * Now walk the cc list of the cell in question.
     */
    while (line->chars[col].cc_next)
        col += line->chars[col].cc_next;

    /*
     * `col' now points at the last cc currently in this cell; so
     * we simply add another one.
     */
    newcc = line->cc_free;
    if (line->chars[newcc].cc_next)
        line->cc_free = newcc + line->chars[newcc].cc_next;
    else
        line->cc_free = 0;
    line->chars[newcc].cc_next = 0;
    line->chars[newcc].chr = chr;
    line->chars[col].cc_next = newcc - col;

#ifdef TERM_CC_DIAGS
    cc_check(line);
#endif
}

/*
 * Clear the combining character list in a character cell.
 */
static void clear_cc(termline *line, int col)
{
    int oldfree, origcol = col;

    assert(col >= 0 && col < line->cols);

    if (!line->chars[col].cc_next)
        return;                        /* nothing needs doing */

    oldfree = line->cc_free;
    line->cc_free = col + line->chars[col].cc_next;
    while (line->chars[col].cc_next)
        col += line->chars[col].cc_next;
    if (oldfree)
        line->chars[col].cc_next = oldfree - col;
    else
        line->chars[col].cc_next = 0;

    line->chars[origcol].cc_next = 0;

#ifdef TERM_CC_DIAGS
    cc_check(line);
#endif
}

/*
 * Compare two character cells for equality. Special case required
 * in do_paint() where we override what we expect the chr and attr
 * fields to be.
 */
static int termchars_equal_override(termchar *a, termchar *b,
                                    unsigned long bchr, unsigned long battr)
{
    /* FULL-TERMCHAR */
    if (a->chr != bchr)
        return FALSE;
    if ((a->attr &~ DATTR_MASK) != (battr &~ DATTR_MASK))
        return FALSE;
    while (a->cc_next || b->cc_next) {
        if (!a->cc_next || !b->cc_next)
            return FALSE;              /* one cc-list ends, other does not */
        a += a->cc_next;
        b += b->cc_next;
        if (a->chr != b->chr)
            return FALSE;
    }
    return TRUE;
}

static int termchars_equal(termchar *a, termchar *b)
{
    return termchars_equal_override(a, b, b->chr, b->attr);
}

/*
 * Copy a character cell. (Requires a pointer to the destination
 * termline, so as to access its free list.)
 */
static void copy_termchar(termline *destline, int x, termchar *src)
{
    clear_cc(destline, x);

    destline->chars[x] = *src;         /* copy everything except cc-list */
    destline->chars[x].cc_next = 0;    /* and make sure this is zero */

    while (src->cc_next) {
        src += src->cc_next;
        add_cc(destline, x, src->chr);
    }

#ifdef TERM_CC_DIAGS
    cc_check(destline);
#endif
}

/*
 * Move a character cell within its termline.
 */
static void move_termchar(termline *line, termchar *dest, termchar *src)
{
    /* First clear the cc list from the original char, just in case. */
    clear_cc(line, dest - line->chars);

    /* Move the character cell and adjust its cc_next. */
    *dest = *src;                      /* copy everything except cc-list */
    if (src->cc_next)
        dest->cc_next = src->cc_next - (dest-src);

    /* Ensure the original cell doesn't have a cc list. */
    src->cc_next = 0;

#ifdef TERM_CC_DIAGS
    cc_check(line);
#endif
}

/*
 * Compress and decompress a termline into an RLE-based format for
 * storing in scrollback. (Since scrollback almost never needs to
 * be modified and exists in huge quantities, this is a sensible
 * tradeoff, particularly since it allows us to continue adding
 * features to the main termchar structure without proportionally
 * bloating the terminal emulator's memory footprint unless those
 * features are in constant use.)
 */
struct buf {
    unsigned char *data;
    int len, size;
};
static void add(struct buf *b, unsigned char c)
{
    if (b->len >= b->size) {
        b->size = (b->len * 3 / 2) + 512;
        b->data = sresize(b->data, b->size, unsigned char);
    }
    b->data[b->len++] = c;
}
static int get(struct buf *b)
{
    return b->data[b->len++];
}
static void makerle(struct buf *b, termline *ldata,
                    void (*makeliteral)(struct buf *b, termchar *c,
                                        unsigned long *state))
{
    int hdrpos, hdrsize, n, prevlen, prevpos, thislen, thispos, prev2;
    termchar *c = ldata->chars;
    unsigned long state = 0, oldstate;

    n = ldata->cols;

    hdrpos = b->len;
    hdrsize = 0;
    add(b, 0);
    prevlen = prevpos = 0;
    prev2 = FALSE;

    while (n-- > 0) {
        thispos = b->len;
        makeliteral(b, c++, &state);
        thislen = b->len - thispos;
        if (thislen == prevlen &&
            !memcmp(b->data + prevpos, b->data + thispos, thislen)) {
            /*
             * This literal precisely matches the previous one.
             * Turn it into a run if it's worthwhile.
             * 
             * With one-byte literals, it costs us two bytes to
             * encode a run, plus another byte to write the header
             * to resume normal output; so a three-element run is
             * neutral, and anything beyond that is unconditionally
             * worthwhile. With two-byte literals or more, even a
             * 2-run is a win.
             */
            if (thislen > 1 || prev2) {
                int runpos, runlen;

                /*
                 * It's worth encoding a run. Start at prevpos,
                 * unless hdrsize==0 in which case we can back up
                 * another one and start by overwriting hdrpos.
                 */

                hdrsize--;             /* remove the literal at prevpos */
                if (prev2) {
                    assert(hdrsize > 0);
                    hdrsize--;
                    prevpos -= prevlen;/* and possibly another one */
                }

                if (hdrsize == 0) {
                    assert(prevpos == hdrpos + 1);
                    runpos = hdrpos;
                    b->len = prevpos+prevlen;
                } else {
                    memmove(b->data + prevpos+1, b->data + prevpos, prevlen);
                    runpos = prevpos;
                    b->len = prevpos+prevlen+1;
                    /*
                     * Terminate the previous run of ordinary
                     * literals.
                     */
                    assert(hdrsize >= 1 && hdrsize <= 128);
                    b->data[hdrpos] = hdrsize - 1;
                }

                runlen = prev2 ? 3 : 2;

                while (n > 0 && runlen < 129) {
                    int tmppos, tmplen;
                    tmppos = b->len;
                    oldstate = state;
                    makeliteral(b, c, &state);
                    tmplen = b->len - tmppos;
                    b->len = tmppos;
                    if (tmplen != thislen ||
                        memcmp(b->data + runpos+1, b->data + tmppos, tmplen)) {
                        state = oldstate;
                        break;         /* run over */
                    }
                    n--, c++, runlen++;
                }

                assert(runlen >= 2 && runlen <= 129);
                b->data[runpos] = runlen + 0x80 - 2;

                hdrpos = b->len;
                hdrsize = 0;
                add(b, 0);
                /* And ensure this run doesn't interfere with the next. */
                prevlen = prevpos = 0;
                prev2 = FALSE;

                continue;
            } else {
                /*
                 * Just flag that the previous two literals were
                 * identical, in case we find a third identical one
                 * we want to turn into a run.
                 */
                prev2 = TRUE;
                prevlen = thislen;
                prevpos = thispos;
            }
        } else {
            prev2 = FALSE;
            prevlen = thislen;
            prevpos = thispos;
        }

        /*
         * This character isn't (yet) part of a run. Add it to
         * hdrsize.
         */
        hdrsize++;
        if (hdrsize == 128) {
            b->data[hdrpos] = hdrsize - 1;
            hdrpos = b->len;
            hdrsize = 0;
            add(b, 0);
            prevlen = prevpos = 0;
            prev2 = FALSE;
        }
    }

    /*
     * Clean up.
     */
    if (hdrsize > 0) {
        assert(hdrsize <= 128);
        b->data[hdrpos] = hdrsize - 1;
    } else {
        b->len = hdrpos;
    }
}
static void makeliteral_chr(struct buf *b, termchar *c, unsigned long *state)
{
    /*
     * My encoding for characters is UTF-8-like, in that it stores
     * 7-bit ASCII in one byte and uses high-bit-set bytes as
     * introducers to indicate a longer sequence. However, it's
     * unlike UTF-8 in that it doesn't need to be able to
     * resynchronise, and therefore I don't want to waste two bits
     * per byte on having recognisable continuation characters.
     * Also I don't want to rule out the possibility that I may one
     * day use values 0x80000000-0xFFFFFFFF for interesting
     * purposes, so unlike UTF-8 I need a full 32-bit range.
     * Accordingly, here is my encoding:
     * 
     * 00000000-0000007F: 0xxxxxxx (but see below)
     * 00000080-00003FFF: 10xxxxxx xxxxxxxx
     * 00004000-001FFFFF: 110xxxxx xxxxxxxx xxxxxxxx
     * 00200000-0FFFFFFF: 1110xxxx xxxxxxxx xxxxxxxx xxxxxxxx
     * 10000000-FFFFFFFF: 11110ZZZ xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx
     * 
     * (`Z' is like `x' but is always going to be zero since the
     * values I'm encoding don't go above 2^32. In principle the
     * five-byte form of the encoding could extend to 2^35, and
     * there could be six-, seven-, eight- and nine-byte forms as
     * well to allow up to 64-bit values to be encoded. But that's
     * completely unnecessary for these purposes!)
     * 
     * The encoding as written above would be very simple, except
     * that 7-bit ASCII can occur in several different ways in the
     * terminal data; sometimes it crops up in the D800 page
     * (CSET_ASCII) but at other times it's in the 0000 page (real
     * Unicode). Therefore, this encoding is actually _stateful_:
     * the one-byte encoding of 00-7F actually indicates `reuse the
     * upper three bytes of the last character', and to encode an
     * absolute value of 00-7F you need to use the two-byte form
     * instead.
     */
    if ((c->chr & ~0x7F) == *state) {
        add(b, (unsigned char)(c->chr & 0x7F));
    } else if (c->chr < 0x4000) {
        add(b, (unsigned char)(((c->chr >> 8) & 0x3F) | 0x80));
        add(b, (unsigned char)(c->chr & 0xFF));
    } else if (c->chr < 0x200000) {
        add(b, (unsigned char)(((c->chr >> 16) & 0x1F) | 0xC0));
        add(b, (unsigned char)((c->chr >> 8) & 0xFF));
        add(b, (unsigned char)(c->chr & 0xFF));
    } else if (c->chr < 0x10000000) {
        add(b, (unsigned char)(((c->chr >> 24) & 0x0F) | 0xE0));
        add(b, (unsigned char)((c->chr >> 16) & 0xFF));
        add(b, (unsigned char)((c->chr >> 8) & 0xFF));
        add(b, (unsigned char)(c->chr & 0xFF));
    } else {
        add(b, 0xF0);
        add(b, (unsigned char)((c->chr >> 24) & 0xFF));
        add(b, (unsigned char)((c->chr >> 16) & 0xFF));
        add(b, (unsigned char)((c->chr >> 8) & 0xFF));
        add(b, (unsigned char)(c->chr & 0xFF));
    }
    *state = c->chr & ~0xFF;
}
static void makeliteral_attr(struct buf *b, termchar *c, unsigned long *state)
{
    /*
     * My encoding for attributes is 16-bit-granular and assumes
     * that the top bit of the word is never required. I either
     * store a two-byte value with the top bit clear (indicating
     * just that value), or a four-byte value with the top bit set
     * (indicating the same value with its top bit clear).
     * 
     * However, first I permute the bits of the attribute value, so
     * that the eight bits of colour (four in each of fg and bg)
     * which are never non-zero unless xterm 256-colour mode is in
     * use are placed higher up the word than everything else. This
     * ensures that attribute values remain 16-bit _unless_ the
     * user uses extended colour.
     */
    unsigned attr, colourbits;

    attr = c->attr;

    assert(ATTR_BGSHIFT > ATTR_FGSHIFT);

    colourbits = (attr >> (ATTR_BGSHIFT + 4)) & 0xF;
    colourbits <<= 4;
    colourbits |= (attr >> (ATTR_FGSHIFT + 4)) & 0xF;

    attr = (((attr >> (ATTR_BGSHIFT + 8)) << (ATTR_BGSHIFT + 4)) |
            (attr & ((1 << (ATTR_BGSHIFT + 4))-1)));
    attr = (((attr >> (ATTR_FGSHIFT + 8)) << (ATTR_FGSHIFT + 4)) |
            (attr & ((1 << (ATTR_FGSHIFT + 4))-1)));

    attr |= (colourbits << (32-9));

    if (attr < 0x8000) {
        add(b, (unsigned char)((attr >> 8) & 0xFF));
        add(b, (unsigned char)(attr & 0xFF));
    } else {
        add(b, (unsigned char)(((attr >> 24) & 0x7F) | 0x80));
        add(b, (unsigned char)((attr >> 16) & 0xFF));
        add(b, (unsigned char)((attr >> 8) & 0xFF));
        add(b, (unsigned char)(attr & 0xFF));
    }
}
static void makeliteral_cc(struct buf *b, termchar *c, unsigned long *state)
{
    /*
     * For combining characters, I just encode a bunch of ordinary
     * chars using makeliteral_chr, and terminate with a \0
     * character (which I know won't come up as a combining char
     * itself).
     * 
     * I don't use the stateful encoding in makeliteral_chr.
     */
    unsigned long zstate;
    termchar z;

    while (c->cc_next) {
        c += c->cc_next;

        assert(c->chr != 0);

        zstate = 0;
        makeliteral_chr(b, c, &zstate);
    }

    z.chr = 0;
    zstate = 0;
    makeliteral_chr(b, &z, &zstate);
}

static termline *decompressline(unsigned char *data, int *bytes_used);

static unsigned char *compressline(termline *ldata)
{
    struct buf buffer = { NULL, 0, 0 }, *b = &buffer;

    /*
     * First, store the column count, 7 bits at a time, least
     * significant `digit' first, with the high bit set on all but
     * the last.
     */
    {
        int n = ldata->cols;
        while (n >= 128) {
            add(b, (unsigned char)((n & 0x7F) | 0x80));
            n >>= 7;
        }
        add(b, (unsigned char)(n));
    }

    /*
     * Next store the lattrs; same principle.
     */
    {
        int n = ldata->lattr;
        while (n >= 128) {
            add(b, (unsigned char)((n & 0x7F) | 0x80));
            n >>= 7;
        }
        add(b, (unsigned char)(n));
    }

    /*
     * Now we store a sequence of separate run-length encoded
     * fragments, each containing exactly as many symbols as there
     * are columns in the ldata.
     * 
     * All of these have a common basic format:
     * 
     *  - a byte 00-7F indicates that X+1 literals follow it
     *  - a byte 80-FF indicates that a single literal follows it
     *    and expects to be repeated (X-0x80)+2 times.
     * 
     * The format of the `literals' varies between the fragments.
     */
    makerle(b, ldata, makeliteral_chr);
    makerle(b, ldata, makeliteral_attr);
    makerle(b, ldata, makeliteral_cc);

    /*
     * Diagnostics: ensure that the compressed data really does
     * decompress to the right thing.
     * 
     * This is a bit performance-heavy for production code.
     */
#ifdef TERM_CC_DIAGS
#ifndef CHECK_SB_COMPRESSION
    {
        int dused;
        termline *dcl;
        int i;

#ifdef DIAGNOSTIC_SB_COMPRESSION
        for (i = 0; i < b->len; i++) {
            printf(" %02x ", b->data[i]);
        }
        printf("\n");
#endif

        dcl = decompressline(b->data, &dused);
        assert(b->len == dused);
        assert(ldata->cols == dcl->cols);
        assert(ldata->lattr == dcl->lattr);
        for (i = 0; i < ldata->cols; i++)
            assert(termchars_equal(&ldata->chars[i], &dcl->chars[i]));

#ifdef DIAGNOSTIC_SB_COMPRESSION
        printf("%d cols (%d bytes) -> %d bytes (factor of %g)\n",
               ldata->cols, 4 * ldata->cols, dused,
               (double)dused / (4 * ldata->cols));
#endif

        freeline(dcl);
    }
#endif
#endif /* TERM_CC_DIAGS */

    /*
     * Trim the allocated memory so we don't waste any, and return.
     */
    return sresize(b->data, b->len, unsigned char);
}

static void readrle(struct buf *b, termline *ldata,
                    void (*readliteral)(struct buf *b, termchar *c,
                                        termline *ldata, unsigned long *state))
{
    int n = 0;
    unsigned long state = 0;

    while (n < ldata->cols) {
        int hdr = get(b);

        if (hdr >= 0x80) {
            /* A run. */

            int pos = b->len, count = hdr + 2 - 0x80;
            while (count--) {
                assert(n < ldata->cols);
                b->len = pos;
                readliteral(b, ldata->chars + n, ldata, &state);
                n++;
            }
        } else {
            /* Just a sequence of consecutive literals. */

            int count = hdr + 1;
            while (count--) {
                assert(n < ldata->cols);
                readliteral(b, ldata->chars + n, ldata, &state);
                n++;
            }
        }
    }

    assert(n == ldata->cols);
}
static void readliteral_chr(struct buf *b, termchar *c, termline *ldata,
                            unsigned long *state)
{
    int byte;

    /*
     * 00000000-0000007F: 0xxxxxxx
     * 00000080-00003FFF: 10xxxxxx xxxxxxxx
     * 00004000-001FFFFF: 110xxxxx xxxxxxxx xxxxxxxx
     * 00200000-0FFFFFFF: 1110xxxx xxxxxxxx xxxxxxxx xxxxxxxx
     * 10000000-FFFFFFFF: 11110ZZZ xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx
     */

    byte = get(b);
    if (byte < 0x80) {
        c->chr = byte | *state;
    } else if (byte < 0xC0) {
        c->chr = (byte &~ 0xC0) << 8;
        c->chr |= get(b);
    } else if (byte < 0xE0) {
        c->chr = (byte &~ 0xE0) << 16;
        c->chr |= get(b) << 8;
        c->chr |= get(b);
    } else if (byte < 0xF0) {
        c->chr = (byte &~ 0xF0) << 24;
        c->chr |= get(b) << 16;
        c->chr |= get(b) << 8;
        c->chr |= get(b);
    } else {
        assert(byte == 0xF0);
        c->chr = get(b) << 24;
        c->chr |= get(b) << 16;
        c->chr |= get(b) << 8;
        c->chr |= get(b);
    }
    *state = c->chr & ~0xFF;
}
static void readliteral_attr(struct buf *b, termchar *c, termline *ldata,
                             unsigned long *state)
{
    unsigned val, attr, colourbits;

    val = get(b) << 8;
    val |= get(b);

    if (val >= 0x8000) {
        val &= ~0x8000;
        val <<= 16;
        val |= get(b) << 8;
        val |= get(b);
    }

    colourbits = (val >> (32-9)) & 0xFF;
    attr = (val & ((1<<(32-9))-1));

    attr = (((attr >> (ATTR_FGSHIFT + 4)) << (ATTR_FGSHIFT + 8)) |
            (attr & ((1 << (ATTR_FGSHIFT + 4))-1)));
    attr = (((attr >> (ATTR_BGSHIFT + 4)) << (ATTR_BGSHIFT + 8)) |
            (attr & ((1 << (ATTR_BGSHIFT + 4))-1)));

    attr |= (colourbits >> 4) << (ATTR_BGSHIFT + 4);
    attr |= (colourbits & 0xF) << (ATTR_FGSHIFT + 4);

    c->attr = attr;
}
static void readliteral_cc(struct buf *b, termchar *c, termline *ldata,
                           unsigned long *state)
{
    termchar n;
    unsigned long zstate;
    int x = c - ldata->chars;

    c->cc_next = 0;

    while (1) {
        zstate = 0;
        readliteral_chr(b, &n, ldata, &zstate);
        if (!n.chr)
            break;
        add_cc(ldata, x, n.chr);
    }
}

static termline *decompressline(unsigned char *data, int *bytes_used)
{
    int ncols, byte, shift;
    struct buf buffer, *b = &buffer;
    termline *ldata;

    b->data = data;
    b->len = 0;

    /*
     * First read in the column count.
     */
    ncols = shift = 0;
    do {
        byte = get(b);
        ncols |= (byte & 0x7F) << shift;
        shift += 7;
    } while (byte & 0x80);

    /*
     * Now create the output termline.
     */
    ldata = snew(termline);
    ldata->chars = snewn(ncols, termchar);
    ldata->cols = ldata->size = ncols;
    ldata->temporary = TRUE;
    ldata->cc_free = 0;

    /*
     * We must set all the cc pointers in ldata->chars to 0 right
     * now, so that cc diagnostics that verify the integrity of the
     * whole line will make sense while we're in the middle of
     * building it up.
     */
    {
        int i;
        for (i = 0; i < ldata->cols; i++)
            ldata->chars[i].cc_next = 0;
    }

    /*
     * Now read in the lattr.
     */
    ldata->lattr = shift = 0;
    do {
        byte = get(b);
        ldata->lattr |= (byte & 0x7F) << shift;
        shift += 7;
    } while (byte & 0x80);

    /*
     * Now we read in each of the RLE streams in turn.
     */
    readrle(b, ldata, readliteral_chr);
    readrle(b, ldata, readliteral_attr);
    readrle(b, ldata, readliteral_cc);

    /* Return the number of bytes read, for diagnostic purposes. */
    if (bytes_used)
        *bytes_used = b->len;

    return ldata;
}

/*
 * Resize a line to make it `cols' columns wide.
 */
static void resizeline(Terminal *term, termline *line, int cols)
{
    int i, oldcols;

    if (line->cols != cols) {

        oldcols = line->cols;

        /*
         * This line is the wrong length, which probably means it
         * hasn't been accessed since a resize. Resize it now.
         * 
         * First, go through all the characters that will be thrown
         * out in the resize (if we're shrinking the line) and
         * return their cc lists to the cc free list.
         */
        for (i = cols; i < oldcols; i++)
            clear_cc(line, i);

        /*
         * If we're shrinking the line, we now bodily move the
         * entire cc section from where it started to where it now
         * needs to be. (We have to do this before the resize, so
         * that the data we're copying is still there. However, if
         * we're expanding, we have to wait until _after_ the
         * resize so that the space we're copying into is there.)
         */
        if (cols < oldcols)
            memmove(line->chars + cols, line->chars + oldcols,
                    (line->size - line->cols) * TSIZE);

        /*
         * Now do the actual resize, leaving the _same_ amount of
         * cc space as there was to begin with.
         */
        line->size += cols - oldcols;
        line->chars = sresize(line->chars, line->size, TTYPE);
        line->cols = cols;

        /*
         * If we're expanding the line, _now_ we move the cc
         * section.
         */
        if (cols > oldcols)
            memmove(line->chars + cols, line->chars + oldcols,
                    (line->size - line->cols) * TSIZE);

        /*
         * Go through what's left of the original line, and adjust
         * the first cc_next pointer in each list. (All the
         * subsequent ones are still valid because they are
         * relative offsets within the cc block.) Also do the same
         * to the head of the cc_free list.
         */
        for (i = 0; i < oldcols && i < cols; i++)
            if (line->chars[i].cc_next)
                line->chars[i].cc_next += cols - oldcols;
        if (line->cc_free)
            line->cc_free += cols - oldcols;

        /*
         * And finally fill in the new space with erase chars. (We
         * don't have to worry about cc lists here, because we
         * _know_ the erase char doesn't have one.)
         */
        for (i = oldcols; i < cols; i++)
            line->chars[i] = term->basic_erase_char;

#ifdef TERM_CC_DIAGS
        cc_check(line);
#endif
    }
}

/*
 * Get the number of lines in the scrollback.
 */
static int sblines(Terminal *term)
{
    int sblines = count234(term->scrollback);
    if (term->cfg.erase_to_scrollback &&
        term->alt_which && term->alt_screen) {
            sblines += term->alt_sblines;
    }
    return sblines;
}

/*
 * Retrieve a line of the screen or of the scrollback, according to
 * whether the y coordinate is non-negative or negative
 * (respectively).
 */
static termline *lineptr(Terminal *term, int y, int lineno, int screen)
{
    termline *line;
    tree234 *whichtree;
    int treeindex;

    if (y >= 0) {
        whichtree = term->screen;
        treeindex = y;
    } else {
        int altlines = 0;

        assert(!screen);

        if (term->cfg.erase_to_scrollback &&
            term->alt_which && term->alt_screen) {
            altlines = term->alt_sblines;
        }
        if (y < -altlines) {
            whichtree = term->scrollback;
            treeindex = y + altlines + count234(term->scrollback);
        } else {
            whichtree = term->alt_screen;
            treeindex = y + term->alt_sblines;
            /* treeindex = y + count234(term->alt_screen); */
        }
    }
    if (whichtree == term->scrollback) {
        unsigned char *cline = index234(whichtree, treeindex);
        line = decompressline(cline, NULL);
    } else {
        line = index234(whichtree, treeindex);
    }

