/* Copyright (C) 2001-2006 Artifex Software, Inc.
   All Rights Reserved.

   This software is provided AS-IS with no warranty, either express or
   implied.

   This software is distributed under license and may not be copied, modified
   or distributed except as expressly authorized under the terms of that
   license.  Refer to licensing information at http://www.artifex.com/
   or contact Artifex Software, Inc.,  7 Mt. Lassen Drive - Suite A-134,
   San Rafael, CA  94903, U.S.A., +1(415)492-9861, for further information.
*/
/* $Id$*/
/*
 * This is a driver for the AT&T 3b1/7300/UnixPC console display.
 *
 * The image is built in a buffer the size of the page.  Once complete,
 * a screen-sized subset is copied to the screen, and one can scroll
 * through the entire image (move with "vi" or arrow keys).
 *
 * Written by Andy Fyfe, andy@cs.caltech.edu.
 *
 * There are a couple of undesirable "features" that I have found no
 * way to work around.
 *
 * 1) Gs attempts to save the contents of the window before using it, and
 *    then restores the contents afterward.  However, if the gs window is
 *    not the current window, and there are small windows present, then
 *    the saved image is incorrect, and thus the screen will not be correctly
 *    restored.  This seems to be a bug in the 3b1 window driver.  Making
 *    the gs window current before saving its contents is not an acceptable
 *    solution.
 *
 * 2) Gs will enable the scrolling/help/cancel icons if the window has
 *    a border.  Changing these border icons has the side effect of making
 *    the gs window current.  This does circumvent the first problem though.
 */

/*
 * About the ATT3B1_PERF flag (notes by Andy Fyfe):
 *
 * I am unable to profile gs on the 3b1, so I added ATT3B1_PERF as a
 * quick way to find out how much time was spent in the 3b1 driver,
 * through dynamically suppressing parts of the code at run time by
 * setting environment variables.  I can then get the time spent in
 * those parts by comparing the results of "time gs ....".
 *
 * At one point this was very useful, and led to a fairly substantial
 * speedup of the fill and copy_mono routines.  It also showed that I
 * wasn't going to get too much more, overall, by further attempts to
 * optimize the 3b1 driver.  So those parts of the code controlled by
 * ATT3B1_PERF have really now outlived their usefulness.
 */

#include "gx.h"
#include "gxdevice.h"
#include "gserrors.h"

#include <errno.h>
#include <sys/window.h>
#include <sys/termio.h>

typedef struct gx_device_att3b1_s {
    gx_device_common;
    int fd;				/* window file descriptor */
    uchar *screen;			/* pointer to screen image */
    ushort line_size;			/* size of screen line in bytes */
    ulong screen_size;			/* size of screen image in bytes */
    int page_num;				/* page number */
#ifdef ATT3B1_PERF
    char *no_output, *no_fill, *no_copy;
#endif
} gx_device_att3b1;
#define att3b1dev ((gx_device_att3b1 *)dev)

#define XDPI	100		/* to get a more-or-less square aspect ratio */
#define YDPI	72
#define XSIZE (8.5 * XDPI)	/* 8.5 x 11 inch page, by default */
#define YSIZE (11 * YDPI)

static const ushort masks[] = { 0,
    0x0001, 0x0003, 0x0007, 0x000f,
    0x001f, 0x003f, 0x007f, 0x00ff,
    0x01ff, 0x03ff, 0x07ff, 0x0fff,
    0x1fff, 0x3fff, 0x7fff, 0xffff,
};
static uchar reverse_bits[256] = {
  0, 128, 64, 192, 32, 160, 96, 224, 16, 144, 80, 208, 48, 176, 112, 240,
  8, 136, 72, 200, 40, 168, 104, 232, 24, 152, 88, 216, 56, 184, 120, 248,
  4, 132, 68, 196, 36, 164, 100, 228, 20, 148, 84, 212, 52, 180, 116, 244,
  12, 140, 76, 204, 44, 172, 108, 236, 28, 156, 92, 220, 60, 188, 124, 252,
  2, 130, 66, 194, 34, 162, 98, 226, 18, 146, 82, 210, 50, 178, 114, 242,
  10, 138, 74, 202, 42, 170, 106, 234, 26, 154, 90, 218, 58, 186, 122, 250,
  6, 134, 70, 198, 38, 166, 102, 230, 22, 150, 86, 214, 54, 182, 118, 246,
  14, 142, 78, 206, 46, 174, 110, 238, 30, 158, 94, 222, 62, 190, 126, 254,
  1, 129, 65, 193, 33, 161, 97, 225, 17, 145, 81, 209, 49, 177, 113, 241,
  9, 137, 73, 201, 41, 169, 105, 233, 25, 153, 89, 217, 57, 185, 121, 249,
  5, 133, 69, 197, 37, 165, 101, 229, 21, 149, 85, 213, 53, 181, 117, 245,
  13, 141, 77, 205, 45, 173, 109, 237, 29, 157, 93, 221, 61, 189, 125, 253,
  3, 131, 67, 195, 35, 163, 99, 227, 19, 147, 83, 211, 51, 179, 115, 243,
  11, 139, 75, 203, 43, 171, 107, 235, 27, 155, 91, 219, 59, 187, 123, 251,
  7, 135, 71, 199, 39, 167, 103, 231, 23, 151, 87, 215, 55, 183, 119, 247,
  15, 143, 79, 207, 47, 175, 111, 239, 31, 159, 95, 223, 63, 191, 127, 255
};

