/* $OpenBSD: tty_update.c,v 1.18 2023/10/17 09:52:09 nicm Exp $ */

/****************************************************************************
 * Copyright 2018-2021,2022 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                         2009                    *
 ****************************************************************************/

/*-----------------------------------------------------------------
 *
 *      lib_doupdate.c
 *
 *      The routine doupdate() and its dependents.
 *      All physical output is concentrated here (except _nc_outch()
 *      in lib_tputs.c).
 *
 *-----------------------------------------------------------------*/

#define NEW_PAIR_INTERNAL 1

#include <curses.priv.h>

#ifndef CUR
#define CUR SP_TERMTYPE
#endif

#if defined __HAIKU__ && defined __BEOS__
#undef __BEOS__
#endif

#ifdef __BEOS__
#undef false
#undef true
#include <OS.h>
#endif

#if defined(TRACE) && HAVE_SYS_TIMES_H && HAVE_TIMES
#define USE_TRACE_TIMES 1
#else
#define USE_TRACE_TIMES 0
#endif

#if HAVE_SYS_TIME_H && HAVE_SYS_TIME_SELECT
#include <sys/time.h>
#endif

#if USE_TRACE_TIMES
#include <sys/times.h>
#endif

#if USE_FUNC_POLL
#elif HAVE_SELECT
#if HAVE_SYS_SELECT_H
#include <sys/select.h>
#endif
#endif

#include <ctype.h>

MODULE_ID("$Id: tty_update.c,v 1.18 2023/10/17 09:52:09 nicm Exp $")

/*
 * This define controls the line-breakout optimization.  Every once in a
 * while during screen refresh, we want to check for input and abort the
 * update if there's some waiting.  CHECK_INTERVAL controls the number of
 * changed lines to be emitted between input checks.
 *
 * Note: Input-check-and-abort is no longer done if the screen is being
 * updated from scratch.  This is a feature, not a bug.
 */
#define CHECK_INTERVAL  5

#define FILL_BCE(sp) (sp->_coloron && !sp->_default_color && !back_color_erase)

static const NCURSES_CH_T blankchar = NewChar(BLANK_TEXT);
static NCURSES_CH_T normal = NewChar(BLANK_TEXT);

/*
 * Enable checking to see if doupdate and friends are tracking the true
 * cursor position correctly.  NOTE: this is a debugging hack which will
 * work ONLY on ANSI-compatible terminals!
 */
/* #define POSITION_DEBUG */

static NCURSES_INLINE NCURSES_CH_T ClrBlank(NCURSES_SP_DCLx WINDOW *win);

#if NCURSES_SP_FUNCS
static int ClrBottom(SCREEN *, int total);
static void ClearScreen(SCREEN *, NCURSES_CH_T blank);
static void ClrUpdate(SCREEN *);
static void DelChar(SCREEN *, int count);
static void InsStr(SCREEN *, NCURSES_CH_T *line, int count);
static void TransformLine(SCREEN *, int const lineno);
#else
static int ClrBottom(int total);
static void ClearScreen(NCURSES_CH_T blank);
static void ClrUpdate(void);
static void DelChar(int count);
static void InsStr(NCURSES_CH_T *line, int count);
static void TransformLine(int const lineno);
#endif

#ifdef POSITION_DEBUG
/****************************************************************************
 *
 * Debugging code.  Only works on ANSI-standard terminals.
 *
 ****************************************************************************/

static void
position_check(NCURSES_SP_DCLx int expected_y, int expected_x, const char *legend)
/* check to see if the real cursor position matches the virtual */
{
    char buf[20];
    char *s;
    int y, x;

    if (!_nc_tracing || (expected_y < 0 && expected_x < 0))
        return;

    NCURSES_SP_NAME(_nc_flush) (NCURSES_SP_ARG);
    memset(buf, '\0', sizeof(buf));
    NCURSES_PUTP2_FLUSH("cpr", "\033[6n");      /* only works on ANSI-compatibles */
    *(s = buf) = 0;
    do {
        int ask = sizeof(buf) - 1 - (s - buf);
        int got = read(0, s, ask);
        if (got == 0)
            break;
        s += got;
    } while (strchr(buf, 'R') == 0);
    _tracef("probe returned %s", _nc_visbuf(buf));

    /* try to interpret as a position report */
    if (sscanf(buf, "\033[%d;%dR", &y, &x) != 2) {
        _tracef("position probe failed in %s", legend);
    } else {
        if (expected_x < 0)
            expected_x = x - 1;
        if (expected_y < 0)
            expected_y = y - 1;
        if (y - 1 != expected_y || x - 1 != expected_x) {
            NCURSES_SP_NAME(beep) (NCURSES_SP_ARG);
            NCURSES_SP_NAME(tputs) (NCURSES_SP_ARGx
                                    TIPARM_2("\033[%d;%dH",
                                             expected_y + 1,
                                             expected_x + 1),
                                    1, NCURSES_SP_NAME(_nc_outch));
            _tracef("position seen (%d, %d) doesn't match expected one (%d, %d) in %s",
                    y - 1, x - 1, expected_y, expected_x, legend);
        } else {
            _tracef("position matches OK in %s", legend);
        }
    }
}
#else
#define position_check(expected_y, expected_x, legend)  /* nothing */
#endif /* POSITION_DEBUG */

/****************************************************************************
 *
 * Optimized update code
 *
 ****************************************************************************/

static NCURSES_INLINE void
GoTo(NCURSES_SP_DCLx int const row, int const col)
{
    TR(TRACE_MOVE, ("GoTo(%p, %d, %d) from (%d, %d)",
                    (void *) SP_PARM, row, col, SP_PARM->_cursrow, SP_PARM->_curscol));

    position_check(NCURSES_SP_ARGx
                   SP_PARM->_cursrow,
                   SP_PARM->_curscol, "GoTo");

    TINFO_MVCUR(NCURSES_SP_ARGx
                SP_PARM->_cursrow,
                SP_PARM->_curscol,
                row, col);
    position_check(NCURSES_SP_ARGx
                   SP_PARM->_cursrow,
                   SP_PARM->_curscol, "GoTo2");
}

#if !NCURSES_WCWIDTH_GRAPHICS
#define is_wacs_value(ch) (_nc_wacs_width(ch) == 1 && wcwidth(ch) > 1)
#endif /* !NCURSES_WCWIDTH_GRAPHICS */

static NCURSES_INLINE void
PutAttrChar(NCURSES_SP_DCLx CARG_CH_T ch)
{
    int chlen = 1;
    NCURSES_CH_T my_ch;
#if USE_WIDEC_SUPPORT
    PUTC_DATA;
#endif
    NCURSES_CH_T tilde;
    NCURSES_CH_T attr = CHDEREF(ch);

    TR(TRACE_CHARPUT, ("PutAttrChar(%s) at (%d, %d)",
                       _tracech_t(ch),
                       SP_PARM->_cursrow, SP_PARM->_curscol));
#if USE_WIDEC_SUPPORT
    /*
     * If this is not a valid character, there is nothing more to do.
     */
    if (isWidecExt(CHDEREF(ch))) {
        TR(TRACE_CHARPUT, ("...skip"));
        return;
    }
    /*
     * Determine the number of character cells which the 'ch' value will use
     * on the screen.  It should be at least one.
     */
    if ((chlen = _nc_wacs_width(CharOf(CHDEREF(ch)))) <= 0) {
        static const NCURSES_CH_T blank = NewChar(BLANK_TEXT);

        /*
         * If the character falls into any of these special cases, do
         * not force the result to a blank:
         *
         * a) it is printable (this works around a bug in wcwidth()).
         * b) use_legacy_coding() has been called to modify the treatment
         *    of codes 128-255.
         * c) the acs_map[] has been initialized to allow codes 0-31
         *    to be rendered.  This supports Linux console's "PC"
         *    characters.  Codes 128-255 are allowed though this is
         *    not checked.
         */
        if (is8bits(CharOf(CHDEREF(ch)))
            && (isprint(CharOf(CHDEREF(ch)))
                || (SP_PARM->_legacy_coding > 0 && CharOf(CHDEREF(ch)) >= 160)
                || (SP_PARM->_legacy_coding > 1 && CharOf(CHDEREF(ch)) >= 128)
                || (AttrOf(attr) & A_ALTCHARSET
                    && ((CharOfD(ch) < ACS_LEN
                         && SP_PARM->_acs_map != 0
                         && SP_PARM->_acs_map[CharOfD(ch)] != 0)
                        || (CharOfD(ch) >= 128))))) {
            ;
        } else {
            ch = CHREF(blank);
            TR(TRACE_CHARPUT, ("forced to blank"));
        }
        chlen = 1;
    }
#endif

    if ((AttrOf(attr) & A_ALTCHARSET)
        && SP_PARM->_acs_map != 0
        && ((CharOfD(ch) < ACS_LEN)
#if !NCURSES_WCWIDTH_GRAPHICS
            || is_wacs_value(CharOfD(ch))
#endif
        )) {
        int c8;
        my_ch = CHDEREF(ch);    /* work around const param */
        c8 = CharOf(my_ch);
#if USE_WIDEC_SUPPORT
        /*
         * This is crude & ugly, but works most of the time.  It checks if the
         * acs_chars string specified that we have a mapping for this
         * character, and uses the wide-character mapping when we expect the
         * normal one to be broken (by mis-design ;-).
         */
        if (SP_PARM->_screen_unicode
            && _nc_wacs[CharOf(my_ch)].chars[0]) {
            if (SP_PARM->_screen_acs_map[CharOf(my_ch)]) {
                if (SP_PARM->_screen_acs_fix) {
                    RemAttr(attr, A_ALTCHARSET);
                    my_ch = _nc_wacs[CharOf(my_ch)];
                }
            } else {
                RemAttr(attr, A_ALTCHARSET);
                my_ch = _nc_wacs[CharOf(my_ch)];
            }
#if !NCURSES_WCWIDTH_GRAPHICS
            if (!(AttrOf(attr) & A_ALTCHARSET)) {
                chlen = 1;
            }
#endif /* !NCURSES_WCWIDTH_GRAPHICS */
        } else
#endif
        if (!SP_PARM->_screen_acs_map[c8]) {
            /*
             * If we found no mapping for a given alternate-character set item
             * in the terminal description, attempt to use the ASCII fallback
             * code which is populated in the _acs_map[] array.  If that did
             * not correspond to a line-drawing, etc., graphics character, the
             * array entry would be empty.
             */
            chtype temp = UChar(SP_PARM->_acs_map[c8]);
            if (temp) {
                RemAttr(attr, A_ALTCHARSET);
                SetChar(my_ch, temp, AttrOf(attr));
            }
        }

