/* $OpenBSD: lib_mouse.c,v 1.15 2023/10/17 09:52:08 nicm Exp $ */

/****************************************************************************
 * Copyright 2018-2022,2023 Thomas E. Dickey                                *
 * Copyright 1998-2016,2017 Free Software Foundation, Inc.                  *
 *                                                                          *
 * Permission is hereby granted, free of charge, to any person obtaining a  *
 * copy of this software and associated documentation files (the            *
 * "Software"), to deal in the Software without restriction, including      *
 * without limitation the rights to use, copy, modify, merge, publish,      *
 * distribute, distribute with modifications, sublicense, and/or sell       *
 * copies of the Software, and to permit persons to whom the Software is    *
 * furnished to do so, subject to the following conditions:                 *
 *                                                                          *
 * The above copyright notice and this permission notice shall be included  *
 * in all copies or substantial portions of the Software.                   *
 *                                                                          *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS  *
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF               *
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.   *
 * IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,   *
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR    *
 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR    *
 * THE USE OR OTHER DEALINGS IN THE SOFTWARE.                               *
 *                                                                          *
 * Except as contained in this notice, the name(s) of the above copyright   *
 * holders shall not be used in advertising or otherwise to promote the     *
 * sale, use or other dealings in this Software without prior written       *
 * authorization.                                                           *
 ****************************************************************************/

/****************************************************************************
 *  Author: Zeyd M. Ben-Halim <zmbenhal@netcom.com> 1992,1995               *
 *     and: Eric S. Raymond <esr@snark.thyrsus.com>                         *
 *     and: Thomas E. Dickey                        1996-on                 *
 *     and: Juergen Pfeifer                         2008                    *
 ****************************************************************************/

/*
 * This module is intended to encapsulate ncurses's interface to pointing
 * devices.
 *
 * The primary method used is xterm's internal mouse-tracking facility.
 * Additional methods depend on the platform:
 *      Alessandro Rubini's GPM server (Linux)
 *      sysmouse (FreeBSD)
 *      special-purpose mouse interface for OS/2 EMX.
 *
 * Notes for implementors of new mouse-interface methods:
 *
 * The code is logically split into a lower level that accepts event reports
 * in a device-dependent format and an upper level that parses mouse gestures
 * and filters events.  The mediating data structure is a circular queue of
 * MEVENT structures.
 *
 * Functionally, the lower level's job is to pick up primitive events and
 * put them on the circular queue.  This can happen in one of two ways:
 * either (a) _nc_mouse_event() detects a series of incoming mouse reports
 * and queues them, or (b) code in lib_getch.c detects the kmous prefix in
 * the keyboard input stream and calls _nc_mouse_inline to queue up a series
 * of adjacent mouse reports.
 *
 * In either case, _nc_mouse_parse() should be called after the series is
 * accepted to parse the digested mouse reports (low-level MEVENTs) into
 * a gesture (a high-level or composite MEVENT).
 *
 * Don't be too shy about adding new event types or modifiers, if you can find
 * room for them in the 32-bit mask.  The API is written so that users get
 * feedback on which theoretical event types they won't see when they call
 * mousemask. There's one bit per button (the RESERVED_EVENT bit) not being
 * used yet, and a couple of bits open at the high end.
 */

#ifdef __EMX__
#  include <io.h>
#  define  INCL_DOS
#  define  INCL_VIO
#  define  INCL_KBD
#  define  INCL_MOU
#  define  INCL_DOSPROCESS
#  include <os2.h>              /* Need to include before the others */
#endif

#include <curses.priv.h>

#ifndef CUR
#define CUR SP_TERMTYPE
#endif

MODULE_ID("$Id: lib_mouse.c,v 1.15 2023/10/17 09:52:08 nicm Exp $")

#include <tic.h>

#if USE_GPM_SUPPORT
#include <linux/keyboard.h>     /* defines KG_* macros */

#ifdef HAVE_LIBDL
/* use dynamic loader to avoid linkage dependency */
#include <dlfcn.h>

#ifdef RTLD_NOW
#define my_RTLD RTLD_NOW
#else
#ifdef RTLD_LAZY
#define my_RTLD RTLD_LAZY
#else
make an error
#endif
#endif                          /* RTLD_NOW */
#endif                          /* HAVE_LIBDL */

#endif                          /* USE_GPM_SUPPORT */

#if USE_SYSMOUSE
#undef buttons                  /* symbol conflict in consio.h */
#undef mouse_info               /* symbol conflict in consio.h */
#include <osreldate.h>
#if defined(__DragonFly_version) || (defined(__FreeBSD__) && (__FreeBSD_version >= 400017))
#include <sys/consio.h>
#include <sys/fbio.h>
#else
#include <machine/console.h>
#endif
#endif                          /* use_SYSMOUSE */

#if USE_KLIBC_MOUSE
#include <sys/socket.h>
#define pipe(handles) socketpair(AF_LOCAL, SOCK_STREAM, 0, handles)
#define DosWrite(hfile, pbuffer, cbwrite, pcbactual) \
                write(hfile, pbuffer, cbwrite)
#define DosExit(action, result )        /* do nothing */
#define DosCreateThread(ptid, pfn, param, flag, cbStack) \
                (*(ptid) = _beginthread(pfn, NULL, cbStack, \
                                        (void *)param), (*(ptid) == -1))
#endif

#define MY_TRACE TRACE_ICALLS|TRACE_IEVENT

#define MASK_RELEASE(x)         (mmask_t) NCURSES_MOUSE_MASK(x, 001)
#define MASK_PRESS(x)           (mmask_t) NCURSES_MOUSE_MASK(x, 002)
#define MASK_CLICK(x)           (mmask_t) NCURSES_MOUSE_MASK(x, 004)
#define MASK_DOUBLE_CLICK(x)    (mmask_t) NCURSES_MOUSE_MASK(x, 010)
#define MASK_TRIPLE_CLICK(x)    (mmask_t) NCURSES_MOUSE_MASK(x, 020)
#define MASK_RESERVED_EVENT(x)  (mmask_t) NCURSES_MOUSE_MASK(x, 040)

#if NCURSES_MOUSE_VERSION == 1

#define BUTTON_CLICKED        (BUTTON1_CLICKED        | BUTTON2_CLICKED        | BUTTON3_CLICKED        | BUTTON4_CLICKED)
#define BUTTON_PRESSED        (BUTTON1_PRESSED        | BUTTON2_PRESSED        | BUTTON3_PRESSED        | BUTTON4_PRESSED)
#define BUTTON_RELEASED       (BUTTON1_RELEASED       | BUTTON2_RELEASED       | BUTTON3_RELEASED       | BUTTON4_RELEASED)
#define BUTTON_DOUBLE_CLICKED (BUTTON1_DOUBLE_CLICKED | BUTTON2_DOUBLE_CLICKED | BUTTON3_DOUBLE_CLICKED | BUTTON4_DOUBLE_CLICKED)
#define BUTTON_TRIPLE_CLICKED (BUTTON1_TRIPLE_CLICKED | BUTTON2_TRIPLE_CLICKED | BUTTON3_TRIPLE_CLICKED | BUTTON4_TRIPLE_CLICKED)

#define MAX_BUTTONS  4

#else

#define BUTTON_CLICKED        (BUTTON1_CLICKED        | BUTTON2_CLICKED        | BUTTON3_CLICKED        | BUTTON4_CLICKED        | BUTTON5_CLICKED)
#define BUTTON_PRESSED        (BUTTON1_PRESSED        | BUTTON2_PRESSED        | BUTTON3_PRESSED        | BUTTON4_PRESSED        | BUTTON5_PRESSED)
#define BUTTON_RELEASED       (BUTTON1_RELEASED       | BUTTON2_RELEASED       | BUTTON3_RELEASED       | BUTTON4_RELEASED       | BUTTON5_RELEASED)
#define BUTTON_DOUBLE_CLICKED (BUTTON1_DOUBLE_CLICKED | BUTTON2_DOUBLE_CLICKED | BUTTON3_DOUBLE_CLICKED | BUTTON4_DOUBLE_CLICKED | BUTTON5_DOUBLE_CLICKED)
#define BUTTON_TRIPLE_CLICKED (BUTTON1_TRIPLE_CLICKED | BUTTON2_TRIPLE_CLICKED | BUTTON3_TRIPLE_CLICKED | BUTTON4_TRIPLE_CLICKED | BUTTON5_TRIPLE_CLICKED)

#if NCURSES_MOUSE_VERSION == 2
#define MAX_BUTTONS  5
#else
#define MAX_BUTTONS  11
#endif

#endif

#define INVALID_EVENT   -1
#define NORMAL_EVENT    0

#define ValidEvent(ep) ((ep)->id != INVALID_EVENT)
#define Invalidate(ep) (ep)->id = INVALID_EVENT

