Created a shiny new abstraction for the socket handling. Has many

[u/mdw/putty] / terminal.c

#include <windows.h>

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

#include "putty.h"

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

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

static int compatibility_level = TM_PUTTY;


static unsigned long *text;            /* buffer of text on terminal screen */
static unsigned long *scrtop;          /* top of working screen */
static unsigned long *disptop;         /* top of displayed screen */
static unsigned long *sbtop;           /* top of scrollback */
static unsigned long *sbbot;           /* furthest extent of scrollback */
static unsigned long *cpos;            /* cursor position (convenience) */
static unsigned long *disptext;        /* buffer of text on real screen */
static unsigned long *wanttext;        /* buffer of text we want on screen */
static unsigned long *alttext;         /* buffer of text on alt. screen */

static unsigned char *selspace;        /* buffer for building selections in */

#define TSIZE (sizeof(*text))
#define fix_cpos  do { cpos = scrtop + curs_y * (cols+1) + curs_x; } while(0)

static unsigned long curr_attr, save_attr;
static unsigned long erase_char = ERASE_CHAR;

static int curs_x, curs_y;             /* cursor */
static int save_x, save_y;             /* saved cursor position */
static int marg_t, marg_b;             /* scroll margins */
static int dec_om;                     /* DEC origin mode flag */
static int wrap, wrapnext;             /* wrap flags */
static int insert;                     /* insert-mode flag */
static int cset;                       /* 0 or 1: which char set */
static int save_cset, save_csattr;     /* saved with cursor position */
static int rvideo;                     /* global reverse video flag */
static int cursor_on;                  /* cursor enabled flag */
static int reset_132;                  /* Flag ESC c resets to 80 cols */
static int use_bce;                    /* Use Background coloured erase */
static int blinker;                    /* When blinking is the cursor on ? */
static int tblinker;                   /* When the blinking text is on */
static int blink_is_real;              /* Actually blink blinking text */

static unsigned long cset_attr[2];

/*
 * Saved settings on the alternate screen.
 */
static int alt_x, alt_y, alt_om, alt_wrap, alt_wnext, alt_ins, alt_cset;
static int alt_t, alt_b;
static int alt_which;

#define ARGS_MAX 32                    /* max # of esc sequence arguments */
#define ARG_DEFAULT 0                  /* if an arg isn't specified */
#define def(a,d) ( (a) == ARG_DEFAULT ? (d) : (a) )
static int esc_args[ARGS_MAX];
static int esc_nargs;
static int esc_query;
#define ANSI(x,y)       ((x)+((y)<<8))
#define ANSI_QUE(x)     ANSI(x,TRUE)

#define OSC_STR_MAX 2048
static int osc_strlen;
static char osc_string[OSC_STR_MAX+1];
static int osc_w;

static char id_string[1024] = "\033[?6c";

static unsigned char *tabs;

static enum {
    TOPLEVEL,
    SEEN_ESC,
    SEEN_CSI,
    SEEN_OSC,
    SEEN_OSC_W,

    DO_CTRLS,

    IGNORE_NEXT,
    SET_GL, SET_GR,
    SEEN_OSC_P,
    OSC_STRING, OSC_MAYBE_ST,
    SEEN_ESCHASH,
    VT52_ESC,
    VT52_Y1,
    VT52_Y2
} termstate;

static enum {
    NO_SELECTION, ABOUT_TO, DRAGGING, SELECTED
} selstate;
static enum {
    SM_CHAR, SM_WORD, SM_LINE
} selmode;
static unsigned long *selstart, *selend, *selanchor;

static short wordness[256] = {
    0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, /* 01 */
    0,1,2,1,1,1,1,1,1,1,1,1,1,2,2,2, 2,2,2,2,2,2,2,2,2,2,1,1,1,1,1,1, /* 23 */
    1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2, 2,2,2,2,2,2,2,2,2,2,2,1,1,1,1,2, /* 45 */
    1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2, 2,2,2,2,2,2,2,2,2,2,2,1,1,1,1,1, /* 67 */
    1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, /* 89 */
    1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, /* AB */
    2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2, 2,2,2,2,2,2,2,1,2,2,2,2,2,2,2,2, /* CD */
    2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2, 2,2,2,2,2,2,2,1,2,2,2,2,2,2,2,2, /* EF */
};

static unsigned char sel_nl[] = SEL_NL;
static char * paste_buffer = 0;
static int paste_len, paste_pos, paste_hold;

/*
 * Internal prototypes.
 */
static void do_paint (Context, int);
static void erase_lots (int, int, int);
static void swap_screen (int);
static void update_sbar (void);
static void deselect (void);

/*
 * Set up power-on settings for the terminal.
 */
static void power_on(void) {
    curs_x = curs_y = alt_x = alt_y = save_x = save_y = 0;
    alt_t = marg_t = 0;
    if (rows != -1)
        alt_b = marg_b = rows - 1;
    else
        alt_b = marg_b = 0;
    if (cols != -1) {
        int i;
        for (i = 0; i < cols; i++)
            tabs[i] = (i % 8 == 0 ? TRUE : FALSE);
    }
    alt_om = dec_om = cfg.dec_om;
    alt_wnext = wrapnext = alt_ins = insert = FALSE;
    alt_wrap = wrap = cfg.wrap_mode;
    alt_cset = cset = 0;
    cset_attr[0] = cset_attr[1] = ATTR_ASCII;
    rvideo = 0;
    cursor_on = 1;
    save_attr = curr_attr = ATTR_DEFAULT;
    app_cursor_keys = cfg.app_cursor;
    app_keypad_keys = cfg.app_keypad;
    use_bce = cfg.bce;
    blink_is_real = cfg.blinktext;
    erase_char = ERASE_CHAR;
    alt_which = 0;
    {
        int i;
        for (i = 0; i < 256; i++)
            wordness[i] = cfg.wordness[i];
    }
    if (text) {
        swap_screen (1);
        erase_lots (FALSE, TRUE, TRUE);
        swap_screen (0);
        erase_lots (FALSE, TRUE, TRUE);
    }
}

/*
 * Force a screen update.
 */
void term_update(void) {
    Context ctx;
    ctx = get_ctx();
    if (ctx) {
        if ( (seen_key_event && (cfg.scroll_on_key)) ||
             (seen_disp_event && (cfg.scroll_on_disp)) ) {
            disptop = scrtop;
            seen_disp_event = seen_key_event = 0;
            update_sbar();
        }
        do_paint (ctx, TRUE);
        sys_cursor(curs_x, curs_y + (scrtop - disptop) / (cols+1));
        free_ctx (ctx);
    }
}

/*
 * Same as power_on(), but an external function.
 */
void term_pwron(void) {
    power_on();
    fix_cpos;
    disptop = scrtop;
    deselect();
    term_update();
}

/*
 * Clear the scrollback.
 */
void term_clrsb(void) {
    disptop = sbtop = scrtop;
    update_sbar();
}

/*
 * Initialise the terminal.
 */
void term_init(void) {
    text = sbtop = sbbot = scrtop = disptop = cpos = NULL;
    disptext = wanttext = NULL;
    tabs = NULL;
    selspace = NULL;
    deselect();
    rows = cols = -1;
    power_on();
}

/*
 * Set up the terminal for a given size.
 */
void term_size(int newrows, int newcols, int newsavelines) {
    unsigned long *newtext, *newdisp, *newwant, *newalt;
    int i, j, crows, ccols;

    int save_alt_which = alt_which;