    /* We assume that we don't screw up and retrieve something out of range. */
    if (line == NULL) {
        fatalbox("line==NULL in terminal.c\n"
                 "lineno=%d y=%d w=%d h=%d\n"
                 "count(scrollback=%p)=%d\n"
                 "count(screen=%p)=%d\n"
                 "count(alt=%p)=%d alt_sblines=%d\n"
                 "whichtree=%p treeindex=%d\n\n"
                 "Please contact <putty@projects.tartarus.org> "
                 "and pass on the above information.",
                 lineno, y, term->cols, term->rows,
                 term->scrollback, count234(term->scrollback),
                 term->screen, count234(term->screen),
                 term->alt_screen, count234(term->alt_screen), term->alt_sblines,
                 whichtree, treeindex);
    }
    assert(line != NULL);

    resizeline(term, line, term->cols);
    /* FIXME: should we sort the compressed scrollback out here? */

    return line;
}

#define lineptr(x) (lineptr)(term,x,__LINE__,FALSE)
#define scrlineptr(x) (lineptr)(term,x,__LINE__,TRUE)

static void term_schedule_tblink(Terminal *term);
static void term_schedule_cblink(Terminal *term);

static void term_timer(void *ctx, long now)
{
    Terminal *term = (Terminal *)ctx;
    int update = FALSE;

    if (term->tblink_pending && now - term->next_tblink >= 0) {
        term->tblinker = !term->tblinker;
        term->tblink_pending = FALSE;
        term_schedule_tblink(term);
        update = TRUE;
    }

    if (term->cblink_pending && now - term->next_cblink >= 0) {
        term->cblinker = !term->cblinker;
        term->cblink_pending = FALSE;
        term_schedule_cblink(term);
        update = TRUE;
    }

    if (term->in_vbell && now - term->vbell_end >= 0) {
        term->in_vbell = FALSE;
        update = TRUE;
    }

    if (update ||
        (term->window_update_pending && now - term->next_update >= 0))
        term_update(term);
}

static void term_schedule_update(Terminal *term)
{
    if (!term->window_update_pending) {
        term->window_update_pending = TRUE;
        term->next_update = schedule_timer(UPDATE_DELAY, term_timer, term);
    }
}

/*
 * Call this whenever the terminal window state changes, to queue
 * an update.
 */
static void seen_disp_event(Terminal *term)
{
    term->seen_disp_event = TRUE;      /* for scrollback-reset-on-activity */
    term_schedule_update(term);
}

/*
 * Call when the terminal's blinking-text settings change, or when
 * a text blink has just occurred.
 */
static void term_schedule_tblink(Terminal *term)
{
    if (term->blink_is_real) {
        if (!term->tblink_pending)
            term->next_tblink = schedule_timer(TBLINK_DELAY, term_timer, term);
        term->tblink_pending = TRUE;
    } else {
        term->tblinker = 1;            /* reset when not in use */
        term->tblink_pending = FALSE;
    }
}

/*
 * Likewise with cursor blinks.
 */
static void term_schedule_cblink(Terminal *term)
{
    if (term->cfg.blink_cur && term->has_focus) {
        if (!term->cblink_pending)
            term->next_cblink = schedule_timer(CBLINK_DELAY, term_timer, term);
        term->cblink_pending = TRUE;
    } else {
        term->cblinker = 1;            /* reset when not in use */
        term->cblink_pending = FALSE;
    }
}

/*
 * Call to reset cursor blinking on new output.
 */
static void term_reset_cblink(Terminal *term)
{
    seen_disp_event(term);
    term->cblinker = 1;
    term->cblink_pending = FALSE;
    term_schedule_cblink(term);
}

/*
 * Call to begin a visual bell.
 */
static void term_schedule_vbell(Terminal *term, int already_started,
                                long startpoint)
{
    long ticks_already_gone;

    if (already_started)
        ticks_already_gone = GETTICKCOUNT() - startpoint;
    else
        ticks_already_gone = 0;

    if (ticks_already_gone < VBELL_DELAY) {
        term->in_vbell = TRUE;
        term->vbell_end = schedule_timer(VBELL_DELAY - ticks_already_gone,
                                         term_timer, term);
    } else {
        term->in_vbell = FALSE;
    }
}

/*
 * Set up power-on settings for the terminal.
 */
static void power_on(Terminal *term)
{
    term->curs.x = term->curs.y = 0;
    term->alt_x = term->alt_y = 0;
    term->savecurs.x = term->savecurs.y = 0;
    term->alt_t = term->marg_t = 0;
    if (term->rows != -1)
        term->alt_b = term->marg_b = term->rows - 1;
    else
        term->alt_b = term->marg_b = 0;
    if (term->cols != -1) {
        int i;
        for (i = 0; i < term->cols; i++)
            term->tabs[i] = (i % 8 == 0 ? TRUE : FALSE);
    }
    term->alt_om = term->dec_om = term->cfg.dec_om;
    term->alt_ins = term->insert = FALSE;
    term->alt_wnext = term->wrapnext = term->save_wnext = FALSE;
    term->alt_wrap = term->wrap = term->cfg.wrap_mode;
    term->alt_cset = term->cset = term->save_cset = 0;
    term->alt_utf = term->utf = term->save_utf = 0;
    term->utf_state = 0;
    term->alt_sco_acs = term->sco_acs = term->save_sco_acs = 0;
    term->cset_attr[0] = term->cset_attr[1] = term->save_csattr = CSET_ASCII;
    term->rvideo = 0;
    term->in_vbell = FALSE;
    term->cursor_on = 1;
    term->big_cursor = 0;
    term->default_attr = term->save_attr = term->curr_attr = ATTR_DEFAULT;
    term->term_editing = term->term_echoing = FALSE;
    term->app_cursor_keys = term->cfg.app_cursor;
    term->app_keypad_keys = term->cfg.app_keypad;
    term->use_bce = term->cfg.bce;
    term->blink_is_real = term->cfg.blinktext;
    term->erase_char = term->basic_erase_char;
    term->alt_which = 0;
    term_print_finish(term);
    {
        int i;
        for (i = 0; i < 256; i++)
            term->wordness[i] = term->cfg.wordness[i];
    }
    if (term->screen) {
        swap_screen(term, 1, FALSE, FALSE);
        erase_lots(term, FALSE, TRUE, TRUE);
        swap_screen(term, 0, FALSE, FALSE);
        erase_lots(term, FALSE, TRUE, TRUE);
    }
    term_schedule_tblink(term);
    term_schedule_cblink(term);
}

/*
 * Force a screen update.
 */
void term_update(Terminal *term)
{
    Context ctx;

    term->window_update_pending = FALSE;

    ctx = get_ctx(term->frontend);
    if (ctx) {
        int need_sbar_update = term->seen_disp_event;
        if (term->seen_disp_event && term->cfg.scroll_on_disp) {
            term->disptop = 0;         /* return to main screen */
            term->seen_disp_event = 0;
            need_sbar_update = TRUE;
        }

        if (need_sbar_update)
            update_sbar(term);
        do_paint(term, ctx, TRUE);
        sys_cursor(term->frontend, term->curs.x, term->curs.y - term->disptop);
        free_ctx(ctx);
    }
}

/*
 * Called from front end when a keypress occurs, to trigger
 * anything magical that needs to happen in that situation.
 */
void term_seen_key_event(Terminal *term)
{
    /*
     * On any keypress, clear the bell overload mechanism
     * completely, on the grounds that large numbers of
     * beeps coming from deliberate key action are likely
     * to be intended (e.g. beeps from filename completion
     * blocking repeatedly).
     */
    term->beep_overloaded = FALSE;
    while (term->beephead) {
        struct beeptime *tmp = term->beephead;
        term->beephead = tmp->next;
        sfree(tmp);
    }
    term->beeptail = NULL;
    term->nbeeps = 0;

    /*
     * Reset the scrollback on keypress, if we're doing that.
     */
    if (term->cfg.scroll_on_key) {
        term->disptop = 0;             /* return to main screen */
        seen_disp_event(term);
    }
}

/*
 * Same as power_on(), but an external function.
 */
void term_pwron(Terminal *term)
{
    power_on(term);
    if (term->ldisc)                   /* cause ldisc to notice changes */
        ldisc_send(term->ldisc, NULL, 0, 0);
    term->disptop = 0;
    deselect(term);
    term_update(term);
}

static void set_erase_char(Terminal *term)
{
    term->erase_char = term->basic_erase_char;
    if (term->use_bce)
        term->erase_char.attr = (term->curr_attr &
                                 (ATTR_FGMASK | ATTR_BGMASK));
}

/*
 * When the user reconfigures us, we need to check the forbidden-
 * alternate-screen config option, disable raw mouse mode if the
 * user has disabled mouse reporting, and abandon a print job if
 * the user has disabled printing.
 */
void term_reconfig(Terminal *term, Config *cfg)
{
    /*
     * Before adopting the new config, check all those terminal
     * settings which control power-on defaults; and if they've
     * changed, we will modify the current state as well as the
     * default one. The full list is: Auto wrap mode, DEC Origin
     * Mode, BCE, blinking text, character classes.
     */
    int reset_wrap, reset_decom, reset_bce, reset_tblink, reset_charclass;
    int i;

    reset_wrap = (term->cfg.wrap_mode != cfg->wrap_mode);
    reset_decom = (term->cfg.dec_om != cfg->dec_om);
    reset_bce = (term->cfg.bce != cfg->bce);
    reset_tblink = (term->cfg.blinktext != cfg->blinktext);
    reset_charclass = 0;
    for (i = 0; i < lenof(term->cfg.wordness); i++)
        if (term->cfg.wordness[i] != cfg->wordness[i])
            reset_charclass = 1;

    /*
     * If the bidi or shaping settings have changed, flush the bidi
     * cache completely.
     */
    if (term->cfg.arabicshaping != cfg->arabicshaping ||
        term->cfg.bidi != cfg->bidi) {
        for (i = 0; i < term->bidi_cache_size; i++) {
            sfree(term->pre_bidi_cache[i].chars);
            sfree(term->post_bidi_cache[i].chars);
            term->pre_bidi_cache[i].width = -1;
            term->pre_bidi_cache[i].chars = NULL;
            term->post_bidi_cache[i].width = -1;
            term->post_bidi_cache[i].chars = NULL;
        }
    }

    term->cfg = *cfg;                  /* STRUCTURE COPY */

    if (reset_wrap)
        term->alt_wrap = term->wrap = term->cfg.wrap_mode;
    if (reset_decom)
        term->alt_om = term->dec_om = term->cfg.dec_om;
    if (reset_bce) {
        term->use_bce = term->cfg.bce;
        set_erase_char(term);
    }
    if (reset_tblink) {
        term->blink_is_real = term->cfg.blinktext;
    }
    if (reset_charclass)
        for (i = 0; i < 256; i++)
            term->wordness[i] = term->cfg.wordness[i];

    if (term->cfg.no_alt_screen)
        swap_screen(term, 0, FALSE, FALSE);
    if (term->cfg.no_mouse_rep) {
        term->xterm_mouse = 0;
        set_raw_mouse_mode(term->frontend, 0);
    }
    if (term->cfg.no_remote_charset) {
        term->cset_attr[0] = term->cset_attr[1] = CSET_ASCII;
        term->sco_acs = term->alt_sco_acs = 0;
        term->utf = 0;
    }
    if (!*term->cfg.printer) {
        term_print_finish(term);
    }
    term_schedule_tblink(term);
    term_schedule_cblink(term);
}

/*
 * Clear the scrollback.
 */
void term_clrsb(Terminal *term)
{
    termline *line;
    term->disptop = 0;
    while ((line = delpos234(term->scrollback, 0)) != NULL) {
        sfree(line);            /* this is compressed data, not a termline */
    }
    term->tempsblines = 0;
    term->alt_sblines = 0;
    update_sbar(term);
}

/*
 * Initialise the terminal.
 */
Terminal *term_init(Config *mycfg, struct unicode_data *ucsdata,
                    void *frontend)
{
    Terminal *term;

    /*
     * Allocate a new Terminal structure and initialise the fields
     * that need it.
     */
    term = snew(Terminal);
    term->frontend = frontend;
    term->ucsdata = ucsdata;
    term->cfg = *mycfg;                /* STRUCTURE COPY */
    term->logctx = NULL;
    term->compatibility_level = TM_PUTTY;
    strcpy(term->id_string, "\033[?6c");
    term->cblink_pending = term->tblink_pending = FALSE;
    term->paste_buffer = NULL;
    term->paste_len = 0;
    term->last_paste = 0;
    bufchain_init(&term->inbuf);
    bufchain_init(&term->printer_buf);
    term->printing = term->only_printing = FALSE;
    term->print_job = NULL;
    term->vt52_mode = FALSE;
    term->cr_lf_return = FALSE;
    term->seen_disp_event = FALSE;
    term->xterm_mouse = term->mouse_is_down = FALSE;
    term->reset_132 = FALSE;
    term->cblinker = term->tblinker = 0;
    term->has_focus = 1;
    term->repeat_off = FALSE;
    term->termstate = TOPLEVEL;
    term->selstate = NO_SELECTION;
    term->curstype = 0;

    term->screen = term->alt_screen = term->scrollback = NULL;
    term->tempsblines = 0;
    term->alt_sblines = 0;
    term->disptop = 0;
    term->disptext = NULL;
    term->dispcursx = term->dispcursy = -1;
    term->tabs = NULL;
    deselect(term);
    term->rows = term->cols = -1;
    power_on(term);
    term->beephead = term->beeptail = NULL;
#ifdef OPTIMISE_SCROLL
    term->scrollhead = term->scrolltail = NULL;
#endif /* OPTIMISE_SCROLL */
    term->nbeeps = 0;
    term->lastbeep = FALSE;
    term->beep_overloaded = FALSE;
    term->attr_mask = 0xffffffff;
    term->resize_fn = NULL;
    term->resize_ctx = NULL;
    term->in_term_out = FALSE;
    term->ltemp = NULL;
    term->ltemp_size = 0;
    term->wcFrom = NULL;
    term->wcTo = NULL;
    term->wcFromTo_size = 0;

    term->window_update_pending = FALSE;

    term->bidi_cache_size = 0;
    term->pre_bidi_cache = term->post_bidi_cache = NULL;

    /* FULL-TERMCHAR */
    term->basic_erase_char.chr = CSET_ASCII | ' ';
    term->basic_erase_char.attr = ATTR_DEFAULT;
    term->basic_erase_char.cc_next = 0;
    term->erase_char = term->basic_erase_char;

    return term;
}

void term_free(Terminal *term)
{
    termline *line;
    struct beeptime *beep;
    int i;

    while ((line = delpos234(term->scrollback, 0)) != NULL)
        sfree(line);                   /* compressed data, not a termline */
    freetree234(term->scrollback);
    while ((line = delpos234(term->screen, 0)) != NULL)
        freeline(line);
    freetree234(term->screen);
    while ((line = delpos234(term->alt_screen, 0)) != NULL)
        freeline(line);
    freetree234(term->alt_screen);
    if (term->disptext) {
        for (i = 0; i < term->rows; i++)
            freeline(term->disptext[i]);
    }
    sfree(term->disptext);
    while (term->beephead) {
        beep = term->beephead;
        term->beephead = beep->next;
        sfree(beep);
    }
    bufchain_clear(&term->inbuf);
    if(term->print_job)
        printer_finish_job(term->print_job);
    bufchain_clear(&term->printer_buf);
    sfree(term->paste_buffer);
    sfree(term->ltemp);
    sfree(term->wcFrom);
    sfree(term->wcTo);

    for (i = 0; i < term->bidi_cache_size; i++) {
        sfree(term->pre_bidi_cache[i].chars);
        sfree(term->post_bidi_cache[i].chars);
    }
    sfree(term->pre_bidi_cache);
    sfree(term->post_bidi_cache);

    expire_timer_context(term);

    sfree(term);
}

/*
 * Set up the terminal for a given size.
 */
void term_size(Terminal *term, int newrows, int newcols, int newsavelines)
{
    tree234 *newalt;
    termline **newdisp, *line;
    int i, j, oldrows = term->rows;
    int sblen;
    int save_alt_which = term->alt_which;

    if (newrows == term->rows && newcols == term->cols &&
        newsavelines == term->savelines)
        return;                        /* nothing to do */

    deselect(term);
    swap_screen(term, 0, FALSE, FALSE);

    term->alt_t = term->marg_t = 0;
    term->alt_b = term->marg_b = newrows - 1;

    if (term->rows == -1) {
        term->scrollback = newtree234(NULL);
        term->screen = newtree234(NULL);
        term->tempsblines = 0;
        term->rows = 0;
    }

    /*
     * Resize the screen and scrollback. We only need to shift
     * lines around within our data structures, because lineptr()
     * will take care of resizing each individual line if
     * necessary. So:
     * 
     *  - If the new screen is longer, we shunt lines in from temporary
     *    scrollback if possible, otherwise we add new blank lines at
     *    the bottom.
     *
     *  - If the new screen is shorter, we remove any blank lines at
     *    the bottom if possible, otherwise shunt lines above the cursor
     *    to scrollback if possible, otherwise delete lines below the
     *    cursor.
     * 
     *  - Then, if the new scrollback length is less than the
     *    amount of scrollback we actually have, we must throw some
     *    away.
     */
    sblen = count234(term->scrollback);
    /* Do this loop to expand the screen if newrows > rows */
    assert(term->rows == count234(term->screen));
    while (term->rows < newrows) {
        if (term->tempsblines > 0) {
            unsigned char *cline;
            /* Insert a line from the scrollback at the top of the screen. */
            assert(sblen >= term->tempsblines);
            cline = delpos234(term->scrollback, --sblen);
            line = decompressline(cline, NULL);
            sfree(cline);
            line->temporary = FALSE;   /* reconstituted line is now real */
            term->tempsblines -= 1;
            addpos234(term->screen, line, 0);
            term->curs.y += 1;
            term->savecurs.y += 1;
        } else {
            /* Add a new blank line at the bottom of the screen. */
            line = newline(term, newcols, FALSE);
            addpos234(term->screen, line, count234(term->screen));
        }
        term->rows += 1;
    }
    /* Do this loop to shrink the screen if newrows < rows */
    while (term->rows > newrows) {
        if (term->curs.y < term->rows - 1) {
            /* delete bottom row, unless it contains the cursor */
            sfree(delpos234(term->screen, term->rows - 1));
        } else {
            /* push top row to scrollback */
            line = delpos234(term->screen, 0);
            addpos234(term->scrollback, compressline(line), sblen++);
            freeline(line);
            term->tempsblines += 1;
            term->curs.y -= 1;
            term->savecurs.y -= 1;
        }
        term->rows -= 1;
    }
    assert(term->rows == newrows);
    assert(count234(term->screen) == newrows);

    /* Delete any excess lines from the scrollback. */
    while (sblen > newsavelines) {
        line = delpos234(term->scrollback, 0);
        sfree(line);
        sblen--;
    }
    if (sblen < term->tempsblines)
        term->tempsblines = sblen;
    assert(count234(term->scrollback) <= newsavelines);
    assert(count234(term->scrollback) >= term->tempsblines);
    term->disptop = 0;

    /* Make a new displayed text buffer. */
    newdisp = snewn(newrows, termline *);
    for (i = 0; i < newrows; i++) {
        newdisp[i] = newline(term, newcols, FALSE);
        for (j = 0; j < newcols; j++)
            newdisp[i]->chars[j].attr = ATTR_INVALID;
    }
    if (term->disptext) {
        for (i = 0; i < oldrows; i++)
            freeline(term->disptext[i]);
    }
    sfree(term->disptext);
    term->disptext = newdisp;
    term->dispcursx = term->dispcursy = -1;

    /* Make a new alternate screen. */
    newalt = newtree234(NULL);
    for (i = 0; i < newrows; i++) {
        line = newline(term, newcols, TRUE);
        addpos234(newalt, line, i);
    }
    if (term->alt_screen) {
        while (NULL != (line = delpos234(term->alt_screen, 0)))
            freeline(line);
        freetree234(term->alt_screen);
    }
    term->alt_screen = newalt;
    term->alt_sblines = 0;

    term->tabs = sresize(term->tabs, newcols, unsigned char);
    {
        int i;
        for (i = (term->cols > 0 ? term->cols : 0); i < newcols; i++)
            term->tabs[i] = (i % 8 == 0 ? TRUE : FALSE);
    }

    /* Check that the cursor positions are still valid. */
    if (term->savecurs.y < 0)
        term->savecurs.y = 0;
    if (term->savecurs.y >= newrows)
        term->savecurs.y = newrows - 1;
    if (term->curs.y < 0)
        term->curs.y = 0;
    if (term->curs.y >= newrows)
        term->curs.y = newrows - 1;
    if (term->curs.x >= newcols)
        term->curs.x = newcols - 1;
    term->alt_x = term->alt_y = 0;
    term->wrapnext = term->alt_wnext = FALSE;

    term->rows = newrows;
    term->cols = newcols;
    term->savelines = newsavelines;

    swap_screen(term, save_alt_which, FALSE, FALSE);

    update_sbar(term);
    term_update(term);
    if (term->resize_fn)
        term->resize_fn(term->resize_ctx, term->cols, term->rows);
}

/*
 * Hand a function and context pointer to the terminal which it can
 * use to notify a back end of resizes.
 */
void term_provide_resize_fn(Terminal *term,
                            void (*resize_fn)(void *, int, int),
                            void *resize_ctx)
{
    term->resize_fn = resize_fn;
    term->resize_ctx = resize_ctx;
    if (term->cols > 0 && term->rows > 0)
        resize_fn(resize_ctx, term->cols, term->rows);
}

/* Find the bottom line on the screen that has any content.
 * If only the top line has content, returns 0.
 * If no lines have content, return -1.
 */ 
static int find_last_nonempty_line(Terminal * term, tree234 * screen)
{
    int i;
    for (i = count234(screen) - 1; i >= 0; i--) {
        termline *line = index234(screen, i);
        int j;
        for (j = 0; j < line->cols; j++)
            if (!termchars_equal(&line->chars[j], &term->erase_char))
                break;
        if (j != line->cols) break;
    }
    return i;
}

/*
 * Swap screens. If `reset' is TRUE and we have been asked to
 * switch to the alternate screen, we must bring most of its
 * configuration from the main screen and erase the contents of the
 * alternate screen completely. (This is even true if we're already
 * on it! Blame xterm.)
 */
static void swap_screen(Terminal *term, int which, int reset, int keep_cur_pos)
{
    int t;
    tree234 *ttr;

    if (!which)
        reset = FALSE;                 /* do no weird resetting if which==0 */

    if (which != term->alt_which) {
        term->alt_which = which;

        ttr = term->alt_screen;
        term->alt_screen = term->screen;
        term->screen = ttr;
        term->alt_sblines = find_last_nonempty_line(term, term->alt_screen) + 1;
        t = term->curs.x;
        if (!reset && !keep_cur_pos)
            term->curs.x = term->alt_x;
        term->alt_x = t;
        t = term->curs.y;
        if (!reset && !keep_cur_pos)
            term->curs.y = term->alt_y;
        term->alt_y = t;
        t = term->marg_t;
        if (!reset) term->marg_t = term->alt_t;
        term->alt_t = t;
        t = term->marg_b;
        if (!reset) term->marg_b = term->alt_b;
        term->alt_b = t;
        t = term->dec_om;
        if (!reset) term->dec_om = term->alt_om;
        term->alt_om = t;
        t = term->wrap;
        if (!reset) term->wrap = term->alt_wrap;
        term->alt_wrap = t;
        t = term->wrapnext;
        if (!reset) term->wrapnext = term->alt_wnext;
        term->alt_wnext = t;
        t = term->insert;
        if (!reset) term->insert = term->alt_ins;
        term->alt_ins = t;
        t = term->cset;
        if (!reset) term->cset = term->alt_cset;
        term->alt_cset = t;
        t = term->utf;
        if (!reset) term->utf = term->alt_utf;
        term->alt_utf = t;
        t = term->sco_acs;
        if (!reset) term->sco_acs = term->alt_sco_acs;
        term->alt_sco_acs = t;
    }

    if (reset && term->screen) {
        /*
         * Yes, this _is_ supposed to honour background-colour-erase.
         */
        erase_lots(term, FALSE, TRUE, TRUE);
    }
}

/*
 * Update the scroll bar.
 */
static void update_sbar(Terminal *term)
{
    int nscroll = sblines(term);
    set_sbar(term->frontend, nscroll + term->rows,
             nscroll + term->disptop, term->rows);
}