#if USE_GPM_SUPPORT

#ifndef LIBGPM_SONAME
#define LIBGPM_SONAME "libgpm.so"
#endif

#define GET_DLSYM(name) (my_##name = (TYPE_##name) dlsym(sp->_dlopen_gpm, #name))

#endif                          /* USE_GPM_SUPPORT */

static bool _nc_mouse_parse(SCREEN *, int);
static void _nc_mouse_resume(SCREEN *);
static void _nc_mouse_wrap(SCREEN *);

/* maintain a circular list of mouse events */

#define FirstEV(sp)     ((sp)->_mouse_events)
#define LastEV(sp)      ((sp)->_mouse_events + EV_MAX - 1)

#undef  NEXT
#define NEXT(ep)        ((ep >= LastEV(SP_PARM)) \
                         ? FirstEV(SP_PARM) \
                         : ep + 1)

#undef  PREV
#define PREV(ep)        ((ep <= FirstEV(SP_PARM)) \
                         ? LastEV(SP_PARM) \
                         : ep - 1)

#define IndexEV(sp, ep) (ep - FirstEV(sp))

#define RunParams(sp, eventp, runp) \
                (long) IndexEV(sp, runp), \
                (long) (IndexEV(sp, eventp) + (EV_MAX - 1)) % EV_MAX

#ifdef TRACE
static void
_trace_slot(SCREEN *sp, const char *tag)
{
    MEVENT *ep;

    _tracef("%s", tag);

    for (ep = FirstEV(sp); ep <= LastEV(sp); ep++)
        _tracef("mouse event queue slot %ld = %s",
                (long) IndexEV(sp, ep),
                _nc_tracemouse(sp, ep));
}
#endif

#if USE_EMX_MOUSE

#  define TOP_ROW          0
#  define LEFT_COL         0

#  define M_FD(sp) sp->_mouse_fd

static void
write_event(SCREEN *sp, int down, int button, int x, int y)
{
    char buf[6];
    unsigned long ignore;

    _nc_STRCPY(buf, "\033[M", sizeof(buf));     /* should be the same as key_mouse */
    buf[3] = ' ' + (button - 1) + (down ? 0 : 0x40);
    buf[4] = ' ' + x - LEFT_COL + 1;
    buf[5] = ' ' + y - TOP_ROW + 1;
    DosWrite(sp->_emxmouse_wfd, buf, 6, &ignore);
}

static void
#if USE_KLIBC_MOUSE
mouse_server(void *param)
#else
mouse_server(unsigned long param)
#endif
{
    SCREEN *sp = (SCREEN *) param;
    unsigned short fWait = MOU_WAIT;
    /* NOPTRRECT mourt = { 0,0,24,79 }; */
    MOUEVENTINFO mouev;
    HMOU hmou;
    unsigned short mask = MOUSE_BN1_DOWN | MOUSE_BN2_DOWN | MOUSE_BN3_DOWN;
    int nbuttons = 3;
    int oldstate = 0;
    char err[80];
    unsigned long rc;

    /* open the handle for the mouse */
    if (MouOpen(NULL, &hmou) == 0) {
        rc = MouSetEventMask(&mask, hmou);
        if (rc) {               /* retry with 2 buttons */
            mask = MOUSE_BN1_DOWN | MOUSE_BN2_DOWN;
            rc = MouSetEventMask(&mask, hmou);
            nbuttons = 2;
        }
        if (rc == 0 && MouDrawPtr(hmou) == 0) {
            for (;;) {
                /* sit and wait on the event queue */
                rc = MouReadEventQue(&mouev, &fWait, hmou);
                if (rc) {
                    _nc_SPRINTF(err, _nc_SLIMIT(sizeof(err))
                                "Error reading mouse queue, rc=%lu.\r\n", rc);
                    break;
                }
                if (!sp->_emxmouse_activated)
                    goto finish;

                /*
                 * OS/2 numbers a 3-button mouse inconsistently from other
                 * platforms:
                 *      1 = left
                 *      2 = right
                 *      3 = middle.
                 */
                if ((mouev.fs ^ oldstate) & MOUSE_BN1_DOWN)
                    write_event(sp, mouev.fs & MOUSE_BN1_DOWN,
                                sp->_emxmouse_buttons[1], mouev.col, mouev.row);
                if ((mouev.fs ^ oldstate) & MOUSE_BN2_DOWN)
                    write_event(sp, mouev.fs & MOUSE_BN2_DOWN,
                                sp->_emxmouse_buttons[3], mouev.col, mouev.row);
                if ((mouev.fs ^ oldstate) & MOUSE_BN3_DOWN)
                    write_event(sp, mouev.fs & MOUSE_BN3_DOWN,
                                sp->_emxmouse_buttons[2], mouev.col, mouev.row);

              finish:
                oldstate = mouev.fs;
            }
        } else {
            _nc_SPRINTF(err, _nc_SLIMIT(sizeof(err))
                        "Error setting event mask, buttons=%d, rc=%lu.\r\n",
                        nbuttons, rc);
        }

        DosWrite(2, err, strlen(err), &rc);
        MouClose(hmou);
    }
    DosExit(EXIT_THREAD, 0L);
}

#endif /* USE_EMX_MOUSE */

#if USE_SYSMOUSE
static void
sysmouse_server(SCREEN *sp)
{
    struct mouse_info the_mouse;
    MEVENT *work;

    the_mouse.operation = MOUSE_GETINFO;
    if (sp != 0
        && sp->_mouse_fd >= 0
        && sp->_sysmouse_tail < FIFO_SIZE
        && ioctl(sp->_mouse_fd, CONS_MOUSECTL, &the_mouse) != -1) {

        if (sp->_sysmouse_head > sp->_sysmouse_tail) {
            sp->_sysmouse_tail = 0;
            sp->_sysmouse_head = 0;
        }
        work = &(sp->_sysmouse_fifo[sp->_sysmouse_tail]);
        memset(work, 0, sizeof(*work));
        work->id = NORMAL_EVENT;        /* there's only one mouse... */

        sp->_sysmouse_old_buttons = sp->_sysmouse_new_buttons;
        sp->_sysmouse_new_buttons = the_mouse.u.data.buttons & 0x7;

        if (sp->_sysmouse_new_buttons) {
            if (sp->_sysmouse_new_buttons & 1)
                work->bstate |= BUTTON1_PRESSED;
            if (sp->_sysmouse_new_buttons & 2)
                work->bstate |= BUTTON2_PRESSED;
            if (sp->_sysmouse_new_buttons & 4)
                work->bstate |= BUTTON3_PRESSED;
        } else {
            if (sp->_sysmouse_old_buttons & 1)
                work->bstate |= BUTTON1_RELEASED;
            if (sp->_sysmouse_old_buttons & 2)
                work->bstate |= BUTTON2_RELEASED;
            if (sp->_sysmouse_old_buttons & 4)
                work->bstate |= BUTTON3_RELEASED;
        }

        /* for cosmetic bug in syscons.c on FreeBSD 3.[34] */
        the_mouse.operation = MOUSE_HIDE;
        ioctl(sp->_mouse_fd, CONS_MOUSECTL, &the_mouse);
        the_mouse.operation = MOUSE_SHOW;
        ioctl(sp->_mouse_fd, CONS_MOUSECTL, &the_mouse);

        /*
         * We're only interested if the button is pressed or released.
         * FIXME: implement continuous event-tracking.
         */
        if (sp->_sysmouse_new_buttons != sp->_sysmouse_old_buttons) {
            sp->_sysmouse_tail += 1;
        }
        work->x = the_mouse.u.data.x / sp->_sysmouse_char_width;
        work->y = the_mouse.u.data.y / sp->_sysmouse_char_height;
    }
}

static void
handle_sysmouse(int sig GCC_UNUSED)
{
    sysmouse_server(CURRENT_SCREEN);
}
#endif /* USE_SYSMOUSE */