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

    deselect();
    swap_screen(0);

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

    newtext = smalloc ((newrows+newsavelines)*(newcols+1)*TSIZE);
    sbbot = newtext + newsavelines*(newcols+1);
    for (i=0; i<(newrows+newsavelines)*(newcols+1); i++)
        newtext[i] = erase_char;
    if (rows != -1) {
        crows = rows + (scrtop - sbtop) / (cols+1);
        if (crows > newrows+newsavelines)
            crows = newrows+newsavelines;
        if (newrows>crows)
            disptop = newtext;
        else
            disptop = newtext + (crows-newrows)*(newcols+1);
        ccols = (cols < newcols ? cols : newcols);
        for (i=0; i<crows; i++) {
            int oldidx = (rows - crows + i) * (cols+1);
            int newidx = (newrows - crows + i) * (newcols+1);

            for (j=0; j<ccols; j++)
                disptop[newidx+j] = scrtop[oldidx+j];
            disptop[newidx+newcols] =
                (cols == newcols ? scrtop[oldidx+cols] 
                                 : (scrtop[oldidx+cols]&LATTR_MODE));
        }
        sbtop = newtext;
    } else {
        sbtop = disptop = newtext;
    }
    scrtop = disptop;
    sfree (text);
    text = newtext;

    newdisp = smalloc (newrows*(newcols+1)*TSIZE);
    for (i=0; i<newrows*(newcols+1); i++)
        newdisp[i] = ATTR_INVALID;
    sfree (disptext);
    disptext = newdisp;

    newwant = smalloc (newrows*(newcols+1)*TSIZE);
    for (i=0; i<newrows*(newcols+1); i++)
        newwant[i] = ATTR_INVALID;
    sfree (wanttext);
    wanttext = newwant;

    newalt = smalloc (newrows*(newcols+1)*TSIZE);
    for (i=0; i<newrows*(newcols+1); i++)
        newalt[i] = erase_char;
    sfree (alttext);
    alttext = newalt;

    sfree (selspace);
    selspace = smalloc ( (newrows+newsavelines) * (newcols+sizeof(sel_nl)) );

    tabs = srealloc (tabs, newcols*sizeof(*tabs));
    {
        int i;
        for (i = (cols > 0 ? cols : 0); i < newcols; i++)
            tabs[i] = (i % 8 == 0 ? TRUE : FALSE);
    }

    if (rows > 0)
        curs_y += newrows - rows;
    if (curs_y < 0)
        curs_y = 0;
    if (curs_y >= newrows)
        curs_y = newrows-1;
    if (curs_x >= newcols)
        curs_x = newcols-1;
    alt_x = alt_y = 0;
    wrapnext = alt_wnext = FALSE;

    rows = newrows;
    cols = newcols;
    savelines = newsavelines;
    fix_cpos;

    swap_screen(save_alt_which);

    update_sbar();
    term_update();
}

/*
 * Swap screens.
 */
static void swap_screen (int which) {
    int t;
    unsigned long tt;

    if (which == alt_which)
        return;

    alt_which = which;

    for (t=0; t<rows*(cols+1); t++) {
        tt = scrtop[t]; scrtop[t] = alttext[t]; alttext[t] = tt;
    }

    t = curs_x; curs_x = alt_x; alt_x = t;
    t = curs_y; curs_y = alt_y; alt_y = t;
    t = marg_t; marg_t = alt_t; alt_t = t;
    t = marg_b; marg_b = alt_b; alt_b = t;
    t = dec_om; dec_om = alt_om; alt_om = t;
    t = wrap; wrap = alt_wrap; alt_wrap = t;
    t = wrapnext; wrapnext = alt_wnext; alt_wnext = t;
    t = insert; insert = alt_ins; alt_ins = t;
    t = cset; cset = alt_cset; alt_cset = t;

    fix_cpos;
}

/*
 * Update the scroll bar.
 */
static void update_sbar(void) {
    int min;

    min = (sbtop - text) / (cols+1);
    set_sbar ((scrtop - text) / (cols+1) + rows - min,
              (disptop - text) / (cols+1) - min,
              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 (unsigned long *from, unsigned long *to) {
    if (from < selend && selstart < to)
        deselect();
}

/*
 * 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 (int topline, int botline, int lines, int sb) {
    unsigned long *scroll_top;
    unsigned long *newscr;
    int scroll_size, size, i;
    int scrtop_is_disptop = (scrtop==disptop);
static int recursive = 0;

    /* Only scroll more than the window if we're doing a 10% scroll */
    if (!recursive && lines > botline - topline + 1)
        lines = botline - topline + 1;

    scroll_top = scrtop + topline*(cols+1);
    size = (lines < 0 ? -lines : lines) * (cols+1);
    scroll_size = (botline - topline + 1) * (cols+1) - size;

    if (lines > 0 && topline == 0 && alt_which == 0 && sb) {
        /*
         * Since we're going to scroll the top line and we're on the 
         * scrolling screen let's also effect the scrollback buffer.
         *
         * This is normally done by moving the position the screen
         * painter reads from to reduce the amount of memory copying
         * required.
         */
        if (scroll_size >= 0 && !recursive) {
            newscr = scrtop + lines * (cols+1);

            if (newscr > sbbot && botline == rows-1) {
                /* We've hit the bottom of memory, so we have to do a 
                 * physical scroll. But instead of just 1 line do it
                 * by 10% of the available memory.
                 *
                 * If the scroll region isn't the whole screen then we can't
                 * do this as it stands. We would need to recover the bottom
                 * of the screen from the scroll buffer after being sure that
                 * it doesn't get deleted.
                 */

                i = (rows+savelines)/10;

                /* Make it simple and ensure safe recursion */
                if ( i<savelines-1) {
                    recursive ++;
                    scroll(topline, botline, i, sb);
                    recursive --;

                    newscr = scrtop - i * (cols+1);
                    if (scrtop_is_disptop) disptop = newscr;
                    scrtop = newscr;
                }

                newscr = scrtop + lines * (cols+1);
            }

            if (newscr <= sbbot) {
                if (scrtop_is_disptop) disptop = newscr;
                scrtop = newscr;

                if (botline == rows-1 )
                    for (i = 0; i < size; i++)
                        scrtop[i+scroll_size] = erase_char;

                update_sbar();
                fix_cpos;

                if (botline != rows-1) {
                    /* This fastscroll only works for full window scrolls. 
                     * If the caller wanted a partial one we have to reverse
                     * scroll the bottom of the screen.
                     */
                    scroll(botline-lines+1, rows-1, -lines, 0);
                }
                return ;
            }