/*
 * Check whether the region bounded by the two pointers intersects
 * the scroll region, and de-select the on-screen selection if so.
 */
static void check_selection(Terminal *term, pos from, pos to)
{
    if (poslt(from, term->selend) && poslt(term->selstart, to))
        deselect(term);
}

/*
 * Scroll the screen. (`lines' is +ve for scrolling forward, -ve
 * for backward.) `sb' is TRUE if the scrolling is permitted to
 * affect the scrollback buffer.
 */
static void scroll(Terminal *term, int topline, int botline, int lines, int sb)
{
    termline *line;
    int i, seltop, olddisptop, shift;

    if (topline != 0 || term->alt_which != 0)
        sb = FALSE;

    olddisptop = term->disptop;
    shift = lines;
    if (lines < 0) {
        while (lines < 0) {
            line = delpos234(term->screen, botline);
            resizeline(term, line, term->cols);
            for (i = 0; i < term->cols; i++)
                copy_termchar(line, i, &term->erase_char);
            line->lattr = LATTR_NORM;
            addpos234(term->screen, line, topline);

            if (term->selstart.y >= topline && term->selstart.y <= botline) {
                term->selstart.y++;
                if (term->selstart.y > botline) {
                    term->selstart.y = botline + 1;
                    term->selstart.x = 0;
                }
            }
            if (term->selend.y >= topline && term->selend.y <= botline) {
                term->selend.y++;
                if (term->selend.y > botline) {
                    term->selend.y = botline + 1;
                    term->selend.x = 0;
                }
            }

            lines++;
        }
    } else {
        while (lines > 0) {
            line = delpos234(term->screen, topline);
#ifdef TERM_CC_DIAGS
            cc_check(line);
#endif
            if (sb && term->savelines > 0) {
                int sblen = count234(term->scrollback);
                /*
                 * We must add this line to the scrollback. We'll
                 * remove a line from the top of the scrollback if
                 * the scrollback is full.
                 */
                if (sblen == term->savelines) {
                    unsigned char *cline;

                    sblen--;
                    cline = delpos234(term->scrollback, 0);
                    sfree(cline);
                } else
                    term->tempsblines += 1;

                addpos234(term->scrollback, compressline(line), sblen);

                /* now `line' itself can be reused as the bottom line */

                /*
                 * If the user is currently looking at part of the
                 * scrollback, and they haven't enabled any options
                 * that are going to reset the scrollback as a
                 * result of this movement, then the chances are
                 * they'd like to keep looking at the same line. So
                 * we move their viewpoint at the same rate as the
                 * scroll, at least until their viewpoint hits the
                 * top end of the scrollback buffer, at which point
                 * we don't have the choice any more.
                 * 
                 * Thanks to Jan Holmen Holsten for the idea and
                 * initial implementation.
                 */
                if (term->disptop > -term->savelines && term->disptop < 0)
                    term->disptop--;
            }
            resizeline(term, line, term->cols);
            for (i = 0; i < term->cols; i++)
                copy_termchar(line, i, &term->erase_char);
            line->lattr = LATTR_NORM;
            addpos234(term->screen, line, botline);

            /*
             * If the selection endpoints move into the scrollback,
             * we keep them moving until they hit the top. However,
             * of course, if the line _hasn't_ moved into the
             * scrollback then we don't do this, and cut them off
             * at the top of the scroll region.
             * 
             * This applies to selstart and selend (for an existing
             * selection), and also selanchor (for one being
             * selected as we speak).
             */
            seltop = sb ? -term->savelines : topline;

            if (term->selstate != NO_SELECTION) {
                if (term->selstart.y >= seltop &&
                    term->selstart.y <= botline) {
                    term->selstart.y--;
                    if (term->selstart.y < seltop) {
                        term->selstart.y = seltop;
                        term->selstart.x = 0;
                    }
                }
                if (term->selend.y >= seltop && term->selend.y <= botline) {
                    term->selend.y--;
                    if (term->selend.y < seltop) {
                        term->selend.y = seltop;
                        term->selend.x = 0;
                    }
                }
                if (term->selanchor.y >= seltop &&
                    term->selanchor.y <= botline) {
                    term->selanchor.y--;
                    if (term->selanchor.y < seltop) {
                        term->selanchor.y = seltop;
                        term->selanchor.x = 0;
                    }
                }
            }

            lines--;
        }
    }
#ifdef OPTIMISE_SCROLL
    shift += term->disptop - olddisptop;
    if (shift < term->rows && shift > -term->rows && shift != 0)
        scroll_display(term, topline, botline, shift);
#endif /* OPTIMISE_SCROLL */
}

#ifdef OPTIMISE_SCROLL
/*
 * Add a scroll of a region on the screen into the pending scroll list.
 * `lines' is +ve for scrolling forward, -ve for backward.
 *
 * If the scroll is on the same area as the last scroll in the list,
 * merge them.
 */
static void save_scroll(Terminal *term, int topline, int botline, int lines)
{
    struct scrollregion *newscroll;
    if (term->scrolltail &&
        term->scrolltail->topline == topline && 
        term->scrolltail->botline == botline) {
        term->scrolltail->lines += lines;
    } else {
        newscroll = snew(struct scrollregion);
        newscroll->topline = topline;
        newscroll->botline = botline;
        newscroll->lines = lines;
        newscroll->next = NULL;

        if (!term->scrollhead)
            term->scrollhead = newscroll;
        else
            term->scrolltail->next = newscroll;
        term->scrolltail = newscroll;
    }
}

/*
 * Scroll the physical display, and our conception of it in disptext.
 */
static void scroll_display(Terminal *term, int topline, int botline, int lines)
{
    int distance, nlines, i, j;

    distance = lines > 0 ? lines : -lines;
    nlines = botline - topline + 1 - distance;
    if (lines > 0) {
        for (i = 0; i < nlines; i++)
            for (j = 0; j < term->cols; j++)
                copy_termchar(term->disptext[i], j,
                              term->disptext[i+distance]->chars+j);
        if (term->dispcursy >= 0 &&
            term->dispcursy >= topline + distance &&
            term->dispcursy < topline + distance + nlines)
            term->dispcursy -= distance;
        for (i = 0; i < distance; i++)
            for (j = 0; j < term->cols; j++)
                term->disptext[nlines+i]->chars[j].attr |= ATTR_INVALID;
    } else {
        for (i = nlines; i-- ;)
            for (j = 0; j < term->cols; j++)
                copy_termchar(term->disptext[i+distance], j,
                              term->disptext[i]->chars+j);
        if (term->dispcursy >= 0 &&
            term->dispcursy >= topline &&
            term->dispcursy < topline + nlines)
            term->dispcursy += distance;
        for (i = 0; i < distance; i++)
            for (j = 0; j < term->cols; j++)
                term->disptext[i]->chars[j].attr |= ATTR_INVALID;
    }
    save_scroll(term, topline, botline, lines);
}
#endif /* OPTIMISE_SCROLL */

/*
 * Move the cursor to a given position, clipping at boundaries. We
 * may or may not want to clip at the scroll margin: marg_clip is 0
 * not to, 1 to disallow _passing_ the margins, and 2 to disallow
 * even _being_ outside the margins.
 */
static void move(Terminal *term, int x, int y, int marg_clip)
{
    if (x < 0)
        x = 0;
    if (x >= term->cols)
        x = term->cols - 1;
    if (marg_clip) {
        if ((term->curs.y >= term->marg_t || marg_clip == 2) &&
            y < term->marg_t)
            y = term->marg_t;
        if ((term->curs.y <= term->marg_b || marg_clip == 2) &&
            y > term->marg_b)
            y = term->marg_b;
    }
    if (y < 0)
        y = 0;
    if (y >= term->rows)
        y = term->rows - 1;
    term->curs.x = x;
    term->curs.y = y;
    term->wrapnext = FALSE;
}

/*
 * Save or restore the cursor and SGR mode.
 */
static void save_cursor(Terminal *term, int save)
{
    if (save) {
        term->savecurs = term->curs;
        term->save_attr = term->curr_attr;
        term->save_cset = term->cset;
        term->save_utf = term->utf;
        term->save_wnext = term->wrapnext;
        term->save_csattr = term->cset_attr[term->cset];
        term->save_sco_acs = term->sco_acs;
    } else {
        term->curs = term->savecurs;
        /* Make sure the window hasn't shrunk since the save */
        if (term->curs.x >= term->cols)
            term->curs.x = term->cols - 1;
        if (term->curs.y >= term->rows)
            term->curs.y = term->rows - 1;

        term->curr_attr = term->save_attr;
        term->cset = term->save_cset;
        term->utf = term->save_utf;
        term->wrapnext = term->save_wnext;
        /*
         * wrapnext might reset to False if the x position is no
         * longer at the rightmost edge.
         */
        if (term->wrapnext && term->curs.x < term->cols-1)
            term->wrapnext = FALSE;
        term->cset_attr[term->cset] = term->save_csattr;
        term->sco_acs = term->save_sco_acs;
        set_erase_char(term);
    }
}

/*
 * This function is called before doing _anything_ which affects
 * only part of a line of text. It is used to mark the boundary
 * between two character positions, and it indicates that some sort
 * of effect is going to happen on only one side of that boundary.
 * 
 * The effect of this function is to check whether a CJK
 * double-width character is straddling the boundary, and to remove
 * it and replace it with two spaces if so. (Of course, one or
 * other of those spaces is then likely to be replaced with
 * something else again, as a result of whatever happens next.)
 * 
 * Also, if the boundary is at the right-hand _edge_ of the screen,
 * it implies something deliberate is being done to the rightmost
 * column position; hence we must clear LATTR_WRAPPED2.
 * 
 * The input to the function is the coordinates of the _second_
 * character of the pair.
 */
static void check_boundary(Terminal *term, int x, int y)
{
    termline *ldata;

    /* Validate input coordinates, just in case. */
    if (x == 0 || x > term->cols)
        return;

    ldata = scrlineptr(y);
    if (x == term->cols) {
        ldata->lattr &= ~LATTR_WRAPPED2;
    } else {
        if (ldata->chars[x].chr == UCSWIDE) {
            clear_cc(ldata, x-1);
            clear_cc(ldata, x);
            ldata->chars[x-1].chr = ' ' | CSET_ASCII;
            ldata->chars[x] = ldata->chars[x-1];
        }
    }
}

/*
 * Erase a large portion of the screen: the whole screen, or the
 * whole line, or parts thereof.
 */
static void erase_lots(Terminal *term,
                       int line_only, int from_begin, int to_end)
{
    pos start, end;
    int erase_lattr;
    int erasing_lines_from_top = 0;

    if (line_only) {
        start.y = term->curs.y;
        start.x = 0;
        end.y = term->curs.y + 1;
        end.x = 0;
        erase_lattr = FALSE;
    } else {
        start.y = 0;
        start.x = 0;
        end.y = term->rows;
        end.x = 0;
        erase_lattr = TRUE;
    }
    if (!from_begin) {
        start = term->curs;
    }
    if (!to_end) {
        end = term->curs;
        incpos(end);
    }
    if (!from_begin || !to_end)
        check_boundary(term, term->curs.x, term->curs.y);
    check_selection(term, start, end);

    /* Clear screen also forces a full window redraw, just in case. */
    if (start.y == 0 && start.x == 0 && end.y == term->rows)
        term_invalidate(term);

    /* Lines scrolled away shouldn't be brought back on if the terminal
     * resizes. */
    if (start.y == 0 && start.x == 0 && end.x == 0 && erase_lattr)
        erasing_lines_from_top = 1;

    if (term->cfg.erase_to_scrollback && erasing_lines_from_top) {
        /* If it's a whole number of lines, starting at the top, and
         * we're fully erasing them, erase by scrolling and keep the
         * lines in the scrollback. */
        int scrolllines = end.y;
        if (end.y == term->rows) {
            /* Shrink until we find a non-empty row.*/
            scrolllines = find_last_nonempty_line(term, term->screen) + 1;
        }
        if (scrolllines > 0)
            scroll(term, 0, scrolllines - 1, scrolllines, TRUE);
    } else {
        termline *ldata = scrlineptr(start.y);
        while (poslt(start, end)) {
            if (start.x == term->cols) {
                if (!erase_lattr)
                    ldata->lattr &= ~(LATTR_WRAPPED | LATTR_WRAPPED2);
                else
                    ldata->lattr = LATTR_NORM;
            } else {
                copy_termchar(ldata, start.x, &term->erase_char);
            }
            if (incpos(start) && start.y < term->rows) {
                ldata = scrlineptr(start.y);
            }
        }
    }

    /* After an erase of lines from the top of the screen, we shouldn't
     * bring the lines back again if the terminal enlarges (since the user or
     * application has explictly thrown them away). */
    if (erasing_lines_from_top && !(term->alt_which))
        term->tempsblines = 0;
}

/*
 * Insert or delete characters within the current line. n is +ve if
 * insertion is desired, and -ve for deletion.
 */
static void insch(Terminal *term, int n)
{
    int dir = (n < 0 ? -1 : +1);
    int m, j;
    pos cursplus;
    termline *ldata;

    n = (n < 0 ? -n : n);
    if (n > term->cols - term->curs.x)
        n = term->cols - term->curs.x;
    m = term->cols - term->curs.x - n;
    cursplus.y = term->curs.y;
    cursplus.x = term->curs.x + n;
    check_selection(term, term->curs, cursplus);
    check_boundary(term, term->curs.x, term->curs.y);
    if (dir < 0)
        check_boundary(term, term->curs.x + n, term->curs.y);
    ldata = scrlineptr(term->curs.y);
    if (dir < 0) {
        for (j = 0; j < m; j++)
            move_termchar(ldata,
                          ldata->chars + term->curs.x + j,
                          ldata->chars + term->curs.x + j + n);
        while (n--)
            copy_termchar(ldata, term->curs.x + m++, &term->erase_char);
    } else {
        for (j = m; j-- ;)
            move_termchar(ldata,
                          ldata->chars + term->curs.x + j + n,
                          ldata->chars + term->curs.x + j);
        while (n--)
            copy_termchar(ldata, term->curs.x + n, &term->erase_char);
    }
}

/*
 * Toggle terminal mode `mode' to state `state'. (`query' indicates
 * whether the mode is a DEC private one or a normal one.)
 */
static void toggle_mode(Terminal *term, int mode, int query, int state)
{
    if (query)
        switch (mode) {
          case 1:                      /* DECCKM: application cursor keys */
            term->app_cursor_keys = state;
            break;
          case 2:                      /* DECANM: VT52 mode */
            term->vt52_mode = !state;
            if (term->vt52_mode) {
                term->blink_is_real = FALSE;
                term->vt52_bold = FALSE;
            } else {
                term->blink_is_real = term->cfg.blinktext;
            }
            term_schedule_tblink(term);
            break;
          case 3:                      /* DECCOLM: 80/132 columns */
            deselect(term);
            if (!term->cfg.no_remote_resize)
                request_resize(term->frontend, state ? 132 : 80, term->rows);
            term->reset_132 = state;
            term->alt_t = term->marg_t = 0;
            term->alt_b = term->marg_b = term->rows - 1;
            move(term, 0, 0, 0);
            erase_lots(term, FALSE, TRUE, TRUE);
            break;
          case 5:                      /* DECSCNM: reverse video */
            /*
             * Toggle reverse video. If we receive an OFF within the
             * visual bell timeout period after an ON, we trigger an
             * effective visual bell, so that ESC[?5hESC[?5l will
             * always be an actually _visible_ visual bell.
             */
            if (term->rvideo && !state) {
                /* This is an OFF, so set up a vbell */
                term_schedule_vbell(term, TRUE, term->rvbell_startpoint);
            } else if (!term->rvideo && state) {
                /* This is an ON, so we notice the time and save it. */
                term->rvbell_startpoint = GETTICKCOUNT();
            }
            term->rvideo = state;
            seen_disp_event(term);
            break;
          case 6:                      /* DECOM: DEC origin mode */
            term->dec_om = state;
            break;
          case 7:                      /* DECAWM: auto wrap */
            term->wrap = state;
            break;
          case 8:                      /* DECARM: auto key repeat */
            term->repeat_off = !state;
            break;
          case 10:                     /* DECEDM: set local edit mode */
            term->term_editing = state;
            if (term->ldisc)           /* cause ldisc to notice changes */
                ldisc_send(term->ldisc, NULL, 0, 0);
            break;
          case 25:                     /* DECTCEM: enable/disable cursor */
            compatibility2(OTHER, VT220);
            term->cursor_on = state;
            seen_disp_event(term);
            break;
          case 47:                     /* alternate screen */
            compatibility(OTHER);
            deselect(term);
            swap_screen(term, term->cfg.no_alt_screen ? 0 : state, FALSE, FALSE);
            term->disptop = 0;
            break;
          case 1000:                   /* xterm mouse 1 */
            term->xterm_mouse = state ? 1 : 0;
            set_raw_mouse_mode(term->frontend, state);
            break;
          case 1002:                   /* xterm mouse 2 */
            term->xterm_mouse = state ? 2 : 0;
            set_raw_mouse_mode(term->frontend, state);
            break;
          case 1047:                   /* alternate screen */
            compatibility(OTHER);
            deselect(term);
            swap_screen(term, term->cfg.no_alt_screen ? 0 : state, TRUE, TRUE);
            term->disptop = 0;
            break;
          case 1048:                   /* save/restore cursor */
            if (!term->cfg.no_alt_screen)
                save_cursor(term, state);
            if (!state) seen_disp_event(term);
            break;
          case 1049:                   /* cursor & alternate screen */
            if (state && !term->cfg.no_alt_screen)
                save_cursor(term, state);
            if (!state) seen_disp_event(term);
            compatibility(OTHER);
            deselect(term);
            swap_screen(term, term->cfg.no_alt_screen ? 0 : state, TRUE, FALSE);
            if (!state && !term->cfg.no_alt_screen)
                save_cursor(term, state);
            term->disptop = 0;
            break;
    } else
        switch (mode) {
          case 4:                      /* IRM: set insert mode */
            compatibility(VT102);
            term->insert = state;
            break;
          case 12:                     /* SRM: set echo mode */
            term->term_echoing = !state;
            if (term->ldisc)           /* cause ldisc to notice changes */
                ldisc_send(term->ldisc, NULL, 0, 0);
            break;
          case 20:                     /* LNM: Return sends ... */
            term->cr_lf_return = state;
            break;
          case 34:                     /* WYULCURM: Make cursor BIG */
            compatibility2(OTHER, VT220);
            term->big_cursor = !state;
        }
}

/*
 * Process an OSC sequence: set window title or icon name.
 */
static void do_osc(Terminal *term)
{
    if (term->osc_w) {
        while (term->osc_strlen--)
            term->wordness[(unsigned char)
                term->osc_string[term->osc_strlen]] = term->esc_args[0];
    } else {
        term->osc_string[term->osc_strlen] = '\0';
        switch (term->esc_args[0]) {
          case 0:
          case 1:
            if (!term->cfg.no_remote_wintitle)
                set_icon(term->frontend, term->osc_string);
            if (term->esc_args[0] == 1)
                break;
            /* fall through: parameter 0 means set both */
          case 2:
          case 21:
            if (!term->cfg.no_remote_wintitle)
                set_title(term->frontend, term->osc_string);
            break;
        }
    }
}

/*
 * ANSI printing routines.
 */
static void term_print_setup(Terminal *term)
{
    bufchain_clear(&term->printer_buf);
    term->print_job = printer_start_job(term->cfg.printer);
}
static void term_print_flush(Terminal *term)
{
    void *data;
    int len;
    int size;
    while ((size = bufchain_size(&term->printer_buf)) > 5) {
        bufchain_prefix(&term->printer_buf, &data, &len);
        if (len > size-5)
            len = size-5;
        printer_job_data(term->print_job, data, len);
        bufchain_consume(&term->printer_buf, len);
    }
}
static void term_print_finish(Terminal *term)
{
    void *data;
    int len, size;
    char c;

    if (!term->printing && !term->only_printing)
        return;                        /* we need do nothing */

    term_print_flush(term);
    while ((size = bufchain_size(&term->printer_buf)) > 0) {
        bufchain_prefix(&term->printer_buf, &data, &len);
        c = *(char *)data;
        if (c == '\033' || c == '\233') {
            bufchain_consume(&term->printer_buf, size);
            break;
        } else {
            printer_job_data(term->print_job, &c, 1);
            bufchain_consume(&term->printer_buf, 1);
        }
    }
    printer_finish_job(term->print_job);
    term->print_job = NULL;
    term->printing = term->only_printing = FALSE;
}

/*
 * Remove everything currently in `inbuf' and stick it up on the
 * in-memory display. There's a big state machine in here to
 * process escape sequences...
 */
static void term_out(Terminal *term)
{
    unsigned long c;
    int unget;
    unsigned char localbuf[256], *chars;
    int nchars = 0;

    unget = -1;

    chars = NULL;                      /* placate compiler warnings */
    while (nchars > 0 || bufchain_size(&term->inbuf) > 0) {
        if (unget == -1) {
            if (nchars == 0) {
                void *ret;
                bufchain_prefix(&term->inbuf, &ret, &nchars);
                if (nchars > sizeof(localbuf))
                    nchars = sizeof(localbuf);
                memcpy(localbuf, ret, nchars);
                bufchain_consume(&term->inbuf, nchars);
                chars = localbuf;
                assert(chars != NULL);
            }
            c = *chars++;
            nchars--;

            /*
             * Optionally log the session traffic to a file. Useful for
             * debugging and possibly also useful for actual logging.
             */
            if (term->cfg.logtype == LGTYP_DEBUG && term->logctx)
                logtraffic(term->logctx, (unsigned char) c, LGTYP_DEBUG);
        } else {
            c = unget;
            unget = -1;
        }

        /* Note only VT220+ are 8-bit VT102 is seven bit, it shouldn't even
         * be able to display 8-bit characters, but I'll let that go 'cause
         * of i18n.
         */

        /*
         * If we're printing, add the character to the printer
         * buffer.
         */
        if (term->printing) {
            bufchain_add(&term->printer_buf, &c, 1);

            /*
             * If we're in print-only mode, we use a much simpler
             * state machine designed only to recognise the ESC[4i
             * termination sequence.
             */
            if (term->only_printing) {
                if (c == '\033')
                    term->print_state = 1;
                else if (c == (unsigned char)'\233')
                    term->print_state = 2;
                else if (c == '[' && term->print_state == 1)
                    term->print_state = 2;
                else if (c == '4' && term->print_state == 2)
                    term->print_state = 3;
                else if (c == 'i' && term->print_state == 3)
                    term->print_state = 4;
                else
                    term->print_state = 0;
                if (term->print_state == 4) {
                    term_print_finish(term);
                }
                continue;
            }
        }

        /* First see about all those translations. */
        if (term->termstate == TOPLEVEL) {
            if (in_utf(term))
                switch (term->utf_state) {
                  case 0:
                    if (c < 0x80) {
                        /* UTF-8 must be stateless so we ignore iso2022. */
                        if (term->ucsdata->unitab_ctrl[c] != 0xFF) 
                             c = term->ucsdata->unitab_ctrl[c];
                        else c = ((unsigned char)c) | CSET_ASCII;
                        break;
                    } else if ((c & 0xe0) == 0xc0) {
                        term->utf_size = term->utf_state = 1;
                        term->utf_char = (c & 0x1f);
                    } else if ((c & 0xf0) == 0xe0) {
                        term->utf_size = term->utf_state = 2;
                        term->utf_char = (c & 0x0f);
                    } else if ((c & 0xf8) == 0xf0) {
                        term->utf_size = term->utf_state = 3;
                        term->utf_char = (c & 0x07);
                    } else if ((c & 0xfc) == 0xf8) {
                        term->utf_size = term->utf_state = 4;
                        term->utf_char = (c & 0x03);
                    } else if ((c & 0xfe) == 0xfc) {
                        term->utf_size = term->utf_state = 5;
                        term->utf_char = (c & 0x01);
                    } else {
                        c = UCSERR;
                        break;
                    }
                    continue;
                  case 1:
                  case 2:
                  case 3:
                  case 4:
                  case 5:
                    if ((c & 0xC0) != 0x80) {
                        unget = c;
                        c = UCSERR;
                        term->utf_state = 0;
                        break;
                    }
                    term->utf_char = (term->utf_char << 6) | (c & 0x3f);
                    if (--term->utf_state)
                        continue;

                    c = term->utf_char;

                    /* Is somebody trying to be evil! */
                    if (c < 0x80 ||
                        (c < 0x800 && term->utf_size >= 2) ||
                        (c < 0x10000 && term->utf_size >= 3) ||
                        (c < 0x200000 && term->utf_size >= 4) ||
                        (c < 0x4000000 && term->utf_size >= 5))
                        c = UCSERR;