#if !defined(USE_TERM_DRIVER) || defined(EXP_WIN32_DRIVER)
#define xterm_kmous "\033[M"

static void
init_xterm_mouse(SCREEN *sp)
{
    sp->_mouse_type = M_XTERM;
    sp->_mouse_format = MF_X10;
    sp->_mouse_xtermcap = tigetstr("XM");
    if (VALID_STRING(sp->_mouse_xtermcap)) {
        char *code = strstr(sp->_mouse_xtermcap, "[?");
        if (code != 0) {
            code += 2;
            while ((*code >= '0') && (*code <= '9')) {
                char *next = code;
                while ((*next >= '0') && (*next <= '9')) {
                    ++next;
                }
                if (!strncmp(code, "1006", (size_t) (next - code))) {
                    sp->_mouse_format = MF_SGR1006;
                }
#ifdef EXP_XTERM_1005
                if (!strncmp(code, "1005", (size_t) (next - code))) {
                    sp->_mouse_format = MF_XTERM_1005;
                }
#endif
                if (*next == ';') {
                    while (*next == ';') {
                        ++next;
                    }
                    code = next;
                } else {
                    break;
                }
            }
        }
    } else {
        int code = tigetnum("XM");
        switch (code) {
#ifdef EXP_XTERM_1005
        case 1005:
            /* see "xterm+sm+1005" */
            sp->_mouse_xtermcap = "\033[?1005;1000%?%p1%{1}%=%th%el%;";
            sp->_mouse_format = MF_XTERM_1005;
            break;
#endif
        case 1006:
            /* see "xterm+sm+1006" */
            sp->_mouse_xtermcap = "\033[?1006;1000%?%p1%{1}%=%th%el%;";
            sp->_mouse_format = MF_SGR1006;
            break;
        default:
            sp->_mouse_xtermcap = "\033[?1000%?%p1%{1}%=%th%el%;";
            break;
        }
    }
}
#endif

static void
enable_xterm_mouse(SCREEN *sp, int enable)
{
    TPUTS_TRACE(enable
                ? "xterm mouse initialization"
                : "xterm mouse deinitialization");
#if USE_EMX_MOUSE
    sp->_emxmouse_activated = enable;
#else
    NCURSES_PUTP2("xterm-mouse", TIPARM_1(sp->_mouse_xtermcap, enable));
#endif
    sp->_mouse_active = enable;
}

#if defined(USE_TERM_DRIVER)
static void
enable_win32_mouse(SCREEN *sp, int enable)
{
#if defined(EXP_WIN32_DRIVER)
    enable_xterm_mouse(sp, enable);
#else
    sp->_mouse_active = enable;
#endif
}
#endif

#if USE_GPM_SUPPORT
static bool
allow_gpm_mouse(SCREEN *sp GCC_UNUSED)
{
    bool result = FALSE;

#if USE_WEAK_SYMBOLS
    /* Danger Robinson: do not use dlopen for libgpm if already loaded */
    if ((Gpm_Wgetch) != 0) {
        if (!sp->_mouse_gpm_loaded) {
            T(("GPM library was already dlopen'd, not by us"));
        }
    } else
#endif
        /* GPM does printf's without checking if stdout is a terminal */
    if (NC_ISATTY(fileno(stdout))) {
        const char *list = getenv("NCURSES_GPM_TERMS");
        const char *env = getenv("TERM");
        if (list != 0) {
            if (env != 0) {
                result = _nc_name_match(list, env, "|:");
            }
        } else {
            /* GPM checks the beginning of the $TERM variable to decide if it
             * should pass xterm events through.  There is no real advantage in
             * allowing GPM to do this.  Recent versions relax that check, and
             * pretend that GPM can work with any terminal having the kmous
             * capability.  Perhaps that works for someone.  If so, they can
             * set the environment variable (above).
             */
            if (env != 0 && strstr(env, "linux") != 0) {
                result = TRUE;
            }
        }
    }
    return result;
}

#ifdef HAVE_LIBDL
static void
unload_gpm_library(SCREEN *sp)
{
    if (sp->_dlopen_gpm != 0) {
        T(("unload GPM library"));
        sp->_mouse_gpm_loaded = FALSE;
        sp->_mouse_fd = -1;
    }
}

static void
load_gpm_library(SCREEN *sp)
{
    sp->_mouse_gpm_found = FALSE;

    /*
     * If we already had a successful dlopen, reuse it.
     */
    if (sp->_dlopen_gpm != 0) {
        sp->_mouse_gpm_found = TRUE;
        sp->_mouse_gpm_loaded = TRUE;
    } else if ((sp->_dlopen_gpm = dlopen(LIBGPM_SONAME, my_RTLD)) != 0) {
#if (defined(__GNUC__) && (__GNUC__ >= 5)) || defined(__clang__)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wpedantic"
#endif
        if (GET_DLSYM(gpm_fd) == 0 ||
            GET_DLSYM(Gpm_Open) == 0 ||
            GET_DLSYM(Gpm_Close) == 0 ||
            GET_DLSYM(Gpm_GetEvent) == 0) {
#if (defined(__GNUC__) && (__GNUC__ >= 5)) || defined(__clang__)
#pragma GCC diagnostic pop
#endif
            T(("GPM initialization failed: %s", dlerror()));
            unload_gpm_library(sp);
            dlclose(sp->_dlopen_gpm);
            sp->_dlopen_gpm = 0;
        } else {
            sp->_mouse_gpm_found = TRUE;
            sp->_mouse_gpm_loaded = TRUE;
        }
    }
}
#endif /* HAVE_LIBDL */

static bool
enable_gpm_mouse(SCREEN *sp, bool enable)
{
    bool result;

    T((T_CALLED("enable_gpm_mouse(%d)"), enable));

    if (enable && !sp->_mouse_active) {
#ifdef HAVE_LIBDL
        if (sp->_mouse_gpm_found && !sp->_mouse_gpm_loaded) {
            load_gpm_library(sp);
        }
#endif
        if (sp->_mouse_gpm_loaded) {
            int code;

            /* GPM: initialize connection to gpm server */
            sp->_mouse_gpm_connect.eventMask = GPM_DOWN | GPM_UP;
            sp->_mouse_gpm_connect.defaultMask =
                (unsigned short) (~(sp->_mouse_gpm_connect.eventMask | GPM_HARD));
            sp->_mouse_gpm_connect.minMod = 0;
            sp->_mouse_gpm_connect.maxMod =
                (unsigned short) (~((1 << KG_SHIFT) |
                                    (1 << KG_SHIFTL) |
                                    (1 << KG_SHIFTR)));
            /*
             * Note: GPM hardcodes \E[?1001s and \E[?1000h during its open.
             * The former is recognized by wscons (SunOS), and the latter by
             * xterm.  Those will not show up in ncurses' traces.
             */
            code = my_Gpm_Open(&sp->_mouse_gpm_connect, 0);
            result = (code >= 0);

            /*
             * GPM can return a -2 if it is trying to do something with xterm.
             * Ignore that, since it conflicts with our use of stdin.
             */
            if (code == -2) {
                my_Gpm_Close();
            }
        } else {
            result = FALSE;
        }
        sp->_mouse_active = result;
        T(("GPM open %s", result ? "succeeded" : "failed"));
    } else {
        if (!enable && sp->_mouse_active) {
            /* GPM: close connection to gpm server */
            my_Gpm_Close();
            sp->_mouse_active = FALSE;
            T(("GPM closed"));
        }
        result = enable;
    }
#ifdef HAVE_LIBDL
    if (!result) {
        unload_gpm_library(sp);
    }
#endif
    returnBool(result);
}
#endif /* USE_GPM_SUPPORT */

static void
initialize_mousetype(SCREEN *sp)
{
    T((T_CALLED("initialize_mousetype()")));

    /* Try gpm first, because gpm may be configured to run in xterm */
#if USE_GPM_SUPPORT
    if (allow_gpm_mouse(sp)) {
        if (!sp->_mouse_gpm_loaded) {
#ifdef HAVE_LIBDL
            load_gpm_library(sp);
#else /* !HAVE_LIBDL */
            sp->_mouse_gpm_found = TRUE;
            sp->_mouse_gpm_loaded = TRUE;
#endif
        }

        /*
         * The gpm_fd file-descriptor may be negative (xterm).  So we have to
         * maintain our notion of whether the mouse connection is active
         * without testing the file-descriptor.
         */
        if (sp->_mouse_gpm_found && enable_gpm_mouse(sp, TRUE)) {
            sp->_mouse_type = M_GPM;
            sp->_mouse_fd = *(my_gpm_fd);
            T(("GPM mouse_fd %d", sp->_mouse_fd));
            returnVoid;
        }
    }
#endif /* USE_GPM_SUPPORT */

    /* OS/2 VIO */
#if USE_EMX_MOUSE
    if (!sp->_emxmouse_thread
        && strstr(SP_TERMTYPE term_names, "xterm") == 0
        && NonEmpty(key_mouse)) {
        int handles[2];

        if (pipe(handles) < 0) {
            perror("mouse pipe error");
            returnVoid;
        } else {
            int rc;

            if (!sp->_emxmouse_buttons[0]) {
                const char *s = getenv("MOUSE_BUTTONS_123");

                sp->_emxmouse_buttons[0] = 1;
                if (s && strlen(s) >= 3) {
                    sp->_emxmouse_buttons[1] = s[0] - '0';
                    sp->_emxmouse_buttons[2] = s[1] - '0';
                    sp->_emxmouse_buttons[3] = s[2] - '0';
                } else {
                    sp->_emxmouse_buttons[1] = 1;
                    sp->_emxmouse_buttons[2] = 3;
                    sp->_emxmouse_buttons[3] = 2;
                }
            }
            sp->_emxmouse_wfd = handles[1];
            M_FD(sp) = handles[0];
            /* Needed? */
            setmode(handles[0], O_BINARY);
            setmode(handles[1], O_BINARY);
            /* Do not use CRT functions, we may single-threaded. */
            rc = DosCreateThread((unsigned long *) &sp->_emxmouse_thread,
                                 mouse_server, (long) sp, 0, 8192);
            if (rc) {
                printf("mouse thread error %d=%#x", rc, rc);
            } else {
                sp->_mouse_type = M_XTERM;
            }
            returnVoid;
        }
    }
#endif /* USE_EMX_MOUSE */