        /*
         * If we (still) have alternate character set, it is the normal 8bit
         * flavor.  The _screen_acs_map[] array tells if the character was
         * really in acs_chars, needed because of the way wide/normal line
         * drawing flavors are integrated.
         */
        if (AttrOf(attr) & A_ALTCHARSET) {
            int j = CharOfD(ch);
            chtype temp = UChar(SP_PARM->_acs_map[j]);

            if (temp != 0) {
                SetChar(my_ch, temp, AttrOf(attr));
            } else {
                my_ch = CHDEREF(ch);
                RemAttr(attr, A_ALTCHARSET);
            }
        }
        ch = CHREF(my_ch);
    }
#if USE_WIDEC_SUPPORT && !NCURSES_WCWIDTH_GRAPHICS
    else if (chlen > 1 && is_wacs_value(CharOfD(ch))) {
        chlen = 1;
    }
#endif
    if (tilde_glitch && (CharOfD(ch) == L('~'))) {
        SetChar(tilde, L('`'), AttrOf(attr));
        ch = CHREF(tilde);
    }

    UpdateAttrs(SP_PARM, attr);
    PUTC(CHDEREF(ch));
#if !USE_WIDEC_SUPPORT
    COUNT_OUTCHARS(1);
#endif
    SP_PARM->_curscol += chlen;
    if (char_padding) {
        NCURSES_PUTP2("char_padding", char_padding);
    }
}

static bool
check_pending(NCURSES_SP_DCL0)
/* check for pending input */
{
    bool have_pending = FALSE;

    /*
     * Only carry out this check when the flag is zero, otherwise we'll
     * have the refreshing slow down drastically (or stop) if there's an
     * unread character available.
     */
    if (SP_PARM->_fifohold != 0)
        return FALSE;

    if (SP_PARM->_checkfd >= 0) {
#if USE_FUNC_POLL
        struct pollfd fds[1];
        fds[0].fd = SP_PARM->_checkfd;
        fds[0].events = POLLIN;
        if (poll(fds, (size_t) 1, 0) > 0) {
            have_pending = TRUE;
        }
#elif defined(__BEOS__)
        /*
         * BeOS's select() is declared in socket.h, so the configure script does
         * not see it.  That's just as well, since that function works only for
         * sockets.  This (using snooze and ioctl) was distilled from Be's patch
         * for ncurses which uses a separate thread to simulate select().
         *
         * FIXME: the return values from the ioctl aren't very clear if we get
         * interrupted.
         */
        int n = 0;
        int howmany = ioctl(0, 'ichr', &n);
        if (howmany >= 0 && n > 0) {
            have_pending = TRUE;
        }
#elif HAVE_SELECT
        fd_set fdset;
        struct timeval ktimeout;

        ktimeout.tv_sec =
            ktimeout.tv_usec = 0;

        FD_ZERO(&fdset);
        FD_SET(SP_PARM->_checkfd, &fdset);
        if (select(SP_PARM->_checkfd + 1, &fdset, NULL, NULL, &ktimeout) != 0) {
            have_pending = TRUE;
        }
#endif
    }
    if (have_pending) {
        SP_PARM->_fifohold = 5;
        NCURSES_SP_NAME(_nc_flush) (NCURSES_SP_ARG);
    }
    return FALSE;
}

/* put char at lower right corner */
static void
PutCharLR(NCURSES_SP_DCLx const ARG_CH_T ch)
{
    if (!auto_right_margin) {
        /* we can put the char directly */
        PutAttrChar(NCURSES_SP_ARGx ch);
    } else if (enter_am_mode && exit_am_mode) {
        int oldcol = SP_PARM->_curscol;
        /* we can suppress automargin */
        NCURSES_PUTP2("exit_am_mode", exit_am_mode);

        PutAttrChar(NCURSES_SP_ARGx ch);
        SP_PARM->_curscol = oldcol;
        position_check(NCURSES_SP_ARGx
                       SP_PARM->_cursrow,
                       SP_PARM->_curscol,
                       "exit_am_mode");

        NCURSES_PUTP2("enter_am_mode", enter_am_mode);
    } else if ((enter_insert_mode && exit_insert_mode)
               || insert_character || parm_ich) {
        GoTo(NCURSES_SP_ARGx
             screen_lines(SP_PARM) - 1,
             screen_columns(SP_PARM) - 2);
        PutAttrChar(NCURSES_SP_ARGx ch);
        GoTo(NCURSES_SP_ARGx
             screen_lines(SP_PARM) - 1,
             screen_columns(SP_PARM) - 2);
        InsStr(NCURSES_SP_ARGx
               NewScreen(SP_PARM)->_line[screen_lines(SP_PARM) - 1].text +
               screen_columns(SP_PARM) - 2, 1);
    }
}

/*
 * Wrap the cursor position, i.e., advance to the beginning of the next line.
 */
static void
wrap_cursor(NCURSES_SP_DCL0)
{
    if (eat_newline_glitch) {
        /*
         * xenl can manifest two different ways.  The vt100 way is that, when
         * you'd expect the cursor to wrap, it stays hung at the right margin
         * (on top of the character just emitted) and doesn't wrap until the
         * *next* graphic char is emitted.  The c100 way is to ignore LF
         * received just after an am wrap.
         *
         * An aggressive way to handle this would be to emit CR/LF after the
         * char and then assume the wrap is done, you're on the first position
         * of the next line, and the terminal out of its weird state.  Here
         * it is safe to just tell the code that the cursor is in hyperspace and
         * let the next mvcur() call straighten things out.
         */
        SP_PARM->_curscol = -1;
        SP_PARM->_cursrow = -1;
    } else if (auto_right_margin) {
        SP_PARM->_curscol = 0;
        SP_PARM->_cursrow++;
        /*
         * We've actually moved - but may have to work around problems with
         * video attributes not working.
         */
        if (!move_standout_mode && AttrOf(SCREEN_ATTRS(SP_PARM))) {
            TR(TRACE_CHARPUT, ("turning off (%#lx) %s before wrapping",
                               (unsigned long) AttrOf(SCREEN_ATTRS(SP_PARM)),
                               _traceattr(AttrOf(SCREEN_ATTRS(SP_PARM)))));
            VIDPUTS(SP_PARM, A_NORMAL, 0);
        }
    } else {
        SP_PARM->_curscol--;
    }
    position_check(NCURSES_SP_ARGx
                   SP_PARM->_cursrow,
                   SP_PARM->_curscol,
                   "wrap_cursor");
}

static NCURSES_INLINE void
PutChar(NCURSES_SP_DCLx const ARG_CH_T ch)
/* insert character, handling automargin stuff */
{
    if (SP_PARM->_cursrow == screen_lines(SP_PARM) - 1 &&
        SP_PARM->_curscol == screen_columns(SP_PARM) - 1) {
        PutCharLR(NCURSES_SP_ARGx ch);
    } else {
        PutAttrChar(NCURSES_SP_ARGx ch);
    }

    if (SP_PARM->_curscol >= screen_columns(SP_PARM))
        wrap_cursor(NCURSES_SP_ARG);

    position_check(NCURSES_SP_ARGx
                   SP_PARM->_cursrow,
                   SP_PARM->_curscol, "PutChar");
}

/*
 * Check whether the given character can be output by clearing commands.  This
 * includes test for being a space and not including any 'bad' attributes, such
 * as A_REVERSE.  All attribute flags which don't affect appearance of a space
 * or can be output by clearing (A_COLOR in case of bce-terminal) are excluded.
 */
static NCURSES_INLINE bool
can_clear_with(NCURSES_SP_DCLx ARG_CH_T ch)
{
    if (!back_color_erase && SP_PARM->_coloron) {
#if NCURSES_EXT_FUNCS
        int pair;

        if (!SP_PARM->_default_color)
            return FALSE;
        if (!(isDefaultColor(SP_PARM->_default_fg) &&
              isDefaultColor(SP_PARM->_default_bg)))
            return FALSE;
        if ((pair = GetPair(CHDEREF(ch))) != 0) {
            NCURSES_COLOR_T fg, bg;
            if (NCURSES_SP_NAME(pair_content) (NCURSES_SP_ARGx
                                               (short) pair,
                                               &fg, &bg) == ERR
                || !(isDefaultColor(fg) && isDefaultColor(bg))) {
                return FALSE;
            }
        }
#else
        if (AttrOfD(ch) & A_COLOR)
            return FALSE;
#endif
    }
    return (ISBLANK(CHDEREF(ch)) &&
            (AttrOfD(ch) & ~(NONBLANK_ATTR | A_COLOR)) == BLANK_ATTR);
}

/*
 * Issue a given span of characters from an array.
 * Must be functionally equivalent to:
 *      for (i = 0; i < num; i++)
 *          PutChar(ntext[i]);
 * but can leave the cursor positioned at the middle of the interval.
 *
 * Returns: 0 - cursor is at the end of interval
 *          1 - cursor is somewhere in the middle
 *
 * This code is optimized using ech and rep.
 */
static int
EmitRange(NCURSES_SP_DCLx const NCURSES_CH_T *ntext, int num)
{
    int i;

    TR(TRACE_CHARPUT, ("EmitRange %d:%s", num, _nc_viscbuf(ntext, num)));

    if (erase_chars || repeat_char) {
        while (num > 0) {
            int runcount;
            NCURSES_CH_T ntext0;

            while (num > 1 && !CharEq(ntext[0], ntext[1])) {
                PutChar(NCURSES_SP_ARGx CHREF(ntext[0]));
                ntext++;
                num--;
            }
            ntext0 = ntext[0];
            if (num == 1) {
                PutChar(NCURSES_SP_ARGx CHREF(ntext0));
                return 0;
            }
            runcount = 2;

            while (runcount < num && CharEq(ntext[runcount], ntext0))
                runcount++;