dev_proc_open_device(att3b1_open);
dev_proc_close_device(att3b1_close);
dev_proc_fill_rectangle(att3b1_fill_rectangle);
dev_proc_copy_mono(att3b1_copy_mono);
dev_proc_output_page(att3b1_output_page);

static gx_device_procs att3b1_procs = {
    att3b1_open,
    gx_default_get_initial_matrix,
    gx_default_sync_output,
    att3b1_output_page,
    att3b1_close,
    gx_default_map_rgb_color,
    gx_default_map_color_rgb,
    att3b1_fill_rectangle,
    gx_default_tile_rectangle,
    att3b1_copy_mono,
    gx_default_copy_color,
    gx_default_draw_line,
    gx_default_get_bits
};

gx_device_att3b1 gs_att3b1_device = {
    std_device_std_body(gx_device_att3b1, &att3b1_procs, "att3b1",
      XSIZE, YSIZE, XDPI, YDPI),
     { 0 },			/* std_procs */
    -1, 0, 0,			/* fd, screen, line_size, */
    0, 0,			/* screen size, page */
#ifdef ATT3B1_PERF
    0, 0, 0,			/* no_output, no_fill, no_copy */
#endif
};

int
att3b1_open(gx_device *dev)
{
    struct uwdata uw;

#ifdef ATT3B1_PERF
    char *getenv(const char *);
#endif

    if (att3b1dev->fd >= 0) {
        close(att3b1dev->fd);
        att3b1dev->fd = -1;
    }

    if (att3b1dev->screen != NULL) {
        gs_free(dev->memory, (char *)att3b1dev->screen,
                att3b1dev->screen_size, 1, "att3b1_open");
        att3b1dev->screen = 0;
        att3b1dev->screen_size = 0;
    }

    att3b1dev->fd = open("/dev/tty", 2);
    if (att3b1dev->fd < 0) {
        lprintf1("att3b1_open: open /dev/tty failed [%d]\n", errno);
        return_error(gs_error_ioerror);
    }

    /* Verify that /dev/tty is associated with a console window. */
    if (ioctl(att3b1dev->fd, WIOCGETD, &uw) < 0) {
        lprintf1("att3b1_open: can not obtain window data [%d]\n", errno);
        lprintf("att3b1_open: the att3b1 device requires a console window\n");
        att3b1_close(dev);
        return_error(gs_error_ioerror);
    }

    /* we need an even number of bytes per line */
    att3b1dev->line_size = ((att3b1dev->width + 15) / 16) * 2;
    att3b1dev->screen_size = att3b1dev->line_size * att3b1dev->height;

    att3b1dev->screen =
        (uchar *)gs_malloc(dev->memory, att3b1dev->screen_size, 1, "att3b1_open");
    if (att3b1dev->screen == NULL) {
        att3b1_close(dev);
        return_error(gs_error_VMerror);
    }

    att3b1dev->page_num = 1;

