[ncurses.git] / ncurses / lib_mvcur.c

/***************************************************************************
*                            COPYRIGHT NOTICE                              *
****************************************************************************
*                ncurses is copyright (C) 1992-1995                        *
*                          Zeyd M. Ben-Halim                               *
*                          zmbenhal@netcom.com                             *
*                          Eric S. Raymond                                 *
*                          esr@snark.thyrsus.com                           *
*                                                                          *
*        Permission is hereby granted to reproduce and distribute ncurses  *
*        by any means and for any fee, whether alone or as part of a       *
*        larger distribution, in source or in binary form, PROVIDED        *
*        this notice is included with any such distribution, and is not    *
*        removed from any of its header files. Mention of ncurses in any   *
*        applications linked with it is highly appreciated.                *
*                                                                          *
*        ncurses comes AS IS with no warranty, implied or expressed.       *
*                                                                          *
***************************************************************************/


/*
**      lib_mvcur.c
**
**      The routines for moving the physical cursor and scrolling:
**
**              void _nc_mvcur_init(void), mvcur_wrap(void)
**
**              void _nc_mvcur_resume(void)
**
**              int mvcur(int old_y, int old_x, int new_y, int new_x)
**
**              void _nc_mvcur_wrap(void)
**
**              int _nc_mvcur_scrolln(int n, int top, int bot, int maxy)
**
** Comparisons with older movement optimizers:
**    SVr3 curses mvcur() can't use cursor_to_ll or auto_left_margin.
**    4.4BSD curses can't use cuu/cud/cuf/cub/hpa/vpa/tab/cbt for local
** motions.  It doesn't use tactics based on auto_left_margin.  Weirdly
** enough, it doesn't use its own hardware-scrolling routine to scroll up
** destination lines for out-of-bounds addresses!
**    old ncurses optimizer: less accurate cost computations (in fact,
** it was broken and had to be commented out!).
**
** Compile with -DMAIN to build an interactive tester/timer for the movement
** optimizer.  You can use it to investigate the optimizer's behavior.
** You can also use it for tuning the formulas used to determine whether
** or not full optimization is attempted.
**
** This code has a nasty tendency to find bugs in terminfo entries, because it
** exercises the non-cup movement capabilities heavily.  If you think you've
** found a bug, try deleting subsets of the following capabilities (arranged
** in decreasing order of suspiciousness): it, tab, cbt, hpa, vpa, cuu, cud,
** cuf, cub, cuu1, cud1, cuf1, cub1.  It may be that one or more are wrong.
**
** Note: you should expect this code to look like a resource hog in a profile.
** That's because it does a lot of I/O, through the tputs() calls.  The I/O
** cost swamps the computation overhead (and as machines get faster, this
** will become even more true).  Comments in the test exerciser at the end
** go into detail about tuning and how you can gauge the optimizer's
** effectiveness.
**/

/****************************************************************************
 *
 * Constants and macros for optimizer tuning.
 *
 ****************************************************************************/

/*
 * The average overhead of a full optimization computation in character
 * transmission times.  If it's too high, the algorithm will be a bit
 * over-biased toward using cup rather than local motions; if it's too
 * low, the algorithm may spend more time than is strictly optimal
 * looking for non-cup motions.  Profile the optimizer using the `t'
 * command of the exerciser (see below), and round to the nearest integer.
 *
 * Yes, I (esr) thought about computing expected overhead dynamically, say
 * by derivation from a running average of optimizer times.  But the
 * whole point of this optimization is to *decrease* the frequency of
 * system calls. :-)
 */
#define COMPUTE_OVERHEAD        1       /* I use a 90MHz Pentium @ 9.6Kbps */

/*
 * LONG_DIST is the distance we consider to be just as costly to move over as a
 * cup sequence is to emit.  In other words, it's the length of a cup sequence
 * adjusted for average computation overhead.  The magic number is the length
 * of "\033[yy;xxH", the typical cup sequence these days.
 */
#define LONG_DIST               (8 - COMPUTE_OVERHEAD)

/*
 * Tell whether a motion is optimizable by local motions.  Needs to be cheap to
 * compute. In general, all the fast moves go to either the right or left edge
 * of the screen.  So any motion to a location that is (a) further away than
 * LONG_DIST and (b) further inward from the right or left edge than LONG_DIST,
 * we'll consider nonlocal.
 */
#define NOT_LOCAL(fy, fx, ty, tx)       ((tx > LONG_DIST) && (tx < screen_lines - 1 - LONG_DIST) && (abs(ty-fy) + abs(tx-fx) > LONG_DIST))