                    /* Unicode line separator and paragraph separator are CR-LF */
                    if (c == 0x2028 || c == 0x2029)
                        c = 0x85;

                    /* High controls are probably a Baaad idea too. */
                    if (c < 0xA0)
                        c = 0xFFFD;

                    /* The UTF-16 surrogates are not nice either. */
                    /*       The standard give the option of decoding these: 
                     *       I don't want to! */
                    if (c >= 0xD800 && c < 0xE000)
                        c = UCSERR;

                    /* ISO 10646 characters now limited to UTF-16 range. */
                    if (c > 0x10FFFF)
                        c = UCSERR;

                    /* This is currently a TagPhobic application.. */
                    if (c >= 0xE0000 && c <= 0xE007F)
                        continue;

                    /* U+FEFF is best seen as a null. */
                    if (c == 0xFEFF)
                        continue;
                    /* But U+FFFE is an error. */
                    if (c == 0xFFFE || c == 0xFFFF)
                        c = UCSERR;

                    break;
            }
            /* Are we in the nasty ACS mode? Note: no sco in utf mode. */
            else if(term->sco_acs && 
                    (c!='\033' && c!='\012' && c!='\015' && c!='\b'))
            {
               if (term->sco_acs == 2) c |= 0x80;
               c |= CSET_SCOACS;
            } else {
                switch (term->cset_attr[term->cset]) {
                    /* 
                     * Linedraw characters are different from 'ESC ( B'
                     * only for a small range. For ones outside that
                     * range, make sure we use the same font as well as
                     * the same encoding.
                     */
                  case CSET_LINEDRW:
                    if (term->ucsdata->unitab_ctrl[c] != 0xFF)
                        c = term->ucsdata->unitab_ctrl[c];
                    else
                        c = ((unsigned char) c) | CSET_LINEDRW;
                    break;

                  case CSET_GBCHR:
                    /* If UK-ASCII, make the '#' a LineDraw Pound */
                    if (c == '#') {
                        c = '}' | CSET_LINEDRW;
                        break;
                    }
                  /*FALLTHROUGH*/ case CSET_ASCII:
                    if (term->ucsdata->unitab_ctrl[c] != 0xFF)
                        c = term->ucsdata->unitab_ctrl[c];
                    else
                        c = ((unsigned char) c) | CSET_ASCII;
                    break;
                case CSET_SCOACS:
                    if (c>=' ') c = ((unsigned char)c) | CSET_SCOACS;
                    break;
                }
            }
        }

        /*
         * How about C1 controls? 
         * Explicitly ignore SCI (0x9a), which we don't translate to DECID.
         */
        if ((c & -32) == 0x80 && term->termstate < DO_CTRLS &&
            !term->vt52_mode && has_compat(VT220)) {
            if (c == 0x9a)
                c = 0;
            else {
                term->termstate = SEEN_ESC;
                term->esc_query = FALSE;
                c = '@' + (c & 0x1F);
            }
        }

        /* Or the GL control. */
        if (c == '\177' && term->termstate < DO_CTRLS && has_compat(OTHER)) {
            if (term->curs.x && !term->wrapnext)
                term->curs.x--;
            term->wrapnext = FALSE;
            /* destructive backspace might be disabled */
            if (!term->cfg.no_dbackspace) {
                check_boundary(term, term->curs.x, term->curs.y);
                check_boundary(term, term->curs.x+1, term->curs.y);
                copy_termchar(scrlineptr(term->curs.y),
                              term->curs.x, &term->erase_char);
            }
        } else
            /* Or normal C0 controls. */
        if ((c & ~0x1F) == 0 && term->termstate < DO_CTRLS) {
            switch (c) {
              case '\005':             /* ENQ: terminal type query */
                /* 
                 * Strictly speaking this is VT100 but a VT100 defaults to
                 * no response. Other terminals respond at their option.
                 *
                 * Don't put a CR in the default string as this tends to
                 * upset some weird software.
                 */
                compatibility(ANSIMIN);
                if (term->ldisc) {
                    char abuf[lenof(term->cfg.answerback)], *s, *d;
                    for (s = term->cfg.answerback, d = abuf; *s;) {
                        char *n;
                        char c = ctrlparse(s, &n);
                        if (n) {
                            *d++ = c;
                            s = n;
                        } else {
                            *d++ = *s++;
                        }
                    }
                    lpage_send(term->ldisc, DEFAULT_CODEPAGE,
                               abuf, d - abuf, 0);
                }
                break;
              case '\007':            /* BEL: Bell */
                {
                    struct beeptime *newbeep;
                    unsigned long ticks;

                    ticks = GETTICKCOUNT();

                    if (!term->beep_overloaded) {
                        newbeep = snew(struct beeptime);
                        newbeep->ticks = ticks;
                        newbeep->next = NULL;
                        if (!term->beephead)
                            term->beephead = newbeep;
                        else
                            term->beeptail->next = newbeep;
                        term->beeptail = newbeep;
                        term->nbeeps++;
                    }

                    /*
                     * Throw out any beeps that happened more than
                     * t seconds ago.
                     */
                    while (term->beephead &&
                           term->beephead->ticks < ticks - term->cfg.bellovl_t) {
                        struct beeptime *tmp = term->beephead;
                        term->beephead = tmp->next;
                        sfree(tmp);
                        if (!term->beephead)
                            term->beeptail = NULL;
                        term->nbeeps--;
                    }

                    if (term->cfg.bellovl && term->beep_overloaded &&
                        ticks - term->lastbeep >= (unsigned)term->cfg.bellovl_s) {
                        /*
                         * If we're currently overloaded and the
                         * last beep was more than s seconds ago,
                         * leave overload mode.
                         */
                        term->beep_overloaded = FALSE;
                    } else if (term->cfg.bellovl && !term->beep_overloaded &&
                               term->nbeeps >= term->cfg.bellovl_n) {
                        /*
                         * Now, if we have n or more beeps
                         * remaining in the queue, go into overload
                         * mode.
                         */
                        term->beep_overloaded = TRUE;
                    }
                    term->lastbeep = ticks;

                    /*
                     * Perform an actual beep if we're not overloaded.
                     */
                    if (!term->cfg.bellovl || !term->beep_overloaded) {
                        beep(term->frontend, term->cfg.beep);

                        if (term->cfg.beep == BELL_VISUAL) {
                            term_schedule_vbell(term, FALSE, 0);
                        }
                    }
                    seen_disp_event(term);
                }
                break;
              case '\b':              /* BS: Back space */
                if (term->curs.x == 0 &&
                    (term->curs.y == 0 || term->wrap == 0))
                    /* do nothing */ ;
                else if (term->curs.x == 0 && term->curs.y > 0)
                    term->curs.x = term->cols - 1, term->curs.y--;
                else if (term->wrapnext)
                    term->wrapnext = FALSE;
                else
                    term->curs.x--;
                seen_disp_event(term);
                break;
              case '\016':            /* LS1: Locking-shift one */
                compatibility(VT100);
                term->cset = 1;
                break;
              case '\017':            /* LS0: Locking-shift zero */
                compatibility(VT100);
                term->cset = 0;
                break;
              case '\033':            /* ESC: Escape */
                if (term->vt52_mode)
                    term->termstate = VT52_ESC;
                else {
                    compatibility(ANSIMIN);
                    term->termstate = SEEN_ESC;
                    term->esc_query = FALSE;
                }
                break;
              case '\015':            /* CR: Carriage return */
                term->curs.x = 0;
                term->wrapnext = FALSE;
                seen_disp_event(term);
                term->paste_hold = 0;
                if (term->logctx)
                    logtraffic(term->logctx, (unsigned char) c, LGTYP_ASCII);
                break;
              case '\014':            /* FF: Form feed */
                if (has_compat(SCOANSI)) {
                    move(term, 0, 0, 0);
                    erase_lots(term, FALSE, FALSE, TRUE);
                    term->disptop = 0;
                    term->wrapnext = FALSE;
                    seen_disp_event(term);
                    break;
                }
              case '\013':            /* VT: Line tabulation */
                compatibility(VT100);
              case '\012':            /* LF: Line feed */
                if (term->curs.y == term->marg_b)
                    scroll(term, term->marg_t, term->marg_b, 1, TRUE);
                else if (term->curs.y < term->rows - 1)
                    term->curs.y++;
                if (term->cfg.lfhascr)
                    term->curs.x = 0;
                term->wrapnext = FALSE;
                seen_disp_event(term);
                term->paste_hold = 0;
                if (term->logctx)
                    logtraffic(term->logctx, (unsigned char) c, LGTYP_ASCII);
                break;
              case '\t':              /* HT: Character tabulation */
                {
                    pos old_curs = term->curs;
                    termline *ldata = scrlineptr(term->curs.y);

                    do {
                        term->curs.x++;
                    } while (term->curs.x < term->cols - 1 &&
                             !term->tabs[term->curs.x]);

                    if ((ldata->lattr & LATTR_MODE) != LATTR_NORM) {
                        if (term->curs.x >= term->cols / 2)
                            term->curs.x = term->cols / 2 - 1;
                    } else {
                        if (term->curs.x >= term->cols)
                            term->curs.x = term->cols - 1;
                    }

                    check_selection(term, old_curs, term->curs);
                }
                seen_disp_event(term);
                break;
            }
        } else
            switch (term->termstate) {
              case TOPLEVEL:
                /* Only graphic characters get this far;
                 * ctrls are stripped above */
                {
                    termline *cline = scrlineptr(term->curs.y);
                    int width = 0;
                    if (DIRECT_CHAR(c))
                        width = 1;
                    if (!width)
                        width = (term->cfg.cjk_ambig_wide ?
                                 mk_wcwidth_cjk((wchar_t) c) :
                                 mk_wcwidth((wchar_t) c));

                    if (term->wrapnext && term->wrap && width > 0) {
                        cline->lattr |= LATTR_WRAPPED;
                        if (term->curs.y == term->marg_b)
                            scroll(term, term->marg_t, term->marg_b, 1, TRUE);
                        else if (term->curs.y < term->rows - 1)
                            term->curs.y++;
                        term->curs.x = 0;
                        term->wrapnext = FALSE;
                        cline = scrlineptr(term->curs.y);
                    }
                    if (term->insert && width > 0)
                        insch(term, width);
                    if (term->selstate != NO_SELECTION) {
                        pos cursplus = term->curs;
                        incpos(cursplus);
                        check_selection(term, term->curs, cursplus);
                    }
                    if (((c & CSET_MASK) == CSET_ASCII ||
                         (c & CSET_MASK) == 0) &&
                        term->logctx)
                        logtraffic(term->logctx, (unsigned char) c,
                                   LGTYP_ASCII);

                    switch (width) {
                      case 2:
                        /*
                         * If we're about to display a double-width
                         * character starting in the rightmost
                         * column, then we do something special
                         * instead. We must print a space in the
                         * last column of the screen, then wrap;
                         * and we also set LATTR_WRAPPED2 which
                         * instructs subsequent cut-and-pasting not
                         * only to splice this line to the one
                         * after it, but to ignore the space in the
                         * last character position as well.
                         * (Because what was actually output to the
                         * terminal was presumably just a sequence
                         * of CJK characters, and we don't want a
                         * space to be pasted in the middle of
                         * those just because they had the
                         * misfortune to start in the wrong parity
                         * column. xterm concurs.)
                         */
                        check_boundary(term, term->curs.x, term->curs.y);
                        check_boundary(term, term->curs.x+2, term->curs.y);
                        if (term->curs.x == term->cols-1) {
                            copy_termchar(cline, term->curs.x,
                                          &term->erase_char);
                            cline->lattr |= LATTR_WRAPPED | LATTR_WRAPPED2;
                            if (term->curs.y == term->marg_b)
                                scroll(term, term->marg_t, term->marg_b,
                                       1, TRUE);
                            else if (term->curs.y < term->rows - 1)
                                term->curs.y++;
                            term->curs.x = 0;
                            cline = scrlineptr(term->curs.y);
                            /* Now we must check_boundary again, of course. */
                            check_boundary(term, term->curs.x, term->curs.y);
                            check_boundary(term, term->curs.x+2, term->curs.y);
                        }

                        /* FULL-TERMCHAR */
                        clear_cc(cline, term->curs.x);
                        cline->chars[term->curs.x].chr = c;
                        cline->chars[term->curs.x].attr = term->curr_attr;

                        term->curs.x++;

                        /* FULL-TERMCHAR */
                        clear_cc(cline, term->curs.x);
                        cline->chars[term->curs.x].chr = UCSWIDE;
                        cline->chars[term->curs.x].attr = term->curr_attr;

                        break;
                      case 1:
                        check_boundary(term, term->curs.x, term->curs.y);
                        check_boundary(term, term->curs.x+1, term->curs.y);

                        /* FULL-TERMCHAR */
                        clear_cc(cline, term->curs.x);
                        cline->chars[term->curs.x].chr = c;
                        cline->chars[term->curs.x].attr = term->curr_attr;

                        break;
                      case 0:
                        if (term->curs.x > 0) {
                            int x = term->curs.x - 1;

                            /* If we're in wrapnext state, the character
                             * to combine with is _here_, not to our left. */
                            if (term->wrapnext)
                                x++;

                            /*
                             * If the previous character is
                             * UCSWIDE, back up another one.
                             */
                            if (cline->chars[x].chr == UCSWIDE) {
                                assert(x > 0);
                                x--;
                            }

                            add_cc(cline, x, c);
                            seen_disp_event(term);
                        }
                        continue;
                      default:
                        continue;
                    }
                    term->curs.x++;
                    if (term->curs.x == term->cols) {
                        term->curs.x--;
                        term->wrapnext = TRUE;
                        if (term->wrap && term->vt52_mode) {
                            cline->lattr |= LATTR_WRAPPED;
                            if (term->curs.y == term->marg_b)
                                scroll(term, term->marg_t, term->marg_b, 1, TRUE);
                            else if (term->curs.y < term->rows - 1)
                                term->curs.y++;
                            term->curs.x = 0;
                            term->wrapnext = FALSE;
                        }
                    }
                    seen_disp_event(term);
                }
                break;

              case OSC_MAYBE_ST:
                /*
                 * This state is virtually identical to SEEN_ESC, with the
                 * exception that we have an OSC sequence in the pipeline,
                 * and _if_ we see a backslash, we process it.
                 */
                if (c == '\\') {
                    do_osc(term);
                    term->termstate = TOPLEVEL;
                    break;
                }
                /* else fall through */
              case SEEN_ESC:
                if (c >= ' ' && c <= '/') {
                    if (term->esc_query)
                        term->esc_query = -1;
                    else
                        term->esc_query = c;
                    break;
                }
                term->termstate = TOPLEVEL;
                switch (ANSI(c, term->esc_query)) {
                  case '[':             /* enter CSI mode */
                    term->termstate = SEEN_CSI;
                    term->esc_nargs = 1;
                    term->esc_args[0] = ARG_DEFAULT;
                    term->esc_query = FALSE;
                    break;
                  case ']':             /* OSC: xterm escape sequences */
                    /* Compatibility is nasty here, xterm, linux, decterm yuk! */
                    compatibility(OTHER);
                    term->termstate = SEEN_OSC;
                    term->esc_args[0] = 0;
                    break;
                  case '7':             /* DECSC: save cursor */
                    compatibility(VT100);
                    save_cursor(term, TRUE);
                    break;
                  case '8':             /* DECRC: restore cursor */
                    compatibility(VT100);
                    save_cursor(term, FALSE);
                    seen_disp_event(term);
                    break;
                  case '=':             /* DECKPAM: Keypad application mode */
                    compatibility(VT100);
                    term->app_keypad_keys = TRUE;
                    break;
                  case '>':             /* DECKPNM: Keypad numeric mode */
                    compatibility(VT100);
                    term->app_keypad_keys = FALSE;
                    break;
                  case 'D':            /* IND: exactly equivalent to LF */
                    compatibility(VT100);
                    if (term->curs.y == term->marg_b)
                        scroll(term, term->marg_t, term->marg_b, 1, TRUE);
                    else if (term->curs.y < term->rows - 1)
                        term->curs.y++;
                    term->wrapnext = FALSE;
                    seen_disp_event(term);
                    break;
                  case 'E':            /* NEL: exactly equivalent to CR-LF */
                    compatibility(VT100);
                    term->curs.x = 0;
                    if (term->curs.y == term->marg_b)
                        scroll(term, term->marg_t, term->marg_b, 1, TRUE);
                    else if (term->curs.y < term->rows - 1)
                        term->curs.y++;
                    term->wrapnext = FALSE;
                    seen_disp_event(term);
                    break;
                  case 'M':            /* RI: reverse index - backwards LF */
                    compatibility(VT100);
                    if (term->curs.y == term->marg_t)
                        scroll(term, term->marg_t, term->marg_b, -1, TRUE);
                    else if (term->curs.y > 0)
                        term->curs.y--;
                    term->wrapnext = FALSE;
                    seen_disp_event(term);
                    break;
                  case 'Z':            /* DECID: terminal type query */
                    compatibility(VT100);
                    if (term->ldisc)
                        ldisc_send(term->ldisc, term->id_string,
                                   strlen(term->id_string), 0);
                    break;
                  case 'c':            /* RIS: restore power-on settings */
                    compatibility(VT100);
                    power_on(term);
                    if (term->ldisc)   /* cause ldisc to notice changes */
                        ldisc_send(term->ldisc, NULL, 0, 0);
                    if (term->reset_132) {
                        if (!term->cfg.no_remote_resize)
                            request_resize(term->frontend, 80, term->rows);
                        term->reset_132 = 0;
                    }
                    term->disptop = 0;
                    seen_disp_event(term);
                    break;
                  case 'H':            /* HTS: set a tab */
                    compatibility(VT100);
                    term->tabs[term->curs.x] = TRUE;
                    break;

                  case ANSI('8', '#'):  /* DECALN: fills screen with Es :-) */
                    compatibility(VT100);
                    {
                        termline *ldata;
                        int i, j;
                        pos scrtop, scrbot;

                        for (i = 0; i < term->rows; i++) {
                            ldata = scrlineptr(i);
                            for (j = 0; j < term->cols; j++) {
                                copy_termchar(ldata, j,
                                              &term->basic_erase_char);
                                ldata->chars[j].chr = 'E';
                            }
                            ldata->lattr = LATTR_NORM;
                        }
                        term->disptop = 0;
                        seen_disp_event(term);
                        scrtop.x = scrtop.y = 0;
                        scrbot.x = 0;
                        scrbot.y = term->rows;
                        check_selection(term, scrtop, scrbot);
                    }
                    break;

                  case ANSI('3', '#'):
                  case ANSI('4', '#'):
                  case ANSI('5', '#'):
                  case ANSI('6', '#'):
                    compatibility(VT100);
                    {
                        int nlattr;