            /*
             * The cost expression in the middle isn't exactly right.
             * _cup_ch_cost is an upper bound on the cost for moving to the
             * end of the erased area, but not the cost itself (which we
             * can't compute without emitting the move).  This may result
             * in erase_chars not getting used in some situations for
             * which it would be marginally advantageous.
             */
            if (erase_chars
                && runcount > SP_PARM->_ech_cost + SP_PARM->_cup_ch_cost
                && can_clear_with(NCURSES_SP_ARGx CHREF(ntext0))) {
                UpdateAttrs(SP_PARM, ntext0);
                NCURSES_PUTP2("erase_chars", TIPARM_1(erase_chars, runcount));

                /*
                 * If this is the last part of the given interval,
                 * don't bother moving cursor, since it can be the
                 * last update on the line.
                 */
                if (runcount < num) {
                    GoTo(NCURSES_SP_ARGx
                         SP_PARM->_cursrow,
                         SP_PARM->_curscol + runcount);
                } else {
                    return 1;   /* cursor stays in the middle */
                }
            } else if (repeat_char != 0 &&
#if BSD_TPUTS
                       !isdigit(UChar(CharOf(ntext0))) &&
#endif
#if USE_WIDEC_SUPPORT
                       (!SP_PARM->_screen_unicode &&
                        (CharOf(ntext0) < ((AttrOf(ntext0) & A_ALTCHARSET)
                                           ? ACS_LEN
                                           : 256))) &&
#endif
                       runcount > SP_PARM->_rep_cost) {
                NCURSES_CH_T temp;
                bool wrap_possible = (SP_PARM->_curscol + runcount >=
                                      screen_columns(SP_PARM));
                int rep_count = runcount;

                if (wrap_possible)
                    rep_count--;

                UpdateAttrs(SP_PARM, ntext0);
                temp = ntext0;
                if ((AttrOf(temp) & A_ALTCHARSET) &&
                    SP_PARM->_acs_map != 0 &&
                    (SP_PARM->_acs_map[CharOf(temp)] & A_CHARTEXT) != 0) {
                    SetChar(temp,
                            (SP_PARM->_acs_map[CharOf(ntext0)] & A_CHARTEXT),
                            AttrOf(ntext0) | A_ALTCHARSET);
                }
                NCURSES_SP_NAME(tputs) (NCURSES_SP_ARGx
                                        TIPARM_2(repeat_char,
                                                 CharOf(temp),
                                                 rep_count),
                                        1,
                                        NCURSES_SP_NAME(_nc_outch));
                SP_PARM->_curscol += rep_count;

                if (wrap_possible)
                    PutChar(NCURSES_SP_ARGx CHREF(ntext0));
            } else {
                for (i = 0; i < runcount; i++)
                    PutChar(NCURSES_SP_ARGx CHREF(ntext[i]));
            }
            ntext += runcount;
            num -= runcount;
        }
        return 0;
    }

    for (i = 0; i < num; i++)
        PutChar(NCURSES_SP_ARGx CHREF(ntext[i]));
    return 0;
}

/*
 * Output the line in the given range [first .. last]
 *
 * If there's a run of identical characters that's long enough to justify
 * cursor movement, use that also.
 *
 * Returns: same as EmitRange
 */
static int
PutRange(NCURSES_SP_DCLx
         const NCURSES_CH_T *otext,
         const NCURSES_CH_T *ntext,
         int row,
         int first, int last)
{
    int rc;

    TR(TRACE_CHARPUT, ("PutRange(%p, %p, %p, %d, %d, %d)",
                       (void *) SP_PARM,
                       (const void *) otext,
                       (const void *) ntext,
                       row, first, last));

    if (otext != ntext
        && (last - first + 1) > SP_PARM->_inline_cost) {
        int i, j, same;

        for (j = first, same = 0; j <= last; j++) {
            if (!same && isWidecExt(otext[j]))
                continue;
            if (CharEq(otext[j], ntext[j])) {
                same++;
            } else {
                if (same > SP_PARM->_inline_cost) {
                    EmitRange(NCURSES_SP_ARGx ntext + first, j - same - first);
                    GoTo(NCURSES_SP_ARGx row, first = j);
                }
                same = 0;
            }
        }
        i = EmitRange(NCURSES_SP_ARGx ntext + first, j - same - first);
        /*
         * Always return 1 for the next GoTo() after a PutRange() if we found
         * identical characters at end of interval
         */
        rc = (same == 0 ? i : 1);
    } else {
        rc = EmitRange(NCURSES_SP_ARGx ntext + first, last - first + 1);
    }
    return rc;
}

/* leave unbracketed here so 'indent' works */
#define MARK_NOCHANGE(win,row) \
                win->_line[row].firstchar = _NOCHANGE; \
                win->_line[row].lastchar = _NOCHANGE; \
                if_USE_SCROLL_HINTS(win->_line[row].oldindex = row)

NCURSES_EXPORT(int)
TINFO_DOUPDATE(NCURSES_SP_DCL0)
{
    int i;
    int nonempty;
#if USE_TRACE_TIMES
    struct tms before, after;
#endif /* USE_TRACE_TIMES */

    T((T_CALLED("_nc_tinfo:doupdate(%p)"), (void *) SP_PARM));

    _nc_lock_global(update);

    if (SP_PARM == 0) {
        _nc_unlock_global(update);
        returnCode(ERR);
    }
#if !USE_REENTRANT
    /*
     * It is "legal" but unlikely that an application could assign a new
     * value to one of the standard windows.  Check for that possibility
     * and try to recover.
     *
     * We do not allow applications to assign new values in the reentrant
     * model.
     */
#if NCURSES_SP_FUNCS
    if (SP_PARM == CURRENT_SCREEN) {
#endif
#define SyncScreens(internal,exported) \
        if (internal == 0) internal = exported; \
        if (internal != exported) exported = internal

        SyncScreens(CurScreen(SP_PARM), curscr);
        SyncScreens(NewScreen(SP_PARM), newscr);
        SyncScreens(StdScreen(SP_PARM), stdscr);
#if NCURSES_SP_FUNCS
    }
#endif
#endif /* !USE_REENTRANT */

    if (CurScreen(SP_PARM) == 0
        || NewScreen(SP_PARM) == 0
        || StdScreen(SP_PARM) == 0) {
        _nc_unlock_global(update);
        returnCode(ERR);
    }
#ifdef TRACE
    if (USE_TRACEF(TRACE_UPDATE)) {
        if (CurScreen(SP_PARM)->_clear)
            _tracef("curscr is clear");
        else
            _tracedump("curscr", CurScreen(SP_PARM));
        _tracedump("newscr", NewScreen(SP_PARM));
        _nc_unlock_global(tracef);
    }
#endif /* TRACE */

    _nc_signal_handler(FALSE);

    if (SP_PARM->_fifohold)
        SP_PARM->_fifohold--;

#if USE_SIZECHANGE
    if ((SP_PARM->_endwin == ewSuspend)
        || _nc_handle_sigwinch(SP_PARM)) {
        /*
         * This is a transparent extension:  XSI does not address it,
         * and applications need not know that ncurses can do it.
         *
         * Check if the terminal size has changed while curses was off
         * (this can happen in an xterm, for example), and resize the
         * ncurses data structures accordingly.
         */
        _nc_update_screensize(SP_PARM);
    }
#endif

    if (SP_PARM->_endwin == ewSuspend) {

        T(("coming back from shell mode"));
        NCURSES_SP_NAME(reset_prog_mode) (NCURSES_SP_ARG);

        NCURSES_SP_NAME(_nc_mvcur_resume) (NCURSES_SP_ARG);
        NCURSES_SP_NAME(_nc_screen_resume) (NCURSES_SP_ARG);
        SP_PARM->_mouse_resume(SP_PARM);

        SP_PARM->_endwin = ewRunning;
    }
#if USE_TRACE_TIMES
    /* zero the metering machinery */
    RESET_OUTCHARS();
    (void) times(&before);
#endif /* USE_TRACE_TIMES */

    /*
     * This is the support for magic-cookie terminals.  The theory:  we scan
     * the virtual screen looking for attribute turnons.  Where we find one,
     * check to make sure it is realizable by seeing if the required number of
     * un-attributed blanks are present before and after the attributed range;
     * try to shift the range boundaries over blanks (not changing the screen
     * display) so this becomes true.  If it is, shift the beginning attribute
     * change appropriately (the end one, if we've gotten this far, is
     * guaranteed room for its cookie).  If not, nuke the added attributes out
     * of the span.
     */
#if USE_XMC_SUPPORT
    if (magic_cookie_glitch > 0) {
        int j, k;
        attr_t rattr = A_NORMAL;

        for (i = 0; i < screen_lines(SP_PARM); i++) {
            for (j = 0; j < screen_columns(SP_PARM); j++) {
                bool failed = FALSE;
                NCURSES_CH_T *thisline = NewScreen(SP_PARM)->_line[i].text;
                attr_t thisattr = AttrOf(thisline[j]) & SP_PARM->_xmc_triggers;
                attr_t turnon = thisattr & ~rattr;

                /* is an attribute turned on here? */
                if (turnon == 0) {
                    rattr = thisattr;
                    continue;
                }

                TR(TRACE_ATTRS, ("At (%d, %d): from %s...", i, j, _traceattr(rattr)));
                TR(TRACE_ATTRS, ("...to %s", _traceattr(turnon)));

                /*
                 * If the attribute change location is a blank with a "safe"
                 * attribute, undo the attribute turnon.  This may ensure
                 * there's enough room to set the attribute before the first
                 * non-blank in the run.
                 */
#define SAFE(scr,a)     (!((a) & (scr)->_xmc_triggers))
                if (ISBLANK(thisline[j]) && SAFE(SP_PARM, turnon)) {
                    RemAttr(thisline[j], turnon);
                    continue;
                }

                /* check that there's enough room at start of span */
                for (k = 1; k <= magic_cookie_glitch; k++) {
                    if (j - k < 0
                        || !ISBLANK(thisline[j - k])
                        || !SAFE(SP_PARM, AttrOf(thisline[j - k]))) {
                        failed = TRUE;
                        TR(TRACE_ATTRS, ("No room at start in %d,%d%s%s",
                                         i, j - k,
                                         (ISBLANK(thisline[j - k])
                                          ? ""
                                          : ":nonblank"),
                                         (SAFE(SP_PARM, AttrOf(thisline[j - k]))
                                          ? ""
                                          : ":unsafe")));
                        break;
                    }
                }
                if (!failed) {
                    bool end_onscreen = FALSE;
                    int m, n = j;