            /* If we can't scroll by memory remapping do it physically.
             * But rather than expensivly doing the scroll buffer just
             * scroll the screen. All it means is that sometimes we choose
             * to not add lines from a scroll region to the scroll buffer.
             */

            if (savelines <= 400) {
                sbtop -= lines * (cols+1);
                if (sbtop < text)
                    sbtop = text;
                scroll_size += scroll_top - sbtop;
                scroll_top = sbtop;
    
                update_sbar();
            }
        } else { 
            /* Ho hum, expensive scroll required. */

            sbtop -= lines * (cols+1);
            if (sbtop < text)
                sbtop = text;
            scroll_size += scroll_top - sbtop;
            scroll_top = sbtop;

            update_sbar();
        }
    }

    if (scroll_size < 0) {
        size += scroll_size;
        scroll_size = 0;
    }

    if (lines > 0) {
        if (scroll_size)
            memmove (scroll_top, scroll_top + size, scroll_size*TSIZE);
        for (i = 0; i < size; i++)
            scroll_top[i+scroll_size] = erase_char;
        if (selstart > scroll_top &&
            selstart < scroll_top + size + scroll_size) {
            selstart -= size;
            if (selstart < scroll_top)
                selstart = scroll_top;
        }
        if (selend > scroll_top &&
            selend < scroll_top + size + scroll_size) {
            selend -= size;
            if (selend < scroll_top)
                selend = scroll_top;
        }
        if (scrtop_is_disptop)
            disptop = scrtop;
        else
            if (disptop > scroll_top &&
                disptop < scroll_top + size + scroll_size) {
                disptop -= size;
                if (disptop < scroll_top)
                    disptop = scroll_top;
        }
    } else {
        if (scroll_size)
            memmove (scroll_top + size, scroll_top, scroll_size*TSIZE);
        for (i = 0; i < size; i++)
            scroll_top[i] = erase_char;
        if (selstart > scroll_top &&
            selstart < scroll_top + size + scroll_size) {
            selstart += size;
            if (selstart > scroll_top + size + scroll_size)
                selstart = scroll_top + size + scroll_size;
        }
        if (selend > scroll_top &&
            selend < scroll_top + size + scroll_size) {
            selend += size;
            if (selend > scroll_top + size + scroll_size)
                selend = scroll_top + size + scroll_size;
        }
        if (scrtop_is_disptop)
            disptop = scrtop;
        else if (disptop > scroll_top &&
                disptop < scroll_top + size + scroll_size) {
                disptop += size;
                if (disptop > scroll_top + size + scroll_size)
                    disptop = scroll_top + size + scroll_size;
        }
    }
}

/*
 * 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 (int x, int y, int marg_clip) {
    if (x < 0)
        x = 0;
    if (x >= cols)
        x = cols-1;
    if (marg_clip) {
        if ((curs_y >= marg_t || marg_clip == 2) && y < marg_t)
            y = marg_t;
        if ((curs_y <= marg_b || marg_clip == 2) && y > marg_b)
            y = marg_b;
    }
    if (y < 0)
        y = 0;
    if (y >= rows)
        y = rows-1;
    curs_x = x;
    curs_y = y;
    fix_cpos;
    wrapnext = FALSE;
}

/*
 * Save or restore the cursor and SGR mode.
 */
static void save_cursor(int save) {
    if (save) {
        save_x = curs_x;
        save_y = curs_y;
        save_attr = curr_attr;
        save_cset = cset;
        save_csattr = cset_attr[cset];
    } else {
        curs_x = save_x;
        curs_y = save_y;
        /* Make sure the window hasn't shrunk since the save */
        if (curs_x >= cols) curs_x = cols-1;
        if (curs_y >= rows) curs_y = rows-1;

        curr_attr = save_attr;
        cset = save_cset;
        cset_attr[cset] = save_csattr;
        fix_cpos;
        if (use_bce) erase_char = (' ' |(curr_attr&(ATTR_FGMASK|ATTR_BGMASK)));
    }
}

/*
 * Erase a large portion of the screen: the whole screen, or the
 * whole line, or parts thereof.
 */
static void erase_lots (int line_only, int from_begin, int to_end) {
    unsigned long *startpos, *endpos;

    if (line_only) {
        startpos = cpos - curs_x;
        endpos = startpos + cols;
        /* I've removed the +1 so that the Wide screen stuff is not
         * removed when it shouldn't be.
         */
    } else {
        startpos = scrtop;
        endpos = startpos + rows * (cols+1);
    }
    if (!from_begin)
        startpos = cpos;
    if (!to_end)
        endpos = cpos+1;
    check_selection (startpos, endpos);

    /* Clear screen also forces a full window redraw, just in case. */
    if (startpos == scrtop && endpos == scrtop + rows * (cols+1))
       term_invalidate();

    while (startpos < endpos)
        *startpos++ = erase_char;
}

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

    n = (n < 0 ? -n : n);
    if (n > cols - curs_x)
        n = cols - curs_x;
    m = cols - curs_x - n;
    check_selection (cpos, cpos+n);
    if (dir < 0) {
        memmove (cpos, cpos+n, m*TSIZE);
        while (n--)
            cpos[m++] = erase_char;
    } else {
        memmove (cpos+n, cpos, m*TSIZE);
        while (n--)
            cpos[n] = 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 (int mode, int query, int state) {
    if (query) switch (mode) {
      case 1:                          /* application cursor keys */
        app_cursor_keys = state;
        break;
      case 2:                          /* VT52 mode */
        vt52_mode = !state;
        break;
      case 3:                          /* 80/132 columns */
        deselect();
        request_resize (state ? 132 : 80, rows, 1);
        reset_132 = state;
        break;
      case 5:                          /* reverse video */
        rvideo = state;
        seen_disp_event = TRUE;
        if (state) term_update();
        break;
      case 6:                          /* DEC origin mode */
        dec_om = state;
        break;
      case 7:                          /* auto wrap */
        wrap = state;
        break;
      case 8:                          /* auto key repeat */
        repeat_off = !state;
        break;
      case 25:                         /* enable/disable cursor */
        compatibility2(OTHER,VT220);
        cursor_on = state;
        seen_disp_event = TRUE;
        break;
      case 47:                         /* alternate screen */
        compatibility(OTHER);
        deselect();
        swap_screen (state);
        disptop = scrtop;
        break;
    } else switch (mode) {
      case 4:                          /* set insert mode */
        compatibility(VT102);
        insert = state;
        break;
      case 12:                         /* set echo mode */
        /* 
         * This may be very good in smcup and rmcup (or smkx & rmkx) if you
         * have a long RTT and the telnet client/daemon doesn't understand
         * linemode.
         *
         * DONT send TS_RECHO/TS_LECHO; the telnet daemon tries to fix the
         * tty and _really_ confuses some programs.
         */
        compatibility2(OTHER,VT220);
        ldisc = (state? &ldisc_simple : &ldisc_term);
        break;
      case 20:                         /* Return sends ... */
        cr_lf_return = state;
        break;
    }
}

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

/*
 * 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...
 */
void term_out(void) {
    int c, inbuf_reap;

static int beep_overload = 0;
    int beep_count = 0;

    for(inbuf_reap = 0; inbuf_reap < inbuf_head; inbuf_reap++)
    {
        c = inbuf[inbuf_reap];