                        switch (ANSI(c, term->esc_query)) {
                          case ANSI('3', '#'): /* DECDHL: 2*height, top */
                            nlattr = LATTR_TOP;
                            break;
                          case ANSI('4', '#'): /* DECDHL: 2*height, bottom */
                            nlattr = LATTR_BOT;
                            break;
                          case ANSI('5', '#'): /* DECSWL: normal */
                            nlattr = LATTR_NORM;
                            break;
                          default: /* case ANSI('6', '#'): DECDWL: 2*width */
                            nlattr = LATTR_WIDE;
                            break;
                        }
                        scrlineptr(term->curs.y)->lattr = nlattr;
                    }
                    break;
                  /* GZD4: G0 designate 94-set */
                  case ANSI('A', '('):
                    compatibility(VT100);
                    if (!term->cfg.no_remote_charset)
                        term->cset_attr[0] = CSET_GBCHR;
                    break;
                  case ANSI('B', '('):
                    compatibility(VT100);
                    if (!term->cfg.no_remote_charset)
                        term->cset_attr[0] = CSET_ASCII;
                    break;
                  case ANSI('0', '('):
                    compatibility(VT100);
                    if (!term->cfg.no_remote_charset)
                        term->cset_attr[0] = CSET_LINEDRW;
                    break;
                  case ANSI('U', '('): 
                    compatibility(OTHER);
                    if (!term->cfg.no_remote_charset)
                        term->cset_attr[0] = CSET_SCOACS; 
                    break;
                  /* G1D4: G1-designate 94-set */
                  case ANSI('A', ')'):
                    compatibility(VT100);
                    if (!term->cfg.no_remote_charset)
                        term->cset_attr[1] = CSET_GBCHR;
                    break;
                  case ANSI('B', ')'):
                    compatibility(VT100);
                    if (!term->cfg.no_remote_charset)
                        term->cset_attr[1] = CSET_ASCII;
                    break;
                  case ANSI('0', ')'):
                    compatibility(VT100);
                    if (!term->cfg.no_remote_charset)
                        term->cset_attr[1] = CSET_LINEDRW;
                    break;
                  case ANSI('U', ')'): 
                    compatibility(OTHER);
                    if (!term->cfg.no_remote_charset)
                        term->cset_attr[1] = CSET_SCOACS; 
                    break;
                  /* DOCS: Designate other coding system */
                  case ANSI('8', '%'):  /* Old Linux code */
                  case ANSI('G', '%'):
                    compatibility(OTHER);
                    if (!term->cfg.no_remote_charset)
                        term->utf = 1;
                    break;
                  case ANSI('@', '%'):
                    compatibility(OTHER);
                    if (!term->cfg.no_remote_charset)
                        term->utf = 0;
                    break;
                }
                break;
              case SEEN_CSI:
                term->termstate = TOPLEVEL;  /* default */
                if (isdigit(c)) {
                    if (term->esc_nargs <= ARGS_MAX) {
                        if (term->esc_args[term->esc_nargs - 1] == ARG_DEFAULT)
                            term->esc_args[term->esc_nargs - 1] = 0;
                        term->esc_args[term->esc_nargs - 1] =
                            10 * term->esc_args[term->esc_nargs - 1] + c - '0';
                    }
                    term->termstate = SEEN_CSI;
                } else if (c == ';') {
                    if (++term->esc_nargs <= ARGS_MAX)
                        term->esc_args[term->esc_nargs - 1] = ARG_DEFAULT;
                    term->termstate = SEEN_CSI;
                } else if (c < '@') {
                    if (term->esc_query)
                        term->esc_query = -1;
                    else if (c == '?')
                        term->esc_query = TRUE;
                    else
                        term->esc_query = c;
                    term->termstate = SEEN_CSI;
                } else
                    switch (ANSI(c, term->esc_query)) {
                      case 'A':       /* CUU: move up N lines */
                        move(term, term->curs.x,
                             term->curs.y - def(term->esc_args[0], 1), 1);
                        seen_disp_event(term);
                        break;
                      case 'e':         /* VPR: move down N lines */
                        compatibility(ANSI);
                        /* FALLTHROUGH */
                      case 'B':         /* CUD: Cursor down */
                        move(term, term->curs.x,
                             term->curs.y + def(term->esc_args[0], 1), 1);
                        seen_disp_event(term);
                        break;
                      case ANSI('c', '>'):      /* DA: report xterm version */
                        compatibility(OTHER);
                        /* this reports xterm version 136 so that VIM can
                           use the drag messages from the mouse reporting */
                        if (term->ldisc)
                            ldisc_send(term->ldisc, "\033[>0;136;0c", 11, 0);
                        break;
                      case 'a':         /* HPR: move right N cols */
                        compatibility(ANSI);
                        /* FALLTHROUGH */
                      case 'C':         /* CUF: Cursor right */ 
                        move(term, term->curs.x + def(term->esc_args[0], 1),
                             term->curs.y, 1);
                        seen_disp_event(term);
                        break;
                      case 'D':       /* CUB: move left N cols */
                        move(term, term->curs.x - def(term->esc_args[0], 1),
                             term->curs.y, 1);
                        seen_disp_event(term);
                        break;
                      case 'E':       /* CNL: move down N lines and CR */
                        compatibility(ANSI);
                        move(term, 0,
                             term->curs.y + def(term->esc_args[0], 1), 1);
                        seen_disp_event(term);
                        break;
                      case 'F':       /* CPL: move up N lines and CR */
                        compatibility(ANSI);
                        move(term, 0,
                             term->curs.y - def(term->esc_args[0], 1), 1);
                        seen_disp_event(term);
                        break;
                      case 'G':       /* CHA */
                      case '`':       /* HPA: set horizontal posn */
                        compatibility(ANSI);
                        move(term, def(term->esc_args[0], 1) - 1,
                             term->curs.y, 0);
                        seen_disp_event(term);
                        break;
                      case 'd':       /* VPA: set vertical posn */
                        compatibility(ANSI);
                        move(term, term->curs.x,
                             ((term->dec_om ? term->marg_t : 0) +
                              def(term->esc_args[0], 1) - 1),
                             (term->dec_om ? 2 : 0));
                        seen_disp_event(term);
                        break;
                      case 'H':      /* CUP */
                      case 'f':      /* HVP: set horz and vert posns at once */
                        if (term->esc_nargs < 2)
                            term->esc_args[1] = ARG_DEFAULT;
                        move(term, def(term->esc_args[1], 1) - 1,
                             ((term->dec_om ? term->marg_t : 0) +
                              def(term->esc_args[0], 1) - 1),
                             (term->dec_om ? 2 : 0));
                        seen_disp_event(term);
                        break;
                      case 'J':       /* ED: erase screen or parts of it */
                        {
                            unsigned int i = def(term->esc_args[0], 0) + 1;
                            if (i > 3)
                                i = 0;
                            erase_lots(term, FALSE, !!(i & 2), !!(i & 1));
                        }
                        term->disptop = 0;
                        seen_disp_event(term);
                        break;
                      case 'K':       /* EL: erase line or parts of it */
                        {
                            unsigned int i = def(term->esc_args[0], 0) + 1;
                            if (i > 3)
                                i = 0;
                            erase_lots(term, TRUE, !!(i & 2), !!(i & 1));
                        }
                        seen_disp_event(term);
                        break;
                      case 'L':       /* IL: insert lines */
                        compatibility(VT102);
                        if (term->curs.y <= term->marg_b)
                            scroll(term, term->curs.y, term->marg_b,
                                   -def(term->esc_args[0], 1), FALSE);
                        seen_disp_event(term);
                        break;
                      case 'M':       /* DL: delete lines */
                        compatibility(VT102);
                        if (term->curs.y <= term->marg_b)
                            scroll(term, term->curs.y, term->marg_b,
                                   def(term->esc_args[0], 1),
                                   TRUE);
                        seen_disp_event(term);
                        break;
                      case '@':       /* ICH: insert chars */
                        /* XXX VTTEST says this is vt220, vt510 manual says vt102 */
                        compatibility(VT102);
                        insch(term, def(term->esc_args[0], 1));
                        seen_disp_event(term);
                        break;
                      case 'P':       /* DCH: delete chars */
                        compatibility(VT102);
                        insch(term, -def(term->esc_args[0], 1));
                        seen_disp_event(term);
                        break;
                      case 'c':       /* DA: terminal type query */
                        compatibility(VT100);
                        /* This is the response for a VT102 */
                        if (term->ldisc)
                            ldisc_send(term->ldisc, term->id_string,
                                       strlen(term->id_string), 0);
                        break;
                      case 'n':       /* DSR: cursor position query */
                        if (term->ldisc) {
                            if (term->esc_args[0] == 6) {
                                char buf[32];
                                sprintf(buf, "\033[%d;%dR", term->curs.y + 1,
                                        term->curs.x + 1);
                                ldisc_send(term->ldisc, buf, strlen(buf), 0);
                            } else if (term->esc_args[0] == 5) {
                                ldisc_send(term->ldisc, "\033[0n", 4, 0);
                            }
                        }
                        break;
                      case 'h':       /* SM: toggle modes to high */
                      case ANSI_QUE('h'):
                        compatibility(VT100);
                        {
                            int i;
                            for (i = 0; i < term->esc_nargs; i++)
                                toggle_mode(term, term->esc_args[i],
                                            term->esc_query, TRUE);
                        }
                        break;
                      case 'i':         /* MC: Media copy */
                      case ANSI_QUE('i'):
                        compatibility(VT100);
                        {
                            if (term->esc_nargs != 1) break;
                            if (term->esc_args[0] == 5 && *term->cfg.printer) {
                                term->printing = TRUE;
                                term->only_printing = !term->esc_query;
                                term->print_state = 0;
                                term_print_setup(term);
                            } else if (term->esc_args[0] == 4 &&
                                       term->printing) {
                                term_print_finish(term);
                            }
                        }
                        break;                  
                      case 'l':       /* RM: toggle modes to low */
                      case ANSI_QUE('l'):
                        compatibility(VT100);
                        {
                            int i;
                            for (i = 0; i < term->esc_nargs; i++)
                                toggle_mode(term, term->esc_args[i],
                                            term->esc_query, FALSE);
                        }
                        break;
                      case 'g':       /* TBC: clear tabs */
                        compatibility(VT100);
                        if (term->esc_nargs == 1) {
                            if (term->esc_args[0] == 0) {
                                term->tabs[term->curs.x] = FALSE;
                            } else if (term->esc_args[0] == 3) {
                                int i;
                                for (i = 0; i < term->cols; i++)
                                    term->tabs[i] = FALSE;
                            }
                        }
                        break;
                      case 'r':       /* DECSTBM: set scroll margins */
                        compatibility(VT100);
                        if (term->esc_nargs <= 2) {
                            int top, bot;
                            top = def(term->esc_args[0], 1) - 1;
                            bot = (term->esc_nargs <= 1
                                   || term->esc_args[1] == 0 ?
                                   term->rows :
                                   def(term->esc_args[1], term->rows)) - 1;
                            if (bot >= term->rows)
                                bot = term->rows - 1;
                            /* VTTEST Bug 9 - if region is less than 2 lines
                             * don't change region.
                             */
                            if (bot - top > 0) {
                                term->marg_t = top;
                                term->marg_b = bot;
                                term->curs.x = 0;
                                /*
                                 * I used to think the cursor should be
                                 * placed at the top of the newly marginned
                                 * area. Apparently not: VMS TPU falls over
                                 * if so.
                                 *
                                 * Well actually it should for
                                 * Origin mode - RDB
                                 */
                                term->curs.y = (term->dec_om ?
                                                term->marg_t : 0);
                                seen_disp_event(term);
                            }
                        }
                        break;
                      case 'm':       /* SGR: set graphics rendition */
                        {
                            /* 
                             * A VT100 without the AVO only had one
                             * attribute, either underline or
                             * reverse video depending on the
                             * cursor type, this was selected by
                             * CSI 7m.
                             *
                             * case 2:
                             *  This is sometimes DIM, eg on the
                             *  GIGI and Linux
                             * case 8:
                             *  This is sometimes INVIS various ANSI.
                             * case 21:
                             *  This like 22 disables BOLD, DIM and INVIS
                             *
                             * The ANSI colours appear on any
                             * terminal that has colour (obviously)
                             * but the interaction between sgr0 and
                             * the colours varies but is usually
                             * related to the background colour
                             * erase item. The interaction between
                             * colour attributes and the mono ones
                             * is also very implementation
                             * dependent.
                             *
                             * The 39 and 49 attributes are likely
                             * to be unimplemented.
                             */
                            int i;
                            for (i = 0; i < term->esc_nargs; i++) {
                                switch (def(term->esc_args[i], 0)) {
                                  case 0:       /* restore defaults */
                                    term->curr_attr = term->default_attr;
                                    break;
                                  case 1:       /* enable bold */
                                    compatibility(VT100AVO);
                                    term->curr_attr |= ATTR_BOLD;
                                    break;
                                  case 21:      /* (enable double underline) */
                                    compatibility(OTHER);
                                  case 4:       /* enable underline */
                                    compatibility(VT100AVO);
                                    term->curr_attr |= ATTR_UNDER;
                                    break;
                                  case 5:       /* enable blink */
                                    compatibility(VT100AVO);
                                    term->curr_attr |= ATTR_BLINK;
                                    break;
                                  case 6:       /* SCO light bkgrd */
                                    compatibility(SCOANSI);
                                    term->blink_is_real = FALSE;
                                    term->curr_attr |= ATTR_BLINK;
                                    term_schedule_tblink(term);
                                    break;
                                  case 7:       /* enable reverse video */
                                    term->curr_attr |= ATTR_REVERSE;
                                    break;
                                  case 10:      /* SCO acs off */
                                    compatibility(SCOANSI);
                                    if (term->cfg.no_remote_charset) break;
                                    term->sco_acs = 0; break;
                                  case 11:      /* SCO acs on */
                                    compatibility(SCOANSI);
                                    if (term->cfg.no_remote_charset) break;
                                    term->sco_acs = 1; break;
                                  case 12:      /* SCO acs on, |0x80 */
                                    compatibility(SCOANSI);
                                    if (term->cfg.no_remote_charset) break;
                                    term->sco_acs = 2; break;
                                  case 22:      /* disable bold */
                                    compatibility2(OTHER, VT220);
                                    term->curr_attr &= ~ATTR_BOLD;
                                    break;
                                  case 24:      /* disable underline */
                                    compatibility2(OTHER, VT220);
                                    term->curr_attr &= ~ATTR_UNDER;
                                    break;
                                  case 25:      /* disable blink */
                                    compatibility2(OTHER, VT220);
                                    term->curr_attr &= ~ATTR_BLINK;
                                    break;
                                  case 27:      /* disable reverse video */
                                    compatibility2(OTHER, VT220);
                                    term->curr_attr &= ~ATTR_REVERSE;
                                    break;
                                  case 30:
                                  case 31:
                                  case 32:
                                  case 33:
                                  case 34:
                                  case 35:
                                  case 36:
                                  case 37:
                                    /* foreground */
                                    term->curr_attr &= ~ATTR_FGMASK;
                                    term->curr_attr |=
                                        (term->esc_args[i] - 30)<<ATTR_FGSHIFT;
                                    break;
                                  case 90:
                                  case 91:
                                  case 92:
                                  case 93:
                                  case 94:
                                  case 95:
                                  case 96:
                                  case 97:
                                    /* aixterm-style bright foreground */
                                    term->curr_attr &= ~ATTR_FGMASK;
                                    term->curr_attr |=
                                        ((term->esc_args[i] - 90 + 8)
                                         << ATTR_FGSHIFT);
                                    break;
                                  case 39:      /* default-foreground */
                                    term->curr_attr &= ~ATTR_FGMASK;
                                    term->curr_attr |= ATTR_DEFFG;
                                    break;
                                  case 40:
                                  case 41:
                                  case 42:
                                  case 43:
                                  case 44:
                                  case 45:
                                  case 46:
                                  case 47:
                                    /* background */
                                    term->curr_attr &= ~ATTR_BGMASK;
                                    term->curr_attr |=
                                        (term->esc_args[i] - 40)<<ATTR_BGSHIFT;
                                    break;
                                  case 100:
                                  case 101:
                                  case 102:
                                  case 103:
                                  case 104:
                                  case 105:
                                  case 106:
                                  case 107:
                                    /* aixterm-style bright background */
                                    term->curr_attr &= ~ATTR_BGMASK;
                                    term->curr_attr |=
                                        ((term->esc_args[i] - 100 + 8)
                                         << ATTR_BGSHIFT);
                                    break;
                                  case 49:      /* default-background */
                                    term->curr_attr &= ~ATTR_BGMASK;
                                    term->curr_attr |= ATTR_DEFBG;
                                    break;
                                  case 38:   /* xterm 256-colour mode */
                                    if (i+2 < term->esc_nargs &&
                                        term->esc_args[i+1] == 5) {
                                        term->curr_attr &= ~ATTR_FGMASK;
                                        term->curr_attr |=
                                            ((term->esc_args[i+2] & 0xFF)
                                             << ATTR_FGSHIFT);
                                        i += 2;
                                    }
                                    break;
                                  case 48:   /* xterm 256-colour mode */
                                    if (i+2 < term->esc_nargs &&
                                        term->esc_args[i+1] == 5) {
                                        term->curr_attr &= ~ATTR_BGMASK;
                                        term->curr_attr |=
                                            ((term->esc_args[i+2] & 0xFF)
                                             << ATTR_BGSHIFT);
                                        i += 2;
                                    }
                                    break;
                                }
                            }
                            set_erase_char(term);
                        }
                        break;
                      case 's':       /* save cursor */
                        save_cursor(term, TRUE);
                        break;
                      case 'u':       /* restore cursor */
                        save_cursor(term, FALSE);
                        seen_disp_event(term);
                        break;
                      case 't': /* DECSLPP: set page size - ie window height */
                        /*
                         * VT340/VT420 sequence DECSLPP, DEC only allows values
                         *  24/25/36/48/72/144 other emulators (eg dtterm) use
                         * illegal values (eg first arg 1..9) for window changing 
                         * and reports.
                         */
                        if (term->esc_nargs <= 1
                            && (term->esc_args[0] < 1 ||
                                term->esc_args[0] >= 24)) {
                            compatibility(VT340TEXT);
                            if (!term->cfg.no_remote_resize)
                                request_resize(term->frontend, term->cols,
                                               def(term->esc_args[0], 24));
                            deselect(term);
                        } else if (term->esc_nargs >= 1 &&
                                   term->esc_args[0] >= 1 &&
                                   term->esc_args[0] < 24) {
                            compatibility(OTHER);

                            switch (term->esc_args[0]) {
                                int x, y, len;
                                char buf[80], *p;
                              case 1:
                                set_iconic(term->frontend, FALSE);
                                break;
                              case 2:
                                set_iconic(term->frontend, TRUE);
                                break;
                              case 3:
                                if (term->esc_nargs >= 3) {
                                    if (!term->cfg.no_remote_resize)
                                        move_window(term->frontend,
                                                    def(term->esc_args[1], 0),
                                                    def(term->esc_args[2], 0));
                                }
                                break;
                              case 4:
                                /* We should resize the window to a given
                                 * size in pixels here, but currently our
                                 * resizing code isn't healthy enough to
                                 * manage it. */
                                break;
                              case 5:
                                /* move to top */
                                set_zorder(term->frontend, TRUE);
                                break;
                              case 6:
                                /* move to bottom */
                                set_zorder(term->frontend, FALSE);
                                break;
                              case 7:
                                refresh_window(term->frontend);
                                break;
                              case 8:
                                if (term->esc_nargs >= 3) {
                                    if (!term->cfg.no_remote_resize)
                                        request_resize(term->frontend,
                                                       def(term->esc_args[2], term->cfg.width),
                                                       def(term->esc_args[1], term->cfg.height));
                                }
                                break;
                              case 9:
                                if (term->esc_nargs >= 2)
                                    set_zoomed(term->frontend,
                                               term->esc_args[1] ?
                                               TRUE : FALSE);
                                break;
                              case 11:
                                if (term->ldisc)
                                    ldisc_send(term->ldisc,
                                               is_iconic(term->frontend) ?
                                               "\033[1t" : "\033[2t", 4, 0);
                                break;
                              case 13:
                                if (term->ldisc) {
                                    get_window_pos(term->frontend, &x, &y);
                                    len = sprintf(buf, "\033[3;%d;%dt", x, y);
                                    ldisc_send(term->ldisc, buf, len, 0);
                                }
                                break;
                              case 14:
                                if (term->ldisc) {
                                    get_window_pixels(term->frontend, &x, &y);
                                    len = sprintf(buf, "\033[4;%d;%dt", x, y);
                                    ldisc_send(term->ldisc, buf, len, 0);
                                }
                                break;
                              case 18:
                                if (term->ldisc) {
                                    len = sprintf(buf, "\033[8;%d;%dt",
                                                  term->rows, term->cols);
                                    ldisc_send(term->ldisc, buf, len, 0);
                                }
                                break;
                              case 19:
                                /*
                                 * Hmmm. Strictly speaking we
                                 * should return `the size of the
                                 * screen in characters', but
                                 * that's not easy: (a) window
                                 * furniture being what it is it's
                                 * hard to compute, and (b) in
                                 * resize-font mode maximising the
                                 * window wouldn't change the
                                 * number of characters. *shrug*. I
                                 * think we'll ignore it for the
                                 * moment and see if anyone
                                 * complains, and then ask them
                                 * what they would like it to do.
                                 */
                                break;
                              case 20:
                                if (term->ldisc &&
                                    !term->cfg.no_remote_qtitle) {
                                    p = get_window_title(term->frontend, TRUE);
                                    len = strlen(p);
                                    ldisc_send(term->ldisc, "\033]L", 3, 0);
                                    ldisc_send(term->ldisc, p, len, 0);
                                    ldisc_send(term->ldisc, "\033\\", 2, 0);
                                }
                                break;
                              case 21:
                                if (term->ldisc &&
                                    !term->cfg.no_remote_qtitle) {
                                    p = get_window_title(term->frontend,FALSE);
                                    len = strlen(p);
                                    ldisc_send(term->ldisc, "\033]l", 3, 0);
                                    ldisc_send(term->ldisc, p, len, 0);
                                    ldisc_send(term->ldisc, "\033\\", 2, 0);
                                }
                                break;
                            }
                        }
                        break;
                      case 'S':         /* SU: Scroll up */
                        compatibility(SCOANSI);
                        scroll(term, term->marg_t, term->marg_b,
                               def(term->esc_args[0], 1), TRUE);
                        term->wrapnext = FALSE;
                        seen_disp_event(term);
                        break;
                      case 'T':         /* SD: Scroll down */
                        compatibility(SCOANSI);
                        scroll(term, term->marg_t, term->marg_b,
                               -def(term->esc_args[0], 1), TRUE);
                        term->wrapnext = FALSE;
                        seen_disp_event(term);
                        break;
                      case ANSI('|', '*'): /* DECSNLS */
                        /* 
                         * Set number of lines on screen
                         * VT420 uses VGA like hardware and can
                         * support any size in reasonable range
                         * (24..49 AIUI) with no default specified.
                         */
                        compatibility(VT420);
                        if (term->esc_nargs == 1 && term->esc_args[0] > 0) {
                            if (!term->cfg.no_remote_resize)
                                request_resize(term->frontend, term->cols,
                                               def(term->esc_args[0],
                                                   term->cfg.height));
                            deselect(term);
                        }
                        break;
                      case ANSI('|', '$'): /* DECSCPP */
                        /*
                         * Set number of columns per page
                         * Docs imply range is only 80 or 132, but
                         * I'll allow any.
                         */
                        compatibility(VT340TEXT);
                        if (term->esc_nargs <= 1) {
                            if (!term->cfg.no_remote_resize)
                                request_resize(term->frontend,
                                               def(term->esc_args[0],
                                                   term->cfg.width), term->rows);
                            deselect(term);
                        }
                        break;
                      case 'X':     /* ECH: write N spaces w/o moving cursor */
                        /* XXX VTTEST says this is vt220, vt510 manual
                         * says vt100 */
                        compatibility(ANSIMIN);
                        {
                            int n = def(term->esc_args[0], 1);
                            pos cursplus;
                            int p = term->curs.x;
                            termline *cline = scrlineptr(term->curs.y);

                            if (n > term->cols - term->curs.x)
                                n = term->cols - term->curs.x;
                            cursplus = term->curs;
                            cursplus.x += n;
                            check_boundary(term, term->curs.x, term->curs.y);
                            check_boundary(term, term->curs.x+n, term->curs.y);
                            check_selection(term, term->curs, cursplus);
                            while (n--)
                                copy_termchar(cline, p++,
                                              &term->erase_char);
                            seen_disp_event(term);
                        }
                        break;
                      case 'x':       /* DECREQTPARM: report terminal characteristics */
                        compatibility(VT100);
                        if (term->ldisc) {
                            char buf[32];
                            int i = def(term->esc_args[0], 0);
                            if (i == 0 || i == 1) {
                                strcpy(buf, "\033[2;1;1;112;112;1;0x");
                                buf[2] += i;
                                ldisc_send(term->ldisc, buf, 20, 0);
                            }
                        }
                        break;
                      case 'Z':         /* CBT */
                        compatibility(OTHER);
                        {
                            int i = def(term->esc_args[0], 1);
                            pos old_curs = term->curs;

                            for(;i>0 && term->curs.x>0; i--) {
                                do {
                                    term->curs.x--;
                                } while (term->curs.x >0 &&
                                         !term->tabs[term->curs.x]);
                            }
                            check_selection(term, old_curs, term->curs);
                        }
                        break;
                      case ANSI('c', '='):      /* Hide or Show Cursor */
                        compatibility(SCOANSI);
                        switch(term->esc_args[0]) {
                          case 0:  /* hide cursor */
                            term->cursor_on = FALSE;
                            break;
                          case 1:  /* restore cursor */
                            term->big_cursor = FALSE;
                            term->cursor_on = TRUE;
                            break;
                          case 2:  /* block cursor */
                            term->big_cursor = TRUE;
                            term->cursor_on = TRUE;
                            break;
                        }
                        break;
                      case ANSI('C', '='):
                        /*
                         * set cursor start on scanline esc_args[0] and
                         * end on scanline esc_args[1].If you set
                         * the bottom scan line to a value less than
                         * the top scan line, the cursor will disappear.
                         */
                        compatibility(SCOANSI);
                        if (term->esc_nargs >= 2) {
                            if (term->esc_args[0] > term->esc_args[1])
                                term->cursor_on = FALSE;
                            else
                                term->cursor_on = TRUE;
                        }
                        break;
                      case ANSI('D', '='):
                        compatibility(SCOANSI);
                        term->blink_is_real = FALSE;
                        term_schedule_tblink(term);
                        if (term->esc_args[0]>=1)
                            term->curr_attr |= ATTR_BLINK;
                        else
                            term->curr_attr &= ~ATTR_BLINK;
                        break;
                      case ANSI('E', '='):
                        compatibility(SCOANSI);
                        term->blink_is_real = (term->esc_args[0] >= 1);
                        term_schedule_tblink(term);
                        break;
                      case ANSI('F', '='):      /* set normal foreground */
                        compatibility(SCOANSI);
                        if (term->esc_args[0] >= 0 && term->esc_args[0] < 16) {
                            long colour =
                                (sco2ansicolour[term->esc_args[0] & 0x7] |
                                 (term->esc_args[0] & 0x8)) <<
                                ATTR_FGSHIFT;
                            term->curr_attr &= ~ATTR_FGMASK;
                            term->curr_attr |= colour;
                            term->default_attr &= ~ATTR_FGMASK;
                            term->default_attr |= colour;
                        }
                        break;
                      case ANSI('G', '='):      /* set normal background */
                        compatibility(SCOANSI);
                        if (term->esc_args[0] >= 0 && term->esc_args[0] < 16) {
                            long colour =
                                (sco2ansicolour[term->esc_args[0] & 0x7] |
                                 (term->esc_args[0] & 0x8)) <<
                                ATTR_BGSHIFT;
                            term->curr_attr &= ~ATTR_BGMASK;
                            term->curr_attr |= colour;
                            term->default_attr &= ~ATTR_BGMASK;
                            term->default_attr |= colour;
                        }
                        break;
                      case ANSI('L', '='):
                        compatibility(SCOANSI);
                        term->use_bce = (term->esc_args[0] <= 0);
                        set_erase_char(term);
                        break;
                      case ANSI('p', '"'): /* DECSCL: set compat level */
                        /*
                         * Allow the host to make this emulator a
                         * 'perfect' VT102. This first appeared in
                         * the VT220, but we do need to get back to
                         * PuTTY mode so I won't check it.
                         *
                         * The arg in 40..42,50 are a PuTTY extension.
                         * The 2nd arg, 8bit vs 7bit is not checked.
                         *
                         * Setting VT102 mode should also change
                         * the Fkeys to generate PF* codes as a
                         * real VT102 has no Fkeys. The VT220 does
                         * this, F11..F13 become ESC,BS,LF other
                         * Fkeys send nothing.
                         *
                         * Note ESC c will NOT change this!
                         */

                        switch (term->esc_args[0]) {
                          case 61:
                            term->compatibility_level &= ~TM_VTXXX;
                            term->compatibility_level |= TM_VT102;
                            break;
                          case 62:
                            term->compatibility_level &= ~TM_VTXXX;
                            term->compatibility_level |= TM_VT220;
                            break;

                          default:
                            if (term->esc_args[0] > 60 &&
                                term->esc_args[0] < 70)
                                term->compatibility_level |= TM_VTXXX;
                            break;

                          case 40:
                            term->compatibility_level &= TM_VTXXX;
                            break;
                          case 41:
                            term->compatibility_level = TM_PUTTY;
                            break;
                          case 42:
                            term->compatibility_level = TM_SCOANSI;
                            break;

                          case ARG_DEFAULT:
                            term->compatibility_level = TM_PUTTY;
                            break;
                          case 50:
                            break;
                        }