                    /* find end of span, if it is onscreen */
                    for (m = i; m < screen_lines(SP_PARM); m++) {
                        for (; n < screen_columns(SP_PARM); n++) {
                            attr_t testattr =
                            AttrOf(NewScreen(SP_PARM)->_line[m].text[n]);
                            if ((testattr & SP_PARM->_xmc_triggers) == rattr) {
                                end_onscreen = TRUE;
                                TR(TRACE_ATTRS,
                                   ("Range attributed with %s ends at (%d, %d)",
                                    _traceattr(turnon), m, n));
                                goto foundit;
                            }
                        }
                        n = 0;
                    }
                    TR(TRACE_ATTRS,
                       ("Range attributed with %s ends offscreen",
                        _traceattr(turnon)));
                  foundit:;

                    if (end_onscreen) {
                        NCURSES_CH_T *lastline =
                        NewScreen(SP_PARM)->_line[m].text;

                        /*
                         * If there are safely-attributed blanks at the end of
                         * the range, shorten the range.  This will help ensure
                         * that there is enough room at end of span.
                         */
                        while (n >= 0
                               && ISBLANK(lastline[n])
                               && SAFE(SP_PARM, AttrOf(lastline[n]))) {
                            RemAttr(lastline[n--], turnon);
                        }

                        /* check that there's enough room at end of span */
                        for (k = 1; k <= magic_cookie_glitch; k++) {
                            if (n + k >= screen_columns(SP_PARM)
                                || !ISBLANK(lastline[n + k])
                                || !SAFE(SP_PARM, AttrOf(lastline[n + k]))) {
                                failed = TRUE;
                                TR(TRACE_ATTRS,
                                   ("No room at end in %d,%d%s%s",
                                    i, j - k,
                                    (ISBLANK(lastline[n + k])
                                     ? ""
                                     : ":nonblank"),
                                    (SAFE(SP_PARM, AttrOf(lastline[n + k]))
                                     ? ""
                                     : ":unsafe")));
                                break;
                            }
                        }
                    }
                }

                if (failed) {
                    int p, q = j;

                    TR(TRACE_ATTRS,
                       ("Clearing %s beginning at (%d, %d)",
                        _traceattr(turnon), i, j));

                    /* turn off new attributes over span */
                    for (p = i; p < screen_lines(SP_PARM); p++) {
                        for (; q < screen_columns(SP_PARM); q++) {
                            attr_t testattr = AttrOf(newscr->_line[p].text[q]);
                            if ((testattr & SP_PARM->_xmc_triggers) == rattr)
                                goto foundend;
                            RemAttr(NewScreen(SP_PARM)->_line[p].text[q], turnon);
                        }
                        q = 0;
                    }
                  foundend:;
                } else {
                    TR(TRACE_ATTRS,
                       ("Cookie space for %s found before (%d, %d)",
                        _traceattr(turnon), i, j));

                    /*
                     * Back up the start of range so there's room for cookies
                     * before the first nonblank character.
                     */
                    for (k = 1; k <= magic_cookie_glitch; k++)
                        AddAttr(thisline[j - k], turnon);
                }

                rattr = thisattr;
            }
        }

#ifdef TRACE
        /* show altered highlights after magic-cookie check */
        if (USE_TRACEF(TRACE_UPDATE)) {
            _tracef("After magic-cookie check...");
            _tracedump("newscr", NewScreen(SP_PARM));
            _nc_unlock_global(tracef);
        }
#endif /* TRACE */
    }
#endif /* USE_XMC_SUPPORT */

    nonempty = 0;
    if (CurScreen(SP_PARM)->_clear || NewScreen(SP_PARM)->_clear) {     /* force refresh ? */
        ClrUpdate(NCURSES_SP_ARG);
        CurScreen(SP_PARM)->_clear = FALSE;     /* reset flag */
        NewScreen(SP_PARM)->_clear = FALSE;     /* reset flag */
    } else {
        int changedlines = CHECK_INTERVAL;

        if (check_pending(NCURSES_SP_ARG))
            goto cleanup;

        nonempty = min(screen_lines(SP_PARM), NewScreen(SP_PARM)->_maxy + 1);

        if (SP_PARM->_scrolling) {
            NCURSES_SP_NAME(_nc_scroll_optimize) (NCURSES_SP_ARG);
        }

        nonempty = ClrBottom(NCURSES_SP_ARGx nonempty);

        TR(TRACE_UPDATE, ("Transforming lines, nonempty %d", nonempty));
        for (i = 0; i < nonempty; i++) {
            /*
             * Here is our line-breakout optimization.
             */
            if (changedlines == CHECK_INTERVAL) {
                if (check_pending(NCURSES_SP_ARG))
                    goto cleanup;
                changedlines = 0;
            }

            /*
             * newscr->line[i].firstchar is normally set
             * by wnoutrefresh.  curscr->line[i].firstchar
             * is normally set by _nc_scroll_window in the
             * vertical-movement optimization code,
             */
            if (NewScreen(SP_PARM)->_line[i].firstchar != _NOCHANGE
                || CurScreen(SP_PARM)->_line[i].firstchar != _NOCHANGE) {
                TransformLine(NCURSES_SP_ARGx i);
                changedlines++;
            }

            /* mark line changed successfully */
            if (i <= NewScreen(SP_PARM)->_maxy) {
                MARK_NOCHANGE(NewScreen(SP_PARM), i);
            }
            if (i <= CurScreen(SP_PARM)->_maxy) {
                MARK_NOCHANGE(CurScreen(SP_PARM), i);
            }
        }
    }

    /* put everything back in sync */
    for (i = nonempty; i <= NewScreen(SP_PARM)->_maxy; i++) {
        MARK_NOCHANGE(NewScreen(SP_PARM), i);
    }
    for (i = nonempty; i <= CurScreen(SP_PARM)->_maxy; i++) {
        MARK_NOCHANGE(CurScreen(SP_PARM), i);
    }

    if (!NewScreen(SP_PARM)->_leaveok) {
        CurScreen(SP_PARM)->_curx = NewScreen(SP_PARM)->_curx;
        CurScreen(SP_PARM)->_cury = NewScreen(SP_PARM)->_cury;

        GoTo(NCURSES_SP_ARGx CurScreen(SP_PARM)->_cury, CurScreen(SP_PARM)->_curx);
    }

  cleanup:
    /*
     * We would like to keep the physical screen in normal mode in case we get
     * other processes writing to the screen.  This goal cannot be met for
     * magic cookies since it interferes with attributes that may propagate
     * past the current position.
     */
#if USE_XMC_SUPPORT
    if (magic_cookie_glitch != 0)
#endif
        UpdateAttrs(SP_PARM, normal);

    NCURSES_SP_NAME(_nc_flush) (NCURSES_SP_ARG);
    WINDOW_ATTRS(CurScreen(SP_PARM)) = WINDOW_ATTRS(NewScreen(SP_PARM));

#if USE_TRACE_TIMES
    (void) times(&after);
    TR(TRACE_TIMES,
       ("Update cost: %ld chars, %ld clocks system time, %ld clocks user time",
        _nc_outchars,
        (long) (after.tms_stime - before.tms_stime),
        (long) (after.tms_utime - before.tms_utime)));
#endif /* USE_TRACE_TIMES */

    _nc_signal_handler(TRUE);

    _nc_unlock_global(update);
    returnCode(OK);
}

#if NCURSES_SP_FUNCS && !defined(USE_TERM_DRIVER)
NCURSES_EXPORT(int)
doupdate(void)
{
    return TINFO_DOUPDATE(CURRENT_SCREEN);
}
#endif

/*
 *      ClrBlank(win)
 *
 *      Returns the attributed character that corresponds to the "cleared"
 *      screen.  If the terminal has the back-color-erase feature, this will be
 *      colored according to the wbkgd() call.
 *
 *      We treat 'curscr' specially because it isn't supposed to be set directly
 *      in the wbkgd() call.  Assume 'stdscr' for this case.
 */
#define BCE_ATTRS (A_NORMAL|A_COLOR)
#define BCE_BKGD(sp,win) (((win) == CurScreen(sp) ? StdScreen(sp) : (win))->_nc_bkgd)

static NCURSES_INLINE NCURSES_CH_T
ClrBlank(NCURSES_SP_DCLx WINDOW *win)
{
    NCURSES_CH_T blank = blankchar;
    if (back_color_erase)
        AddAttr(blank, (AttrOf(BCE_BKGD(SP_PARM, win)) & BCE_ATTRS));
    return blank;
}

/*
**      ClrUpdate()
**
**      Update by clearing and redrawing the entire screen.
**
*/

static void
ClrUpdate(NCURSES_SP_DCL0)
{
    TR(TRACE_UPDATE, (T_CALLED("ClrUpdate")));
    if (0 != SP_PARM) {
        int i;
        NCURSES_CH_T blank = ClrBlank(NCURSES_SP_ARGx StdScreen(SP_PARM));
        int nonempty = min(screen_lines(SP_PARM),
                           NewScreen(SP_PARM)->_maxy + 1);

        ClearScreen(NCURSES_SP_ARGx blank);

        TR(TRACE_UPDATE, ("updating screen from scratch"));

        nonempty = ClrBottom(NCURSES_SP_ARGx nonempty);

        for (i = 0; i < nonempty; i++)
            TransformLine(NCURSES_SP_ARGx i);
    }
    TR(TRACE_UPDATE, (T_RETURN("")));
}

/*
**      ClrToEOL(blank)
**
**      Clear to end of current line, starting at the cursor position
*/

static void
ClrToEOL(NCURSES_SP_DCLx NCURSES_CH_T blank, int needclear)
{
    if (CurScreen(SP_PARM) != 0
        && SP_PARM->_cursrow >= 0) {
        int j;

        for (j = SP_PARM->_curscol; j < screen_columns(SP_PARM); j++) {
            if (j >= 0) {
                NCURSES_CH_T *cp =
                &(CurScreen(SP_PARM)->_line[SP_PARM->_cursrow].text[j]);

                if (!CharEq(*cp, blank)) {
                    *cp = blank;
                    needclear = TRUE;
                }
            }
        }
    }

    if (needclear) {
        UpdateAttrs(SP_PARM, blank);
        if (clr_eol && SP_PARM->_el_cost <= (screen_columns(SP_PARM) - SP_PARM->_curscol)) {
            NCURSES_PUTP2("clr_eol", clr_eol);
        } else {
            int count = (screen_columns(SP_PARM) - SP_PARM->_curscol);
            while (count-- > 0)
                PutChar(NCURSES_SP_ARGx CHREF(blank));
        }
    }
}

