Terminal now uses unsorted counted tree234 as its basic data type.

[u/mdw/putty] / terminal.c

#include <windows.h>

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

#include <time.h>
#include "putty.h"
#include "tree234.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 tree234 *scrollback;            /* lines scrolled off top of screen */
static tree234 *screen;                /* lines on primary screen */
static tree234 *alt_screen;            /* lines on alternate screen */
static int disptop;                    /* distance scrolled back (0 or negative) */

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 */

#define VBELL_TIMEOUT 100              /* millisecond duration of visual bell */

struct beeptime {
    struct beeptime *next;
    long ticks;
};
static struct beeptime *beephead, *beeptail;
int nbeeps;
int beep_overloaded;
long lastbeep;

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

#define TSIZE (sizeof(unsigned long))
#define lineptr(x) ( (unsigned long *) \
                        ((x) >= 0 ? index234(screen, x) : \
                             index234(scrollback, (x)+count234(scrollback)) ) )
#define fix_cpos  do { cpos = lineptr(curs.y) + curs.x; } while(0)

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

typedef struct {
    int y, x;
} pos;
#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) ( ((p2).y - (p1).y) * (cols+1) + (p2).x - (p1).x )
#define incpos(p) ( (p).x == cols ? ((p).x = 0, (p).y++, 1) : ((p).x++, 0) )
#define decpos(p) ( (p).x == 0 ? ((p).x = cols, (p).y--, 1) : ((p).x--, 0) )

static pos curs;                       /* cursor */
static pos savecurs;                   /* 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 int term_echoing;               /* Does terminal want local echo? */
static int term_editing;               /* Does terminal want local edit? */

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 pos 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);
/* log session to file stuff ... */
static FILE *lgfp = NULL;
static void logtraffic(unsigned char c, int logmode);

/*
 * Set up power-on settings for the terminal.
 */
static void power_on(void) {
    curs.x = curs.y = alt_x = alt_y = savecurs.x = savecurs.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;
    in_vbell = FALSE;
    cursor_on = 1;
    save_attr = curr_attr = ATTR_DEFAULT;
    term_editing = term_echoing = FALSE;
    ldisc_send(NULL, 0);               /* cause ldisc to notice changes */
    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 (screen) {
        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 = 0;               /* return to main screen */
            seen_disp_event = seen_key_event = 0;
            update_sbar();
        }
        do_paint (ctx, TRUE);
        sys_cursor(curs.x, curs.y - disptop);
        free_ctx (ctx);
    }
}

/*
 * Same as power_on(), but an external function.
 */
void term_pwron(void) {
    power_on();
    fix_cpos;
    disptop = 0;
    deselect();
    term_update();
}

/*
 * Clear the scrollback.
 */
void term_clrsb(void) {
    unsigned long *line;
    disptop = 0;
    while ((line = delpos234(scrollback, 0)) != NULL) {
        sfree(line);
    }
    update_sbar();
}

/*
 * Initialise the terminal.
 */
void term_init(void) {
    screen = alt_screen = scrollback = NULL;
    disptop = 0;
    disptext = wanttext = NULL;
    tabs = NULL;
    selspace = NULL;
    deselect();
    rows = cols = -1;
    power_on();
    beephead = beeptail = NULL;
    nbeeps = 0;
    lastbeep = FALSE;
    beep_overloaded = FALSE;
}

/*
 * Set up the terminal for a given size.
 */
void term_size(int newrows, int newcols, int newsavelines) {
    tree234 *newsb, *newscreen, *newalt;
    unsigned long *newdisp, *newwant, *oldline, *line;
    int i, j, crows, ccols;
    int posn, oldposn, furthest_back, oldsbsize;
    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;