        /*
         * Optionally log the session traffic to a file. Useful for
         * debugging and possibly also useful for actual logging.
         */
        if (logfile) {
            static FILE *fp = NULL;
            if (!fp) fp = fopen(logfile, "wb");
            if (fp) fputc (c, fp);
        }
        /* 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( ( (c&0x60) == 0 || c == '\177') && 
             termstate < DO_CTRLS &&
            ( (c&0x80) == 0 || has_compat(VT220))) {
            switch (c) {
              case '\005':             /* 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.
                 *
                 * An xterm returns "xterm" (5 characters)
                 */
                compatibility(OTHER);
                ldisc->send ("PuTTY", 5);
                break;
              case '\007':
                beep_count++; 
                if(beep_count>6) beep_overload=1;
                disptop = scrtop;
                break;
              case '\b':
                if (curs_x == 0 && curs_y == 0)
                    ;
                else if (curs_x == 0 && curs_y > 0)
                    curs_x = cols-1, curs_y--;
                else if (wrapnext)
                    wrapnext = FALSE;
                else
                    curs_x--;
                fix_cpos;
                seen_disp_event = TRUE;
                break;
              case '\016':
                compatibility(VT100);
                cset = 1;
                break;
              case '\017':
                compatibility(VT100);
                cset = 0;
                break;
              case '\033':
                if (vt52_mode) 
                   termstate = VT52_ESC;
                else {
                    compatibility(ANSIMIN);
                    termstate = SEEN_ESC;
                }
                break;
              case 0233:
                compatibility(VT220);
                termstate = SEEN_CSI;
                esc_nargs = 1;
                esc_args[0] = ARG_DEFAULT;
                esc_query = FALSE;
                break;
              case 0235:
                compatibility(VT220);
                termstate = SEEN_OSC;
                esc_args[0] = 0;
                break;
              case '\r':
                curs_x = 0;
                wrapnext = FALSE;
                fix_cpos;
                seen_disp_event = TRUE;
                paste_hold = 0;
                break;
              case '\013':
              case '\014':
                compatibility(VT100);
              case '\n':
                if (curs_y == marg_b)
                    scroll (marg_t, marg_b, 1, TRUE);
                else if (curs_y < rows-1)
                    curs_y++;
                if (cfg.lfhascr)
                    curs_x = 0;
                fix_cpos;
                wrapnext = FALSE;
                seen_disp_event = 1;
                paste_hold = 0;
                break;
              case '\t':
                {
                    unsigned long *old_cpos = cpos;
                    unsigned long *p = scrtop + curs_y * (cols+1) + cols;

                    do {
                        curs_x++;
                    } while (curs_x < cols-1 && !tabs[curs_x]);

                    if ((*p & LATTR_MODE) != LATTR_NORM)
                    {
                        if (curs_x >= cols/2)
                            curs_x = cols/2-1;
                    }
                    else
                    {
                        if (curs_x >= cols)
                            curs_x = cols-1;
                    }

                    fix_cpos;
                    check_selection (old_cpos, cpos);
                }
                seen_disp_event = TRUE;
                break;
              case '\177': /* Destructive backspace 
                              This does nothing on a real VT100 */
                compatibility(OTHER);
                if (curs_x && !wrapnext) curs_x--;
                wrapnext = FALSE;
                fix_cpos;
                *cpos = (' ' | curr_attr | ATTR_ASCII);
                break;
            }
        }
        else switch (termstate) {
          case TOPLEVEL:
          /* Only graphic characters get this far, ctrls are stripped above */
            if (wrapnext) {
                cpos[1] |= ATTR_WRAPPED;
                if (curs_y == marg_b)
                    scroll (marg_t, marg_b, 1, TRUE);
                else if (curs_y < rows-1)
                    curs_y++;
                curs_x = 0;
                fix_cpos;
                wrapnext = FALSE;
            }
            if (insert)
                insch (1);
            if (selstate != NO_SELECTION)
                check_selection (cpos, cpos+1);
            switch (cset_attr[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 ATTR_LINEDRW:
                if (c<0x5f || c>0x7F)
                    *cpos++ = xlat_tty2scr((unsigned char)c) | curr_attr |
                              ATTR_ASCII;
                else if (c==0x5F)
                   *cpos++ = ' ' | curr_attr | ATTR_ASCII;
                else
                    *cpos++ = ((unsigned char)c) | curr_attr | ATTR_LINEDRW;
                break;
            case ATTR_GBCHR:
                /* If UK-ASCII, make the '#' a LineDraw Pound */
                if (c == '#') {
                    *cpos++ = '}' | curr_attr | ATTR_LINEDRW;
                    break;
                }
                /*FALLTHROUGH*/
            default:
                *cpos++ = xlat_tty2scr((unsigned char)c) | curr_attr |
                    (c <= 0x7F ? cset_attr[cset] : ATTR_ASCII);
                break;
            }
            curs_x++;
            if (curs_x == cols) {
                cpos--;
                curs_x--;
                wrapnext = wrap;
            }
            seen_disp_event = 1;
            break;