                        /* Change the response to CSI c */
                        if (term->esc_args[0] == 50) {
                            int i;
                            char lbuf[64];
                            strcpy(term->id_string, "\033[?");
                            for (i = 1; i < term->esc_nargs; i++) {
                                if (i != 1)
                                    strcat(term->id_string, ";");
                                sprintf(lbuf, "%d", term->esc_args[i]);
                                strcat(term->id_string, lbuf);
                            }
                            strcat(term->id_string, "c");
                        }
#if 0
                        /* Is this a good idea ? 
                         * Well we should do a soft reset at this point ...
                         */
                        if (!has_compat(VT420) && has_compat(VT100)) {
                            if (!term->cfg.no_remote_resize) {
                                if (term->reset_132)
                                    request_resize(132, 24);
                                else
                                    request_resize(80, 24);
                            }
                        }
#endif
                        break;
                    }
                break;
              case SEEN_OSC:
                term->osc_w = FALSE;
                switch (c) {
                  case 'P':            /* Linux palette sequence */
                    term->termstate = SEEN_OSC_P;
                    term->osc_strlen = 0;
                    break;
                  case 'R':            /* Linux palette reset */
                    palette_reset(term->frontend);
                    term_invalidate(term);
                    term->termstate = TOPLEVEL;
                    break;
                  case 'W':            /* word-set */
                    term->termstate = SEEN_OSC_W;
                    term->osc_w = TRUE;
                    break;
                  case '0':
                  case '1':
                  case '2':
                  case '3':
                  case '4':
                  case '5':
                  case '6':
                  case '7':
                  case '8':
                  case '9':
                    term->esc_args[0] = 10 * term->esc_args[0] + c - '0';
                    break;
                  case 'L':
                    /*
                     * Grotty hack to support xterm and DECterm title
                     * sequences concurrently.
                     */
                    if (term->esc_args[0] == 2) {
                        term->esc_args[0] = 1;
                        break;
                    }
                    /* else fall through */
                  default:
                    term->termstate = OSC_STRING;
                    term->osc_strlen = 0;
                }
                break;
              case OSC_STRING:
                /*
                 * This OSC stuff is EVIL. It takes just one character to get into
                 * sysline mode and it's not initially obvious how to get out.
                 * So I've added CR and LF as string aborts.
                 * This shouldn't effect compatibility as I believe embedded 
                 * control characters are supposed to be interpreted (maybe?) 
                 * and they don't display anything useful anyway.
                 *
                 * -- RDB
                 */
                if (c == '\012' || c == '\015') {
                    term->termstate = TOPLEVEL;
                } else if (c == 0234 || c == '\007') {
                    /*
                     * These characters terminate the string; ST and BEL
                     * terminate the sequence and trigger instant
                     * processing of it, whereas ESC goes back to SEEN_ESC
                     * mode unless it is followed by \, in which case it is
                     * synonymous with ST in the first place.
                     */
                    do_osc(term);
                    term->termstate = TOPLEVEL;
                } else if (c == '\033')
                    term->termstate = OSC_MAYBE_ST;
                else if (term->osc_strlen < OSC_STR_MAX)
                    term->osc_string[term->osc_strlen++] = (char)c;
                break;
              case SEEN_OSC_P:
                {
                    int max = (term->osc_strlen == 0 ? 21 : 16);
                    int val;
                    if ((int)c >= '0' && (int)c <= '9')
                        val = c - '0';
                    else if ((int)c >= 'A' && (int)c <= 'A' + max - 10)
                        val = c - 'A' + 10;
                    else if ((int)c >= 'a' && (int)c <= 'a' + max - 10)
                        val = c - 'a' + 10;
                    else {
                        term->termstate = TOPLEVEL;
                        break;
                    }
                    term->osc_string[term->osc_strlen++] = val;
                    if (term->osc_strlen >= 7) {
                        palette_set(term->frontend, term->osc_string[0],
                                    term->osc_string[1] * 16 + term->osc_string[2],
                                    term->osc_string[3] * 16 + term->osc_string[4],
                                    term->osc_string[5] * 16 + term->osc_string[6]);
                        term_invalidate(term);
                        term->termstate = TOPLEVEL;
                    }
                }
                break;
              case SEEN_OSC_W:
                switch (c) {
                  case '0':
                  case '1':
                  case '2':
                  case '3':
                  case '4':
                  case '5':
                  case '6':
                  case '7':
                  case '8':
                  case '9':
                    term->esc_args[0] = 10 * term->esc_args[0] + c - '0';
                    break;
                  default:
                    term->termstate = OSC_STRING;
                    term->osc_strlen = 0;
                }
                break;
              case VT52_ESC:
                term->termstate = TOPLEVEL;
                seen_disp_event(term);
                switch (c) {
                  case 'A':
                    move(term, term->curs.x, term->curs.y - 1, 1);
                    break;
                  case 'B':
                    move(term, term->curs.x, term->curs.y + 1, 1);
                    break;
                  case 'C':
                    move(term, term->curs.x + 1, term->curs.y, 1);
                    break;
                  case 'D':
                    move(term, term->curs.x - 1, term->curs.y, 1);
                    break;
                    /*
                     * From the VT100 Manual
                     * NOTE: The special graphics characters in the VT100
                     *       are different from those in the VT52
                     *
                     * From VT102 manual:
                     *       137 _  Blank             - Same
                     *       140 `  Reserved          - Humm.
                     *       141 a  Solid rectangle   - Similar
                     *       142 b  1/                - Top half of fraction for the
                     *       143 c  3/                - subscript numbers below.
                     *       144 d  5/
                     *       145 e  7/
                     *       146 f  Degrees           - Same
                     *       147 g  Plus or minus     - Same
                     *       150 h  Right arrow
                     *       151 i  Ellipsis (dots)
                     *       152 j  Divide by
                     *       153 k  Down arrow
                     *       154 l  Bar at scan 0
                     *       155 m  Bar at scan 1
                     *       156 n  Bar at scan 2
                     *       157 o  Bar at scan 3     - Similar
                     *       160 p  Bar at scan 4     - Similar
                     *       161 q  Bar at scan 5     - Similar
                     *       162 r  Bar at scan 6     - Same
                     *       163 s  Bar at scan 7     - Similar
                     *       164 t  Subscript 0
                     *       165 u  Subscript 1
                     *       166 v  Subscript 2
                     *       167 w  Subscript 3
                     *       170 x  Subscript 4
                     *       171 y  Subscript 5
                     *       172 z  Subscript 6
                     *       173 {  Subscript 7
                     *       174 |  Subscript 8
                     *       175 }  Subscript 9
                     *       176 ~  Paragraph
                     *
                     */
                  case 'F':
                    term->cset_attr[term->cset = 0] = CSET_LINEDRW;
                    break;
                  case 'G':
                    term->cset_attr[term->cset = 0] = CSET_ASCII;
                    break;
                  case 'H':
                    move(term, 0, 0, 0);
                    break;
                  case 'I':
                    if (term->curs.y == 0)
                        scroll(term, 0, term->rows - 1, -1, TRUE);
                    else if (term->curs.y > 0)
                        term->curs.y--;
                    term->wrapnext = FALSE;
                    break;
                  case 'J':
                    erase_lots(term, FALSE, FALSE, TRUE);
                    term->disptop = 0;
                    break;
                  case 'K':
                    erase_lots(term, TRUE, FALSE, TRUE);
                    break;
#if 0
                  case 'V':
                    /* XXX Print cursor line */
                    break;
                  case 'W':
                    /* XXX Start controller mode */
                    break;
                  case 'X':
                    /* XXX Stop controller mode */
                    break;
#endif
                  case 'Y':
                    term->termstate = VT52_Y1;
                    break;
                  case 'Z':
                    if (term->ldisc)
                        ldisc_send(term->ldisc, "\033/Z", 3, 0);
                    break;
                  case '=':
                    term->app_keypad_keys = TRUE;
                    break;
                  case '>':
                    term->app_keypad_keys = FALSE;
                    break;
                  case '<':
                    /* XXX This should switch to VT100 mode not current or default
                     *     VT mode. But this will only have effect in a VT220+
                     *     emulation.
                     */
                    term->vt52_mode = FALSE;
                    term->blink_is_real = term->cfg.blinktext;
                    term_schedule_tblink(term);
                    break;
#if 0
                  case '^':
                    /* XXX Enter auto print mode */
                    break;
                  case '_':
                    /* XXX Exit auto print mode */
                    break;
                  case ']':
                    /* XXX Print screen */
                    break;
#endif

#ifdef VT52_PLUS
                  case 'E':
                    /* compatibility(ATARI) */
                    move(term, 0, 0, 0);
                    erase_lots(term, FALSE, FALSE, TRUE);
                    term->disptop = 0;
                    break;
                  case 'L':
                    /* compatibility(ATARI) */
                    if (term->curs.y <= term->marg_b)
                        scroll(term, term->curs.y, term->marg_b, -1, FALSE);
                    break;
                  case 'M':
                    /* compatibility(ATARI) */
                    if (term->curs.y <= term->marg_b)
                        scroll(term, term->curs.y, term->marg_b, 1, TRUE);
                    break;
                  case 'b':
                    /* compatibility(ATARI) */
                    term->termstate = VT52_FG;
                    break;
                  case 'c':
                    /* compatibility(ATARI) */
                    term->termstate = VT52_BG;
                    break;
                  case 'd':
                    /* compatibility(ATARI) */
                    erase_lots(term, FALSE, TRUE, FALSE);
                    term->disptop = 0;
                    break;
                  case 'e':
                    /* compatibility(ATARI) */
                    term->cursor_on = TRUE;
                    break;
                  case 'f':
                    /* compatibility(ATARI) */
                    term->cursor_on = FALSE;
                    break;
                    /* case 'j': Save cursor position - broken on ST */
                    /* case 'k': Restore cursor position */
                  case 'l':
                    /* compatibility(ATARI) */
                    erase_lots(term, TRUE, TRUE, TRUE);
                    term->curs.x = 0;
                    term->wrapnext = FALSE;
                    break;
                  case 'o':
                    /* compatibility(ATARI) */
                    erase_lots(term, TRUE, TRUE, FALSE);
                    break;
                  case 'p':
                    /* compatibility(ATARI) */
                    term->curr_attr |= ATTR_REVERSE;
                    break;
                  case 'q':
                    /* compatibility(ATARI) */
                    term->curr_attr &= ~ATTR_REVERSE;
                    break;
                  case 'v':            /* wrap Autowrap on - Wyse style */
                    /* compatibility(ATARI) */
                    term->wrap = 1;
                    break;
                  case 'w':            /* Autowrap off */
                    /* compatibility(ATARI) */
                    term->wrap = 0;
                    break;

                  case 'R':
                    /* compatibility(OTHER) */
                    term->vt52_bold = FALSE;
                    term->curr_attr = ATTR_DEFAULT;
                    set_erase_char(term);
                    break;
                  case 'S':
                    /* compatibility(VI50) */
                    term->curr_attr |= ATTR_UNDER;
                    break;
                  case 'W':
                    /* compatibility(VI50) */
                    term->curr_attr &= ~ATTR_UNDER;
                    break;
                  case 'U':
                    /* compatibility(VI50) */
                    term->vt52_bold = TRUE;
                    term->curr_attr |= ATTR_BOLD;
                    break;
                  case 'T':
                    /* compatibility(VI50) */
                    term->vt52_bold = FALSE;
                    term->curr_attr &= ~ATTR_BOLD;
                    break;
#endif
                }
                break;
              case VT52_Y1:
                term->termstate = VT52_Y2;
                move(term, term->curs.x, c - ' ', 0);
                break;
              case VT52_Y2:
                term->termstate = TOPLEVEL;
                move(term, c - ' ', term->curs.y, 0);
                break;

#ifdef VT52_PLUS
              case VT52_FG:
                term->termstate = TOPLEVEL;
                term->curr_attr &= ~ATTR_FGMASK;
                term->curr_attr &= ~ATTR_BOLD;
                term->curr_attr |= (c & 0xF) << ATTR_FGSHIFT;
                set_erase_char(term);
                break;
              case VT52_BG:
                term->termstate = TOPLEVEL;
                term->curr_attr &= ~ATTR_BGMASK;
                term->curr_attr &= ~ATTR_BLINK;
                term->curr_attr |= (c & 0xF) << ATTR_BGSHIFT;
                set_erase_char(term);
                break;
#endif
              default: break;          /* placate gcc warning about enum use */
            }
        if (term->selstate != NO_SELECTION) {
            pos cursplus = term->curs;
            incpos(cursplus);
            check_selection(term, term->curs, cursplus);
        }
    }

    term_print_flush(term);
    if (term->cfg.logflush)
        logflush(term->logctx);
}

/*
 * To prevent having to run the reasonably tricky bidi algorithm
 * too many times, we maintain a cache of the last lineful of data
 * fed to the algorithm on each line of the display.
 */
static int term_bidi_cache_hit(Terminal *term, int line,
                               termchar *lbefore, int width)
{
    int i;

    if (!term->pre_bidi_cache)
        return FALSE;                  /* cache doesn't even exist yet! */

    if (line >= term->bidi_cache_size)
        return FALSE;                  /* cache doesn't have this many lines */

    if (!term->pre_bidi_cache[line].chars)
        return FALSE;                  /* cache doesn't contain _this_ line */

    if (term->pre_bidi_cache[line].width != width)
        return FALSE;                  /* line is wrong width */

    for (i = 0; i < width; i++)
        if (!termchars_equal(term->pre_bidi_cache[line].chars+i, lbefore+i))
            return FALSE;              /* line doesn't match cache */

    return TRUE;                       /* it didn't match. */
}

static void term_bidi_cache_store(Terminal *term, int line, termchar *lbefore,
                                  termchar *lafter, bidi_char *wcTo,
                                  int width, int size)
{
    int i;

    if (!term->pre_bidi_cache || term->bidi_cache_size <= line) {
        int j = term->bidi_cache_size;
        term->bidi_cache_size = line+1;
        term->pre_bidi_cache = sresize(term->pre_bidi_cache,
                                       term->bidi_cache_size,
                                       struct bidi_cache_entry);
        term->post_bidi_cache = sresize(term->post_bidi_cache,
                                        term->bidi_cache_size,
                                        struct bidi_cache_entry);
        while (j < term->bidi_cache_size) {
            term->pre_bidi_cache[j].chars =
                term->post_bidi_cache[j].chars = NULL;
            term->pre_bidi_cache[j].width =
                term->post_bidi_cache[j].width = -1;
            term->pre_bidi_cache[j].forward =
                term->post_bidi_cache[j].forward = NULL;
            term->pre_bidi_cache[j].backward =
                term->post_bidi_cache[j].backward = NULL;
            j++;
        }
    }

    sfree(term->pre_bidi_cache[line].chars);
    sfree(term->post_bidi_cache[line].chars);
    sfree(term->post_bidi_cache[line].forward);
    sfree(term->post_bidi_cache[line].backward);

    term->pre_bidi_cache[line].width = width;
    term->pre_bidi_cache[line].chars = snewn(size, termchar);
    term->post_bidi_cache[line].width = width;
    term->post_bidi_cache[line].chars = snewn(size, termchar);
    term->post_bidi_cache[line].forward = snewn(width, int);
    term->post_bidi_cache[line].backward = snewn(width, int);

    memcpy(term->pre_bidi_cache[line].chars, lbefore, size * TSIZE);
    memcpy(term->post_bidi_cache[line].chars, lafter, size * TSIZE);
    memset(term->post_bidi_cache[line].forward, 0, width * sizeof(int));
    memset(term->post_bidi_cache[line].backward, 0, width * sizeof(int));

    for (i = 0; i < width; i++) {
        int p = wcTo[i].index;

        assert(0 <= p && p < width);

        term->post_bidi_cache[line].backward[i] = p;
        term->post_bidi_cache[line].forward[p] = i;
    }
}

/*
 * Prepare the bidi information for a screen line. Returns the
 * transformed list of termchars, or NULL if no transformation at
 * all took place (because bidi is disabled). If return was
 * non-NULL, auxiliary information such as the forward and reverse
 * mappings of permutation position are available in
 * term->post_bidi_cache[scr_y].*.
 */
static termchar *term_bidi_line(Terminal *term, struct termline *ldata,
                                int scr_y)
{
    termchar *lchars;
    int it;

    /* Do Arabic shaping and bidi. */
    if(!term->cfg.bidi || !term->cfg.arabicshaping) {

        if (!term_bidi_cache_hit(term, scr_y, ldata->chars, term->cols)) {

            if (term->wcFromTo_size < term->cols) {
                term->wcFromTo_size = term->cols;
                term->wcFrom = sresize(term->wcFrom, term->wcFromTo_size,
                                       bidi_char);
                term->wcTo = sresize(term->wcTo, term->wcFromTo_size,
                                     bidi_char);
            }

            for(it=0; it<term->cols ; it++)
            {
                unsigned long uc = (ldata->chars[it].chr);

                switch (uc & CSET_MASK) {
                  case CSET_LINEDRW:
                    if (!term->cfg.rawcnp) {
                        uc = term->ucsdata->unitab_xterm[uc & 0xFF];
                        break;
                    }
                  case CSET_ASCII:
                    uc = term->ucsdata->unitab_line[uc & 0xFF];
                    break;
                  case CSET_SCOACS:
                    uc = term->ucsdata->unitab_scoacs[uc&0xFF];
                    break;
                }
                switch (uc & CSET_MASK) {
                  case CSET_ACP:
                    uc = term->ucsdata->unitab_font[uc & 0xFF];
                    break;
                  case CSET_OEMCP:
                    uc = term->ucsdata->unitab_oemcp[uc & 0xFF];
                    break;
                }

                term->wcFrom[it].origwc = term->wcFrom[it].wc =
                    (wchar_t)uc;
                term->wcFrom[it].index = it;
            }

            if(!term->cfg.bidi)
                do_bidi(term->wcFrom, term->cols);

            /* this is saved iff done from inside the shaping */
            if(!term->cfg.bidi && term->cfg.arabicshaping)
                for(it=0; it<term->cols; it++)
                    term->wcTo[it] = term->wcFrom[it];

            if(!term->cfg.arabicshaping)
                do_shape(term->wcFrom, term->wcTo, term->cols);

            if (term->ltemp_size < ldata->size) {
                term->ltemp_size = ldata->size;
                term->ltemp = sresize(term->ltemp, term->ltemp_size,
                                      termchar);
            }

            memcpy(term->ltemp, ldata->chars, ldata->size * TSIZE);

            for(it=0; it<term->cols ; it++)
            {
                term->ltemp[it] = ldata->chars[term->wcTo[it].index];
                if (term->ltemp[it].cc_next)
                    term->ltemp[it].cc_next -=
                    it - term->wcTo[it].index;

                if (term->wcTo[it].origwc != term->wcTo[it].wc)
                    term->ltemp[it].chr = term->wcTo[it].wc;
            }
            term_bidi_cache_store(term, scr_y, ldata->chars,
                                  term->ltemp, term->wcTo,
                                  term->cols, ldata->size);

            lchars = term->ltemp;
        } else {
            lchars = term->post_bidi_cache[scr_y].chars;
        }
    } else {
        lchars = NULL;
    }

    return lchars;
}

/*
 * Given a context, update the window. Out of paranoia, we don't
 * allow WM_PAINT responses to do scrolling optimisations.
 */
static void do_paint(Terminal *term, Context ctx, int may_optimise)
{
    int i, j, our_curs_y, our_curs_x;
    int rv, cursor;
    pos scrpos;
    wchar_t *ch;
    int chlen;
#ifdef OPTIMISE_SCROLL
    struct scrollregion *sr;
#endif /* OPTIMISE_SCROLL */
    termchar *newline;

    chlen = 1024;
    ch = snewn(chlen, wchar_t);

    newline = snewn(term->cols, termchar);

    rv = (!term->rvideo ^ !term->in_vbell ? ATTR_REVERSE : 0);

    /* Depends on:
     * screen array, disptop, scrtop,
     * selection, rv, 
     * cfg.blinkpc, blink_is_real, tblinker, 
     * curs.y, curs.x, cblinker, cfg.blink_cur, cursor_on, has_focus, wrapnext
     */

    /* Has the cursor position or type changed ? */
    if (term->cursor_on) {
        if (term->has_focus) {
            if (term->cblinker || !term->cfg.blink_cur)
                cursor = TATTR_ACTCURS;
            else
                cursor = 0;
        } else
            cursor = TATTR_PASCURS;
        if (term->wrapnext)
            cursor |= TATTR_RIGHTCURS;
    } else
        cursor = 0;
    our_curs_y = term->curs.y - term->disptop;
    {
        /*
         * Adjust the cursor position:
         *  - for bidi
         *  - in the case where it's resting on the right-hand half
         *    of a CJK wide character. xterm's behaviour here,
         *    which seems adequate to me, is to display the cursor
         *    covering the _whole_ character, exactly as if it were
         *    one space to the left.
         */
        termline *ldata = lineptr(term->curs.y);
        termchar *lchars;

        our_curs_x = term->curs.x;

        if ( (lchars = term_bidi_line(term, ldata, our_curs_y)) != NULL) {
            our_curs_x = term->post_bidi_cache[our_curs_y].forward[our_curs_x];
        } else
            lchars = ldata->chars;

        if (our_curs_x > 0 &&
            lchars[our_curs_x].chr == UCSWIDE)
            our_curs_x--;

        unlineptr(ldata);
    }

    /*
     * If the cursor is not where it was last time we painted, and
     * its previous position is visible on screen, invalidate its
     * previous position.
     */
    if (term->dispcursy >= 0 &&
        (term->curstype != cursor ||
         term->dispcursy != our_curs_y ||
         term->dispcursx != our_curs_x)) {
        termchar *dispcurs = term->disptext[term->dispcursy]->chars +
            term->dispcursx;

        if (term->dispcursx > 0 && dispcurs->chr == UCSWIDE)
            dispcurs[-1].attr |= ATTR_INVALID;
        if (term->dispcursx < term->cols-1 && dispcurs[1].chr == UCSWIDE)
            dispcurs[1].attr |= ATTR_INVALID;
        dispcurs->attr |= ATTR_INVALID;

        term->curstype = 0;
    }
    term->dispcursx = term->dispcursy = -1;

#ifdef OPTIMISE_SCROLL
    /* Do scrolls */
    sr = term->scrollhead;
    while (sr) {
        struct scrollregion *next = sr->next;
        do_scroll(ctx, sr->topline, sr->botline, sr->lines);
        sfree(sr);
        sr = next;
    }
    term->scrollhead = term->scrolltail = NULL;
#endif /* OPTIMISE_SCROLL */

    /* The normal screen data */
    for (i = 0; i < term->rows; i++) {
        termline *ldata;
        termchar *lchars;
        int dirty_line, dirty_run, selected;
        unsigned long attr = 0, cset = 0;
        int updated_line = 0;
        int start = 0;
        int ccount = 0;
        int last_run_dirty = 0;
        int laststart, dirtyrect;
        int *backward;

        scrpos.y = i + term->disptop;
        ldata = lineptr(scrpos.y);

        /* Do Arabic shaping and bidi. */
        lchars = term_bidi_line(term, ldata, i);
        if (lchars) {
            backward = term->post_bidi_cache[i].backward;
        } else {
            lchars = ldata->chars;
            backward = NULL;
        }

        /*
         * First loop: work along the line deciding what we want
         * each character cell to look like.
         */
        for (j = 0; j < term->cols; j++) {
            unsigned long tattr, tchar;
            termchar *d = lchars + j;
            scrpos.x = backward ? backward[j] : j;

            tchar = d->chr;
            tattr = d->attr;

            if (!term->cfg.ansi_colour)
                tattr = (tattr & ~(ATTR_FGMASK | ATTR_BGMASK)) | 
                ATTR_DEFFG | ATTR_DEFBG;

            if (!term->cfg.xterm_256_colour) {
                int colour;
                colour = (tattr & ATTR_FGMASK) >> ATTR_FGSHIFT;
                if (colour >= 16 && colour < 256)
                    tattr = (tattr &~ ATTR_FGMASK) | ATTR_DEFFG;
                colour = (tattr & ATTR_BGMASK) >> ATTR_BGSHIFT;
                if (colour >= 16 && colour < 256)
                    tattr = (tattr &~ ATTR_BGMASK) | ATTR_DEFBG;
            }

            switch (tchar & CSET_MASK) {
              case CSET_ASCII:
                tchar = term->ucsdata->unitab_line[tchar & 0xFF];
                break;
              case CSET_LINEDRW:
                tchar = term->ucsdata->unitab_xterm[tchar & 0xFF];
                break;
              case CSET_SCOACS:  
                tchar = term->ucsdata->unitab_scoacs[tchar&0xFF]; 
                break;
            }
            if (j < term->cols-1 && d[1].chr == UCSWIDE)
                tattr |= ATTR_WIDE;

            /* Video reversing things */
            if (term->selstate == DRAGGING || term->selstate == SELECTED) {
                if (term->seltype == LEXICOGRAPHIC)
                    selected = (posle(term->selstart, scrpos) &&
                                poslt(scrpos, term->selend));
                else
                    selected = (posPle(term->selstart, scrpos) &&
                                posPlt(scrpos, term->selend));
            } else
                selected = FALSE;
            tattr = (tattr ^ rv
                     ^ (selected ? ATTR_REVERSE : 0));