    newsb = newtree234(NULL);
    newscreen = newtree234(NULL);
    ccols = (cols < newcols ? cols : newcols);
    oldsbsize = scrollback ? count234(scrollback) : 0;
    furthest_back = newrows - rows - oldsbsize;
    if (furthest_back > 0)
        furthest_back = 0;
    if (furthest_back < -newsavelines)
        furthest_back = -newsavelines;
    for (posn = newrows; posn-- > furthest_back ;) {
        oldposn = posn - newrows + rows;
        if (rows == -1 || oldposn < -oldsbsize) {
            line = smalloc(TSIZE * (newcols + 1));
            for (j = 0; j < newcols; j++)
                line[j] = erase_char;
            line[newcols] = 0;
        } else {
            oldline = (oldposn >= 0 ?
                       delpos234(screen, count234(screen)-1) :
                       delpos234(scrollback, count234(scrollback)-1));
            if (newcols != cols) {
                line = smalloc(TSIZE * (newcols + 1));
                for (j = 0; j < ccols; j++)
                    line[j] = oldline[j];
                for (j = ccols; j < newcols; j++)
                    line[j] = erase_char;
                line[newcols] = oldline[cols] & LATTR_MODE;
                sfree(oldline);
            } else {
                line = oldline;
            }
        }
        if (posn >= 0)
            addpos234(newscreen, line, 0);
        else
            addpos234(newsb, line, 0);
    }
    disptop = 0;
    if (scrollback) freetree234(scrollback);
    if (screen) freetree234(screen);
    scrollback = newsb;
    screen = newscreen;

    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 = newtree234(NULL);
    for (i=0; i<newrows; i++) {
        line = smalloc(TSIZE * (newcols+1));
        for (j = 0; j <= newcols; j++)
            line[i] = erase_char;
        addpos234(newalt, line, i);
    }
    if (alt_screen) {
        while (NULL != (line = delpos234(alt_screen, 0)))
            sfree(line);
        freetree234(alt_screen);
    }
    alt_screen = 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;
    tree234 *ttr;

    if (which == alt_which)
        return;

    alt_which = which;

    ttr = alt_screen; alt_screen = screen; screen = ttr;
    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 nscreen, nscroll;

    nscroll = count234(scrollback);

    set_sbar (nscroll + rows, nscroll + disptop, 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 (pos from, pos to) {
    if (poslt(from, selend) && poslt(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 *line, *line2;
    int i;

    if (topline != 0)
        sb = FALSE;

    if (lines < 0) {
        while (lines < 0) {
            line = delpos234(screen, botline);
            for (i = 0; i < cols; i++)
                line[i] = erase_char;
            line[cols] = 0;
            addpos234(screen, line, topline);

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

            lines++;
        }
    } else {
        while (lines > 0) {
            line = delpos234(screen, topline);
            if (sb) {
                int sblen = count234(scrollback);
                /*
                 * We must add this line to the scrollback. We'll
                 * remove a line from the top of the scrollback to
                 * replace it, or allocate a new one if the
                 * scrollback isn't full.
                 */
                if (sblen == savelines)
                    sblen--, line2 = delpos234(scrollback, 0);
                else
                    line2 = smalloc(TSIZE * (cols+1));
                addpos234(scrollback, line, sblen);
                line = line2;
            }
            for (i = 0; i < cols; i++)
                line[i] = erase_char;
            line[cols] = 0;
            addpos234(screen, line, botline);

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

            lines--;
        }
    }
}

/*
 * 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) {
        savecurs = curs;
        save_attr = curr_attr;
        save_cset = cset;
        save_csattr = cset_attr[cset];
    } else {
        curs = savecurs;
        /* 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) {
    pos start, end, here;
    int erase_lattr;
    unsigned long *ldata;

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

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

    ldata = lineptr(start.y);
    while (poslt(start, end)) {
        if (start.y == cols && !erase_lattr)
            ldata[start.x] &= ~ATTR_WRAPPED;
        else
            ldata[start.x] = erase_char;
        if (incpos(start))
            ldata = lineptr(start.y);
    }
}

/*
 * 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;
    pos cursplus;
    unsigned long *ldata;

    n = (n < 0 ? -n : n);
    if (n > cols - curs.x)
        n = cols - curs.x;
    m = cols - curs.x - n;
    cursplus.y = curs.y;
    cursplus.x = curs.x + n;
    check_selection (curs, cursplus);
    ldata = lineptr(curs.y);
    if (dir < 0) {
        memmove (ldata + curs.x, ldata + curs.x + n, m*TSIZE);
        while (n--)
            ldata[curs.x + m++] = erase_char;
    } else {
        memmove (ldata + curs.x + n, ldata + curs.x, m*TSIZE);
        while (n--)
            ldata[curs.x + 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 10:                         /* set local edit mode */
        term_editing = state;
        ldisc_send(NULL, 0);           /* cause ldisc to notice changes */
        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 = 0;
        break;
    } else switch (mode) {
      case 4:                          /* set insert mode */
        compatibility(VT102);
        insert = state;
        break;
      case 12:                         /* set echo mode */
        term_echoing = !state;
        ldisc_send(NULL, 0);           /* cause ldisc to notice changes */
        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;