#if USE_SYSMOUSE
    {
        static char dev_tty[] = "/dev/tty";
        struct mouse_info the_mouse;
        char *the_device = 0;

        if (NC_ISATTY(sp->_ifd))
            the_device = ttyname(sp->_ifd);
        if (the_device == 0)
            the_device = dev_tty;

        sp->_mouse_fd = open(the_device, O_RDWR);

        if (sp->_mouse_fd >= 0) {
            /*
             * sysmouse does not have a usable user interface for obtaining
             * mouse events.  The logical way to proceed (reading data on a
             * stream) only works if one opens the device as root.  Even in
             * that mode, careful examination shows we lose events
             * occasionally.  The interface provided for user programs is to
             * establish a signal handler.  really.
             *
             * Take over SIGUSR2 for this purpose since SIGUSR1 is more
             * likely to be used by an application.  getch() will have to
             * handle the misleading EINTR's.
             */
            signal(SIGUSR2, SIG_IGN);
            the_mouse.operation = MOUSE_MODE;
            the_mouse.u.mode.mode = 0;
            the_mouse.u.mode.signal = SIGUSR2;
            if (ioctl(sp->_mouse_fd, CONS_MOUSECTL, &the_mouse) != -1) {
                signal(SIGUSR2, handle_sysmouse);
                the_mouse.operation = MOUSE_SHOW;
                ioctl(sp->_mouse_fd, CONS_MOUSECTL, &the_mouse);

#if defined(FBIO_MODEINFO) || defined(CONS_MODEINFO)    /* FreeBSD > 2.x */
                {
#ifndef FBIO_GETMODE            /* FreeBSD 3.x */
#define FBIO_GETMODE    CONS_GET
#define FBIO_MODEINFO   CONS_MODEINFO
#endif /* FBIO_GETMODE */
                    video_info_t the_video;

                    if (ioctl(sp->_mouse_fd,
                              FBIO_GETMODE,
                              &the_video.vi_mode) != -1
                        && ioctl(sp->_mouse_fd,
                                 FBIO_MODEINFO,
                                 &the_video) != -1) {
                        sp->_sysmouse_char_width = the_video.vi_cwidth;
                        sp->_sysmouse_char_height = the_video.vi_cheight;
                    }
                }
#endif /* defined(FBIO_MODEINFO) || defined(CONS_MODEINFO) */

                if (sp->_sysmouse_char_width <= 0)
                    sp->_sysmouse_char_width = 8;
                if (sp->_sysmouse_char_height <= 0)
                    sp->_sysmouse_char_height = 16;
                sp->_mouse_type = M_SYSMOUSE;
                returnVoid;
            }
        }
    }
#endif /* USE_SYSMOUSE */

#ifdef USE_TERM_DRIVER
    CallDriver(sp, td_initmouse);
#endif
#if !defined(USE_TERM_DRIVER) || defined(EXP_WIN32_DRIVER)
    /* we know how to recognize mouse events under "xterm" */
    if (NonEmpty(key_mouse)) {
        init_xterm_mouse(sp);
    } else if (strstr(SP_TERMTYPE term_names, "xterm") != 0) {
        if (_nc_add_to_try(&(sp->_keytry), xterm_kmous, KEY_MOUSE) == OK)
            init_xterm_mouse(sp);
    }
#endif

    returnVoid;
}

static bool
_nc_mouse_init(SCREEN *sp)
/* initialize the mouse */
{
    bool result = FALSE;

    T((T_CALLED("_nc_mouse_init(%p)"), (void *)sp));

    if (sp != 0) {
        if (!sp->_mouse_initialized) {
            int i;

            sp->_mouse_initialized = TRUE;

            TR(MY_TRACE, ("set _mouse_initialized"));

            sp->_mouse_eventp = FirstEV(sp);
            for (i = 0; i < EV_MAX; i++)
                Invalidate(sp->_mouse_events + i);

            initialize_mousetype(sp);

            T(("set _mouse_type to %d", sp->_mouse_type));
        }
        result = sp->_mouse_initialized;
    }
    returnCode(result);
}

/*
 * Query to see if there is a pending mouse event.  This is called from
 * fifo_push() in lib_getch.c
 */
static bool
_nc_mouse_event(SCREEN *sp)
{
    MEVENT *eventp = sp->_mouse_eventp;
    bool result = FALSE;

    (void) eventp;

    switch (sp->_mouse_type) {
    case M_XTERM:
        /* xterm: never have to query, mouse events are in the keyboard stream */
#if USE_EMX_MOUSE
        {
            char kbuf[3];

            int i, res = read(M_FD(sp), &kbuf, 3);      /* Eat the prefix */
            if (res != 3)
                printf("Got %d chars instead of 3 for prefix.\n", res);
            for (i = 0; i < res; i++) {
                if (kbuf[i] != key_mouse[i])
                    printf("Got char %d instead of %d for prefix.\n",
                           (int) kbuf[i], (int) key_mouse[i]);
            }
            result = TRUE;
        }
#endif /* USE_EMX_MOUSE */
        break;

#if USE_GPM_SUPPORT
    case M_GPM:
        if (sp->_mouse_fd >= 0) {
            /* query server for event, return TRUE if we find one */
            Gpm_Event ev;

            switch (my_Gpm_GetEvent(&ev)) {
            case 0:
                /* Connection closed, drop the mouse. */
                sp->_mouse_fd = -1;
                break;
            case 1:
                /* there's only one mouse... */
                eventp->id = NORMAL_EVENT;

                eventp->bstate = 0;
                switch (ev.type & 0x0f) {
                case (GPM_DOWN):
                    if (ev.buttons & GPM_B_LEFT)
                        eventp->bstate |= BUTTON1_PRESSED;
                    if (ev.buttons & GPM_B_MIDDLE)
                        eventp->bstate |= BUTTON2_PRESSED;
                    if (ev.buttons & GPM_B_RIGHT)
                        eventp->bstate |= BUTTON3_PRESSED;
                    break;
                case (GPM_UP):
                    if (ev.buttons & GPM_B_LEFT)
                        eventp->bstate |= BUTTON1_RELEASED;
                    if (ev.buttons & GPM_B_MIDDLE)
                        eventp->bstate |= BUTTON2_RELEASED;
                    if (ev.buttons & GPM_B_RIGHT)
                        eventp->bstate |= BUTTON3_RELEASED;
                    break;
                default:
                    eventp->bstate |= REPORT_MOUSE_POSITION;
                    break;
                }

                eventp->x = ev.x - 1;
                eventp->y = ev.y - 1;
                eventp->z = 0;

                /* bump the next-free pointer into the circular list */
                sp->_mouse_eventp = NEXT(eventp);
                result = TRUE;
                break;
            }
        }
        break;
#endif

#if USE_SYSMOUSE
    case M_SYSMOUSE:
        if (sp->_sysmouse_head < sp->_sysmouse_tail) {
            *eventp = sp->_sysmouse_fifo[sp->_sysmouse_head];

            /*
             * Point the fifo-head to the next possible location.  If there
             * are none, reset the indices.  This may be interrupted by the
             * signal handler, doing essentially the same reset.
             */
            sp->_sysmouse_head += 1;
            if (sp->_sysmouse_head == sp->_sysmouse_tail) {
                sp->_sysmouse_tail = 0;
                sp->_sysmouse_head = 0;
            }

            /* bump the next-free pointer into the circular list */
            sp->_mouse_eventp = eventp = NEXT(eventp);
            result = TRUE;
        }
        break;
#endif /* USE_SYSMOUSE */

#ifdef USE_TERM_DRIVER
    case M_TERM_DRIVER:
        while (sp->_drv_mouse_head < sp->_drv_mouse_tail) {
            *eventp = sp->_drv_mouse_fifo[sp->_drv_mouse_head];

            /*
             * Point the fifo-head to the next possible location.  If there
             * are none, reset the indices.
             */
            sp->_drv_mouse_head += 1;
            if (sp->_drv_mouse_head == sp->_drv_mouse_tail) {
                sp->_drv_mouse_tail = 0;
                sp->_drv_mouse_head = 0;
            }