          case IGNORE_NEXT:
            termstate = TOPLEVEL;
            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();
                termstate = TOPLEVEL;
                break;
            }
            /* else fall through */
          case SEEN_ESC:
            termstate = TOPLEVEL;
            switch (c) {
              case ' ':                /* some weird sequence? */
                compatibility(VT220);
                termstate = IGNORE_NEXT;
                break;
              case '[':                /* enter CSI mode */
                termstate = SEEN_CSI;
                esc_nargs = 1;
                esc_args[0] = ARG_DEFAULT;
                esc_query = FALSE;
                break;
              case ']':                /* xterm escape sequences */
                /* Compatibility is nasty here, xterm, linux, decterm yuk! */
                compatibility(OTHER);
                termstate = SEEN_OSC;
                esc_args[0] = 0;
                break;
              case '(':                /* should set GL */
                compatibility(VT100);
                termstate = SET_GL;
                break;
              case ')':                /* should set GR */
                compatibility(VT100);
                termstate = SET_GR;
                break;
              case '7':                /* save cursor */
                compatibility(VT100);
                save_cursor (TRUE);
                break;
              case '8':                /* restore cursor */
                compatibility(VT100);
                save_cursor (FALSE);
                seen_disp_event = TRUE;
                break;
              case '=':
                compatibility(VT100);
                app_keypad_keys = TRUE;
                break;
              case '>':
                compatibility(VT100);
                app_keypad_keys = FALSE;
                break;
              case 'D':                /* exactly equivalent to LF */
                compatibility(VT100);
                if (curs_y == marg_b)
                    scroll (marg_t, marg_b, 1, TRUE);
                else if (curs_y < rows-1)
                    curs_y++;
                fix_cpos;
                wrapnext = FALSE;
                seen_disp_event = TRUE;
                break;
              case 'E':                /* exactly equivalent to CR-LF */
                compatibility(VT100);
                curs_x = 0;
                if (curs_y == marg_b)
                    scroll (marg_t, marg_b, 1, TRUE);
                else if (curs_y < rows-1)
                    curs_y++;
                fix_cpos;
                wrapnext = FALSE;
                seen_disp_event = TRUE;
                break;
              case 'M':                /* reverse index - backwards LF */
                compatibility(VT100);
                if (curs_y == marg_t)
                    scroll (marg_t, marg_b, -1, TRUE);
                else if (curs_y > 0)
                    curs_y--;
                fix_cpos;
                wrapnext = FALSE;
                seen_disp_event = TRUE;
                break;
              case 'Z':                /* terminal type query */
                compatibility(VT100);
                ldisc->send (id_string, strlen(id_string));
                break;
              case 'c':                /* restore power-on settings */
                compatibility(VT100);
                power_on();
                if (reset_132) {
                    request_resize (80, rows, 1);
                    reset_132 = 0;
                }
                fix_cpos;
                disptop = scrtop;
                seen_disp_event = TRUE;
                break;
              case '#':                /* ESC # 8 fills screen with Es :-) */
                compatibility(VT100);
                termstate = SEEN_ESCHASH;
                break;
              case 'H':                /* set a tab */
                compatibility(VT100);
                tabs[curs_x] = TRUE;
                break;
            }
            break;
          case SEEN_CSI:
            termstate = TOPLEVEL;      /* default */
            if( isdigit(c) )
            {
                if (esc_nargs <= ARGS_MAX) {
                    if (esc_args[esc_nargs-1] == ARG_DEFAULT)
                        esc_args[esc_nargs-1] = 0;
                    esc_args[esc_nargs-1] =
                        10 * esc_args[esc_nargs-1] + c - '0';
                }
                termstate = SEEN_CSI;
            }
            else if( c == ';' )
            {
                if (++esc_nargs <= ARGS_MAX)
                    esc_args[esc_nargs-1] = ARG_DEFAULT;
                termstate = SEEN_CSI;
            }
            else if( c < '@' )
            {
                if( esc_query )     esc_query = -1;
                else if( c == '?' ) esc_query = TRUE;
                else                esc_query = c;
                termstate = SEEN_CSI;
            }
            else switch (ANSI(c,esc_query)) {
              case 'A':                /* move up N lines */
                move (curs_x, curs_y - def(esc_args[0], 1), 1);
                seen_disp_event = TRUE;
                break;
              case 'e':      /* move down N lines */
                compatibility(ANSI);
              case 'B':
                move (curs_x, curs_y + def(esc_args[0], 1), 1);
                seen_disp_event = TRUE;
                break;
              case 'a':      /* move right N cols */
                compatibility(ANSI);
              case 'C':
                move (curs_x + def(esc_args[0], 1), curs_y, 1);
                seen_disp_event = TRUE;
                break;
              case 'D':                /* move left N cols */
                move (curs_x - def(esc_args[0], 1), curs_y, 1);
                seen_disp_event = TRUE;
                break;
              case 'E':                /* move down N lines and CR */
                compatibility(ANSI);
                move (0, curs_y + def(esc_args[0], 1), 1);
                seen_disp_event = TRUE;
                break;
              case 'F':                /* move up N lines and CR */
                compatibility(ANSI);
                move (0, curs_y - def(esc_args[0], 1), 1);
                seen_disp_event = TRUE;
                break;
              case 'G': case '`':      /* set horizontal posn */
                compatibility(ANSI);
                move (def(esc_args[0], 1) - 1, curs_y, 0);
                seen_disp_event = TRUE;
                break;
              case 'd':                /* set vertical posn */
                compatibility(ANSI);
                move (curs_x, (dec_om ? marg_t : 0) + def(esc_args[0], 1) - 1,
                      (dec_om ? 2 : 0));
                seen_disp_event = TRUE;
                break;
              case 'H': case 'f':      /* set horz and vert posns at once */
                if (esc_nargs < 2)
                    esc_args[1] = ARG_DEFAULT;
                move (def(esc_args[1], 1) - 1,
                      (dec_om ? marg_t : 0) + def(esc_args[0], 1) - 1,
                      (dec_om ? 2 : 0));
                seen_disp_event = TRUE;
                break;
              case 'J':                /* erase screen or parts of it */
                {
                    unsigned int i = def(esc_args[0], 0) + 1;
                    if (i > 3)
                        i = 0;
                    erase_lots(FALSE, !!(i & 2), !!(i & 1));
                }
                disptop = scrtop;
                seen_disp_event = TRUE;
                break;
              case 'K':                /* erase line or parts of it */
                {
                    unsigned int i = def(esc_args[0], 0) + 1;
                    if (i > 3)
                        i = 0;
                    erase_lots(TRUE, !!(i & 2), !!(i & 1));
                }
                seen_disp_event = TRUE;
                break;
              case 'L':                /* insert lines */
                compatibility(VT102);
                if (curs_y <= marg_b)
                    scroll (curs_y, marg_b, -def(esc_args[0], 1), FALSE);
                seen_disp_event = TRUE;
                break;
              case 'M':                /* delete lines */
                compatibility(VT102);
                if (curs_y <= marg_b)
                    scroll (curs_y, marg_b, def(esc_args[0], 1), TRUE);
                seen_disp_event = TRUE;
                break;
              case '@':                /* insert chars */
                /* XXX VTTEST says this is vt220, vt510 manual says vt102 */
                compatibility(VT102);   
                insch (def(esc_args[0], 1));
                seen_disp_event = TRUE;
                break;
              case 'P':                /* delete chars */
                compatibility(VT102);   
                insch (-def(esc_args[0], 1));
                seen_disp_event = TRUE;
                break;
              case 'c':                /* terminal type query */
                compatibility(VT100);
                /* This is the response for a VT102 */
                ldisc->send (id_string, strlen(id_string));
                break;
              case 'n':                /* cursor position query */
                if (esc_args[0] == 6) {
                    char buf[32];
                    sprintf (buf, "\033[%d;%dR", curs_y + 1, curs_x + 1);
                    ldisc->send (buf, strlen(buf));
                }
                else if (esc_args[0] == 5) {
                    ldisc->send ("\033[0n", 4);
                }
                break;
              case 'h':                /* toggle modes to high */
              case ANSI_QUE('h'):
                compatibility(VT100);
                {
                    int i;
                    for (i=0; i<esc_nargs; i++)
                        toggle_mode (esc_args[i], esc_query, TRUE);
                }
                break;
              case 'l':                /* toggle modes to low */
              case ANSI_QUE('l'):
                compatibility(VT100);
                {
                    int i;
                    for (i=0; i<esc_nargs; i++)
                        toggle_mode (esc_args[i], esc_query, FALSE);
                }
                break;
              case 'g':                /* clear tabs */
                compatibility(VT100);
                if (esc_nargs == 1) {
                    if (esc_args[0] == 0) {
                        tabs[curs_x] = FALSE;
                    } else if (esc_args[0] == 3) {
                        int i;
                        for (i = 0; i < cols; i++)
                            tabs[i] = FALSE;
                    }
                }
                break;
              case 'r':                /* set scroll margins */
                compatibility(VT100);
                if (esc_nargs <= 2) {
                    int top, bot;
                    top = def(esc_args[0], 1) - 1;
                    bot = (esc_nargs <= 1 || esc_args[1] == 0 ? rows :
                           def(esc_args[1], rows)) - 1;
                    if (bot >= rows)
                        bot = rows-1;
                    /* VTTEST Bug 9 - if region is less than 2 lines
                     * don't change region.
                     */
                    if (bot-top > 0) {
                        marg_t = top;
                        marg_b = bot;
                        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
                         */
                        curs_y = (dec_om ? marg_t : 0);
                        fix_cpos;
                        seen_disp_event = TRUE;
                    }
                }
                break;
              case 'm':                /* 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 DIM on the VT100-AVO and VT102
                     * case 5:
                     *  This is BLINK on the VT100-AVO and VT102+
                     * case 8:
                     *  This is INVIS on the VT100-AVO and VT102
                     * 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<esc_nargs; i++) {
                        switch (def(esc_args[i], 0)) {
                          case 0:      /* restore defaults */
                            curr_attr = ATTR_DEFAULT; break;
                          case 1:      /* enable bold */
                            compatibility(VT100AVO);
                            curr_attr |= ATTR_BOLD; break;
                          case 21:     /* (enable double underline) */
                            compatibility(OTHER);
                          case 4:      /* enable underline */
                            compatibility(VT100AVO);
                            curr_attr |= ATTR_UNDER; break;
                          case 5:      /* enable blink */
                            compatibility(VT100AVO);
                            curr_attr |= ATTR_BLINK; break;
                          case 7:      /* enable reverse video */
                            curr_attr |= ATTR_REVERSE; break;
                          case 22:     /* disable bold */
                            compatibility2(OTHER,VT220);
                            curr_attr &= ~ATTR_BOLD; break;
                          case 24:     /* disable underline */
                            compatibility2(OTHER,VT220);
                            curr_attr &= ~ATTR_UNDER; break;
                          case 25:     /* disable blink */
                            compatibility2(OTHER,VT220);
                            curr_attr &= ~ATTR_BLINK; break;
                          case 27:     /* disable reverse video */
                            compatibility2(OTHER,VT220);
                            curr_attr &= ~ATTR_REVERSE; break;
                          case 30: case 31: case 32: case 33:
                          case 34: case 35: case 36: case 37:
                            /* foreground */
                            curr_attr &= ~ATTR_FGMASK;
                            curr_attr |= (esc_args[i] - 30) << ATTR_FGSHIFT;
                            break;
                          case 39:     /* default-foreground */
                            curr_attr &= ~ATTR_FGMASK;
                            curr_attr |= ATTR_DEFFG;
                            break;
                          case 40: case 41: case 42: case 43:
                          case 44: case 45: case 46: case 47:
                            /* background */
                            curr_attr &= ~ATTR_BGMASK;
                            curr_attr |= (esc_args[i] - 40) << ATTR_BGSHIFT;
                            break;
                          case 49:     /* default-background */
                            curr_attr &= ~ATTR_BGMASK;
                            curr_attr |= ATTR_DEFBG;
                            break;
                        }
                    }
                    if (use_bce) 
                       erase_char = 
                            (' '|
                              (curr_attr&(ATTR_FGMASK|ATTR_BGMASK|ATTR_BLINK))
                            );
                }
                break;
              case 's':                /* save cursor */
                save_cursor (TRUE);
                break;
              case 'u':                /* restore cursor */
                save_cursor (FALSE);
                seen_disp_event = TRUE;
                break;
              case 't':                /* 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.
                 */
                compatibility(VT340TEXT);
                if (esc_nargs<=1 && (esc_args[0]<1 || esc_args[0]>=24)) {
                    request_resize (cols, def(esc_args[0], 24), 0);
                    deselect();
                }
                break;
              case ANSI('|', '*'):
                /* VT420 sequence 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 (esc_nargs==1 && esc_args[0]>0) {
                    request_resize (cols, def(esc_args[0], cfg.height), 0);
                    deselect();
                }
                break;
              case ANSI('|', '$'):
                /* VT340/VT420 sequence DECSCPP
                 * Set number of columns per page
                 * Docs imply range is only 80 or 132, but I'll allow any.
                 */
                compatibility(VT340TEXT);
                if (esc_nargs<=1) {
                    request_resize (def(esc_args[0], cfg.width), rows, 0);
                    deselect();
                }
                break;
              case 'X':                /* write N spaces w/o moving cursor */
                /* XXX VTTEST says this is vt220, vt510 manual says vt100 */
                compatibility(ANSIMIN);
                {
                    int n = def(esc_args[0], 1);
                    unsigned long *p = cpos;
                    if (n > cols - curs_x)
                        n = cols - curs_x;
                    check_selection (cpos, cpos+n);
                    while (n--)
                        *p++ = erase_char;
                    seen_disp_event = TRUE;
                }
                break;
              case 'x':                /* report terminal characteristics */
                compatibility(VT100);
                {
                    char buf[32];
                    int i = def(esc_args[0], 0);
                    if (i == 0 || i == 1) {
                        strcpy (buf, "\033[2;1;1;112;112;1;0x");
                        buf[2] += i;
                        ldisc->send (buf, 20);
                    }
                }
                break;
              case ANSI('L','='):
                compatibility(OTHER);
                use_bce = (esc_args[0]<=0);
                erase_char = ERASE_CHAR;
                if (use_bce)
                    erase_char = (' '|(curr_attr&(ATTR_FGMASK|ATTR_BGMASK)));
                break;
              case ANSI('E','='):
                compatibility(OTHER);
                blink_is_real = (esc_args[0]>=1);
                break;
              case ANSI('p','"'):
                /* 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 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 (esc_args[0]) {
                case 61: compatibility_level &= ~TM_VTXXX;
                         compatibility_level |=  TM_VT102;      break;
                case 62: compatibility_level &= ~TM_VTXXX;
                         compatibility_level |=  TM_VT220;      break;