/****************************************************************************
 *
 * External interfaces
 *
 ****************************************************************************/

/*
 * For this code to work OK, the following components must live in the
 * screen structure:
 *
 *      int             _char_padding;  // cost of character put
 *      int             _cr_cost;       // cost of (carriage_return)
 *      int             _cup_cost;      // cost of (cursor_address)
 *      int             _home_cost;     // cost of (cursor_home)
 *      int             _ll_cost;       // cost of (cursor_to_ll)
 *#ifdef TABS_OK
 *      int             _ht_cost;       // cost of (tab)
 *      int             _cbt_cost;      // cost of (backtab)
 *#endif TABS_OK
 *      int             _cub1_cost;     // cost of (cursor_left)
 *      int             _cuf1_cost;     // cost of (cursor_right)
 *      int             _cud1_cost;     // cost of (cursor_down)
 *      int             _cuu1_cost;     // cost of (cursor_up)
 *      int             _cub_cost;      // cost of (parm_cursor_left)
 *      int             _cuf_cost;      // cost of (parm_cursor_right)
 *      int             _cud_cost;      // cost of (parm_cursor_down)
 *      int             _cuu_cost;      // cost of (parm_cursor_up)
 *      int             _hpa_cost;      // cost of (column_address)
 *      int             _vpa_cost;      // cost of (row_address)
 *      int             _ech_cost;      // cost of (erase_chars)
 *      int             _rep_cost;      // cost of (repeat_char)
 *
 * The TABS_OK switch controls whether it is reliable to use tab/backtabs
 * for local motions.  On many systems, it's not, due to uncertainties about
 * tab delays and whether or not tabs will be expanded in raw mode.  If you
 * have parm_right_cursor, tab motions don't win you a lot anyhow.
 */

#include <curses.priv.h>
#include <term.h>
#include <ctype.h>

MODULE_ID("$Id: lib_mvcur.c,v 1.37 1997/05/03 22:15:26 Peter.Wemm Exp $")

#define STRLEN(s)       (s != 0) ? strlen(s) : 0

#define CURRENT_ATTR    SP->_current_attr       /* current phys attribute */
#define CURRENT_ROW     SP->_cursrow            /* phys cursor row */
#define CURRENT_COLUMN  SP->_curscol            /* phys cursor column */
#define REAL_ATTR       SP->_current_attr       /* phys current attribute */
#define WANT_CHAR(y, x) SP->_newscr->_line[y].text[x]   /* desired state */
#define BAUDRATE        SP->_baudrate           /* bits per second */

#ifdef MAIN
#include <sys/time.h>

static bool profiling = FALSE;
static float diff;
#endif /* MAIN */

#define OPT_SIZE 512

static void save_curs(void);
static void restore_curs(void);
static int cost_of(const char *const cap, int affcnt);
static int normalized_cost(const char *const cap, int affcnt);

/****************************************************************************
 *
 * Initialization/wrapup (including cost pre-computation)
 *
 ****************************************************************************/

#ifdef TRACE
static int
trace_cost_of(const char *capname, const char *cap, int affcnt)
{
        int result = cost_of(cap,affcnt);
        TR(TRACE_CHARPUT|TRACE_MOVE, ("CostOf %s %d", capname, result));
        return result;
}
#define CostOf(cap,affcnt) trace_cost_of(#cap,cap,affcnt);

static int
trace_normalized_cost(const char *capname, const char *cap, int affcnt)
{
        int result = normalized_cost(cap,affcnt);
        TR(TRACE_CHARPUT|TRACE_MOVE, ("NormalizedCost %s %d", capname, result));
        return result;
}
#define NormalizedCost(cap,affcnt) trace_normalized_cost(#cap,cap,affcnt);

#else

#define CostOf(cap,affcnt) cost_of(cap,affcnt);
#define NormalizedCost(cap,affcnt) normalized_cost(cap,affcnt);