            /* bump the next-free pointer into the circular list */
            sp->_mouse_eventp = eventp = NEXT(eventp);
            result = TRUE;
        }
        break;
#endif

    case M_NONE:
        break;
    }

    return result;              /* true if we found an event */
}

#if USE_EMX_MOUSE
#define PRESS_POSITION(n) \
    do { \
            eventp->bstate = MASK_PRESS(n); \
            sp->_mouse_bstate |= MASK_PRESS(n); \
            if (button & 0x40) { \
                    eventp->bstate = MASK_RELEASE(n); \
                    sp->_mouse_bstate &= ~MASK_PRESS(n); \
            } \
    } while (0)
#else
#define PRESS_POSITION(n) \
    do { \
            eventp->bstate = (mmask_t) ((sp->_mouse_bstate & MASK_PRESS(n)) \
                                    ? REPORT_MOUSE_POSITION \
                                    : MASK_PRESS(n)); \
            sp->_mouse_bstate |= MASK_PRESS(n); \
    } while (0)
#endif

static bool
handle_wheel(SCREEN *sp, MEVENT * eventp, int button, int wheel)
{
    bool result = TRUE;

    switch (button & 3) {
    case 0:
        if (wheel) {
            eventp->bstate = MASK_PRESS(4);
            /* Do not record in sp->_mouse_bstate; there will be no
             * corresponding release event.
             */
        } else {
            PRESS_POSITION(1);
        }
        break;
    case 1:
        if (wheel) {
#if NCURSES_MOUSE_VERSION >= 2
            eventp->bstate = MASK_PRESS(5);
            /* See comment above for button 4 */
#else
            /* Ignore this event as it is not a true press of the button */
            eventp->bstate = REPORT_MOUSE_POSITION;
#endif
        } else {
            PRESS_POSITION(2);
        }
        break;
    case 2:
        PRESS_POSITION(3);
        break;
    default:
        /*
         * case 3 is sent when the mouse buttons are released.
         *
         * If the terminal uses xterm mode 1003, a continuous series of
         * button-release events is sent as the mouse moves around the screen,
         * or as the wheel mouse is rotated.
         *
         * Return false in this case, so that when running in X10 mode, we will
         * recalculate bstate.
         */
        eventp->bstate = REPORT_MOUSE_POSITION;
        result = FALSE;
        break;
    }
    return result;
}

static bool
decode_X10_bstate(SCREEN *sp, MEVENT * eventp, unsigned intro)
{
    bool result;
    int button = 0;
    int wheel = (intro & 96) == 96;

    eventp->bstate = 0;

    if (intro >= 96) {
        if (intro >= 160) {
            button = (int) (intro - 152);       /* buttons 8-11 */
        } else {
            button = (int) (intro - 92);        /* buttons 4-7 */
        }
    } else {
        button = (intro & 3);
    }

    if (button > MAX_BUTTONS) {
        eventp->bstate = REPORT_MOUSE_POSITION;
    } else if (!handle_wheel(sp, eventp, (int) intro, wheel)) {

        /*
         * Release events aren't reported for individual buttons, just for
         * the button set as a whole.  However, because there are normally
         * no mouse events under xterm that intervene between press and
         * release, we can infer the button actually released by looking at
         * the previous event.
         */
        if (sp->_mouse_bstate & BUTTON_PRESSED) {
            int b;

            eventp->bstate = BUTTON_RELEASED;
            for (b = 1; b <= MAX_BUTTONS; ++b) {
                if (!(sp->_mouse_bstate & MASK_PRESS(b)))
                    eventp->bstate &= ~MASK_RELEASE(b);
            }
            sp->_mouse_bstate = 0;
        } else {
            /*
             * xterm will return a stream of release-events to let the
             * application know where the mouse is going, if private mode
             * 1002 or 1003 is enabled.
             */
            eventp->bstate = REPORT_MOUSE_POSITION;
        }
    }

    if (intro & 4) {
        eventp->bstate |= BUTTON_SHIFT;
    }
    if (intro & 8) {
        eventp->bstate |= BUTTON_ALT;
    }
    if (intro & 16) {
        eventp->bstate |= BUTTON_CTRL;
    }
    result = (eventp->bstate & REPORT_MOUSE_POSITION) ? TRUE : FALSE;
    return result;
}

/* This code requires that your xterm entry contain the kmous capability and
 * that it be set to the \E[M documented in the Xterm Control Sequences
 * reference.  This is how we arrange for mouse events to be reported via a
 * KEY_MOUSE return value from wgetch().  After this value is received,
 * _nc_mouse_inline() gets called and is immediately responsible for parsing
 * the mouse status information following the prefix.
 *
 * The following quotes from the ctlseqs.ms document in the XTerm distribution,
 * describing the mouse tracking feature:
 *
 * Parameters for all mouse tracking escape sequences generated by xterm encode
 * numeric parameters in a single character as value+040.  For example, ! is
 * 1.
 *
 * On button press or release, xterm sends ESC [ M CbCxCy.  The low two bits of
 * Cb encode button information:  0=MB1 pressed, 1=MB2 pressed, 2=MB3 pressed,
 * 3=release.  The upper bits encode what modifiers were down when the button
 * was pressed and are added together.  4=Shift, 8=Meta, 16=Control.  Cx and Cy
 * are the x and y coordinates of the mouse event.  The upper left corner is
 * (1,1).
 *
 * (End quote) By the time we get here, we've eaten the key prefix.  FYI, the
 * loop below is necessary because mouse click info isn't guaranteed to present
 * as a single clist item.
 *
 * Wheel mice may return buttons 4 and 5 when the wheel is turned.  We encode
 * those as button presses.
 */
static bool
decode_xterm_X10(SCREEN *sp, MEVENT * eventp)
{
#define MAX_KBUF 3
    unsigned char kbuf[MAX_KBUF + 1];
    size_t grabbed;
    int res;
    bool result;

    _nc_set_read_thread(TRUE);
    for (grabbed = 0; grabbed < MAX_KBUF; grabbed += (size_t) res) {

        /* For VIO mouse we add extra bit 64 to disambiguate button-up. */
        res = (int) read(
#if USE_EMX_MOUSE
                            (M_FD(sp) >= 0) ? M_FD(sp) : sp->_ifd,
#else
                            sp->_ifd,
#endif
                            kbuf + grabbed, (size_t) (MAX_KBUF - (int) grabbed));
        if (res == -1)
            break;
    }
    _nc_set_read_thread(FALSE);
    kbuf[MAX_KBUF] = '\0';

    TR(TRACE_IEVENT,
       ("_nc_mouse_inline sees the following xterm data: '%s'", kbuf));

    /* there's only one mouse... */
    eventp->id = NORMAL_EVENT;

    result = decode_X10_bstate(sp, eventp, kbuf[0]);

    eventp->x = (kbuf[1] - ' ') - 1;
    eventp->y = (kbuf[2] - ' ') - 1;

    return result;
}

#ifdef EXP_XTERM_1005
/*
 * This is identical to X10/X11 responses except that there are two UTF-8
 * characters storing the ordinates instead of two bytes.
 */
static bool
decode_xterm_1005(SCREEN *sp, MEVENT * eventp)
{
    char kbuf[80];
    size_t grabbed;
    size_t limit = (sizeof(kbuf) - 1);
    unsigned coords[2];
    bool result;

    coords[0] = 0;
    coords[1] = 0;

    _nc_set_read_thread(TRUE);
    for (grabbed = 0; grabbed < limit;) {
        int res;

        res = (int) read(
#if USE_EMX_MOUSE
                            (M_FD(sp) >= 0) ? M_FD(sp) : sp->_ifd,
#else
                            sp->_ifd,
#endif
                            (kbuf + grabbed), (size_t) 1);
        if (res == -1)
            break;
        grabbed += (size_t) res;
        if (grabbed > 1) {
            size_t check = 1;
            int n;

            for (n = 0; n < 2; ++n) {
                int rc;

                if (check >= grabbed)
                    break;
                rc = _nc_conv_to_utf32(&coords[n], kbuf + check, (unsigned)
                                       (grabbed - check));
                if (!rc)
                    break;
                check += (size_t) rc;
            }
            if (n >= 2)
                break;
        }
    }
    _nc_set_read_thread(FALSE);

    TR(TRACE_IEVENT,
       ("_nc_mouse_inline sees the following xterm data: %s",
        _nc_visbufn(kbuf, (int) grabbed)));

    /* there's only one mouse... */
    eventp->id = NORMAL_EVENT;

    result = decode_X10_bstate(sp, eventp, UChar(kbuf[0]));

    eventp->x = (int) (coords[0] - ' ') - 1;
    eventp->y = (int) (coords[1] - ' ') - 1;

    return result;
}
#endif /* EXP_XTERM_1005 */

/*
 * ECMA-48 section 5.4
 */
#define isInter(c) ((c) >= 0x20 && (c) <= 0x2f)
#define isParam(c) ((c) >= 0x30 && (c) <= 0x3f)
#define isFinal(c) ((c) >= 0x40 && (c) <= 0x7e)