    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.
         */
        logtraffic((unsigned char)c, LGTYP_DEBUG);

        /* 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(ANSIMIN);
                {
                    char abuf[256], *s, *d;
                    int state=0;
                    for(s=cfg.answerback, d=abuf; *s; s++) {
                        if (state)
                        {
                            if (*s >= 'a' && *s <= 'z')
                                *d++ = (*s - ('a'-1));
                            else if ((*s >='@' && *s<='_') ||
                                     *s == '?' || (*s&0x80))
                                *d++ = ('@'^*s);
                            else if (*s == '~')
                                *d++ = '^';
                            state = 0;
                        }
                        else if (*s == '^') {
                            state = 1;
                        }
                        else
                            *d++ = xlat_kbd2tty((unsigned char)*s);
                    }
                    ldisc_send (abuf, d-abuf);
                }
                break;
              case '\007':
                {
                    struct beeptime *newbeep;
                    long ticks;

                    ticks = GetTickCount();

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

                    /*
                     * Throw out any beeps that happened more than
                     * t seconds ago.
                     */
                    while (beephead &&
                           beephead->ticks < ticks - cfg.bellovl_t*1000) {
                        struct beeptime *tmp = beephead;
                        beephead = tmp->next;
                        sfree(tmp);
                        if (!beephead)
                            beeptail = NULL;
                        nbeeps--;
                    }

                    if (cfg.bellovl && beep_overloaded &&
                        ticks-lastbeep >= cfg.bellovl_s * 1000) {
                        /*
                         * If we're currently overloaded and the
                         * last beep was more than s seconds ago,
                         * leave overload mode.
                         */
                        beep_overloaded = FALSE;
                    } else if (cfg.bellovl && !beep_overloaded &&
                               nbeeps >= cfg.bellovl_n) {
                        /*
                         * Now, if we have n or more beeps
                         * remaining in the queue, go into overload
                         * mode.
                         */
                        beep_overloaded = TRUE;
                    }
                    lastbeep = ticks;

                    /*
                     * Perform an actual beep if we're not overloaded.
                     */
                    if ((!cfg.bellovl || !beep_overloaded) && cfg.beep != 0) {
                        if (cfg.beep != 2)
                            beep(cfg.beep);
                        else if(cfg.beep == 2) {
                            in_vbell = TRUE;
                            vbell_timeout = ticks + VBELL_TIMEOUT;
                            term_update();
                        }
                    }
                    disptop = 0;
                }
                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;
                logtraffic((unsigned char)c,LGTYP_ASCII);
                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;
                logtraffic((unsigned char)c,LGTYP_ASCII);
                break;
              case '\t':
                {
                    pos old_curs = curs;
                    unsigned long *ldata = lineptr(curs.y);

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

                    if ((ldata[cols] & 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_curs, curs);
                }
                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 && wrap) {
                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) {
                pos cursplus = curs;
                incpos(cursplus);
                check_selection (curs, cursplus);
            }
            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);
                logtraffic((unsigned char)c, LGTYP_ASCII);
                cpos++;
                break;
            }
            curs.x++;
            if (curs.x == cols) {
                cpos--;
                curs.x--;
                wrapnext = TRUE;
            }
            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 = 0;
                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 = 0;
                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);
                    pos cursplus;
                    unsigned long *p = cpos;
                    if (n > cols - curs.x)
                        n = cols - curs.x;
                    cursplus = curs;
                    cursplus.x += n;
                    check_selection (curs, cursplus);
                    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;
                unsigned long *ldata;
                int i, j;
                pos scrtop, scrbot;

                switch (c) {
                case '8':
                    for (i = 0; i < rows; i++) {
                        ldata = lineptr(i);
                        for (j = 0; j < cols; j++)
                            ldata[j] = ATTR_DEFAULT | 'E';
                        ldata[cols] = 0;
                    }
                    disptop = 0;
                    seen_disp_event = TRUE;
                    scrtop.x = scrtop.y = 0;
                    scrbot.x = 0; scrbot.y = rows;
                    check_selection (scrtop, scrbot);
                    break;

                case '3': nlattr = LATTR_TOP; goto lattr_common;
                case '4': nlattr = LATTR_BOT; goto lattr_common;
                case '5': nlattr = LATTR_NORM; goto lattr_common;
                case '6': nlattr = LATTR_WIDE;
                    lattr_common:

                    ldata = lineptr(curs.y);
                    ldata[cols] &= ~LATTR_MODE;
                    ldata[cols] |=  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 = 0;
                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) {
            pos cursplus = curs;
            incpos(cursplus);
            check_selection (curs, cursplus);
        }
    }
    inbuf_head = 0;
}