#ifdef ATT3B1_PERF
    att3b1dev->no_output = getenv("GS_NOOUTPUT");
    att3b1dev->no_fill = getenv("GS_NOFILL");
    att3b1dev->no_copy = getenv("GS_NOCOPY");
#endif

    return 0;
}

int
att3b1_close(gx_device *dev)
{
    if (att3b1dev->fd >= 0) {
        close(att3b1dev->fd);
        att3b1dev->fd = -1;
    }

    if (att3b1dev->screen != NULL) {
        gs_free(dev->memory, (char *)att3b1dev->screen,
                att3b1dev->screen_size, 1, "att3b1_close");
        att3b1dev->screen = 0;
        att3b1dev->screen_size = 0;
    }

    return 0;
}

int
att3b1_fill_rectangle(gx_device *dev, int x, int y, int w, int h,
                      gx_color_index colour)
{
    uint o, b, wl, wr, w2;
    ushort *p, *q, maskl, maskr;

#ifdef ATT3B1_PERF
    if (att3b1dev->no_fill) return 0;
#endif

    fit_fill(dev, x, y, w, h);

    /* following fit_fill, we can assume x, y, w, h are unsigned. */

    p = (ushort *)&att3b1dev->screen[(ushort)y*att3b1dev->line_size] +
        (uint)x/16;
    o = (uint)x % 16;
    b = 16 - o;
    wl = ((uint)w < b) ? (uint)w : b;
    maskl = masks[wl] << o;
    w -= wl;
    wr = (uint)w % 16;
    maskr = masks[wr];

    if (colour == 0) {
        maskl = ~maskl;
        maskr = ~maskr;
        while (h-- > 0) {
            q = p;
            w2 = w;
            *q++ &= maskl;
            while (w2 >= 16) {
                *q++ = 0;
                w2 -= 16;
            }
            *q &= maskr;
            p += (att3b1dev->line_size / 2);
        }
    }
    else {
        while (h-- > 0) {
            q = p;
            w2 = w;
            *q++ |= maskl;
            while (w2 >= 16) {
                *q++ = 0xffff;
                w2 -= 16;
            }
            *q |= maskr;
            p += (att3b1dev->line_size / 2);
        }
    }

    return 0;
}

#ifdef __GNUC__
#define rotate(value, count) \
    asm("ror%.l	%2,%0" : "=d" (value) : "0" (value), "d" (count))
#else
#define rotate(value, count) \
    value = (value >> count) | (value << (32-count))
#endif

int
att3b1_copy_mono(gx_device *dev, const uchar *data,
                 int data_x, int raster, gx_bitmap_id id,
                 int x, int y, int width, int height,
                 gx_color_index colour0, gx_color_index colour1)
{
    const ushort *src_p, *src_q;
    ushort *dst_p, *dst_q;
    ulong bits, mask, *p;
    uint src_o, src_b, dst_o, dst_b, op;
    uint w1, w2;

#ifdef ATT3B1_PERF
    if (att3b1dev->no_copy) return 0;
#endif

    if (colour1 == colour0)		/* vacuous case */
        return att3b1_fill_rectangle(dev, x, y, width, height, colour0);

    fit_copy(dev, data, data_x, raster, id, x, y, width, height);

    /* following fit_copy, we can assume x, y, width, height are unsigned. */

    /*
     * In what follows, we're assuming that each row of the input bitmap
     * is short-aligned, that is, that both "data" and "raster" are even.
     */
    src_p = ((const ushort *)data) + (uint)data_x/16;
    src_o = (uint)data_x % 16;
    src_b = 16 - src_o;

    dst_p = (ushort *)&att3b1dev->screen[(ushort)y*att3b1dev->line_size] +
            (uint)x/16;
    dst_o = (uint)x % 16;
    dst_b = 16 - dst_o;

    op = (int)colour0 * 3 + (int)colour1 + 4;

    while (height-- > 0) {
        w2 = width;
        src_q = src_p;
        dst_q = dst_p;