/*
**      ClrToEOS(blank)
**
**      Clear to end of screen, starting at the cursor position
*/

static void
ClrToEOS(NCURSES_SP_DCLx NCURSES_CH_T blank)
{
    int row, col;

    row = SP_PARM->_cursrow;
    col = SP_PARM->_curscol;

    if (row < 0)
        row = 0;
    if (col < 0)
        col = 0;

    UpdateAttrs(SP_PARM, blank);
    TPUTS_TRACE("clr_eos");
    NCURSES_SP_NAME(tputs) (NCURSES_SP_ARGx
                            clr_eos,
                            screen_lines(SP_PARM) - row,
                            NCURSES_SP_NAME(_nc_outch));

    while (col < screen_columns(SP_PARM))
        CurScreen(SP_PARM)->_line[row].text[col++] = blank;

    for (row++; row < screen_lines(SP_PARM); row++) {
        for (col = 0; col < screen_columns(SP_PARM); col++)
            CurScreen(SP_PARM)->_line[row].text[col] = blank;
    }
}

/*
 *      ClrBottom(total)
 *
 *      Test if clearing the end of the screen would satisfy part of the
 *      screen-update.  Do this by scanning backwards through the lines in the
 *      screen, checking if each is blank, and one or more are changed.
 */
static int
ClrBottom(NCURSES_SP_DCLx int total)
{
    int top = total;
    int last = min(screen_columns(SP_PARM), NewScreen(SP_PARM)->_maxx + 1);
    NCURSES_CH_T blank = NewScreen(SP_PARM)->_line[total - 1].text[last - 1];

    if (clr_eos && can_clear_with(NCURSES_SP_ARGx CHREF(blank))) {
        int row;

        for (row = total - 1; row >= 0; row--) {
            int col;
            bool ok;

            for (col = 0, ok = TRUE; ok && col < last; col++) {
                ok = (CharEq(NewScreen(SP_PARM)->_line[row].text[col], blank));
            }
            if (!ok)
                break;

            for (col = 0; ok && col < last; col++) {
                ok = (CharEq(CurScreen(SP_PARM)->_line[row].text[col], blank));
            }
            if (!ok)
                top = row;
        }

        /* don't use clr_eos for just one line if clr_eol available */
        if (top < total) {
            GoTo(NCURSES_SP_ARGx top, 0);
            ClrToEOS(NCURSES_SP_ARGx blank);
            if (SP_PARM->oldhash && SP_PARM->newhash) {
                for (row = top; row < screen_lines(SP_PARM); row++)
                    SP_PARM->oldhash[row] = SP_PARM->newhash[row];
            }
        }
    }
    return top;
}

#if USE_XMC_SUPPORT
#if USE_WIDEC_SUPPORT
#define check_xmc_transition(sp, a, b)                                  \
    ((((a)->attr ^ (b)->attr) & ~((a)->attr) & (sp)->_xmc_triggers) != 0)
#define xmc_turn_on(sp,a,b) check_xmc_transition(sp,&(a), &(b))
#else
#define xmc_turn_on(sp,a,b) ((((a)^(b)) & ~(a) & (sp)->_xmc_triggers) != 0)
#endif

#define xmc_new(sp,r,c) NewScreen(sp)->_line[r].text[c]
#define xmc_turn_off(sp,a,b) xmc_turn_on(sp,b,a)
#endif /* USE_XMC_SUPPORT */

/*
**      TransformLine(lineno)
**
**      Transform the given line in curscr to the one in newscr, using
**      Insert/Delete Character if idcok && has_ic().
**
**              firstChar = position of first different character in line
**              oLastChar = position of last different character in old line
**              nLastChar = position of last different character in new line
**
**              move to firstChar
**              overwrite chars up to min(oLastChar, nLastChar)
**              if oLastChar < nLastChar
**                      insert newLine[oLastChar+1..nLastChar]
**              else
**                      delete oLastChar - nLastChar spaces
*/

static void
TransformLine(NCURSES_SP_DCLx int const lineno)
{
    int firstChar, oLastChar, nLastChar;
    NCURSES_CH_T *newLine = NewScreen(SP_PARM)->_line[lineno].text;
    NCURSES_CH_T *oldLine = CurScreen(SP_PARM)->_line[lineno].text;
    int n;
    bool attrchanged = FALSE;

    TR(TRACE_UPDATE, (T_CALLED("TransformLine(%p, %d)"), (void *) SP_PARM, lineno));

    /* copy new hash value to old one */
    if (SP_PARM->oldhash && SP_PARM->newhash)
        SP_PARM->oldhash[lineno] = SP_PARM->newhash[lineno];

    /*
     * If we have colors, there is the possibility of having two color pairs
     * that display as the same colors.  For instance, Lynx does this.  Check
     * for this case, and update the old line with the new line's colors when
     * they are equivalent.
     */
    if (SP_PARM->_coloron) {
        int oldPair;
        int newPair;

        for (n = 0; n < screen_columns(SP_PARM); n++) {
            if (!CharEq(newLine[n], oldLine[n])) {
                oldPair = GetPair(oldLine[n]);
                newPair = GetPair(newLine[n]);
                if (oldPair != newPair
                    && unColor(oldLine[n]) == unColor(newLine[n])) {
                    if (oldPair < SP_PARM->_pair_alloc
                        && newPair < SP_PARM->_pair_alloc
                        && (isSamePair(SP_PARM->_color_pairs[oldPair],
                                       SP_PARM->_color_pairs[newPair]))) {
                        SetPair(oldLine[n], GetPair(newLine[n]));
                    }
                }
            }
        }
    }

    if (ceol_standout_glitch && clr_eol) {
        firstChar = 0;
        while (firstChar < screen_columns(SP_PARM)) {
            if (!SameAttrOf(newLine[firstChar], oldLine[firstChar])) {
                attrchanged = TRUE;
                break;
            }
            firstChar++;
        }
    }

    firstChar = 0;

    if (attrchanged) {          /* we may have to disregard the whole line */
        GoTo(NCURSES_SP_ARGx lineno, firstChar);
        ClrToEOL(NCURSES_SP_ARGx
                 ClrBlank(NCURSES_SP_ARGx
                          CurScreen(SP_PARM)), FALSE);
        PutRange(NCURSES_SP_ARGx
                 oldLine, newLine, lineno, 0,
                 screen_columns(SP_PARM) - 1);
#if USE_XMC_SUPPORT

        /*
         * This is a very simple loop to paint characters which may have the
         * magic cookie glitch embedded.  It doesn't know much about video
         * attributes which are continued from one line to the next.  It
         * assumes that we have filtered out requests for attribute changes
         * that do not get mapped to blank positions.
         *
         * FIXME: we are not keeping track of where we put the cookies, so this
         * will work properly only once, since we may overwrite a cookie in a
         * following operation.
         */
    } else if (magic_cookie_glitch > 0) {
        GoTo(NCURSES_SP_ARGx lineno, firstChar);
        for (n = 0; n < screen_columns(SP_PARM); n++) {
            int m = n + magic_cookie_glitch;

            /* check for turn-on:
             * If we are writing an attributed blank, where the
             * previous cell is not attributed.
             */
            if (ISBLANK(newLine[n])
                && ((n > 0
                     && xmc_turn_on(SP_PARM, newLine[n - 1], newLine[n]))
                    || (n == 0
                        && lineno > 0
                        && xmc_turn_on(SP_PARM,
                                       xmc_new(SP_PARM, lineno - 1,
                                               screen_columns(SP_PARM) - 1),
                                       newLine[n])))) {
                n = m;
            }

            PutChar(NCURSES_SP_ARGx CHREF(newLine[n]));

            /* check for turn-off:
             * If we are writing an attributed non-blank, where the
             * next cell is blank, and not attributed.
             */
            if (!ISBLANK(newLine[n])
                && ((n + 1 < screen_columns(SP_PARM)
                     && xmc_turn_off(SP_PARM, newLine[n], newLine[n + 1]))
                    || (n + 1 >= screen_columns(SP_PARM)
                        && lineno + 1 < screen_lines(SP_PARM)
                        && xmc_turn_off(SP_PARM,
                                        newLine[n],
                                        xmc_new(SP_PARM, lineno + 1, 0))))) {
                n = m;
            }

        }
#endif
    } else {
        NCURSES_CH_T blank;

        /* it may be cheap to clear leading whitespace with clr_bol */
        blank = newLine[0];
        if (clr_bol && can_clear_with(NCURSES_SP_ARGx CHREF(blank))) {
            int oFirstChar, nFirstChar;

            for (oFirstChar = 0;
                 oFirstChar < screen_columns(SP_PARM);
                 oFirstChar++)
                if (!CharEq(oldLine[oFirstChar], blank))
                    break;
            for (nFirstChar = 0;
                 nFirstChar < screen_columns(SP_PARM);
                 nFirstChar++)
                if (!CharEq(newLine[nFirstChar], blank))
                    break;

            if (nFirstChar == oFirstChar) {
                firstChar = nFirstChar;
                /* find the first differing character */
                while (firstChar < screen_columns(SP_PARM)
                       && CharEq(newLine[firstChar], oldLine[firstChar]))
                    firstChar++;
            } else if (oFirstChar > nFirstChar) {
                firstChar = nFirstChar;
            } else {            /* oFirstChar < nFirstChar */
                firstChar = oFirstChar;
                if (SP_PARM->_el1_cost < nFirstChar - oFirstChar) {
                    if (nFirstChar >= screen_columns(SP_PARM)
                        && SP_PARM->_el_cost <= SP_PARM->_el1_cost) {
                        GoTo(NCURSES_SP_ARGx lineno, 0);
                        UpdateAttrs(SP_PARM, blank);
                        NCURSES_PUTP2("clr_eol", clr_eol);
                    } else {
                        GoTo(NCURSES_SP_ARGx lineno, nFirstChar - 1);
                        UpdateAttrs(SP_PARM, blank);
                        NCURSES_PUTP2("clr_bol", clr_bol);
                    }

                    while (firstChar < nFirstChar)
                        oldLine[firstChar++] = blank;
                }
            }
        } else {
            /* find the first differing character */
            while (firstChar < screen_columns(SP_PARM)
                   && CharEq(newLine[firstChar], oldLine[firstChar]))
                firstChar++;
        }
        /* if there wasn't one, we're done */
        if (firstChar >= screen_columns(SP_PARM)) {
            TR(TRACE_UPDATE, (T_RETURN("")));
            return;
        }

        blank = newLine[screen_columns(SP_PARM) - 1];

        if (!can_clear_with(NCURSES_SP_ARGx CHREF(blank))) {
            /* find the last differing character */
            nLastChar = screen_columns(SP_PARM) - 1;

            while (nLastChar > firstChar
                   && CharEq(newLine[nLastChar], oldLine[nLastChar]))
                nLastChar--;

            if (nLastChar >= firstChar) {
                GoTo(NCURSES_SP_ARGx lineno, firstChar);
                PutRange(NCURSES_SP_ARGx
                         oldLine,
                         newLine,
                         lineno,
                         firstChar,
                         nLastChar);
                memcpy(oldLine + firstChar,
                       newLine + firstChar,
                       (unsigned) (nLastChar - firstChar + 1) * sizeof(NCURSES_CH_T));
            }
            TR(TRACE_UPDATE, (T_RETURN("")));
            return;
        }