            /* 'Real' blinking ? */
            if (term->blink_is_real && (tattr & ATTR_BLINK)) {
                if (term->has_focus && term->tblinker) {
                    tchar = term->ucsdata->unitab_line[(unsigned char)' '];
                }
                tattr &= ~ATTR_BLINK;
            }

            /*
             * Check the font we'll _probably_ be using to see if 
             * the character is wide when we don't want it to be.
             */
            if (tchar != term->disptext[i]->chars[j].chr ||
                tattr != (term->disptext[i]->chars[j].attr &~
                          (ATTR_NARROW | DATTR_MASK))) {
                if ((tattr & ATTR_WIDE) == 0 && char_width(ctx, tchar) == 2)
                    tattr |= ATTR_NARROW;
            } else if (term->disptext[i]->chars[j].attr & ATTR_NARROW)
                tattr |= ATTR_NARROW;

            if (i == our_curs_y && j == our_curs_x) {
                tattr |= cursor;
                term->curstype = cursor;
                term->dispcursx = j;
                term->dispcursy = i;
            }

            /* FULL-TERMCHAR */
            newline[j].attr = tattr;
            newline[j].chr = tchar;
            /* Combining characters are still read from lchars */
            newline[j].cc_next = 0;
        }

        /*
         * Now loop over the line again, noting where things have
         * changed.
         * 
         * During this loop, we keep track of where we last saw
         * DATTR_STARTRUN. Any mismatch automatically invalidates
         * _all_ of the containing run that was last printed: that
         * is, any rectangle that was drawn in one go in the
         * previous update should be either left completely alone
         * or overwritten in its entirety. This, along with the
         * expectation that front ends clip all text runs to their
         * bounding rectangle, should solve any possible problems
         * with fonts that overflow their character cells.
         */
        laststart = 0;
        dirtyrect = FALSE;
        for (j = 0; j < term->cols; j++) {
            if (term->disptext[i]->chars[j].attr & DATTR_STARTRUN) {
                laststart = j;
                dirtyrect = FALSE;
            }

            if (term->disptext[i]->chars[j].chr != newline[j].chr ||
                (term->disptext[i]->chars[j].attr &~ DATTR_MASK)
                != newline[j].attr) {
                int k;

                for (k = laststart; k < j; k++)
                    term->disptext[i]->chars[k].attr |= ATTR_INVALID;

                dirtyrect = TRUE;
            }

            if (dirtyrect)
                term->disptext[i]->chars[j].attr |= ATTR_INVALID;
        }

        /*
         * Finally, loop once more and actually do the drawing.
         */
        dirty_run = dirty_line = (ldata->lattr !=
                                  term->disptext[i]->lattr);
        term->disptext[i]->lattr = ldata->lattr;

        for (j = 0; j < term->cols; j++) {
            unsigned long tattr, tchar;
            int break_run, do_copy;
            termchar *d = lchars + j;

            tattr = newline[j].attr;
            tchar = newline[j].chr;

            if ((term->disptext[i]->chars[j].attr ^ tattr) & ATTR_WIDE)
                dirty_line = TRUE;

            break_run = ((tattr ^ attr) & term->attr_mask) != 0;

            /* Special hack for VT100 Linedraw glyphs */
            if (tchar >= 0x23BA && tchar <= 0x23BD)
                break_run = TRUE;

            /*
             * Separate out sequences of characters that have the
             * same CSET, if that CSET is a magic one.
             */
            if (CSET_OF(tchar) != cset)
                break_run = TRUE;

            /*
             * Break on both sides of any combined-character cell.
             */
            if (d->cc_next != 0 ||
                (j > 0 && d[-1].cc_next != 0))
                break_run = TRUE;

            if (!term->ucsdata->dbcs_screenfont && !dirty_line) {
                if (term->disptext[i]->chars[j].chr == tchar &&
                    (term->disptext[i]->chars[j].attr &~ DATTR_MASK) == tattr)
                    break_run = TRUE;
                else if (!dirty_run && ccount == 1)
                    break_run = TRUE;
            }

            if (break_run) {
                if ((dirty_run || last_run_dirty) && ccount > 0) {
                    do_text(ctx, start, i, ch, ccount, attr,
                            ldata->lattr);
                    if (attr & (TATTR_ACTCURS | TATTR_PASCURS))
                        do_cursor(ctx, start, i, ch, ccount, attr,
                                  ldata->lattr);

                    updated_line = 1;
                }
                start = j;
                ccount = 0;
                attr = tattr;
                cset = CSET_OF(tchar);
                if (term->ucsdata->dbcs_screenfont)
                    last_run_dirty = dirty_run;
                dirty_run = dirty_line;
            }

            do_copy = FALSE;
            if (!termchars_equal_override(&term->disptext[i]->chars[j],
                                          d, tchar, tattr)) {
                do_copy = TRUE;
                dirty_run = TRUE;
            }

            if (ccount >= chlen) {
                chlen = ccount + 256;
                ch = sresize(ch, chlen, wchar_t);
            }
            ch[ccount++] = (wchar_t) tchar;

            if (d->cc_next) {
                termchar *dd = d;

                while (dd->cc_next) {
                    unsigned long schar;

                    dd += dd->cc_next;

                    schar = dd->chr;
                    switch (schar & CSET_MASK) {
                      case CSET_ASCII:
                        schar = term->ucsdata->unitab_line[schar & 0xFF];
                        break;
                      case CSET_LINEDRW:
                        schar = term->ucsdata->unitab_xterm[schar & 0xFF];
                        break;
                      case CSET_SCOACS:
                        schar = term->ucsdata->unitab_scoacs[schar&0xFF];
                        break;
                    }

                    if (ccount >= chlen) {
                        chlen = ccount + 256;
                        ch = sresize(ch, chlen, wchar_t);
                    }
                    ch[ccount++] = (wchar_t) schar;
                }

                attr |= TATTR_COMBINING;
            }

            if (do_copy) {
                copy_termchar(term->disptext[i], j, d);
                term->disptext[i]->chars[j].chr = tchar;
                term->disptext[i]->chars[j].attr = tattr;
                if (start == j)
                    term->disptext[i]->chars[j].attr |= DATTR_STARTRUN;
            }

            /* If it's a wide char step along to the next one. */
            if (tattr & ATTR_WIDE) {
                if (++j < term->cols) {
                    d++;
                    /*
                     * By construction above, the cursor should not
                     * be on the right-hand half of this character.
                     * Ever.
                     */
                    assert(!(i == our_curs_y && j == our_curs_x));
                    if (!termchars_equal(&term->disptext[i]->chars[j], d))
                        dirty_run = TRUE;
                    copy_termchar(term->disptext[i], j, d);
                }
            }
        }
        if (dirty_run && ccount > 0) {
            do_text(ctx, start, i, ch, ccount, attr,
                    ldata->lattr);
            if (attr & (TATTR_ACTCURS | TATTR_PASCURS))
                do_cursor(ctx, start, i, ch, ccount, attr,
                          ldata->lattr);

            updated_line = 1;
        }

        unlineptr(ldata);
    }

    sfree(newline);
    sfree(ch);
}

/*
 * Invalidate the whole screen so it will be repainted in full.
 */
void term_invalidate(Terminal *term)
{
    int i, j;

    for (i = 0; i < term->rows; i++)
        for (j = 0; j < term->cols; j++)
            term->disptext[i]->chars[j].attr |= ATTR_INVALID;

    term_schedule_update(term);
}

/*
 * Paint the window in response to a WM_PAINT message.
 */
void term_paint(Terminal *term, Context ctx,
                int left, int top, int right, int bottom, int immediately)
{
    int i, j;
    if (left < 0) left = 0;
    if (top < 0) top = 0;
    if (right >= term->cols) right = term->cols-1;
    if (bottom >= term->rows) bottom = term->rows-1;

    for (i = top; i <= bottom && i < term->rows; i++) {
        if ((term->disptext[i]->lattr & LATTR_MODE) == LATTR_NORM)
            for (j = left; j <= right && j < term->cols; j++)
                term->disptext[i]->chars[j].attr |= ATTR_INVALID;
        else
            for (j = left / 2; j <= right / 2 + 1 && j < term->cols; j++)
                term->disptext[i]->chars[j].attr |= ATTR_INVALID;
    }

    if (immediately) {
        do_paint (term, ctx, FALSE);
    } else {
        term_schedule_update(term);
    }
}

/*
 * Attempt to scroll the scrollback. The second parameter gives the
 * position we want to scroll to; the first is +1 to denote that
 * this position is relative to the beginning of the scrollback, -1
 * to denote it is relative to the end, and 0 to denote that it is
 * relative to the current position.
 */
void term_scroll(Terminal *term, int rel, int where)
{
    int sbtop = -sblines(term);
#ifdef OPTIMISE_SCROLL
    int olddisptop = term->disptop;
    int shift;
#endif /* OPTIMISE_SCROLL */

    term->disptop = (rel < 0 ? 0 : rel > 0 ? sbtop : term->disptop) + where;
    if (term->disptop < sbtop)
        term->disptop = sbtop;
    if (term->disptop > 0)
        term->disptop = 0;
    update_sbar(term);
#ifdef OPTIMISE_SCROLL
    shift = (term->disptop - olddisptop);
    if (shift < term->rows && shift > -term->rows)
        scroll_display(term, 0, term->rows - 1, shift);
#endif /* OPTIMISE_SCROLL */
    term_update(term);
}

static void clipme(Terminal *term, pos top, pos bottom, int rect, int desel)
{
    wchar_t *workbuf;
    wchar_t *wbptr;                    /* where next char goes within workbuf */
    int old_top_x;
    int wblen = 0;                     /* workbuf len */
    int buflen;                        /* amount of memory allocated to workbuf */

    buflen = 5120;                     /* Default size */
    workbuf = snewn(buflen, wchar_t);
    wbptr = workbuf;                   /* start filling here */
    old_top_x = top.x;                 /* needed for rect==1 */

    while (poslt(top, bottom)) {
        int nl = FALSE;
        termline *ldata = lineptr(top.y);
        pos nlpos;

        /*
         * nlpos will point at the maximum position on this line we
         * should copy up to. So we start it at the end of the
         * line...
         */
        nlpos.y = top.y;
        nlpos.x = term->cols;

        /*
         * ... move it backwards if there's unused space at the end
         * of the line (and also set `nl' if this is the case,
         * because in normal selection mode this means we need a
         * newline at the end)...
         */
        if (!(ldata->lattr & LATTR_WRAPPED)) {
            while (IS_SPACE_CHR(ldata->chars[nlpos.x - 1].chr) &&
                   !ldata->chars[nlpos.x - 1].cc_next &&
                   poslt(top, nlpos))
                decpos(nlpos);
            if (poslt(nlpos, bottom))
                nl = TRUE;
        } else if (ldata->lattr & LATTR_WRAPPED2) {
            /* Ignore the last char on the line in a WRAPPED2 line. */
            decpos(nlpos);
        }

        /*
         * ... and then clip it to the terminal x coordinate if
         * we're doing rectangular selection. (In this case we
         * still did the above, so that copying e.g. the right-hand
         * column from a table doesn't fill with spaces on the
         * right.)
         */
        if (rect) {
            if (nlpos.x > bottom.x)
                nlpos.x = bottom.x;
            nl = (top.y < bottom.y);
        }

        while (poslt(top, bottom) && poslt(top, nlpos)) {
#if 0
            char cbuf[16], *p;
            sprintf(cbuf, "<U+%04x>", (ldata[top.x] & 0xFFFF));
#else
            wchar_t cbuf[16], *p;
            int set, c;
            int x = top.x;

            if (ldata->chars[x].chr == UCSWIDE) {
                top.x++;
                continue;
            }

            while (1) {
                int uc = ldata->chars[x].chr;

                switch (uc & CSET_MASK) {
                  case CSET_LINEDRW:
                    if (!term->cfg.rawcnp) {
                        uc = term->ucsdata->unitab_xterm[uc & 0xFF];
                        break;
                    }
                  case CSET_ASCII:
                    uc = term->ucsdata->unitab_line[uc & 0xFF];
                    break;
                  case CSET_SCOACS:
                    uc = term->ucsdata->unitab_scoacs[uc&0xFF];
                    break;
                }
                switch (uc & CSET_MASK) {
                  case CSET_ACP:
                    uc = term->ucsdata->unitab_font[uc & 0xFF];
                    break;
                  case CSET_OEMCP:
                    uc = term->ucsdata->unitab_oemcp[uc & 0xFF];
                    break;
                }

                set = (uc & CSET_MASK);
                c = (uc & ~CSET_MASK);
                cbuf[0] = uc;
                cbuf[1] = 0;

                if (DIRECT_FONT(uc)) {
                    if (c >= ' ' && c != 0x7F) {
                        char buf[4];
                        WCHAR wbuf[4];
                        int rv;
                        if (is_dbcs_leadbyte(term->ucsdata->font_codepage, (BYTE) c)) {
                            buf[0] = c;
                            buf[1] = (char) (0xFF & ldata->chars[top.x + 1].chr);
                            rv = mb_to_wc(term->ucsdata->font_codepage, 0, buf, 2, wbuf, 4);
                            top.x++;
                        } else {
                            buf[0] = c;
                            rv = mb_to_wc(term->ucsdata->font_codepage, 0, buf, 1, wbuf, 4);
                        }

                        if (rv > 0) {
                            memcpy(cbuf, wbuf, rv * sizeof(wchar_t));
                            cbuf[rv] = 0;
                        }
                    }
                }
#endif

                for (p = cbuf; *p; p++) {
                    /* Enough overhead for trailing NL and nul */
                    if (wblen >= buflen - 16) {
                        buflen += 100;
                        workbuf = sresize(workbuf, buflen, wchar_t);
                        wbptr = workbuf + wblen;
                    }
                    wblen++;
                    *wbptr++ = *p;
                }

                if (ldata->chars[x].cc_next)
                    x += ldata->chars[x].cc_next;
                else
                    break;
            }
            top.x++;
        }
        if (nl) {
            int i;
            for (i = 0; i < sel_nl_sz; i++) {
                wblen++;
                *wbptr++ = sel_nl[i];
            }
        }
        top.y++;
        top.x = rect ? old_top_x : 0;

        unlineptr(ldata);
    }
#if SELECTION_NUL_TERMINATED
    wblen++;
    *wbptr++ = 0;
#endif
    write_clip(term->frontend, workbuf, wblen, desel); /* transfer to clipbd */
    if (buflen > 0)                    /* indicates we allocated this buffer */
        sfree(workbuf);
}

void term_copyall(Terminal *term)
{
    pos top;
    pos bottom;
    tree234 *screen = term->screen;
    top.y = -sblines(term);
    top.x = 0;
    bottom.y = find_last_nonempty_line(term, screen);
    bottom.x = term->cols;
    clipme(term, top, bottom, 0, TRUE);
}

/*
 * The wordness array is mainly for deciding the disposition of the
 * US-ASCII characters.
 */
static int wordtype(Terminal *term, int uc)
{
    struct ucsword {
        int start, end, ctype;
    };
    static const struct ucsword ucs_words[] = {
        {
        128, 160, 0}, {
        161, 191, 1}, {
        215, 215, 1}, {
        247, 247, 1}, {
        0x037e, 0x037e, 1},            /* Greek question mark */
        {
        0x0387, 0x0387, 1},            /* Greek ano teleia */
        {
        0x055a, 0x055f, 1},            /* Armenian punctuation */
        {
        0x0589, 0x0589, 1},            /* Armenian full stop */
        {
        0x0700, 0x070d, 1},            /* Syriac punctuation */
        {
        0x104a, 0x104f, 1},            /* Myanmar punctuation */
        {
        0x10fb, 0x10fb, 1},            /* Georgian punctuation */
        {
        0x1361, 0x1368, 1},            /* Ethiopic punctuation */
        {
        0x166d, 0x166e, 1},            /* Canadian Syl. punctuation */
        {
        0x17d4, 0x17dc, 1},            /* Khmer punctuation */
        {
        0x1800, 0x180a, 1},            /* Mongolian punctuation */
        {
        0x2000, 0x200a, 0},            /* Various spaces */
        {
        0x2070, 0x207f, 2},            /* superscript */
        {
        0x2080, 0x208f, 2},            /* subscript */
        {
        0x200b, 0x27ff, 1},            /* punctuation and symbols */
        {
        0x3000, 0x3000, 0},            /* ideographic space */
        {
        0x3001, 0x3020, 1},            /* ideographic punctuation */
        {
        0x303f, 0x309f, 3},            /* Hiragana */
        {
        0x30a0, 0x30ff, 3},            /* Katakana */
        {
        0x3300, 0x9fff, 3},            /* CJK Ideographs */
        {
        0xac00, 0xd7a3, 3},            /* Hangul Syllables */
        {
        0xf900, 0xfaff, 3},            /* CJK Ideographs */
        {
        0xfe30, 0xfe6b, 1},            /* punctuation forms */
        {
        0xff00, 0xff0f, 1},            /* half/fullwidth ASCII */
        {
        0xff1a, 0xff20, 1},            /* half/fullwidth ASCII */
        {
        0xff3b, 0xff40, 1},            /* half/fullwidth ASCII */
        {
        0xff5b, 0xff64, 1},            /* half/fullwidth ASCII */
        {
        0xfff0, 0xffff, 0},            /* half/fullwidth ASCII */
        {
        0, 0, 0}
    };
    const struct ucsword *wptr;

    switch (uc & CSET_MASK) {
      case CSET_LINEDRW:
        uc = term->ucsdata->unitab_xterm[uc & 0xFF];
        break;
      case CSET_ASCII:
        uc = term->ucsdata->unitab_line[uc & 0xFF];
        break;
      case CSET_SCOACS:  
        uc = term->ucsdata->unitab_scoacs[uc&0xFF]; 
        break;
    }
    switch (uc & CSET_MASK) {
      case CSET_ACP:
        uc = term->ucsdata->unitab_font[uc & 0xFF];
        break;
      case CSET_OEMCP:
        uc = term->ucsdata->unitab_oemcp[uc & 0xFF];
        break;
    }

    /* For DBCS fonts I can't do anything useful. Even this will sometimes
     * fail as there's such a thing as a double width space. :-(
     */
    if (term->ucsdata->dbcs_screenfont &&
        term->ucsdata->font_codepage == term->ucsdata->line_codepage)
        return (uc != ' ');

    if (uc < 0x80)
        return term->wordness[uc];

    for (wptr = ucs_words; wptr->start; wptr++) {
        if (uc >= wptr->start && uc <= wptr->end)
            return wptr->ctype;
    }

    return 2;
}

/*
 * Spread the selection outwards according to the selection mode.
 */
static pos sel_spread_half(Terminal *term, pos p, int dir)
{
    termline *ldata;
    short wvalue;
    int topy = -sblines(term);

    ldata = lineptr(p.y);

    switch (term->selmode) {
      case SM_CHAR:
        /*
         * In this mode, every character is a separate unit, except
         * for runs of spaces at the end of a non-wrapping line.
         */
        if (!(ldata->lattr & LATTR_WRAPPED)) {
            termchar *q = ldata->chars + term->cols;
            while (q > ldata->chars &&
                   IS_SPACE_CHR(q[-1].chr) && !q[-1].cc_next)
                q--;
            if (q == ldata->chars + term->cols)
                q--;
            if (p.x >= q - ldata->chars)
                p.x = (dir == -1 ? q - ldata->chars : term->cols - 1);
        }
        break;
      case SM_WORD:
        /*
         * In this mode, the units are maximal runs of characters
         * whose `wordness' has the same value.
         */
        wvalue = wordtype(term, UCSGET(ldata->chars, p.x));
        if (dir == +1) {
            while (1) {
                int maxcols = (ldata->lattr & LATTR_WRAPPED2 ?
                               term->cols-1 : term->cols);
                if (p.x < maxcols-1) {
                    if (wordtype(term, UCSGET(ldata->chars, p.x+1)) == wvalue)
                        p.x++;
                    else
                        break;
                } else {
                    if (ldata->lattr & LATTR_WRAPPED) {
                        termline *ldata2;
                        ldata2 = lineptr(p.y+1);
                        if (wordtype(term, UCSGET(ldata2->chars, 0))
                            == wvalue) {
                            p.x = 0;
                            p.y++;
                            unlineptr(ldata);
                            ldata = ldata2;
                        } else {
                            unlineptr(ldata2);
                            break;
                        }
                    } else
                        break;
                }
            }
        } else {
            while (1) {
                if (p.x > 0) {
                    if (wordtype(term, UCSGET(ldata->chars, p.x-1)) == wvalue)
                        p.x--;
                    else
                        break;
                } else {
                    termline *ldata2;
                    int maxcols;
                    if (p.y <= topy)
                        break;
                    ldata2 = lineptr(p.y-1);
                    maxcols = (ldata2->lattr & LATTR_WRAPPED2 ?
                              term->cols-1 : term->cols);
                    if (ldata2->lattr & LATTR_WRAPPED) {
                        if (wordtype(term, UCSGET(ldata2->chars, maxcols-1))
                            == wvalue) {
                            p.x = maxcols-1;
                            p.y--;
                            unlineptr(ldata);
                            ldata = ldata2;
                        } else {
                            unlineptr(ldata2);
                            break;
                        }
                    } else
                        break;
                }
            }
        }
        break;
      case SM_LINE:
        /*
         * In this mode, every line is a unit.
         */
        p.x = (dir == -1 ? 0 : term->cols - 1);
        break;
    }

    unlineptr(ldata);
    return p;
}

static void sel_spread(Terminal *term)
{
    if (term->seltype == LEXICOGRAPHIC) {
        term->selstart = sel_spread_half(term, term->selstart, -1);
        decpos(term->selend);
        term->selend = sel_spread_half(term, term->selend, +1);
        incpos(term->selend);
    }
}

void term_do_paste(Terminal *term)
{
    wchar_t *data;
    int len;

    get_clip(term->frontend, &data, &len);
    if (data && len > 0) {
        wchar_t *p, *q;

        term_seen_key_event(term);     /* pasted data counts */

        if (term->paste_buffer)
            sfree(term->paste_buffer);
        term->paste_pos = term->paste_hold = term->paste_len = 0;
        term->paste_buffer = snewn(len, wchar_t);

        p = q = data;
        while (p < data + len) {
            while (p < data + len &&
                   !(p <= data + len - sel_nl_sz &&
                     !memcmp(p, sel_nl, sizeof(sel_nl))))
                p++;

            {
                int i;
                for (i = 0; i < p - q; i++) {
                    term->paste_buffer[term->paste_len++] = q[i];
                }
            }

            if (p <= data + len - sel_nl_sz &&
                !memcmp(p, sel_nl, sizeof(sel_nl))) {
                term->paste_buffer[term->paste_len++] = '\015';
                p += sel_nl_sz;
            }
            q = p;
        }

        /* Assume a small paste will be OK in one go. */
        if (term->paste_len < 256) {
            if (term->ldisc)
                luni_send(term->ldisc, term->paste_buffer, term->paste_len, 0);
            if (term->paste_buffer)
                sfree(term->paste_buffer);
            term->paste_buffer = 0;
            term->paste_pos = term->paste_hold = term->paste_len = 0;
        }
    }
    get_clip(term->frontend, NULL, NULL);
}

void term_mouse(Terminal *term, Mouse_Button braw, Mouse_Button bcooked,
                Mouse_Action a, int x, int y, int shift, int ctrl, int alt)
{
    pos selpoint;
    termline *ldata;
    int raw_mouse = (term->xterm_mouse &&
                     !term->cfg.no_mouse_rep &&
                     !(term->cfg.mouse_override && shift));
    int default_seltype;

    if (y < 0) {
        y = 0;
        if (a == MA_DRAG && !raw_mouse)
            term_scroll(term, 0, -1);
    }
    if (y >= term->rows) {
        y = term->rows - 1;
        if (a == MA_DRAG && !raw_mouse)
            term_scroll(term, 0, +1);
    }
    if (x < 0) {
        if (y > 0) {
            x = term->cols - 1;
            y--;
        } else
            x = 0;
    }
    if (x >= term->cols)
        x = term->cols - 1;

    selpoint.y = y + term->disptop;
    ldata = lineptr(selpoint.y);

    if ((ldata->lattr & LATTR_MODE) != LATTR_NORM)
        x /= 2;