        while (w2 > 0) {
            w1 = (w2 < 16) ? w2 : 16;
            mask = masks[w1];
            /*
             * We are assuming that the bitmap "data" is typically aligned.
             * Thus the test for this special case is typically a win over
             * a 16-bit shift.
             */
            if (src_o == 0)
                bits = *src_q++;
            else {
                bits = *((ulong *)src_q) >> src_b;
                bits &= 0xffff;
                src_q++;
            }
            if (w1 <= 8)
                bits = reverse_bits[bits>>8];
            else
                bits = (reverse_bits[bits&0xff] << 8) | reverse_bits[bits>>8];
            /*
             * While the input bit map is assumed to be typically aligned, we
             * assume that the place in the image is not.  Thus we don't
             * separate out the aligned case.  Doing so would cost a test,
             * and only reduce the average shift by about 1.
             */
            p = (ulong *)dst_q;
            switch(op) {
            case 1:	/* not src and dst */
                bits = ~(bits & mask);
                rotate(bits,dst_b);
                *p &= bits;
                break;
            case 2:	/* src or dst */
                bits = bits & mask;
                rotate(bits,dst_b);
                *p |= bits;
                break;
            case 3:	/* src and dst */
                bits = bits | ~mask;
                rotate(bits,dst_b);
                *p &= bits;
                break;
            case 5:	/* src */
                rotate(bits,dst_b);
                rotate(mask,dst_b);
                *p = (*p & ~mask) | (bits & mask);
                break;
            case 6:	/* not src or dst */
                bits = ~bits & mask;
                rotate(bits,dst_b);
                *p |= bits;
                break;
            case 7:	/* not src */
                rotate(bits,dst_b);
                rotate(mask,dst_b);
                *p = (*p & ~mask) | (~bits & mask);
                break;
            }
            dst_q++;
            w2 -= w1;
        }

        src_p += (raster / 2);
        dst_p += (att3b1dev->line_size / 2);
    }

    return 0;
}

static int getKeyboard(gx_device *);

const char *help_msg[] = {
    "h, j, k, l, UP, DOWN, LEFT, RIGHT  move the page (0.25\" h, 0.5\" v)",
    "H, J, K, L, BEG, END               move to far edge of the page",
    "^U, ^D, ROLL UP, ROLL DOWN	        scroll up or down (1/2 screen height)",
    "^F, ^B, PAGE UP, PAGE DOWN	        scroll up or down (full screen height)",
    "c, C                               centre page horizontally, vertically",
    "<, >, ^, _                         fine movements (single pixel)",
    "^L, ^R, r, HOME                    move to default position",
    "=, MARK                            make current position the default",
    "I                                  invert the image (black <-> white)",
    "q, x, ^C, EXIT, CANCL, n, f, NEXT,",
    "    SPACE, RETURN, ENTER           end the page",
    "?, HELP                            help screen",
};

static void
do_help(gx_device *dev)
{
    int i;
    struct utdata ut;

    /* we would like to save the cursor position, but we can't */
    write(att3b1dev->fd, "\033[2J\033[H", 7);

    /* write help screen */
    for (i=0; i < sizeof(help_msg)/sizeof(help_msg[0]); ++i) {
        write(att3b1dev->fd, help_msg[i], strlen(help_msg[i]));
        write(att3b1dev->fd, "\n", 1);
    }
    ut.ut_num = WTXTSLK1;
    strcpy(ut.ut_text, "Press any key to continue");
    ioctl(att3b1dev->fd, WIOCSETTEXT, &ut);

    /* wait for keyboard input */
    i = getKeyboard(dev);

    /* clear screen and put cursor at the bottom of the screen */
    write(att3b1dev->fd, "\033[2J\033[99;1H", 11);
}

static int
att3b1_do_output_page(gx_device *dev, int num_copies, int flush)
{
    struct urdata ur;
    struct utdata ut, ut_orig;
    struct uwdata uw;
    int uflags;
    struct termio old, new;
    int xorigin, yorigin;
    static int def_xorigin = 0, def_yorigin = 0;
    int screen_width, screen_height;
    int inverted = 0;
    int error = 0;
    int ch;
    ushort *p;
    ushort save_image[WINWIDTH * WINHEIGHT / 16];

#ifdef ATT3B1_PERF
    if (att3b1dev->no_output) return 0;
#endif

    /*
     * initialize, and save screen state
     */

    if (ioctl(att3b1dev->fd, WIOCGETD, &uw) < 0) {
        lprintf1("att3b1_output_page: window WIOCGETD ioctl failed [%d]\n",
            errno);
        att3b1_close(dev);
        return_error(gs_error_ioerror);
    }

    /*
     * we assume, henceforth, that screen ioctl calls will succeed
     */

    write(att3b1dev->fd, "\a\033[=1C", 6);

    uflags = uw.uw_uflags;
    if (!(uflags & NBORDER)) {
        uw.uw_uflags = BORDHSCROLL | BORDVSCROLL | BORDHELP | BORDCANCEL;
        ioctl(att3b1dev->fd, WIOCSETD, &uw);
    }

    ut_orig.ut_num = WTXTSLK1;
    ioctl(att3b1dev->fd, WIOCGETTEXT, &ut_orig);