        /* find last non-blank character on old line */
        oLastChar = screen_columns(SP_PARM) - 1;
        while (oLastChar > firstChar && CharEq(oldLine[oLastChar], blank))
            oLastChar--;

        /* find last non-blank character on new line */
        nLastChar = screen_columns(SP_PARM) - 1;
        while (nLastChar > firstChar && CharEq(newLine[nLastChar], blank))
            nLastChar--;

        if ((nLastChar == firstChar)
            && (SP_PARM->_el_cost < (oLastChar - nLastChar))) {
            GoTo(NCURSES_SP_ARGx lineno, firstChar);
            if (!CharEq(newLine[firstChar], blank))
                PutChar(NCURSES_SP_ARGx CHREF(newLine[firstChar]));
            ClrToEOL(NCURSES_SP_ARGx blank, FALSE);
        } else if ((nLastChar != oLastChar)
                   && (!CharEq(newLine[nLastChar], oldLine[oLastChar])
                       || !(SP_PARM->_nc_sp_idcok
                            && NCURSES_SP_NAME(has_ic) (NCURSES_SP_ARG)))) {
            GoTo(NCURSES_SP_ARGx lineno, firstChar);
            if ((oLastChar - nLastChar) > SP_PARM->_el_cost) {
                if (PutRange(NCURSES_SP_ARGx
                             oldLine,
                             newLine,
                             lineno,
                             firstChar,
                             nLastChar)) {
                    GoTo(NCURSES_SP_ARGx lineno, nLastChar + 1);
                }
                ClrToEOL(NCURSES_SP_ARGx blank, FALSE);
            } else {
                n = max(nLastChar, oLastChar);
                PutRange(NCURSES_SP_ARGx
                         oldLine,
                         newLine,
                         lineno,
                         firstChar,
                         n);
            }
        } else {
            int nLastNonblank = nLastChar;
            int oLastNonblank = oLastChar;

            /* find the last characters that really differ */
            /* can be -1 if no characters differ */
            while (CharEq(newLine[nLastChar], oldLine[oLastChar])) {
                /* don't split a wide char */
                if (isWidecExt(newLine[nLastChar]) &&
                    !CharEq(newLine[nLastChar - 1], oldLine[oLastChar - 1]))
                    break;
                nLastChar--;
                oLastChar--;
                if (nLastChar == -1 || oLastChar == -1)
                    break;
            }

            n = min(oLastChar, nLastChar);
            if (n >= firstChar) {
                GoTo(NCURSES_SP_ARGx lineno, firstChar);
                PutRange(NCURSES_SP_ARGx
                         oldLine,
                         newLine,
                         lineno,
                         firstChar,
                         n);
            }

            if (oLastChar < nLastChar) {
                int m = max(nLastNonblank, oLastNonblank);
#if USE_WIDEC_SUPPORT
                if (n) {
                    while (isWidecExt(newLine[n + 1]) && n) {
                        --n;
                        --oLastChar;    /* increase cost */
                    }
                } else if (n >= firstChar &&
                           isWidecBase(newLine[n])) {
                    while (isWidecExt(newLine[n + 1])) {
                        ++n;
                        ++oLastChar;    /* decrease cost */
                    }
                }
#endif
                GoTo(NCURSES_SP_ARGx lineno, n + 1);
                if ((nLastChar < nLastNonblank)
                    || InsCharCost(SP_PARM, nLastChar - oLastChar) > (m - n)) {
                    PutRange(NCURSES_SP_ARGx
                             oldLine,
                             newLine,
                             lineno,
                             n + 1,
                             m);
                } else {
                    InsStr(NCURSES_SP_ARGx &newLine[n + 1], nLastChar - oLastChar);
                }
            } else if (oLastChar > nLastChar) {
                GoTo(NCURSES_SP_ARGx lineno, n + 1);
                if (DelCharCost(SP_PARM, oLastChar - nLastChar)
                    > SP_PARM->_el_cost + nLastNonblank - (n + 1)) {
                    if (PutRange(NCURSES_SP_ARGx oldLine, newLine, lineno,
                                 n + 1, nLastNonblank)) {
                        GoTo(NCURSES_SP_ARGx lineno, nLastNonblank + 1);
                    }
                    ClrToEOL(NCURSES_SP_ARGx blank, FALSE);
                } else {
                    /*
                     * The delete-char sequence will
                     * effectively shift in blanks from the
                     * right margin of the screen.  Ensure
                     * that they are the right color by
                     * setting the video attributes from
                     * the last character on the row.
                     */
                    UpdateAttrs(SP_PARM, blank);
                    DelChar(NCURSES_SP_ARGx oLastChar - nLastChar);
                }
            }
        }
    }

    /* update the code's internal representation */
    if (screen_columns(SP_PARM) > firstChar)
        memcpy(oldLine + firstChar,
               newLine + firstChar,
               (unsigned) (screen_columns(SP_PARM) - firstChar) * sizeof(NCURSES_CH_T));
    TR(TRACE_UPDATE, (T_RETURN("")));
    return;
}

/*
**      ClearScreen(blank)
**
**      Clear the physical screen and put cursor at home
**
*/

static void
ClearScreen(NCURSES_SP_DCLx NCURSES_CH_T blank)
{
    int i, j;
    bool fast_clear = (clear_screen || clr_eos || clr_eol);

    TR(TRACE_UPDATE, ("ClearScreen() called"));

#if NCURSES_EXT_FUNCS
    if (SP_PARM->_coloron
        && !SP_PARM->_default_color) {
        NCURSES_SP_NAME(_nc_do_color) (NCURSES_SP_ARGx
                                       (short) GET_SCREEN_PAIR(SP_PARM),
                                       0,
                                       FALSE,
                                       NCURSES_SP_NAME(_nc_outch));
        if (!back_color_erase) {
            fast_clear = FALSE;
        }
    }
#endif

    if (fast_clear) {
        if (clear_screen) {
            UpdateAttrs(SP_PARM, blank);
            NCURSES_PUTP2("clear_screen", clear_screen);
            SP_PARM->_cursrow = SP_PARM->_curscol = 0;
            position_check(NCURSES_SP_ARGx
                           SP_PARM->_cursrow,
                           SP_PARM->_curscol,
                           "ClearScreen");
        } else if (clr_eos) {
            SP_PARM->_cursrow = SP_PARM->_curscol = -1;
            GoTo(NCURSES_SP_ARGx 0, 0);
            UpdateAttrs(SP_PARM, blank);
            TPUTS_TRACE("clr_eos");
            NCURSES_SP_NAME(tputs) (NCURSES_SP_ARGx
                                    clr_eos,
                                    screen_lines(SP_PARM),
                                    NCURSES_SP_NAME(_nc_outch));
        } else if (clr_eol) {
            SP_PARM->_cursrow = SP_PARM->_curscol = -1;
            UpdateAttrs(SP_PARM, blank);
            for (i = 0; i < screen_lines(SP_PARM); i++) {
                GoTo(NCURSES_SP_ARGx i, 0);
                NCURSES_PUTP2("clr_eol", clr_eol);
            }
            GoTo(NCURSES_SP_ARGx 0, 0);
        }
    } else {
        UpdateAttrs(SP_PARM, blank);
        for (i = 0; i < screen_lines(SP_PARM); i++) {
            GoTo(NCURSES_SP_ARGx i, 0);
            for (j = 0; j < screen_columns(SP_PARM); j++)
                PutChar(NCURSES_SP_ARGx CHREF(blank));
        }
        GoTo(NCURSES_SP_ARGx 0, 0);
    }

    for (i = 0; i < screen_lines(SP_PARM); i++) {
        for (j = 0; j < screen_columns(SP_PARM); j++)
            CurScreen(SP_PARM)->_line[i].text[j] = blank;
    }

    TR(TRACE_UPDATE, ("screen cleared"));
}

/*
**      InsStr(line, count)
**
**      Insert the count characters pointed to by line.
**
*/

static void
InsStr(NCURSES_SP_DCLx NCURSES_CH_T *line, int count)
{
    TR(TRACE_UPDATE, ("InsStr(%p, %p,%d) called",
                      (void *) SP_PARM,
                      (void *) line, count));

    /* Prefer parm_ich as it has the smallest cost - no need to shift
     * the whole line on each character. */
    /* The order must match that of InsCharCost. */
    if (parm_ich) {
        TPUTS_TRACE("parm_ich");
        NCURSES_SP_NAME(tputs) (NCURSES_SP_ARGx
                                TIPARM_1(parm_ich, count),
                                1,
                                NCURSES_SP_NAME(_nc_outch));
        while (count > 0) {
            PutAttrChar(NCURSES_SP_ARGx CHREF(*line));
            line++;
            count--;
        }
    } else if (enter_insert_mode && exit_insert_mode) {
        NCURSES_PUTP2("enter_insert_mode", enter_insert_mode);
        while (count > 0) {
            PutAttrChar(NCURSES_SP_ARGx CHREF(*line));
            if (insert_padding) {
                NCURSES_PUTP2("insert_padding", insert_padding);
            }
            line++;
            count--;
        }
        NCURSES_PUTP2("exit_insert_mode", exit_insert_mode);
    } else {
        while (count > 0) {
            NCURSES_PUTP2("insert_character", insert_character);
            PutAttrChar(NCURSES_SP_ARGx CHREF(*line));
            if (insert_padding) {
                NCURSES_PUTP2("insert_padding", insert_padding);
            }
            line++;
            count--;
        }
    }
    position_check(NCURSES_SP_ARGx
                   SP_PARM->_cursrow,
                   SP_PARM->_curscol, "InsStr");
}