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

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

                case ARG_DEFAULT: 
                         compatibility_level  =  TM_PUTTY;      break;
                case 50: break;
                }

                /* Change the response to CSI c */
                if (esc_args[0] == 50) {
                   int i;
                   char lbuf[64];
                   strcpy(id_string, "\033[?");
                   for (i=1; i<esc_nargs; i++) {
                      if (i!=1) strcat(id_string, ";");
                      sprintf(lbuf, "%d", esc_args[i]);
                      strcat(id_string, lbuf);
                   }
                   strcat(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 (reset_132) request_resize (132, 24, 1);
                    else           request_resize ( 80, 24, 1);
                }
#endif
                break;
            }
            break;
          case SET_GL:
          case SET_GR:
            /* VT100 only here, checked above */
            switch (c) {
              case 'A':
                cset_attr[termstate == SET_GL ? 0 : 1] = ATTR_GBCHR;
                break;
              case '0':
                cset_attr[termstate == SET_GL ? 0 : 1] = ATTR_LINEDRW;
                break;
              case 'B':
              default:                 /* specifically, 'B' */
                cset_attr[termstate == SET_GL ? 0 : 1] = ATTR_ASCII;
                break;
            }
            if( !has_compat(VT220) || c != '%' )
                termstate = TOPLEVEL;
            break;
          case SEEN_OSC:
            osc_w = FALSE;
            switch (c) {
              case 'P':                /* Linux palette sequence */
                termstate = SEEN_OSC_P;
                osc_strlen = 0;
                break;
              case 'R':                /* Linux palette reset */
                palette_reset();
                term_invalidate();
                termstate = TOPLEVEL;
                break;
              case 'W':                /* word-set */
                termstate = SEEN_OSC_W;
                osc_w = TRUE;
                break;
              case '0': case '1': case '2': case '3': case '4':
              case '5': case '6': case '7': case '8': case '9':
                esc_args[0] = 10 * esc_args[0] + c - '0';
                break;
              case 'L':
                /*
                 * Grotty hack to support xterm and DECterm title
                 * sequences concurrently.
                 */
                if (esc_args[0] == 2) {
                    esc_args[0] = 1;
                    break;
                }
                /* else fall through */
              default:
                termstate = OSC_STRING;
                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 == '\n' || c == '\r') {
                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();
                termstate = TOPLEVEL;
            } else if (c == '\033')
                    termstate = OSC_MAYBE_ST;
            else if (osc_strlen < OSC_STR_MAX)
                osc_string[osc_strlen++] = c;
            break;
          case SEEN_OSC_P:
            {
                int max = (osc_strlen == 0 ? 21 : 16);
                int val;
                if (c >= '0' && c <= '9')
                    val = c - '0';
                else if (c >= 'A' && c <= 'A'+max-10)
                    val = c - 'A' + 10;
                else if (c >= 'a' && c <= 'a'+max-10)
                    val = c - 'a' + 10;
                else
                    termstate = TOPLEVEL;
                osc_string[osc_strlen++] = val;
                if (osc_strlen >= 7) {
                    palette_set (osc_string[0],
                                 osc_string[1] * 16 + osc_string[2],
                                 osc_string[3] * 16 + osc_string[4],
                                 osc_string[5] * 16 + osc_string[6]);
                    term_invalidate();
                    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':
                esc_args[0] = 10 * esc_args[0] + c - '0';
                break;
              default:
                termstate = OSC_STRING;
                osc_strlen = 0;
            }
            break;
          case SEEN_ESCHASH:
            {
                unsigned long *p;
                unsigned long nlattr;
                int n;