    /* This isn't necessary, but helps a bit when the following attempt
       to get the current screen image fails (without any indication). */
    memset(save_image, '\0', sizeof(save_image));

    ur.ur_srcbase = 0;
    ur.ur_srcwidth = 0;
    ur.ur_srcx = 0;
    ur.ur_srcy = 0;
    ur.ur_dstbase = save_image;
    ur.ur_dstwidth = WINWIDTH / 8;
    ur.ur_dstx = 0;
    ur.ur_dsty = 0;
    ur.ur_width = uw.uw_width;
    ur.ur_height = uw.uw_height;
    ur.ur_srcop = SRCSRC;
    ur.ur_dstop = DSTSRC;
    ur.ur_pattern = 0;
    ioctl(att3b1dev->fd, WIOCRASTOP, &ur);

    ioctl(att3b1dev->fd, TCGETA, &old);
    new = old;
    new.c_lflag &= ~(ISIG | ICANON | ECHO | ECHOE | ECHOK | ECHONL);
    new.c_cc[VMIN] = 1;
    ioctl(att3b1dev->fd, TCSETAF, &new);

    screen_width = (uw.uw_width < att3b1dev->width) ? uw.uw_width
                                : att3b1dev->width;
    screen_height = (uw.uw_height < att3b1dev->height) ? uw.uw_height
                                : att3b1dev->height;

    write(att3b1dev->fd, "\033[2J", 4);

    ur.ur_srcwidth = att3b1dev->line_size;
    ur.ur_width = screen_width;
    ur.ur_height = screen_height;
    ur.ur_dstbase = 0;
    ur.ur_dstwidth = 0;

    /*
     * allow one to move the screen window through the entire image
     */

    xorigin = def_xorigin;
    yorigin = def_yorigin;

    while (1) {
        /* Things go bad if ur_srcx >= 2048 */
        ur.ur_srcbase = (ushort *)att3b1dev->screen + (xorigin >> 4);
        ur.ur_srcx = xorigin & 15;
        ur.ur_srcy = yorigin;

        if (ioctl(att3b1dev->fd, WIOCRASTOP, &ur) < 0) {
            lprintf1(
                "att3b1_output_page: window WIOCRASTOP ioctl failed [%d]\n",
                errno);
            error = gs_error_ioerror;
        }

        ut.ut_num = WTXTSLK1;
        sprintf(ut.ut_text,
            "%s %d, top right (%d,%d), size (%d,%d), press '?' for help.",
            flush ? "Showpage" : "Copypage", att3b1dev->page_num, xorigin, yorigin,
            att3b1dev->width, att3b1dev->height);
        ioctl(att3b1dev->fd, WIOCSETTEXT, &ut);

        ch = error ? 'q' : getKeyboard(dev);

        switch(ch) {
        case 'h':
            xorigin -= ((uint)(int)att3b1dev->x_pixels_per_inch+3)/4;
            break;

        case 'k':
            yorigin -= ((uint)(int)att3b1dev->y_pixels_per_inch+1)/2;
            break;

        case 'l':
            xorigin += ((uint)(int)att3b1dev->x_pixels_per_inch+3)/4;
            break;

        case 'j':
            yorigin += ((uint)(int)att3b1dev->y_pixels_per_inch+1)/2;
            break;

        case 'H':
            xorigin = 0;
            break;

        case 'K':
            yorigin = 0;
            break;

        case 'L':
            xorigin = att3b1dev->width - screen_width;
            break;

        case 'J':
            yorigin = att3b1dev->height - screen_height;
            break;

        case '<':
            xorigin -= 1;
            break;

        case '>':
            xorigin += 1;
            break;

        case '^':
            yorigin -= 1;
            break;

        case '_':
            yorigin += 1;
            break;

        case '\025':	/* control-U */
            yorigin -= screen_height/2;
            break;

        case '\004':	/* control-D */
            yorigin += screen_height/2;
            break;

        case '\002':	/* control-B */
            yorigin -= screen_height;
            break;

        case '\006':	/* control-F */
            yorigin += screen_height;
            break;

        case '\f':
        case 'r' :
        case '\022':	/* control-R */
            xorigin = def_xorigin;
            yorigin = def_yorigin;
            break;

        case 'c':	/* centre horizontally */
            xorigin = (att3b1dev->width - screen_width) / 2;
            break;

        case 'C':	/* centre vertically */
            yorigin = (att3b1dev->height - screen_height) / 2;
            break;