/*
**      DelChar(count)
**
**      Delete count characters at current position
**
*/

static void
DelChar(NCURSES_SP_DCLx int count)
{
    TR(TRACE_UPDATE, ("DelChar(%p, %d) called, position = (%ld,%ld)",
                      (void *) SP_PARM, count,
                      (long) NewScreen(SP_PARM)->_cury,
                      (long) NewScreen(SP_PARM)->_curx));

    if (parm_dch) {
        TPUTS_TRACE("parm_dch");
        NCURSES_SP_NAME(tputs) (NCURSES_SP_ARGx
                                TIPARM_1(parm_dch, count),
                                1,
                                NCURSES_SP_NAME(_nc_outch));
    } else {
        int n;

        for (n = 0; n < count; n++) {
            NCURSES_PUTP2("delete_character", delete_character);
        }
    }
}

/*
 * Physical-scrolling support
 *
 * This code was adapted from Keith Bostic's hardware scrolling
 * support for 4.4BSD curses.  I (esr) translated it to use terminfo
 * capabilities, narrowed the call interface slightly, and cleaned
 * up some convoluted tests.  I also added support for the memory_above
 * memory_below, and non_dest_scroll_region capabilities.
 *
 * For this code to work, we must have either
 * change_scroll_region and scroll forward/reverse commands, or
 * insert and delete line capabilities.
 * When the scrolling region has been set, the cursor has to
 * be at the last line of the region to make the scroll up
 * happen, or on the first line of region to scroll down.
 *
 * This code makes one aesthetic decision in the opposite way from
 * BSD curses.  BSD curses preferred pairs of il/dl operations
 * over scrolls, allegedly because il/dl looked faster.  We, on
 * the other hand, prefer scrolls because (a) they're just as fast
 * on many terminals and (b) using them avoids bouncing an
 * unchanged bottom section of the screen up and down, which is
 * visually nasty.
 *
 * (lav): added more cases, used dl/il when bot==maxy and in csr case.
 *
 * I used assumption that capabilities il/il1/dl/dl1 work inside
 * changed scroll region not shifting screen contents outside of it.
 * If there are any terminals behaving different way, it would be
 * necessary to add some conditions to scroll_csr_forward/backward.
 */

/* Try to scroll up assuming given csr (miny, maxy). Returns ERR on failure */
static int
scroll_csr_forward(NCURSES_SP_DCLx
                   int n,
                   int top,
                   int bot,
                   int miny,
                   int maxy,
                   NCURSES_CH_T blank)
{
    int i;

    if (n == 1 && scroll_forward && top == miny && bot == maxy) {
        GoTo(NCURSES_SP_ARGx bot, 0);
        UpdateAttrs(SP_PARM, blank);
        NCURSES_PUTP2("scroll_forward", scroll_forward);
    } else if (n == 1 && delete_line && bot == maxy) {
        GoTo(NCURSES_SP_ARGx top, 0);
        UpdateAttrs(SP_PARM, blank);
        NCURSES_PUTP2("delete_line", delete_line);
    } else if (parm_index && top == miny && bot == maxy) {
        GoTo(NCURSES_SP_ARGx bot, 0);
        UpdateAttrs(SP_PARM, blank);
        TPUTS_TRACE("parm_index");
        NCURSES_SP_NAME(tputs) (NCURSES_SP_ARGx
                                TIPARM_1(parm_index, n),
                                n,
                                NCURSES_SP_NAME(_nc_outch));
    } else if (parm_delete_line && bot == maxy) {
        GoTo(NCURSES_SP_ARGx top, 0);
        UpdateAttrs(SP_PARM, blank);
        TPUTS_TRACE("parm_delete_line");
        NCURSES_SP_NAME(tputs) (NCURSES_SP_ARGx
                                TIPARM_1(parm_delete_line, n),
                                n,
                                NCURSES_SP_NAME(_nc_outch));
    } else if (scroll_forward && top == miny && bot == maxy) {
        GoTo(NCURSES_SP_ARGx bot, 0);
        UpdateAttrs(SP_PARM, blank);
        for (i = 0; i < n; i++) {
            NCURSES_PUTP2("scroll_forward", scroll_forward);
        }
    } else if (delete_line && bot == maxy) {
        GoTo(NCURSES_SP_ARGx top, 0);
        UpdateAttrs(SP_PARM, blank);
        for (i = 0; i < n; i++) {
            NCURSES_PUTP2("delete_line", delete_line);
        }
    } else
        return ERR;

#if NCURSES_EXT_FUNCS
    if (FILL_BCE(SP_PARM)) {
        int j;
        for (i = 0; i < n; i++) {
            GoTo(NCURSES_SP_ARGx bot - i, 0);
            for (j = 0; j < screen_columns(SP_PARM); j++)
                PutChar(NCURSES_SP_ARGx CHREF(blank));
        }
    }
#endif
    return OK;
}

/* Try to scroll down assuming given csr (miny, maxy). Returns ERR on failure */
/* n > 0 */
static int
scroll_csr_backward(NCURSES_SP_DCLx
                    int n,
                    int top,
                    int bot,
                    int miny,
                    int maxy,
                    NCURSES_CH_T blank)
{
    int i;

    if (n == 1 && scroll_reverse && top == miny && bot == maxy) {
        GoTo(NCURSES_SP_ARGx top, 0);
        UpdateAttrs(SP_PARM, blank);
        NCURSES_PUTP2("scroll_reverse", scroll_reverse);
    } else if (n == 1 && insert_line && bot == maxy) {
        GoTo(NCURSES_SP_ARGx top, 0);
        UpdateAttrs(SP_PARM, blank);
        NCURSES_PUTP2("insert_line", insert_line);
    } else if (parm_rindex && top == miny && bot == maxy) {
        GoTo(NCURSES_SP_ARGx top, 0);
        UpdateAttrs(SP_PARM, blank);
        TPUTS_TRACE("parm_rindex");
        NCURSES_SP_NAME(tputs) (NCURSES_SP_ARGx
                                TIPARM_1(parm_rindex, n),
                                n,
                                NCURSES_SP_NAME(_nc_outch));
    } else if (parm_insert_line && bot == maxy) {
        GoTo(NCURSES_SP_ARGx top, 0);
        UpdateAttrs(SP_PARM, blank);
        TPUTS_TRACE("parm_insert_line");
        NCURSES_SP_NAME(tputs) (NCURSES_SP_ARGx
                                TIPARM_1(parm_insert_line, n),
                                n,
                                NCURSES_SP_NAME(_nc_outch));
    } else if (scroll_reverse && top == miny && bot == maxy) {
        GoTo(NCURSES_SP_ARGx top, 0);
        UpdateAttrs(SP_PARM, blank);
        for (i = 0; i < n; i++) {
            NCURSES_PUTP2("scroll_reverse", scroll_reverse);
        }
    } else if (insert_line && bot == maxy) {
        GoTo(NCURSES_SP_ARGx top, 0);
        UpdateAttrs(SP_PARM, blank);
        for (i = 0; i < n; i++) {
            NCURSES_PUTP2("insert_line", insert_line);
        }
    } else
        return ERR;

#if NCURSES_EXT_FUNCS
    if (FILL_BCE(SP_PARM)) {
        int j;
        for (i = 0; i < n; i++) {
            GoTo(NCURSES_SP_ARGx top + i, 0);
            for (j = 0; j < screen_columns(SP_PARM); j++)
                PutChar(NCURSES_SP_ARGx CHREF(blank));
        }
    }
#endif
    return OK;
}

/* scroll by using delete_line at del and insert_line at ins */
/* n > 0 */
static int
scroll_idl(NCURSES_SP_DCLx int n, int del, int ins, NCURSES_CH_T blank)
{
    int i;

    if (!((parm_delete_line || delete_line) && (parm_insert_line || insert_line)))
        return ERR;

    GoTo(NCURSES_SP_ARGx del, 0);
    UpdateAttrs(SP_PARM, blank);
    if (n == 1 && delete_line) {
        NCURSES_PUTP2("delete_line", delete_line);
    } else if (parm_delete_line) {
        TPUTS_TRACE("parm_delete_line");
        NCURSES_SP_NAME(tputs) (NCURSES_SP_ARGx
                                TIPARM_1(parm_delete_line, n),
                                n,
                                NCURSES_SP_NAME(_nc_outch));
    } else {                    /* if (delete_line) */
        for (i = 0; i < n; i++) {
            NCURSES_PUTP2("delete_line", delete_line);
        }
    }

    GoTo(NCURSES_SP_ARGx ins, 0);
    UpdateAttrs(SP_PARM, blank);
    if (n == 1 && insert_line) {
        NCURSES_PUTP2("insert_line", insert_line);
    } else if (parm_insert_line) {
        TPUTS_TRACE("parm_insert_line");
        NCURSES_SP_NAME(tputs) (NCURSES_SP_ARGx
                                TIPARM_1(parm_insert_line, n),
                                n,
                                NCURSES_SP_NAME(_nc_outch));
    } else {                    /* if (insert_line) */
        for (i = 0; i < n; i++) {
            NCURSES_PUTP2("insert_line", insert_line);
        }
    }

    return OK;
}

/*
 * Note:  some terminals require the cursor to be within the scrolling margins
 * before setting them.  Generally, the cursor must be at the appropriate end
 * of the scrolling margins when issuing an indexing operation (it is not
 * apparent whether it must also be at the left margin; we do this just to be
 * safe).  To make the related cursor movement a little faster, we use the
 * save/restore cursor capabilities if the terminal has them.
 */
NCURSES_EXPORT(int)
NCURSES_SP_NAME(_nc_scrolln) (NCURSES_SP_DCLx
                              int n,
                              int top,
                              int bot,
                              int maxy)
/* scroll region from top to bot by n lines */
{
    NCURSES_CH_T blank;
    int i;
    bool cursor_saved = FALSE;
    int res;