/*
 * 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;
    pos scrpos;
    char ch[1024];
    long ticks;

    /*
     * Check the visual bell state.
     */
    if (in_vbell) {
        ticks = GetTickCount();
        if (ticks - vbell_timeout >= 0)
            in_vbell = FALSE;
    }

    /* Depends on:
     * screen array, disptop, scrtop,
     * selection, rv, 
     * cfg.blinkpc, blink_is_real, tblinker, 
     * curs.y, curs.x, blinker, cfg.blink_cur, cursor_on, has_focus
     */
    if (cursor_on) {
        if (has_focus) {
            if (blinker || !cfg.blink_cur)
                cursor = ATTR_ACTCURS;
            else
                cursor = 0;
        }
        else
            cursor = ATTR_PASCURS;
        if (wrapnext)
            cursor |= ATTR_RIGHTCURS;
    }
    else
        cursor = 0;
    rv = (!rvideo ^ !in_vbell ? ATTR_REVERSE : 0);
    our_curs_y = curs.y - disptop;

    for (i=0; i<rows; i++) {
        unsigned long *ldata;
        int lattr;
        scrpos.y = i + disptop;
        ldata = lineptr(scrpos.y);
        lattr = (ldata[cols] & LATTR_MODE);
        for (j=0; j<=cols; j++) {
            unsigned long d = ldata[j];
            int idx = i*(cols+1)+j;
            scrpos.x = j;
            
            wanttext[idx] = lattr | (((d &~ ATTR_WRAPPED) ^ rv
                                      ^ (posle(selstart, scrpos) &&
                                         poslt(scrpos, 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 faster than GetCaretBlinkTime() */
    if (blink_diff>=0 && blink_diff<(long)GetCaretBlinkTime())
       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 sbtop = -count234(scrollback);

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

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

    if ( workbuf != NULL ) {    /* user supplied buffer? */
        buflen = -1;            /* assume buffer passed in is big enough */
        wbptr = workbuf;        /* start filling here */
    }
    else
        buflen = 0;             /* No data is available yet */

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

        nlpos.y = top.y;
        nlpos.x = cols;

        if (!(ldata[cols] & ATTR_WRAPPED)) {
            while ((ldata[nlpos.x-1] & CHAR_MASK) == 0x20 && poslt(top, nlpos))
                decpos(nlpos);
            if (poslt(nlpos, bottom))
                nl = TRUE;
        }
        while (poslt(top, bottom) && poslt(top, nlpos)) {
            int ch = (ldata[top.x] & CHAR_MASK);
            int set = (ldata[top.x] & CSET_MASK);

            /* VT Specials -> ISO8859-1 for Cut&Paste */
            static const unsigned char poorman2[] =
"* # HTFFCRLF\xB0 \xB1 NLVT+ + + + + - - - - - + + + + | <=>=PI!=\xA3 \xB7 ";

            if (set && !cfg.rawcnp) {
                if (set == ATTR_LINEDRW && ch >= 0x60 && ch < 0x7F) {
                    int x;
                    if ((x = poorman2[2*(ch-0x60)+1]) == ' ')
                        x = 0;
                    ch = (x<<8) + poorman2[2*(ch-0x60)];
                }
            }

            while(ch != 0) {
                if (cfg.rawcnp || !!(ch&0xE0)) {
                    if ( wblen == buflen )
                    {
                        workbuf = srealloc(workbuf, buflen += 100);
                        wbptr = workbuf + wblen;
                    }
                    wblen++;
                    *wbptr++ = (unsigned char) ch;
                }
                ch>>=8;
            }
            top.x++;
        }
        if (nl) {
            int i;
            for (i=0; i<sizeof(sel_nl); i++)
            {
                if ( wblen == buflen )
                {
                    workbuf = srealloc(workbuf, buflen += 100);
                    wbptr = workbuf + wblen;
                }
                wblen++;
                *wbptr++ = sel_nl[i];
            }
        }
        top.y++;
        top.x = 0;
    }
    write_clip (workbuf, wblen, FALSE); /* transfer to clipboard */
    if ( buflen > 0 )   /* indicates we allocated this buffer */
        sfree(workbuf);