        case '=':
            def_xorigin = xorigin;
            def_yorigin = yorigin;
            break;

        case 'I':
            for (p = (ushort *)att3b1dev->screen;
              p < (ushort *)&att3b1dev->screen[att3b1dev->screen_size]; ++p)
                *p = ~ *p;
            inverted = !inverted;
            break;

        case '?':
            do_help(dev);
            break;

        case -1:
            error = gs_error_ioerror;
            /* fall through, for cleanup */

        case 'q':
        case 'x':
        case '\003':	/* control-C */
        case 'n':
        case 'f':
        case ' ':
        case '\n':
        case '\r':
            if (flush)
                att3b1dev->page_num++;
            else if (inverted)	/* restore inverted image for copypage */
                for (p = (ushort *)att3b1dev->screen;
                  p < (ushort *)&att3b1dev->screen[att3b1dev->screen_size]; ++p)
                    *p = ~ *p;
            if (!(uflags & NBORDER)) {
                ioctl(att3b1dev->fd, WIOCGETD, &uw); /*window may have moved*/
                uw.uw_uflags = uflags;
                ioctl(att3b1dev->fd, WIOCSETD, &uw);
            }
            ur.ur_srcbase = save_image;
            ur.ur_srcwidth = WINWIDTH / 8;
            ur.ur_width = uw.uw_width;
            ur.ur_height = uw.uw_height;
            ur.ur_srcx = 0;
            ur.ur_srcy = 0;
            ioctl(att3b1dev->fd, WIOCRASTOP, &ur);
            ioctl(att3b1dev->fd, WIOCSETTEXT, &ut_orig);
            ioctl(att3b1dev->fd, TCSETAF, &old);
            write(att3b1dev->fd, "\033[=0C", 5);

            if (error) {
                att3b1_close(dev);
                return_error(error);
            }
            else
                return 0;
        }

        if (xorigin >= att3b1dev->width - screen_width)
            xorigin = att3b1dev->width - screen_width;
        if (xorigin < 0)
            xorigin = 0;
        if (yorigin >= att3b1dev->height - screen_height)
            yorigin = att3b1dev->height - screen_height;
        if (yorigin < 0)
            yorigin = 0;
    }
}
int
att3b1_output_page(gx_device *dev, int num_copies, int flush)
{
    int code = att3b1_do_output_page(dev, num_copies, flush);

    if (code >= 0)
        code = gx_finish_output_page(dev, num_copies, flush);
    return code;
}

static int
get_char(gx_device *dev)
{
    char ch;
    int count;

    count = read(att3b1dev->fd, &ch, 1);
    if (count == 0)
        return 'q';
    else if (count < 0)
        return -1;
    else
        return ch;
}

static int
getKeyboard(gx_device *dev)
{
    char ch;

    ch = get_char(dev);

    if (ch != '\033')
        return ch;

    /*
     * If the char is escape, interpret the escape sequence and return
     * an equivalent single character.
     *
     * Note that a mouse click on a window border icon is translated
     * to the corresponding key, for example, the "up" icon generates
     * roll-up/page-up/beg for the left/middle/right mouse button.
     */

    switch (get_char(dev)) {
    case '[':
        switch(get_char(dev)) {
        case 'A':	/* up arrow */
            return 'k';
        case 'T':	/* shift up arrow (roll up) */
            return '\025';
        case 'B':	/* down arrow */
            return 'j';
        case 'S':	/* shift down arrow (roll down) */
            return '\004';
        case 'C':	/* right arrow */
            return 'l';
        case 'D':	/* left arrow */
            return 'h';
        case 'H':	/* home */
            return 'r';
        case 'U':	/* page down */
            return '\006';
        case 'V':	/* page up */
            return '\002';
        }
        break;
    case 'O':
        switch(get_char(dev)) {
        case 'm':	/* help */
        case 'M':	/* shift help */
            return '?';
        case 'k':	/* exit */
        case 'K':	/* shift exit */
        case 'w':	/* cancl */
        case 'W':	/* shift cancl */
            return 'q';
        }
        break;
    case 'N':
        switch(get_char(dev)) {
        case 'h':	/* next */
            return 'f';
        case 'i':	/* mark */
            return '=';
        case 'L':	/* shift right arrow */
            return 'l';
        case 'K':	/* shift left arrow */
            return 'h';
        }
        break;
    case '9':	/* Beg */
        return 'K';
    case '0':	/* End */
        return 'J';
    }
    return '\0';
}