    TR(TRACE_MOVE, ("_nc_scrolln(%p, %d, %d, %d, %d)",
                    (void *) SP_PARM, n, top, bot, maxy));

    if (!IsValidScreen(SP_PARM))
        return (ERR);

    blank = ClrBlank(NCURSES_SP_ARGx StdScreen(SP_PARM));

#if USE_XMC_SUPPORT
    /*
     * If we scroll, we might remove a cookie.
     */
    if (magic_cookie_glitch > 0) {
        return (ERR);
    }
#endif

    if (n > 0) {                /* scroll up (forward) */
        /*
         * Explicitly clear if stuff pushed off top of region might
         * be saved by the terminal.
         */
        res = scroll_csr_forward(NCURSES_SP_ARGx n, top, bot, 0, maxy, blank);

        if (res == ERR && change_scroll_region) {
            if ((((n == 1 && scroll_forward) || parm_index)
                 && (SP_PARM->_cursrow == bot || SP_PARM->_cursrow == bot - 1))
                && save_cursor && restore_cursor) {
                cursor_saved = TRUE;
                NCURSES_PUTP2("save_cursor", save_cursor);
            }
            NCURSES_PUTP2("change_scroll_region",
                          TIPARM_2(change_scroll_region, top, bot));
            if (cursor_saved) {
                NCURSES_PUTP2("restore_cursor", restore_cursor);
            } else {
                SP_PARM->_cursrow = SP_PARM->_curscol = -1;
            }

            res = scroll_csr_forward(NCURSES_SP_ARGx n, top, bot, top, bot, blank);

            NCURSES_PUTP2("change_scroll_region",
                          TIPARM_2(change_scroll_region, 0, maxy));
            SP_PARM->_cursrow = SP_PARM->_curscol = -1;
        }

        if (res == ERR && SP_PARM->_nc_sp_idlok)
            res = scroll_idl(NCURSES_SP_ARGx n, top, bot - n + 1, blank);

        /*
         * Clear the newly shifted-in text.
         */
        if (res != ERR
            && (non_dest_scroll_region || (memory_below && bot == maxy))) {
            static const NCURSES_CH_T blank2 = NewChar(BLANK_TEXT);
            if (bot == maxy && clr_eos) {
                GoTo(NCURSES_SP_ARGx bot - n + 1, 0);
                ClrToEOS(NCURSES_SP_ARGx blank2);
            } else {
                for (i = 0; i < n; i++) {
                    GoTo(NCURSES_SP_ARGx bot - i, 0);
                    ClrToEOL(NCURSES_SP_ARGx blank2, FALSE);
                }
            }
        }

    } else {                    /* (n < 0) - scroll down (backward) */
        res = scroll_csr_backward(NCURSES_SP_ARGx -n, top, bot, 0, maxy, blank);

        if (res == ERR && change_scroll_region) {
            if (top != 0
                && (SP_PARM->_cursrow == top ||
                    SP_PARM->_cursrow == top - 1)
                && save_cursor && restore_cursor) {
                cursor_saved = TRUE;
                NCURSES_PUTP2("save_cursor", save_cursor);
            }
            NCURSES_PUTP2("change_scroll_region",
                          TIPARM_2(change_scroll_region, top, bot));
            if (cursor_saved) {
                NCURSES_PUTP2("restore_cursor", restore_cursor);
            } else {
                SP_PARM->_cursrow = SP_PARM->_curscol = -1;
            }

            res = scroll_csr_backward(NCURSES_SP_ARGx
                                      -n, top, bot, top, bot, blank);

            NCURSES_PUTP2("change_scroll_region",
                          TIPARM_2(change_scroll_region, 0, maxy));
            SP_PARM->_cursrow = SP_PARM->_curscol = -1;
        }

        if (res == ERR && SP_PARM->_nc_sp_idlok)
            res = scroll_idl(NCURSES_SP_ARGx -n, bot + n + 1, top, blank);

        /*
         * Clear the newly shifted-in text.
         */
        if (res != ERR
            && (non_dest_scroll_region || (memory_above && top == 0))) {
            static const NCURSES_CH_T blank2 = NewChar(BLANK_TEXT);
            for (i = 0; i < -n; i++) {
                GoTo(NCURSES_SP_ARGx i + top, 0);
                ClrToEOL(NCURSES_SP_ARGx blank2, FALSE);
            }
        }
    }

    if (res == ERR)
        return (ERR);

    _nc_scroll_window(CurScreen(SP_PARM), n,
                      (NCURSES_SIZE_T) top,
                      (NCURSES_SIZE_T) bot,
                      blank);

    /* shift hash values too - they can be reused */
    NCURSES_SP_NAME(_nc_scroll_oldhash) (NCURSES_SP_ARGx n, top, bot);

    return (OK);
}

#if NCURSES_SP_FUNCS
NCURSES_EXPORT(int)
_nc_scrolln(int n, int top, int bot, int maxy)
{
    return NCURSES_SP_NAME(_nc_scrolln) (CURRENT_SCREEN, n, top, bot, maxy);
}
#endif

NCURSES_EXPORT(void)
NCURSES_SP_NAME(_nc_screen_resume) (NCURSES_SP_DCL0)
{
    assert(SP_PARM);

    /* make sure terminal is in a sane known state */
    SetAttr(SCREEN_ATTRS(SP_PARM), A_NORMAL);
    NewScreen(SP_PARM)->_clear = TRUE;

    /* reset color pairs and definitions */
    if (SP_PARM->_coloron || SP_PARM->_color_defs)
        NCURSES_SP_NAME(_nc_reset_colors) (NCURSES_SP_ARG);

    /* restore user-defined colors, if any */
    if (SP_PARM->_color_defs < 0 && !SP_PARM->_direct_color.value) {
        int n;
        SP_PARM->_color_defs = -(SP_PARM->_color_defs);
        for (n = 0; n < SP_PARM->_color_defs; ++n) {
            if (SP_PARM->_color_table[n].init) {
                _nc_init_color(SP_PARM,
                               n,
                               SP_PARM->_color_table[n].r,
                               SP_PARM->_color_table[n].g,
                               SP_PARM->_color_table[n].b);
            }
        }
    }

    if (exit_attribute_mode)
        NCURSES_PUTP2("exit_attribute_mode", exit_attribute_mode);
    else {
        /* turn off attributes */
        if (exit_alt_charset_mode)
            NCURSES_PUTP2("exit_alt_charset_mode", exit_alt_charset_mode);
        if (exit_standout_mode)
            NCURSES_PUTP2("exit_standout_mode", exit_standout_mode);
        if (exit_underline_mode)
            NCURSES_PUTP2("exit_underline_mode", exit_underline_mode);
    }
    if (exit_insert_mode)
        NCURSES_PUTP2("exit_insert_mode", exit_insert_mode);
    if (enter_am_mode && exit_am_mode) {
        if (auto_right_margin) {
            NCURSES_PUTP2("enter_am_mode", enter_am_mode);
        } else {
            NCURSES_PUTP2("exit_am_mode", exit_am_mode);
        }
    }
}

#if NCURSES_SP_FUNCS
NCURSES_EXPORT(void)
_nc_screen_resume(void)
{
    NCURSES_SP_NAME(_nc_screen_resume) (CURRENT_SCREEN);
}
#endif

NCURSES_EXPORT(void)
NCURSES_SP_NAME(_nc_screen_init) (NCURSES_SP_DCL0)
{
    NCURSES_SP_NAME(_nc_screen_resume) (NCURSES_SP_ARG);
}

#if NCURSES_SP_FUNCS
NCURSES_EXPORT(void)
_nc_screen_init(void)
{
    NCURSES_SP_NAME(_nc_screen_init) (CURRENT_SCREEN);
}
#endif

/* wrap up screen handling */
NCURSES_EXPORT(void)
NCURSES_SP_NAME(_nc_screen_wrap) (NCURSES_SP_DCL0)
{
    if (SP_PARM != 0) {

        UpdateAttrs(SP_PARM, normal);
#if NCURSES_EXT_FUNCS
        if (SP_PARM->_coloron
            && !SP_PARM->_default_color) {
            static const NCURSES_CH_T blank = NewChar(BLANK_TEXT);
            SP_PARM->_default_color = TRUE;
            NCURSES_SP_NAME(_nc_do_color) (NCURSES_SP_ARGx
                                           -1,
                                           0,
                                           FALSE,
                                           NCURSES_SP_NAME(_nc_outch));
            SP_PARM->_default_color = FALSE;

            TINFO_MVCUR(NCURSES_SP_ARGx
                        SP_PARM->_cursrow,
                        SP_PARM->_curscol,
                        screen_lines(SP_PARM) - 1,
                        0);

            ClrToEOL(NCURSES_SP_ARGx blank, TRUE);
        }
#endif
        if (SP_PARM->_color_defs) {
            NCURSES_SP_NAME(_nc_reset_colors) (NCURSES_SP_ARG);
        }
    }
}

#if NCURSES_SP_FUNCS
NCURSES_EXPORT(void)
_nc_screen_wrap(void)
{
    NCURSES_SP_NAME(_nc_screen_wrap) (CURRENT_SCREEN);
}
#endif

#if USE_XMC_SUPPORT
NCURSES_EXPORT(void)
NCURSES_SP_NAME(_nc_do_xmc_glitch) (NCURSES_SP_DCLx attr_t previous)
{
    if (SP_PARM != 0) {
        attr_t chg = XMC_CHANGES(previous ^ AttrOf(SCREEN_ATTRS(SP_PARM)));

        while (chg != 0) {
            if (chg & 1) {
                SP_PARM->_curscol += magic_cookie_glitch;
                if (SP_PARM->_curscol >= SP_PARM->_columns)
                    wrap_cursor(NCURSES_SP_ARG);
                TR(TRACE_UPDATE, ("bumped to %d,%d after cookie",
                                  SP_PARM->_cursrow, SP_PARM->_curscol));
            }
            chg >>= 1;
        }
    }
}

#if NCURSES_SP_FUNCS
NCURSES_EXPORT(void)
_nc_do_xmc_glitch(attr_t previous)
{
    NCURSES_SP_NAME(_nc_do_xmc_glitch) (CURRENT_SCREEN, previous);
}
#endif

#endif /* USE_XMC_SUPPORT */