}
void term_copyall (void) {
    pos top;
    top.y = -count234(scrollback);
    top.x = 0;
    clipme(top, curs, NULL /* dynamic allocation */);
}

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

    ldata = lineptr(p.y);

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

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

void term_mouse (Mouse_Button b, Mouse_Action a, int x, int y) {
    pos selpoint;
    unsigned long *ldata;
    
    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.y = y + disptop;
    selpoint.x = x;
    ldata = lineptr(selpoint.y);
    if ((ldata[cols]&LATTR_MODE) != LATTR_NORM)
        selpoint.x /= 2;

    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;
        incpos(selend);
        sel_spread();
    } else if ((b == MB_SELECT && a == MA_DRAG) ||
               (b == MB_EXTEND && a != MA_RELEASE)) {
        if (selstate == ABOUT_TO && poseq(selanchor, selpoint))
            return;
        if (b == MB_EXTEND && a != MA_DRAG && selstate == SELECTED) {
            if (posdiff(selpoint,selstart) < posdiff(selend,selstart)/2) {
                selanchor = selend;
                decpos(selanchor);
            } else {
                selanchor = selstart;
            }
            selstate = DRAGGING;
        }
        if (selstate != ABOUT_TO && selstate != DRAGGING)
            selanchor = selpoint;
        selstate = DRAGGING;
        if (poslt(selpoint, selanchor)) {
            selstart = selpoint;
            selend = selanchor;
            incpos(selend);
        } else {
            selstart = selanchor;
            selend = selpoint;
            incpos(selpoint);
        }
        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.
             */
            clipme(selstart, selend, selspace);
            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.x = selstart.y = selend.x = selend.y = 0;
}

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

int term_ldisc(int option) {
    if (option == LD_ECHO) return term_echoing;
    if (option == LD_EDIT) return term_editing;
    return FALSE;
}

/*
 * 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++;
    }
}

/*
 * Log session traffic.
 */
void logtraffic(unsigned char c, int logmode) {
    if (cfg.logtype > 0) {
        if (cfg.logtype == logmode) {
            /* deferred open file from pgm start? */
            if (!lgfp) logfopen();
            if (lgfp) fputc (c, lgfp);
        }
    }
}

/* open log file append/overwrite mode */
void logfopen(void) {
    char buf[256];
    time_t t;
    struct tm *tm;
    char writemod[4];

    if (!cfg.logtype)
        return;
    sprintf (writemod, "wb");          /* default to rewrite */
    lgfp = fopen(cfg.logfilename, "r");  /* file already present? */
    if (lgfp) {
        int i;
        fclose(lgfp);
        i = askappend(cfg.logfilename);
        if (i == 1)
            writemod[0] = 'a';         /* set append mode */
        else if (i == 0) {             /* cancelled */
            lgfp = NULL;
            cfg.logtype = 0;           /* disable logging */
            return;
        }
    }

    lgfp = fopen(cfg.logfilename, writemod);
    if (lgfp) { /* enter into event log */
        sprintf(buf, "%s session log (%s mode) to file : ",
                (writemod[0] == 'a') ? "Appending" : "Writing new",
                (cfg.logtype == LGTYP_ASCII ? "ASCII" :
                 cfg.logtype == LGTYP_DEBUG ? "raw" : "<ukwn>")  );
        /* Make sure we do not exceed the output buffer size */
        strncat (buf, cfg.logfilename, 128);
        buf[strlen(buf)] = '\0';
        logevent(buf);

        /* --- write header line iinto log file */
        fputs ("=~=~=~=~=~=~=~=~=~=~=~= PuTTY log ", lgfp);
        time(&t);
        tm = localtime(&t);
        strftime(buf, 24, "%Y.%m.%d %H:%M:%S", tm);
        fputs (buf, lgfp);
        fputs (" =~=~=~=~=~=~=~=~=~=~=~=\r\n", lgfp);
    }
}

void logfclose (void) {
    if (lgfp) { fclose(lgfp); lgfp = NULL; }
}