#define MAX_PARAMS 9

typedef struct {
    int nerror;                 /* nonzero if there are unexpected chars */
    int nparam;                 /* number of numeric parameters */
    int params[MAX_PARAMS];
    int final;                  /* the final-character */
} SGR_DATA;

static bool
read_SGR(SCREEN *sp, SGR_DATA * result)
{
    char kbuf[80];              /* bigger than any possible mouse response */
    int grabbed = 0;
    int ch = 0;
    int now = -1;
    int marker = 1;

    memset(result, 0, sizeof(*result));
    _nc_set_read_thread(TRUE);

    do {
        int res;

        res = (int) read(
#if USE_EMX_MOUSE
                            (M_FD(sp) >= 0) ? M_FD(sp) : sp->_ifd,
#else
                            sp->_ifd,
#endif
                            (kbuf + grabbed), (size_t) 1);
        if (res == -1)
            break;
        if ((grabbed + MAX_KBUF) >= (int) sizeof(kbuf)) {
            result->nerror++;
            break;
        }
        ch = UChar(kbuf[grabbed]);
        kbuf[grabbed + 1] = 0;
        switch (ch) {
        case '0':
        case '1':
        case '2':
        case '3':
        case '4':
        case '5':
        case '6':
        case '7':
        case '8':
        case '9':
            if (marker) {
                ++now;
                result->nparam = (now + 1);
            }
            marker = 0;
            result->params[now] = (result->params[now] * 10) + (ch - '0');
            break;
        case ';':
            if (marker) {
                ++now;
                result->nparam = (now + 1);
            }
            marker = 1;
            break;
        default:
            if (ch < 32 || ch > 126) {
                /*
                 * Technically other characters could be interspersed in the
                 * response.  Ignore those for now.
                 */
                result->nerror++;
                continue;
            } else if (isFinal(ch)) {
                if (marker) {
                    result->nparam++;
                }
                result->final = ch;
            } else {
                result->nerror++;
            }
            break;
        }
        ++grabbed;
    } while (!isFinal(ch));
    _nc_set_read_thread(FALSE);

    kbuf[++grabbed] = 0;
    TR(TRACE_IEVENT,
       ("_nc_mouse_inline sees the following xterm data: '%s'", kbuf));
    return (grabbed > 0) && (result->nerror == 0);
}

static bool
decode_xterm_SGR1006(SCREEN *sp, MEVENT * eventp)
{
    SGR_DATA data;
    bool result = FALSE;
    if (read_SGR(sp, &data)) {
        int b = data.params[0];
        int b3 = 1 + (b & 3);
        int wheel = ((b & 64) == 64);

        if (b >= 132) {
            b3 = MAX_BUTTONS + 1;
        } else if (b >= 128) {
            b3 = (b - 120);     /* buttons 8-11 */
        } else if (b >= 64) {
            b3 = (b - 60);      /* buttons 6-7 */
        }

        eventp->id = NORMAL_EVENT;
        if (data.final == 'M') {
            (void) handle_wheel(sp, eventp, b, wheel);
        } else if (b3 > MAX_BUTTONS) {
            eventp->bstate = REPORT_MOUSE_POSITION;
        } else {
            mmask_t pressed = (mmask_t) NCURSES_MOUSE_MASK(b3, NCURSES_BUTTON_PRESSED);
            mmask_t release = (mmask_t) NCURSES_MOUSE_MASK(b3, NCURSES_BUTTON_RELEASED);
            if (sp->_mouse_bstate & pressed) {
                eventp->bstate = release;
                sp->_mouse_bstate &= ~pressed;
            } else {
                eventp->bstate = REPORT_MOUSE_POSITION;
            }
        }
        if (b & 4) {
            eventp->bstate |= BUTTON_SHIFT;
        }
        if (b & 8) {
            eventp->bstate |= BUTTON_ALT;
        }
        if (b & 16) {
            eventp->bstate |= BUTTON_CTRL;
        }
        result = (eventp->bstate & REPORT_MOUSE_POSITION) ? TRUE : FALSE;
        eventp->x = (data.params[1] ? (data.params[1] - 1) : 0);
        eventp->y = (data.params[2] ? (data.params[2] - 1) : 0);
    }
    return result;
}

static bool
_nc_mouse_inline(SCREEN *sp)
/* mouse report received in the keyboard stream -- parse its info */
{
    bool result = FALSE;
    MEVENT *eventp = sp->_mouse_eventp;

    TR(MY_TRACE, ("_nc_mouse_inline() called"));

    if (sp->_mouse_type == M_XTERM) {
        switch (sp->_mouse_format) {
        case MF_X10:
            result = decode_xterm_X10(sp, eventp);
            break;
        case MF_SGR1006:
            result = decode_xterm_SGR1006(sp, eventp);
            break;
#ifdef EXP_XTERM_1005
        case MF_XTERM_1005:
            result = decode_xterm_1005(sp, eventp);
            break;
#endif
        }

        TR(MY_TRACE,
           ("_nc_mouse_inline: primitive mouse-event %s has slot %ld",
            _nc_tracemouse(sp, eventp),
            (long) IndexEV(sp, eventp)));

        /* bump the next-free pointer into the circular list */
        sp->_mouse_eventp = NEXT(eventp);

        if (!result) {
            /* If this event is from a wheel-mouse, treat it like position
             * reports and avoid waiting for the release-events which will
             * never come.
             */
            if (eventp->bstate & BUTTON_PRESSED) {
                int b;

                for (b = 4; b <= MAX_BUTTONS; ++b) {
                    if ((eventp->bstate & MASK_PRESS(b))) {
                        result = TRUE;
                        break;
                    }
                }
            }
        }
    }

    return (result);
}

static void
mouse_activate(SCREEN *sp, int on)
{
    T((T_CALLED("mouse_activate(%p,%s)"),
       (void *) SP_PARM, on ? "on" : "off"));

    if (!on && !sp->_mouse_initialized)
        returnVoid;

    if (!_nc_mouse_init(sp))
        returnVoid;

    if (on) {
        sp->_mouse_bstate = 0;
        switch (sp->_mouse_type) {
        case M_XTERM:
#if NCURSES_EXT_FUNCS
            NCURSES_SP_NAME(keyok) (NCURSES_SP_ARGx KEY_MOUSE, on);
#endif
            enable_xterm_mouse(sp, 1);
            break;
#if USE_GPM_SUPPORT
        case M_GPM:
            if (enable_gpm_mouse(sp, TRUE)) {
                sp->_mouse_fd = *(my_gpm_fd);
                T(("GPM mouse_fd %d", sp->_mouse_fd));
            }
            break;
#endif
#if USE_SYSMOUSE
        case M_SYSMOUSE:
            signal(SIGUSR2, handle_sysmouse);
            sp->_mouse_active = TRUE;
            break;
#endif
#ifdef USE_TERM_DRIVER
        case M_TERM_DRIVER:
            enable_win32_mouse(sp, TRUE);
            break;
#endif
        case M_NONE:
            returnVoid;
        default:
            T(("unexpected mouse mode"));
            break;
        }
        /* Make runtime binding to cut down on object size of applications that
         * do not use the mouse (e.g., 'clear').
         */
        /* *INDENT-EQLS* */
        sp->_mouse_event  = _nc_mouse_event;
        sp->_mouse_inline = _nc_mouse_inline;
        sp->_mouse_parse  = _nc_mouse_parse;
        sp->_mouse_resume = _nc_mouse_resume;
        sp->_mouse_wrap   = _nc_mouse_wrap;
    } else {

        switch (sp->_mouse_type) {
        case M_XTERM:
            enable_xterm_mouse(sp, 0);
            break;
#if USE_GPM_SUPPORT
        case M_GPM:
            enable_gpm_mouse(sp, FALSE);
            break;
#endif
#if USE_SYSMOUSE
        case M_SYSMOUSE:
            signal(SIGUSR2, SIG_IGN);
            sp->_mouse_active = FALSE;
            break;
#endif
#ifdef USE_TERM_DRIVER
        case M_TERM_DRIVER:
            enable_win32_mouse(sp, FALSE);
            break;
#endif
        case M_NONE:
            returnVoid;
        default:
            T(("unexpected mouse mode"));
            break;
        }
    }
    NCURSES_SP_NAME(_nc_flush) (NCURSES_SP_ARG);
    returnVoid;
}

/**************************************************************************
 *
 * Device-independent code
 *
 **************************************************************************/

static bool
_nc_mouse_parse(SCREEN *sp, int runcount)
/* parse a run of atomic mouse events into a gesture */
{
    MEVENT *eventp = sp->_mouse_eventp;
    MEVENT *next, *ep;
    MEVENT *first_valid = NULL;
    MEVENT *first_invalid = NULL;
    int n;
    int b;
    bool merge;
    bool endLoop;

    TR(MY_TRACE, ("_nc_mouse_parse(%d) called", runcount));