                switch (c) {
                case '8':
                    p = scrtop;
                    n = rows * (cols+1);
                    while (n--)
                        *p++ = ATTR_DEFAULT | 'E';
                    disptop = scrtop;
                    seen_disp_event = TRUE;
                    check_selection (scrtop, scrtop + rows * (cols+1));
                    break;

                case '3': nlattr = LATTR_TOP;     if(0) {
                case '4': nlattr = LATTR_BOT;   } if(0) {
                case '5': nlattr = LATTR_NORM;  } if(0) {
                case '6': nlattr = LATTR_WIDE;  }

                    p = scrtop + curs_y * (cols+1) + cols;
                    *p &= ~LATTR_MODE;
                    *p |=  nlattr;
                }
            }
            termstate = TOPLEVEL;
            break;
          case VT52_ESC:
            termstate = TOPLEVEL;
            seen_disp_event = TRUE;
            switch (c) {
              case 'A':
                move (curs_x, curs_y - 1, 1);
                break;
              case 'B':
                move (curs_x, curs_y + 1, 1);
                break;
              case 'C':
                move (curs_x + 1, curs_y, 1);
                break;
              case 'D':
                move (curs_x - 1, curs_y, 1);
                break;
              case 'F':
                cset_attr[cset=0] = ATTR_LINEDRW;
                break;
              case 'G':
                cset_attr[cset=0] = ATTR_ASCII;
                break;
              case 'H':
                move (0, 0, 0);
                break;
              case 'I':
                if (curs_y == 0)
                    scroll (0, rows-1, -1, TRUE);
                else if (curs_y > 0)
                    curs_y--;
                fix_cpos;
                wrapnext = FALSE;
                break;
              case 'J':
                erase_lots(FALSE, FALSE, TRUE);
                disptop = scrtop;
                break;
              case 'K':
                erase_lots(TRUE, FALSE, TRUE);
                break;
              case 'V':
                /* XXX Print cursor line */
                break;
              case 'W':
                /* XXX Start controller mode */
                break;
              case 'X':
                /* XXX Stop controller mode */
                break;
              case 'Y':
                termstate = VT52_Y1;
                break;
              case 'Z':
                ldisc->send ("\033/Z", 3);
                break;
              case '=':
                app_keypad_keys = TRUE;
                break;
              case '>':
                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.
                 */
                vt52_mode = FALSE;
                break;
              case '^':
                /* XXX Enter auto print mode */
                break;
              case '_':
                /* XXX Exit auto print mode */
                break;
              case ']':
                /* XXX Print screen */
                break;
            }
            break;
          case VT52_Y1:
            termstate = VT52_Y2;
            move(curs_x, c-' ', 0);
            break;
          case VT52_Y2:
            termstate = TOPLEVEL;
            move(c-' ', curs_y, 0);
            break;
        }
        if (selstate != NO_SELECTION)
            check_selection (cpos, cpos+1);
    }
    inbuf_head = 0;

    if (beep_overload)
    {
       if(!beep_count) beep_overload=0;
    }
    else if(beep_count && beep_count<5 && cfg.beep)
       beep(beep_count/3);
}

/*
 * Compare two lines to determine whether they are sufficiently
 * alike to scroll-optimise one to the other. Return the degree of
 * similarity.
 */
static int linecmp (unsigned long *a, unsigned long *b) {
    int i, n;

    for (i=n=0; i < cols; i++)
        n += (*a++ == *b++);
    return n;
}

/*
 * Given a context, update the window. Out of paranoia, we don't
 * allow WM_PAINT responses to do scrolling optimisations.
 */
static void do_paint (Context ctx, int may_optimise){
    int i, j, start, our_curs_y;
    unsigned long attr, rv, cursor;
    char ch[1024];

    if (cursor_on) {
        if (has_focus) {
            if (blinker || !cfg.blink_cur)
                cursor = ATTR_ACTCURS;
            else
                cursor = 0;
        }
        else
            cursor = ATTR_PASCURS;
    }
    else           cursor = 0;
    rv = (rvideo ? ATTR_REVERSE : 0);
    our_curs_y = curs_y + (scrtop - disptop) / (cols+1);

    for (i=0; i<rows; i++) {
        int idx = i*(cols+1);
        int lattr = (disptop[idx+cols] & LATTR_MODE);
        for (j=0; j<=cols; j++,idx++) {
            unsigned long *d = disptop+idx;
            wanttext[idx] = lattr | ((*d ^ rv
                              ^ (selstart <= d && d < selend ?
                                 ATTR_REVERSE : 0)) |
                             (i==our_curs_y && j==curs_x ? cursor : 0));

            if (blink_is_real) {
                if (has_focus && tblinker && (wanttext[idx]&ATTR_BLINK) )
                {
                    wanttext[idx] &= ATTR_MASK;
                    wanttext[idx] += ' ';
                }
                wanttext[idx] &= ~ATTR_BLINK;
            }
        }
    }

    /*
     * We would perform scrolling optimisations in here, if they
     * didn't have a nasty tendency to cause the whole sodding
     * program to hang for a second at speed-critical moments.
     * We'll leave it well alone...
     */

    for (i=0; i<rows; i++) {
        int idx = i*(cols+1);
        int lattr = (wanttext[idx+cols] & LATTR_MODE);
        start = -1;
        for (j=0; j<=cols; j++,idx++) {
            unsigned long t = wanttext[idx];
            int needs_update = (j < cols && t != disptext[idx]);
            int keep_going = (start != -1 && needs_update &&
                              (t & ATTR_MASK) == attr &&
                              j-start < sizeof(ch));
            if (start != -1 && !keep_going) {
                do_text (ctx, start, i, ch, j-start, attr, lattr);
                start = -1;
            }
            if (needs_update) {
                if (start == -1) {
                    start = j;
                    attr = t & ATTR_MASK;
                }
                ch[j-start] = (char) (t & CHAR_MASK);
            }
            disptext[idx] = t;
        }
    }
}

/*
 * Flick the switch that says if blinking things should be shown or hidden.
 */

void term_blink(int flg) {
static long last_blink = 0;
static long last_tblink = 0;
    long now, blink_diff;

    now = GetTickCount();
    blink_diff = now-last_tblink;

    /* Make sure the text blinks no more than 2Hz */
    if (blink_diff<0 || blink_diff>450)
    {
        last_tblink = now;
        tblinker = !tblinker;
    }

    if (flg) {
        blinker = 1;
        last_blink = now;
        return;
    } 

    blink_diff = now-last_blink;

    /* Make sure the cursor blinks no more than 2Hz */
    if (blink_diff>=0 && blink_diff<450)
       return;
 
    last_blink = now;
    blinker = !blinker;
}

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

    for (i=0; i<rows*(cols+1); i++)
        disptext[i] = ATTR_INVALID;
}

/*
 * Paint the window in response to a WM_PAINT message.
 */
void term_paint (Context ctx, int l, int t, int r, int b) {
    int i, j, left, top, right, bottom;

    left = l / font_width;
    right = (r - 1) / font_width;
    top = t / font_height;
    bottom = (b - 1) / font_height;
    for (i = top; i <= bottom && i < rows ; i++)
    {
        if ( (disptext[i*(cols+1)+cols]&LATTR_MODE) == LATTR_NORM)
            for (j = left; j <= right && j < cols ; j++)
                disptext[i*(cols+1)+j] = ATTR_INVALID;
        else
            for (j = left/2; j <= right/2+1 && j < cols ; j++)
                disptext[i*(cols+1)+j] = ATTR_INVALID;
    }