    /*
     * Transform x through the bidi algorithm to find the _logical_
     * click point from the physical one.
     */
    if (term_bidi_line(term, ldata, y) != NULL) {
        x = term->post_bidi_cache[y].backward[x];
    }

    selpoint.x = x;
    unlineptr(ldata);

    if (raw_mouse) {
        int encstate = 0, r, c;
        char abuf[16];

        if (term->ldisc) {

            switch (braw) {
              case MBT_LEFT:
                encstate = 0x20;               /* left button down */
                break;
              case MBT_MIDDLE:
                encstate = 0x21;
                break;
              case MBT_RIGHT:
                encstate = 0x22;
                break;
              case MBT_WHEEL_UP:
                encstate = 0x60;
                break;
              case MBT_WHEEL_DOWN:
                encstate = 0x61;
                break;
              default: break;          /* placate gcc warning about enum use */
            }
            switch (a) {
              case MA_DRAG:
                if (term->xterm_mouse == 1)
                    return;
                encstate += 0x20;
                break;
              case MA_RELEASE:
                encstate = 0x23;
                term->mouse_is_down = 0;
                break;
              case MA_CLICK:
                if (term->mouse_is_down == braw)
                    return;
                term->mouse_is_down = braw;
                break;
              default: break;          /* placate gcc warning about enum use */
            }
            if (shift)
                encstate += 0x04;
            if (ctrl)
                encstate += 0x10;
            r = y + 33;
            c = x + 33;

            sprintf(abuf, "\033[M%c%c%c", encstate, c, r);
            ldisc_send(term->ldisc, abuf, 6, 0);
        }
        return;
    }

    /*
     * Set the selection type (rectangular or normal) at the start
     * of a selection attempt, from the state of Alt.
     */
    if (!alt ^ !term->cfg.rect_select)
        default_seltype = RECTANGULAR;
    else
        default_seltype = LEXICOGRAPHIC;
        
    if (term->selstate == NO_SELECTION) {
        term->seltype = default_seltype;
    }

    if (bcooked == MBT_SELECT && a == MA_CLICK) {
        deselect(term);
        term->selstate = ABOUT_TO;
        term->seltype = default_seltype;
        term->selanchor = selpoint;
        term->selmode = SM_CHAR;
    } else if (bcooked == MBT_SELECT && (a == MA_2CLK || a == MA_3CLK)) {
        deselect(term);
        term->selmode = (a == MA_2CLK ? SM_WORD : SM_LINE);
        term->selstate = DRAGGING;
        term->selstart = term->selanchor = selpoint;
        term->selend = term->selstart;
        incpos(term->selend);
        sel_spread(term);
    } else if ((bcooked == MBT_SELECT && a == MA_DRAG) ||
               (bcooked == MBT_EXTEND && a != MA_RELEASE)) {
        if (term->selstate == ABOUT_TO && poseq(term->selanchor, selpoint))
            return;
        if (bcooked == MBT_EXTEND && a != MA_DRAG &&
            term->selstate == SELECTED) {
            if (term->seltype == LEXICOGRAPHIC) {
                /*
                 * For normal selection, we extend by moving
                 * whichever end of the current selection is closer
                 * to the mouse.
                 */
                if (posdiff(selpoint, term->selstart) <
                    posdiff(term->selend, term->selstart) / 2) {
                    term->selanchor = term->selend;
                    decpos(term->selanchor);
                } else {
                    term->selanchor = term->selstart;
                }
            } else {
                /*
                 * For rectangular selection, we have a choice of
                 * _four_ places to put selanchor and selpoint: the
                 * four corners of the selection.
                 */
                if (2*selpoint.x < term->selstart.x + term->selend.x)
                    term->selanchor.x = term->selend.x-1;
                else
                    term->selanchor.x = term->selstart.x;

                if (2*selpoint.y < term->selstart.y + term->selend.y)
                    term->selanchor.y = term->selend.y;
                else
                    term->selanchor.y = term->selstart.y;
            }
            term->selstate = DRAGGING;
        }
        if (term->selstate != ABOUT_TO && term->selstate != DRAGGING)
            term->selanchor = selpoint;
        term->selstate = DRAGGING;
        if (term->seltype == LEXICOGRAPHIC) {
            /*
             * For normal selection, we set (selstart,selend) to
             * (selpoint,selanchor) in some order.
             */
            if (poslt(selpoint, term->selanchor)) {
                term->selstart = selpoint;
                term->selend = term->selanchor;
                incpos(term->selend);
            } else {
                term->selstart = term->selanchor;
                term->selend = selpoint;
                incpos(term->selend);
            }
        } else {
            /*
             * For rectangular selection, we may need to
             * interchange x and y coordinates (if the user has
             * dragged in the -x and +y directions, or vice versa).
             */
            term->selstart.x = min(term->selanchor.x, selpoint.x);
            term->selend.x = 1+max(term->selanchor.x, selpoint.x);
            term->selstart.y = min(term->selanchor.y, selpoint.y);
            term->selend.y =   max(term->selanchor.y, selpoint.y);
        }
        sel_spread(term);
    } else if ((bcooked == MBT_SELECT || bcooked == MBT_EXTEND) &&
               a == MA_RELEASE) {
        if (term->selstate == DRAGGING) {
            /*
             * We've completed a selection. We now transfer the
             * data to the clipboard.
             */
            clipme(term, term->selstart, term->selend,
                   (term->seltype == RECTANGULAR), FALSE);
            term->selstate = SELECTED;
        } else
            term->selstate = NO_SELECTION;
    } else if (bcooked == MBT_PASTE
               && (a == MA_CLICK
#if MULTICLICK_ONLY_EVENT
                   || a == MA_2CLK || a == MA_3CLK
#endif
                   )) {
        request_paste(term->frontend);
    }

    term_update(term);
}

void term_key(Terminal *term, Key_Sym keysym, wchar_t *text, size_t tlen,
              unsigned int modifiers, unsigned int flags)
{
    char output[10];
    char *p = output;
    int prependesc = FALSE;
#if 0
    int i;

    fprintf(stderr, "keysym = %d, %d chars:", keysym, tlen);
    for (i = 0; i < tlen; i++)
        fprintf(stderr, " %04x", (unsigned)text[i]);
    fprintf(stderr, "\n");
#endif

    /* XXX Num Lock */
    if ((flags & PKF_REPEAT) && term->repeat_off)
        return;

    /* Currently, Meta always just prefixes everything with ESC. */
    if (modifiers & PKM_META)
        prependesc = TRUE;
    modifiers &= ~PKM_META;

    /*
     * Alt is only used for Alt+keypad, which isn't supported yet, so
     * ignore it.
     */
    modifiers &= ~PKM_ALT;

    /* Standard local function keys */
    switch (modifiers & (PKM_SHIFT | PKM_CONTROL)) {
      case PKM_SHIFT:
        if (keysym == PK_PAGEUP)
            /* scroll up one page */;
        if (keysym == PK_PAGEDOWN)
            /* scroll down on page */;
        if (keysym == PK_INSERT)
            term_do_paste(term);
        break;
      case PKM_CONTROL:
        if (keysym == PK_PAGEUP)
            /* scroll up one line */;
        if (keysym == PK_PAGEDOWN)
            /* scroll down one line */;
        /* Control-Numlock for app-keypad mode switch */
        if (keysym == PK_PF1)
            term->app_keypad_keys ^= 1;
        break;
    }

    if (modifiers & PKM_ALT) {
        /* Alt+F4 (close) */
        /* Alt+Return (full screen) */
        /* Alt+Space (system menu) */
    }

    if (keysym == PK_NULL && (modifiers & PKM_CONTROL) && tlen == 1 &&
        text[0] >= 0x20 && text[0] <= 0x7e) {
        /* ASCII chars + Control */
        if ((text[0] >= 0x40 && text[0] <= 0x5f) ||
            (text[0] >= 0x61 && text[0] <= 0x7a))
            text[0] &= 0x1f;
        else {
            /*
             * Control-2 should return ^@ (0x00), Control-6 should return
             * ^^ (0x1E), and Control-Minus should return ^_ (0x1F). Since
             * the DOS keyboard handling did it, and we have nothing better
             * to do with the key combo in question, we'll also map
             * Control-Backquote to ^\ (0x1C).
             */
            switch (text[0]) {
              case ' ': text[0] = 0x00; break;
              case '-': text[0] = 0x1f; break;
              case '/': text[0] = 0x1f; break;
              case '2': text[0] = 0x00; break;
              case '3': text[0] = 0x1b; break;
              case '4': text[0] = 0x1c; break;
              case '5': text[0] = 0x1d; break;
              case '6': text[0] = 0x1e; break;
              case '7': text[0] = 0x1f; break;
              case '8': text[0] = 0x7f; break;
              case '`': text[0] = 0x1c; break;
            }
        }
    }

    /* Nethack keypad */
    if (term->cfg.nethack_keypad) {
        char c = 0;
        switch (keysym) {
          case PK_KP1: c = 'b'; break;
          case PK_KP2: c = 'j'; break;
          case PK_KP3: c = 'n'; break;
          case PK_KP4: c = 'h'; break;
          case PK_KP5: c = '.'; break;
          case PK_KP6: c = 'l'; break;
          case PK_KP7: c = 'y'; break;
          case PK_KP8: c = 'k'; break;
          case PK_KP9: c = 'u'; break;
          default: break; /* else gcc warns `enum value not used' */
        }
        if (c != 0) {
            if (c != '.') {
                if (modifiers & PKM_CONTROL)
                    c &= 0x1f;
                else if (modifiers & PKM_SHIFT)
                    c = toupper(c);
            }
            *p++ = c;
            goto done;
        }
    }

    /* Numeric Keypad */
    if (PK_ISKEYPAD(keysym)) {
        int xkey = 0;

        /*
         * In VT400 mode, PFn always emits an escape sequence.  In
         * Linux and tilde modes, this only happens in app keypad mode.
         */
        if (term->cfg.funky_type == FUNKY_VT400 ||
            ((term->cfg.funky_type == FUNKY_LINUX ||
              term->cfg.funky_type == FUNKY_TILDE) &&
             term->app_keypad_keys && !term->cfg.no_applic_k)) {
            switch (keysym) {
              case PK_PF1: xkey = 'P'; break;
              case PK_PF2: xkey = 'Q'; break;
              case PK_PF3: xkey = 'R'; break;
              case PK_PF4: xkey = 'S'; break;
              default: break; /* else gcc warns `enum value not used' */
            }
        }
        if (term->app_keypad_keys && !term->cfg.no_applic_k) {
            switch (keysym) {
              case PK_KP0: xkey = 'p'; break;
              case PK_KP1: xkey = 'q'; break;
              case PK_KP2: xkey = 'r'; break;
              case PK_KP3: xkey = 's'; break;
              case PK_KP4: xkey = 't'; break;
              case PK_KP5: xkey = 'u'; break;
              case PK_KP6: xkey = 'v'; break;
              case PK_KP7: xkey = 'w'; break;
              case PK_KP8: xkey = 'x'; break;
              case PK_KP9: xkey = 'y'; break;
              case PK_KPDECIMAL: xkey = 'n'; break;
              case PK_KPENTER: xkey = 'M'; break;
              default: break; /* else gcc warns `enum value not used' */
            }
            if (term->cfg.funky_type == FUNKY_XTERM && tlen > 0) {
                /*
                 * xterm can't see the layout of the keypad, so it has
                 * to rely on the X keysyms returned by the keys.
                 * Hence, we look at the strings here, not the PuTTY
                 * keysyms (which describe the layout).
                 */
                switch (text[0]) {
                  case '+':
                    if (modifiers & PKM_SHIFT)
                        xkey = 'l';
                    else
                        xkey = 'k';
                    break;
                  case '/': xkey = 'o'; break;
                  case '*': xkey = 'j'; break;
                  case '-': xkey = 'm'; break;
                }
            } else {
                /*
                 * In all other modes, we try to retain the layout of
                 * the DEC keypad in application mode.
                 */
                switch (keysym) {
                  case PK_KPBIGPLUS:
                    /* This key covers the '-' and ',' keys on a VT220 */
                    if (modifiers & PKM_SHIFT)
                        xkey = 'm'; /* VT220 '-' */
                    else
                        xkey = 'l'; /* VT220 ',' */
                    break;
                  case PK_KPMINUS: xkey = 'm'; break;
                  case PK_KPCOMMA: xkey = 'l'; break;
                  default: break; /* else gcc warns `enum value not used' */
                }
            }
        }
        if (xkey) {
            if (term->vt52_mode) {
                if (xkey >= 'P' && xkey <= 'S')
                    p += sprintf((char *) p, "\x1B%c", xkey);
                else
                    p += sprintf((char *) p, "\x1B?%c", xkey);
            } else
                p += sprintf((char *) p, "\x1BO%c", xkey);
            goto done;
        }
        /* Not in application mode -- treat the number pad as arrow keys? */
        if ((flags & PKF_NUMLOCK) == 0) {
            switch (keysym) {
              case PK_KP0: keysym = PK_INSERT; break;
              case PK_KP1: keysym = PK_END; break;
              case PK_KP2: keysym = PK_DOWN; break;
              case PK_KP3: keysym = PK_PAGEDOWN; break;
              case PK_KP4: keysym = PK_LEFT; break;
              case PK_KP5: keysym = PK_REST; break;
              case PK_KP6: keysym = PK_RIGHT; break;
              case PK_KP7: keysym = PK_HOME; break;
              case PK_KP8: keysym = PK_UP; break;
              case PK_KP9: keysym = PK_PAGEUP; break;
              default: break; /* else gcc warns `enum value not used' */
            }
        }
    }

    /* Miscellaneous keys */
    switch (keysym) {
      case PK_ESCAPE:
        *p++ = 0x1b;
        goto done;
      case PK_BACKSPACE:
            if (modifiers == 0)
                *p++ = (term->cfg.bksp_is_delete ? 0x7F : 0x08);
            else if (modifiers == PKM_SHIFT)
                /* We do the opposite of what is configured */
                *p++ = (term->cfg.bksp_is_delete ? 0x08 : 0x7F);
            else break;
            goto done;
      case PK_TAB:
        if (modifiers == 0)
            *p++ = 0x09;
        else if (modifiers == PKM_SHIFT)
            *p++ = 0x1B, *p++ = '[', *p++ = 'Z';
        else break;
        goto done;
        /* XXX window.c has ctrl+shift+space sending 0xa0 */
      case PK_PAUSE:
        if (modifiers == PKM_CONTROL)
            *p++ = 26;
        else break;
        goto done;
      case PK_RETURN:
      case PK_KPENTER: /* Odd keypad modes handled above */
        if (modifiers == 0) {
            *p++ = 0x0d;
            if (term->cr_lf_return)
                *p++ = 0x0a;
            goto done;
        }
      default: break; /* else gcc warns `enum value not used' */
    }

    /* SCO function keys and editing keys */
    if (term->cfg.funky_type == FUNKY_SCO) {
        if (PK_ISFKEY(keysym) && keysym <= PK_F12) {
            static char const codes[] =
                "MNOPQRSTUVWX" "YZabcdefghij" "klmnopqrstuv" "wxyz@[\\]^_`{";
            int index = keysym - PK_F1;

            if (modifiers & PKM_SHIFT) index += 12;
            if (modifiers & PKM_CONTROL) index += 24;
            p += sprintf((char *) p, "\x1B[%c", codes[index]);
            goto done;
        }
        if (PK_ISEDITING(keysym)) {
            int xkey = 0;

            switch (keysym) {
              case PK_DELETE:   *p++ = 0x7f; goto done;
              case PK_HOME:     xkey = 'H'; break;
              case PK_INSERT:   xkey = 'L'; break;
              case PK_END:      xkey = 'F'; break;
              case PK_PAGEUP:   xkey = 'I'; break;
              case PK_PAGEDOWN: xkey = 'G'; break;
              default: break; /* else gcc warns `enum value not used' */
            }
            p += sprintf((char *) p, "\x1B[%c", xkey);
        }
    }

    if (PK_ISEDITING(keysym) && (modifiers & PKM_SHIFT) == 0) {
        int code;

        if (term->cfg.funky_type == FUNKY_XTERM) {
            /* Xterm shuffles these keys, apparently. */
            switch (keysym) {
              case PK_HOME:     keysym = PK_INSERT;   break;
              case PK_INSERT:   keysym = PK_HOME;     break;
              case PK_DELETE:   keysym = PK_END;      break;
              case PK_END:      keysym = PK_PAGEUP;   break;
              case PK_PAGEUP:   keysym = PK_DELETE;   break;
              case PK_PAGEDOWN: keysym = PK_PAGEDOWN; break;
              default: break; /* else gcc warns `enum value not used' */
            }
        }

        /* RXVT Home/End */
        if (term->cfg.rxvt_homeend &&
            (keysym == PK_HOME || keysym == PK_END)) {
            p += sprintf((char *) p, keysym == PK_HOME ? "\x1B[H" : "\x1BOw");
            goto done;
        }

        if (term->vt52_mode) {
            int xkey;

            /*
             * A real VT52 doesn't have these, and a VT220 doesn't
             * send anything for them in VT52 mode.
             */
            switch (keysym) {
              case PK_HOME:     xkey = 'H'; break;
              case PK_INSERT:   xkey = 'L'; break;
              case PK_DELETE:   xkey = 'M'; break;
              case PK_END:      xkey = 'E'; break;
              case PK_PAGEUP:   xkey = 'I'; break;
              case PK_PAGEDOWN: xkey = 'G'; break;
              default: xkey=0; break; /* else gcc warns `enum value not used'*/
            }
            p += sprintf((char *) p, "\x1B%c", xkey);
            goto done;
        }

        switch (keysym) {
          case PK_HOME:     code = 1; break;
          case PK_INSERT:   code = 2; break;
          case PK_DELETE:   code = 3; break;
          case PK_END:      code = 4; break;
          case PK_PAGEUP:   code = 5; break;
          case PK_PAGEDOWN: code = 6; break;
          default: code = 0; break; /* else gcc warns `enum value not used' */
        }
        p += sprintf((char *) p, "\x1B[%d~", code);
        goto done;
    }

    if (PK_ISFKEY(keysym)) {
        /* Map Shift+F1-F10 to F11-F20 */
        if (keysym >= PK_F1 && keysym <= PK_F10 && (modifiers & PKM_SHIFT))
            keysym += 10;
        if ((term->vt52_mode || term->cfg.funky_type == FUNKY_VT100P) &&
            keysym <= PK_F14) {
            /* XXX This overrides the XTERM/VT52 mode below */
            int offt = 0;
            if (keysym >= PK_F6)  offt++;
            if (keysym >= PK_F12) offt++;
            p += sprintf((char *) p, term->vt52_mode ? "\x1B%c" : "\x1BO%c",
                         'P' + keysym - PK_F1 - offt);
            goto done;
        }
        if (term->cfg.funky_type == FUNKY_LINUX && keysym <= PK_F5) {
            p += sprintf((char *) p, "\x1B[[%c", 'A' + keysym - PK_F1);
            goto done;
        }
        if (term->cfg.funky_type == FUNKY_XTERM && keysym <= PK_F4) {
            if (term->vt52_mode)
                p += sprintf((char *) p, "\x1B%c", 'P' + keysym - PK_F1);
            else
                p += sprintf((char *) p, "\x1BO%c", 'P' + keysym - PK_F1);
            goto done;
        }
        p += sprintf((char *) p, "\x1B[%d~", 11 + keysym - PK_F1);
        goto done;
    }

    if (PK_ISCURSOR(keysym)) {
        int xkey;

        switch (keysym) {
          case PK_UP:    xkey = 'A'; break;
          case PK_DOWN:  xkey = 'B'; break;
          case PK_RIGHT: xkey = 'C'; break;
          case PK_LEFT:  xkey = 'D'; break;
          case PK_REST:  xkey = 'G'; break; /* centre key on number pad */
          default: xkey = 0; break; /* else gcc warns `enum value not used' */
        }
        if (term->vt52_mode)
            p += sprintf((char *) p, "\x1B%c", xkey);
        else {
            int app_flg = (term->app_cursor_keys && !term->cfg.no_applic_c);

            /* Useful mapping of Ctrl-arrows */
            if (modifiers == PKM_CONTROL)
                app_flg = !app_flg;

            if (app_flg)
                p += sprintf((char *) p, "\x1BO%c", xkey);
            else
                p += sprintf((char *) p, "\x1B[%c", xkey);
        }
        goto done;
    }

  done:
    if (p > output || tlen > 0) {
        /*
         * Interrupt an ongoing paste. I'm not sure
         * this is sensible, but for the moment it's
         * preferable to having to faff about buffering
         * things.
         */
        term_nopaste(term);

        /*
         * We need not bother about stdin backlogs
         * here, because in GUI PuTTY we can't do
         * anything about it anyway; there's no means
         * of asking Windows to hold off on KEYDOWN
         * messages. We _have_ to buffer everything
         * we're sent.
         */
        term_seen_key_event(term);

        if (prependesc) {
#if 0
            fprintf(stderr, "sending ESC\n");
#endif
            ldisc_send(term->ldisc, "\x1b", 1, 1);
        }

        if (p > output) {
#if 0
            fprintf(stderr, "sending %d bytes:", p - output);
            for (i = 0; i < p - output; i++)
                fprintf(stderr, " %02x", output[i]);
            fprintf(stderr, "\n");
#endif
            ldisc_send(term->ldisc, output, p - output, 1);
        } else if (tlen > 0) {
#if 0
            fprintf(stderr, "sending %d unichars:", tlen);
            for (i = 0; i < tlen; i++)
                fprintf(stderr, " %04x", (unsigned) text[i]);
            fprintf(stderr, "\n");
#endif
            luni_send(term->ldisc, text, tlen, 1);
        }
    }
}

void term_nopaste(Terminal *term)
{
    if (term->paste_len == 0)
        return;
    sfree(term->paste_buffer);
    term->paste_buffer = NULL;
    term->paste_len = 0;
}

int term_paste_pending(Terminal *term)
{
    return term->paste_len != 0;
}

void term_paste(Terminal *term)
{
    long now, paste_diff;

    if (term->paste_len == 0)
        return;

    /* Don't wait forever to paste */
    if (term->paste_hold) {
        now = GETTICKCOUNT();
        paste_diff = now - term->last_paste;
        if (paste_diff >= 0 && paste_diff < 450)
            return;
    }
    term->paste_hold = 0;

    while (term->paste_pos < term->paste_len) {
        int n = 0;
        while (n + term->paste_pos < term->paste_len) {
            if (term->paste_buffer[term->paste_pos + n++] == '\015')
                break;
        }
        if (term->ldisc)
            luni_send(term->ldisc, term->paste_buffer + term->paste_pos, n, 0);
        term->paste_pos += n;

        if (term->paste_pos < term->paste_len) {
            term->paste_hold = 1;
            return;
        }
    }
    sfree(term->paste_buffer);
    term->paste_buffer = NULL;
    term->paste_len = 0;
}

static void deselect(Terminal *term)
{
    term->selstate = NO_SELECTION;
    term->selstart.x = term->selstart.y = term->selend.x = term->selend.y = 0;
}

void term_deselect(Terminal *term)
{
    deselect(term);
    term_update(term);
}

int term_ldisc(Terminal *term, int option)
{
    if (option == LD_ECHO)
        return term->term_echoing;
    if (option == LD_EDIT)
        return term->term_editing;
    return FALSE;
}

int term_data(Terminal *term, int is_stderr, const char *data, int len)
{
    bufchain_add(&term->inbuf, data, len);

    if (!term->in_term_out) {
        term->in_term_out = TRUE;
        term_reset_cblink(term);
        /*
         * During drag-selects, we do not process terminal input,
         * because the user will want the screen to hold still to
         * be selected.
         */
        if (term->selstate != DRAGGING)
            term_out(term);
        term->in_term_out = FALSE;
    }

    /*
     * term_out() always completely empties inbuf. Therefore,
     * there's no reason at all to return anything other than zero
     * from this function, because there _can't_ be a question of
     * the remote side needing to wait until term_out() has cleared
     * a backlog.
     *
     * This is a slightly suboptimal way to deal with SSH-2 - in
     * principle, the window mechanism would allow us to continue
     * to accept data on forwarded ports and X connections even
     * while the terminal processing was going slowly - but we
     * can't do the 100% right thing without moving the terminal
     * processing into a separate thread, and that might hurt
     * portability. So we manage stdout buffering the old SSH-1 way:
     * if the terminal processing goes slowly, the whole SSH
     * connection stops accepting data until it's ready.
     *
     * In practice, I can't imagine this causing serious trouble.
     */
    return 0;
}

void term_provide_logctx(Terminal *term, void *logctx)
{
    term->logctx = logctx;
}

void term_set_focus(Terminal *term, int has_focus)
{
    term->has_focus = has_focus;
    term_schedule_cblink(term);
}

/*
 * Provide "auto" settings for remote tty modes, suitable for an
 * application with a terminal window.
 */
char *term_get_ttymode(Terminal *term, const char *mode)
{
    char *val = NULL;
    if (strcmp(mode, "ERASE") == 0) {
        val = term->cfg.bksp_is_delete ? "^?" : "^H";
    }
    /* FIXME: perhaps we should set ONLCR based on cfg.lfhascr as well? */
    return dupstr(val);
}