    /*
     * When we enter this routine, the event list next-free pointer
     * points just past a run of mouse events that we know were separated
     * in time by less than the critical click interval. The job of this
     * routine is to collapse this run into a single higher-level event
     * or gesture.
     *
     * We accomplish this in two passes.  The first pass merges press/release
     * pairs into click events.  The second merges runs of click events into
     * double or triple-click events.
     *
     * It's possible that the run may not resolve to a single event (for
     * example, if the user quadruple-clicks).  If so, leading events
     * in the run are ignored if user does not call getmouse in a loop (getting
     * them from newest to older).
     *
     * Note that this routine is independent of the format of the specific
     * format of the pointing-device's reports.  We can use it to parse
     * gestures on anything that reports press/release events on a per-
     * button basis, as long as the device-dependent mouse code puts stuff
     * on the queue in MEVENT format.
     */

    /*
     * Reset all events that were not set, in case the user sometimes calls
     * getmouse only once and other times until there are no more events in
     * queue.
     *
     * This also allows reaching the beginning of the run.
     */
    ep = eventp;
    for (n = runcount; n < EV_MAX; n++) {
        Invalidate(ep);
        ep = NEXT(ep);
    }

#ifdef TRACE
    if (USE_TRACEF(TRACE_IEVENT)) {
        _trace_slot(sp, "before mouse press/release merge:");
        _tracef("_nc_mouse_parse: run starts at %ld, ends at %ld, count %d",
                RunParams(sp, eventp, ep),
                runcount);
        _nc_unlock_global(tracef);
    }
#endif /* TRACE */

    /* first pass; merge press/release pairs */
    endLoop = FALSE;
    while (!endLoop) {
        next = NEXT(ep);
        if (next == eventp) {
            /* Will end the loop, but compact before */
            endLoop = TRUE;
        } else {

#define MASK_CHANGED(x) (!(ep->bstate & MASK_PRESS(x)) \
                      == !(next->bstate & MASK_RELEASE(x)))

            if (ValidEvent(ep) && ValidEvent(next)
                && ep->x == next->x && ep->y == next->y
                && (ep->bstate & BUTTON_PRESSED)
                && (!(next->bstate & BUTTON_PRESSED))) {
                bool changed = TRUE;

                for (b = 1; b <= MAX_BUTTONS; ++b) {
                    if (!MASK_CHANGED(b)) {
                        changed = FALSE;
                        break;
                    }
                }

                if (changed) {
                    merge = FALSE;
                    for (b = 1; b <= MAX_BUTTONS; ++b) {
                        if ((sp->_mouse_mask2 & MASK_CLICK(b))
                            && (ep->bstate & MASK_PRESS(b))) {
                            next->bstate &= ~MASK_RELEASE(b);
                            next->bstate |= MASK_CLICK(b);
                            merge = TRUE;
                        }
                    }
                    if (merge) {
                        Invalidate(ep);
                    }
                }
            }
        }

        /* Compact valid events */
        if (!ValidEvent(ep)) {
            if ((first_valid != NULL) && (first_invalid == NULL)) {
                first_invalid = ep;
            }
        } else {
            if (first_valid == NULL) {
                first_valid = ep;
            } else if (first_invalid != NULL) {
                *first_invalid = *ep;
                Invalidate(ep);
                first_invalid = NEXT(first_invalid);
            }
        }

        ep = next;
    }

    if (first_invalid != NULL) {
        eventp = first_invalid;
    }
#ifdef TRACE
    if (USE_TRACEF(TRACE_IEVENT)) {
        _trace_slot(sp, "before mouse click merge:");
        if (first_valid == NULL) {
            _tracef("_nc_mouse_parse: no valid event");
        } else {
            _tracef("_nc_mouse_parse: run starts at %ld, ends at %ld, count %d",
                    RunParams(sp, eventp, first_valid),
                    runcount);
            _nc_unlock_global(tracef);
        }
    }
#endif /* TRACE */

    /*
     * Second pass; merge click runs.  We merge click events forward in the
     * queue.  For example, double click can be changed to triple click.
     *
     * NOTE: There is a problem with this design!  If the application
     * allows enough click events to pile up in the circular queue so
     * they wrap around, it will cheerfully merge the newest forward
     * into the oldest, creating a bogus doubleclick and confusing
     * the queue-traversal logic rather badly.  Generally this won't
     * happen, because calling getmouse() marks old events invalid and
     * ineligible for merges.  The true solution to this problem would
     * be to timestamp each MEVENT and perform the obvious sanity check,
     * but the timer element would have to have sub-second resolution,
     * which would get us into portability trouble.
     */
    first_invalid = NULL;
    endLoop = (first_valid == NULL);
    ep = first_valid;
    while (!endLoop) {
        next = NEXT(ep);

        if (next == eventp) {
            /* Will end the loop, but check event type and compact before */
            endLoop = TRUE;
        } else if (!ValidEvent(next)) {
            continue;
        } else {
            /* merge click events forward */
            if ((ep->bstate & BUTTON_CLICKED)
                && (next->bstate & BUTTON_CLICKED)) {
                merge = FALSE;
                for (b = 1; b <= MAX_BUTTONS; ++b) {
                    if ((sp->_mouse_mask2 & MASK_DOUBLE_CLICK(b))
                        && (ep->bstate & MASK_CLICK(b))
                        && (next->bstate & MASK_CLICK(b))) {
                        next->bstate &= ~MASK_CLICK(b);
                        next->bstate |= MASK_DOUBLE_CLICK(b);
                        merge = TRUE;
                    }
                }
                if (merge) {
                    Invalidate(ep);
                }
            }

            /* merge double-click events forward */
            if ((ep->bstate & BUTTON_DOUBLE_CLICKED)
                && (next->bstate & BUTTON_CLICKED)) {
                merge = FALSE;
                for (b = 1; b <= MAX_BUTTONS; ++b) {
                    if ((sp->_mouse_mask2 & MASK_TRIPLE_CLICK(b))
                        && (ep->bstate & MASK_DOUBLE_CLICK(b))
                        && (next->bstate & MASK_CLICK(b))) {
                        next->bstate &= ~MASK_CLICK(b);
                        next->bstate |= MASK_TRIPLE_CLICK(b);
                        merge = TRUE;
                    }
                }
                if (merge) {
                    Invalidate(ep);
                }
            }
        }

        /* Discard event if it does not match event mask */
        if (!(ep->bstate & sp->_mouse_mask2)) {
            Invalidate(ep);
        }

        /* Compact valid events */
        if (!ValidEvent(ep)) {
            if (ep == first_valid) {
                first_valid = next;
            } else if (first_invalid == NULL) {
                first_invalid = ep;
            }
        } else if (first_invalid != NULL) {
            *first_invalid = *ep;
            Invalidate(ep);
            first_invalid = NEXT(first_invalid);
        }

        ep = next;
    }

    if (first_invalid == NULL) {
        first_invalid = eventp;
    }
    sp->_mouse_eventp = first_invalid;

#ifdef TRACE
    if (first_valid != NULL) {
        if (USE_TRACEF(TRACE_IEVENT)) {
            _trace_slot(sp, "after mouse event queue compaction:");
            _tracef("_nc_mouse_parse: run starts at %ld, ends at %ld, count %d",
                    RunParams(sp, first_invalid, first_valid),
                    runcount);
            _nc_unlock_global(tracef);
        }
        for (ep = first_valid; ep != first_invalid; ep = NEXT(ep)) {
            if (ValidEvent(ep))
                TR(MY_TRACE,
                   ("_nc_mouse_parse: returning composite mouse event %s at slot %ld",
                    _nc_tracemouse(sp, ep),
                    (long) IndexEV(sp, ep)));
        }
    }
#endif /* TRACE */

    /* after all this, do we have a valid event? */
    ep = PREV(first_invalid);
    return ValidEvent(ep) && ((ep->bstate & sp->_mouse_mask) != 0);
}

static void
_nc_mouse_wrap(SCREEN *sp)
/* release mouse -- called by endwin() before shellout/exit */
{
    TR(MY_TRACE, ("_nc_mouse_wrap() called"));

    switch (sp->_mouse_type) {
    case M_XTERM:
        if (sp->_mouse_mask)
            mouse_activate(sp, FALSE);
        break;
#if USE_GPM_SUPPORT
        /* GPM: pass all mouse events to next client */
    case M_GPM:
        if (sp->_mouse_mask)
            mouse_activate(sp, FALSE);
        break;
#endif
#if USE_SYSMOUSE
    case M_SYSMOUSE:
        mouse_activate(sp, FALSE);
        break;
#endif
#ifdef USE_TERM_DRIVER
    case M_TERM_DRIVER:
        mouse_activate(sp, FALSE);
        break;
#endif
    case M_NONE:
        break;
    }
}

static void
_nc_mouse_resume(SCREEN *sp)
/* re-connect to mouse -- called by doupdate() after shellout */
{
    TR(MY_TRACE, ("_nc_mouse_resume() called"));

    switch (sp->_mouse_type) {
    case M_XTERM:
        /* xterm: re-enable reporting */
        if (sp->_mouse_mask)
            mouse_activate(sp, TRUE);
        break;