    /* This should happen soon enough, also for some reason it sometimes 
     * fails to actually do anything when re-sizing ... painting the wrong
     * window perhaps ?
    do_paint (ctx, FALSE);
    */
}

/*
 * 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 (int rel, int where) {
    int n = where * (cols+1);

    disptop = (rel < 0 ? scrtop :
               rel > 0 ? sbtop : disptop) + n;
    if (disptop < sbtop)
        disptop = sbtop;
    if (disptop > scrtop)
        disptop = scrtop;
    update_sbar();
    term_update();
}

/*
 * Spread the selection outwards according to the selection mode.
 */
static unsigned long *sel_spread_half (unsigned long *p, int dir) {
    unsigned long *linestart, *lineend;
    int x;
    short wvalue;

    x = (p - text) % (cols+1);
    linestart = p - x;
    lineend = linestart + cols;

    switch (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 (!(linestart[cols] & ATTR_WRAPPED)) {
            unsigned long *q = lineend;
            while (q > linestart && (q[-1] & CHAR_MASK) == 0x20)
                q--;
            if (q == lineend)
                q--;
            if (p >= q)
                p = (dir == -1 ? q : lineend - 1);
        }
        break;
      case SM_WORD:
        /*
         * In this mode, the units are maximal runs of characters
         * whose `wordness' has the same value.
         */
        wvalue = wordness[*p & CHAR_MASK];
        if (dir == +1) {
            while (p < lineend && wordness[p[1] & CHAR_MASK] == wvalue)
                p++;
        } else {
            while (p > linestart && wordness[p[-1] & CHAR_MASK] == wvalue)
                p--;
        }
        break;
      case SM_LINE:
        /*
         * In this mode, every line is a unit.
         */
        p = (dir == -1 ? linestart : lineend - 1);
        break;
    }
    return p;
}

static void sel_spread (void) {
    selstart = sel_spread_half (selstart, -1);
    selend = sel_spread_half (selend - 1, +1) + 1;
}

void term_mouse (Mouse_Button b, Mouse_Action a, int x, int y) {
    unsigned long *selpoint;
    
    if (y<0) y = 0;
    if (y>=rows) y = rows-1;
    if (x<0) {
        if (y > 0) {
            x = cols-1;
            y--;
        } else
            x = 0;
    }
    if (x>=cols) x = cols-1;

    selpoint = disptop + y * (cols+1);
    if ((selpoint[cols]&LATTR_MODE) != LATTR_NORM)
        selpoint += x/2;
    else
        selpoint += x;

    if (b == MB_SELECT && a == MA_CLICK) {
        deselect();
        selstate = ABOUT_TO;
        selanchor = selpoint;
        selmode = SM_CHAR;
    } else if (b == MB_SELECT && (a == MA_2CLK || a == MA_3CLK)) {
        deselect();
        selmode = (a == MA_2CLK ? SM_WORD : SM_LINE);
        selstate = DRAGGING;
        selstart = selanchor = selpoint;
        selend = selstart + 1;
        sel_spread();
    } else if ((b == MB_SELECT && a == MA_DRAG) ||
               (b == MB_EXTEND && a != MA_RELEASE)) {
        if (selstate == ABOUT_TO && selanchor == selpoint)
            return;
        if (b == MB_EXTEND && a != MA_DRAG && selstate == SELECTED) {
            if (selpoint-selstart < (selend-selstart)/2)
                selanchor = selend - 1;
            else
                selanchor = selstart;
            selstate = DRAGGING;
        }
        if (selstate != ABOUT_TO && selstate != DRAGGING)
            selanchor = selpoint;
        selstate = DRAGGING;
        if (selpoint < selanchor) {
            selstart = selpoint;
            selend = selanchor + 1;
        } else {
            selstart = selanchor;
            selend = selpoint + 1;
        }
        sel_spread();
    } else if ((b == MB_SELECT || b == MB_EXTEND) && a == MA_RELEASE) {
        if (selstate == DRAGGING) {
            /*
             * We've completed a selection. We now transfer the
             * data to the clipboard.
             */
            unsigned char *p = selspace;
            unsigned long *q = selstart;

            while (q < selend) {
                int nl = FALSE;
                unsigned long *lineend = q - (q-text) % (cols+1) + cols;
                unsigned long *nlpos = lineend;

                if (!(*nlpos & ATTR_WRAPPED)) {
                    while ((nlpos[-1] & CHAR_MASK) == 0x20 && nlpos > q)
                        nlpos--;
                    if (nlpos < selend)
                        nl = TRUE;
                }
                while (q < nlpos && q < selend)
                {
#if 0
                    /* VT Specials -> ISO8859-1  */
                    static const char poorman2[] =
 "* # HTFFCRLF\xB0 \xB1 NLVT+ + + + + - - - - - + + + + | <=>=PI!=\xA3 \xB7 ";
#endif

                    int ch = (*q & CHAR_MASK);

#if 0
                    if ((*q & ATTR_LINEDRW) && ch >= 0x60 && ch < 0x7F) {
                        int x;
                        *p++ = poorman2[2*(ch-0x60)];
                        if ( (x = poorman2[2*(ch-0x60)+1]) != ' ')
                            *p++ = x;
                    } else
#endif
#if 0
                    if ((*q & ATTR_GBCHR) && ch == '#')
                        *p++ = (unsigned char) 0xA3;
                    else
#endif
                        *p++ = (unsigned char) ch;
                    q++;
                }
                if (nl) {
                    int i;
                    for (i=0; i<sizeof(sel_nl); i++)
                        *p++ = sel_nl[i];
                }
                q = lineend + 1;       /* start of next line */
            }
            write_clip (selspace, p - selspace, FALSE);
            selstate = SELECTED;
        } else
            selstate = NO_SELECTION;
    } else if (b == MB_PASTE && (a==MA_CLICK || a==MA_2CLK || a==MA_3CLK)) {
        char *data;
        int len;

        get_clip((void **) &data, &len);
        if (data) {
            char *p, *q;

            if (paste_buffer) sfree(paste_buffer);
            paste_pos = paste_hold = paste_len = 0;
            paste_buffer = smalloc(len);

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

                {
                    int i;
                    unsigned char c;
                    for(i=0;i<p-q;i++)
                    {
                        c=xlat_kbd2tty(q[i]);
                        paste_buffer[paste_len++] = c;
                    }
                }

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

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

    term_update();
}

void term_nopaste() {
    if(paste_len == 0) return;
    sfree(paste_buffer);
    paste_buffer = 0;
    paste_len = 0;
}

void term_paste() {
    static long last_paste = 0;
    long now, paste_diff;

    if(paste_len == 0) return;

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

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

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

static void deselect (void) {
    selstate = NO_SELECTION;
    selstart = selend = scrtop;
}

void term_deselect (void) {
    deselect();
    term_update();
}

/*
 * from_backend(), to get data from the backend for the terminal.
 */
void from_backend(int is_stderr, char *data, int len) {
    while (len--) {
        if (inbuf_head >= INBUF_SIZE)
            term_out();
        inbuf[inbuf_head++] = *data++;
    }
}