#if USE_GPM_SUPPORT
    case M_GPM:
        /* GPM: reclaim our event set */
        if (sp->_mouse_mask)
            mouse_activate(sp, TRUE);
        break;
#endif

#if USE_SYSMOUSE
    case M_SYSMOUSE:
        mouse_activate(sp, TRUE);
        break;
#endif

#ifdef USE_TERM_DRIVER
    case M_TERM_DRIVER:
        mouse_activate(sp, TRUE);
        break;
#endif

    case M_NONE:
        break;
    }
}

/**************************************************************************
 *
 * Mouse interface entry points for the API
 *
 **************************************************************************/

NCURSES_EXPORT(int)
NCURSES_SP_NAME(getmouse) (NCURSES_SP_DCLx MEVENT * aevent)
{
    int result = ERR;
    MEVENT *eventp;

    T((T_CALLED("getmouse(%p,%p)"), (void *) SP_PARM, (void *) aevent));

    if ((aevent != 0) &&
        (SP_PARM != 0) &&
        (SP_PARM->_mouse_type != M_NONE) &&
        (eventp = SP_PARM->_mouse_eventp) != 0) {
        /* compute the current-event pointer */
        MEVENT *prev = PREV(eventp);

        /*
         * Discard events not matching mask (there could be still some if
         * _nc_mouse_parse was not called, e.g., when _nc_mouse_inline returns
         * false).
         */
        while (ValidEvent(prev) && (!(prev->bstate & SP_PARM->_mouse_mask2))) {
            Invalidate(prev);
            prev = PREV(prev);
        }
        if (ValidEvent(prev)) {
            /* copy the event we find there */
            *aevent = *prev;

            TR(TRACE_IEVENT, ("getmouse: returning event %s from slot %ld",
                              _nc_tracemouse(SP_PARM, prev),
                              (long) IndexEV(SP_PARM, prev)));

            Invalidate(prev);   /* so the queue slot becomes free */
            SP_PARM->_mouse_eventp = prev;
            result = OK;
        } else {
            /* Reset the provided event */
            aevent->bstate = 0;
            Invalidate(aevent);
            aevent->x = 0;
            aevent->y = 0;
            aevent->z = 0;
        }
    }
    returnCode(result);
}

#if NCURSES_SP_FUNCS
/* grab a copy of the current mouse event */
NCURSES_EXPORT(int)
getmouse(MEVENT * aevent)
{
    return NCURSES_SP_NAME(getmouse) (CURRENT_SCREEN, aevent);
}
#endif

NCURSES_EXPORT(int)
NCURSES_SP_NAME(ungetmouse) (NCURSES_SP_DCLx MEVENT * aevent)
{
    int result = ERR;
    MEVENT *eventp;

    T((T_CALLED("ungetmouse(%p,%p)"), (void *) SP_PARM, (void *) aevent));

    if (aevent != 0 &&
        SP_PARM != 0 &&
        (eventp = SP_PARM->_mouse_eventp) != 0) {

        /* stick the given event in the next-free slot */
        *eventp = *aevent;

        /* bump the next-free pointer into the circular list */
        SP_PARM->_mouse_eventp = NEXT(eventp);

        /* push back the notification event on the keyboard queue */
        result = NCURSES_SP_NAME(ungetch) (NCURSES_SP_ARGx KEY_MOUSE);
    }
    returnCode(result);
}

#if NCURSES_SP_FUNCS
/* enqueue a synthesized mouse event to be seen by the next wgetch() */
NCURSES_EXPORT(int)
ungetmouse(MEVENT * aevent)
{
    return NCURSES_SP_NAME(ungetmouse) (CURRENT_SCREEN, aevent);
}
#endif

NCURSES_EXPORT(mmask_t)
NCURSES_SP_NAME(mousemask) (NCURSES_SP_DCLx mmask_t newmask, mmask_t * oldmask)
/* set the mouse event mask */
{
    mmask_t result = 0;

    T((T_CALLED("mousemask(%p,%#lx,%p)"),
       (void *) SP_PARM,
       (unsigned long) newmask,
       (void *) oldmask));

    if (SP_PARM != 0) {
        if (oldmask)
            *oldmask = SP_PARM->_mouse_mask;

        if (newmask || SP_PARM->_mouse_initialized) {
            _nc_mouse_init(SP_PARM);

            if (SP_PARM->_mouse_type != M_NONE) {
                int b;

                result = newmask &
                    (REPORT_MOUSE_POSITION
                     | BUTTON_ALT
                     | BUTTON_CTRL
                     | BUTTON_SHIFT
                     | BUTTON_PRESSED
                     | BUTTON_RELEASED
                     | BUTTON_CLICKED
                     | BUTTON_DOUBLE_CLICKED
                     | BUTTON_TRIPLE_CLICKED);

                mouse_activate(SP_PARM, (bool) (result != 0));

                SP_PARM->_mouse_mask = result;
                SP_PARM->_mouse_mask2 = result;

                /*
                 * Make a mask corresponding to the states we will need to
                 * retain (temporarily) while building up the state that the
                 * user asked for.
                 */
                for (b = 1; b <= MAX_BUTTONS; ++b) {
                    if (SP_PARM->_mouse_mask2 & MASK_TRIPLE_CLICK(b))
                        SP_PARM->_mouse_mask2 |= MASK_DOUBLE_CLICK(b);
                    if (SP_PARM->_mouse_mask2 & MASK_DOUBLE_CLICK(b))
                        SP_PARM->_mouse_mask2 |= MASK_CLICK(b);
                    if (SP_PARM->_mouse_mask2 & MASK_CLICK(b))
                        SP_PARM->_mouse_mask2 |= (MASK_PRESS(b) |
                                                  MASK_RELEASE(b));
                }
            }
        }
    }
    returnMMask(result);
}

#if NCURSES_SP_FUNCS
NCURSES_EXPORT(mmask_t)
mousemask(mmask_t newmask, mmask_t * oldmask)
{
    return NCURSES_SP_NAME(mousemask) (CURRENT_SCREEN, newmask, oldmask);
}
#endif

NCURSES_EXPORT(bool)
wenclose(const WINDOW *win, int y, int x)
/* check to see if given window encloses given screen location */
{
    bool result = FALSE;

    T((T_CALLED("wenclose(%p,%d,%d)"), (const void *) win, y, x));

    if (win != 0) {
        y -= win->_yoffset;
        result = ((win->_begy <= y &&
                   win->_begx <= x &&
                   (win->_begx + win->_maxx) >= x &&
                   (win->_begy + win->_maxy) >= y) ? TRUE : FALSE);
    }
    returnBool(result);
}

NCURSES_EXPORT(int)
NCURSES_SP_NAME(mouseinterval) (NCURSES_SP_DCLx int maxclick)
/* set the maximum mouse interval within which to recognize a click */
{
    int oldval;

    T((T_CALLED("mouseinterval(%p,%d)"), (void *) SP_PARM, maxclick));

    if (SP_PARM != 0) {
        oldval = SP_PARM->_maxclick;
        if (maxclick >= 0)
            SP_PARM->_maxclick = maxclick;
    } else {
        oldval = DEFAULT_MAXCLICK;
    }

    returnCode(oldval);
}

#if NCURSES_SP_FUNCS
NCURSES_EXPORT(int)
mouseinterval(int maxclick)
{
    return NCURSES_SP_NAME(mouseinterval) (CURRENT_SCREEN, maxclick);
}
#endif

/* This may be used by other routines to ask for the existence of mouse
   support */
NCURSES_EXPORT(bool)
_nc_has_mouse(SCREEN *sp)
{
    return (((0 == sp) || (sp->_mouse_type == M_NONE)) ? FALSE : TRUE);
}

NCURSES_EXPORT(bool)
NCURSES_SP_NAME(has_mouse) (NCURSES_SP_DCL0)
{
    return _nc_has_mouse(SP_PARM);
}

#if NCURSES_SP_FUNCS
NCURSES_EXPORT(bool)
has_mouse(void)
{
    return _nc_has_mouse(CURRENT_SCREEN);
}
#endif

NCURSES_EXPORT(bool)
wmouse_trafo(const WINDOW *win, int *pY, int *pX, bool to_screen)
{
    bool result = FALSE;

    T((T_CALLED("wmouse_trafo(%p,%p,%p,%d)"),
       (const void *) win,
       (void *) pY,
       (void *) pX,
       to_screen));

    if (win && pY && pX) {
        int y = *pY;
        int x = *pX;

        if (to_screen) {
            y += win->_begy + win->_yoffset;
            x += win->_begx;
            if (wenclose(win, y, x))
                result = TRUE;
        } else {
            if (wenclose(win, y, x)) {
                y -= (win->_begy + win->_yoffset);
                x -= win->_begx;
                result = TRUE;
            }
        }
        if (result) {
            *pX = x;
            *pY = y;
        }
    }
    returnBool(result);
}