#endif

static int cost_of(const char *const cap, int affcnt)
/* compute the cost of a given operation */
{
    if (cap == 0)
        return(INFINITY);
    else
    {
        const   char    *cp;
        float   cum_cost = 0;

        for (cp = cap; *cp; cp++)
        {
            /* extract padding, either mandatory or required */
            if (cp[0] == '$' && cp[1] == '<' && strchr(cp, '>'))
            {
                float   number = 0;

                for (cp += 2; *cp != '>'; cp++)
                {
                    if (isdigit(*cp))
                        number = number * 10 + (*cp - '0');
                    else if (*cp == '.')
                        number += (*++cp - 10) / 10.0;
                    else if (*cp == '*')
                        number *= affcnt;
                }

                cum_cost += number * 10;
            }
            else
                cum_cost += SP->_char_padding;
        }

        return((int)cum_cost);
    }
}

static int normalized_cost(const char *const cap, int affcnt)
/* compute the effective character-count for an operation (round up) */
{
        int cost = cost_of(cap, affcnt);
        if (cost != INFINITY)
                cost = (cost + SP->_char_padding - 1) / SP->_char_padding;
        return cost;
}

static void reset_scroll_region(void)
/* Set the scroll-region to a known state (the default) */
{
    if (change_scroll_region)
    {
        /* change_scroll_region may trash the cursor location */
        save_curs();
        TPUTS_TRACE("change_scroll_region");
        putp(tparm(change_scroll_region, 0, screen_lines - 1));
        restore_curs();
    }
}

void _nc_mvcur_resume(void)
/* what to do at initialization time and after each shellout */
{
    /* initialize screen for cursor access */
    if (enter_ca_mode)
    {
        TPUTS_TRACE("enter_ca_mode");
        putp(enter_ca_mode);
    }

    /*
     * Doing this here rather than in _nc_mvcur_wrap() ensures that
     * ncurses programs will see a reset scroll region even if a
     * program that messed with it died ungracefully.
     *
     * This also undoes the effects of terminal init strings that assume
     * they know the screen size.  This is useful when you're running
     * a vt100 emulation through xterm.
     */
    reset_scroll_region();
}

void _nc_mvcur_init(void)
/* initialize the cost structure */
{
    /*
     * 9 = 7 bits + 1 parity + 1 stop.
     */
    SP->_char_padding = (9 * 1000 * 10) / (BAUDRATE > 0 ? BAUDRATE : 9600);
    if (SP->_char_padding <= 0)
        SP->_char_padding = 1;  /* must be nonzero */
    TR(TRACE_CHARPUT|TRACE_MOVE, ("char_padding %d msecs", SP->_char_padding));

    /* non-parameterized local-motion strings */
    SP->_cr_cost   = CostOf(carriage_return, 0);
    SP->_home_cost = CostOf(cursor_home, 0);
    SP->_ll_cost   = CostOf(cursor_to_ll, 0);
#ifdef TABS_OK
    SP->_ht_cost   = CostOf(tab, 0);
    SP->_cbt_cost  = CostOf(back_tab, 0);
#endif /* TABS_OK */
    SP->_cub1_cost = CostOf(cursor_left, 0);
    SP->_cuf1_cost = CostOf(cursor_right, 0);
    SP->_cud1_cost = CostOf(cursor_down, 0);
    SP->_cuu1_cost = CostOf(cursor_up, 0);

    /*
     * Assumption: if the terminal has memory_relative addressing, the
     * initialization strings or smcup will set single-page mode so we
     * can treat it like absolute screen addressing.  This seems to be true
     * for all cursor_mem_address terminal types in the terminfo database.
     */
    SP->_address_cursor = cursor_address ? cursor_address : cursor_mem_address;

    /*
     * Parametrized local-motion strings.  This static cost computation
     * depends on the following assumptions:
     *
     * (1) They never have * padding.  In the entire master terminfo database
     *     as of March 1995, only the obsolete Zenith Z-100 pc violates this.
     *     (Proportional padding is found mainly in insert, delete and scroll
     *     capabilities).
     *
     * (2) The average case of cup has two two-digit parameters.  Strictly,
     *     the average case for a 24 * 80 screen has ((10*10*(1 + 1)) +
     *     (14*10*(1 + 2)) + (10*70*(2 + 1)) + (14*70*4)) / (24*80) = 3.458
     *     digits of parameters.  On a 25x80 screen the average is 3.6197.
     *     On larger screens the value gets much closer to 4.
     *
     * (3) The average case of cub/cuf/hpa/ech/rep has 2 digits of parameters
     *     (strictly, (((10 * 1) + (70 * 2)) / 80) = 1.8750).
     *
     * (4) The average case of cud/cuu/vpa has 2 digits of parameters
     *     (strictly, (((10 * 1) + (14 * 2)) / 24) = 1.5833).
     *
     * All these averages depend on the assumption that all parameter values
     * are equally probable.
     */
    SP->_cup_cost  = CostOf(tparm(SP->_address_cursor, 23, 23), 1);
    SP->_cub_cost  = CostOf(tparm(parm_left_cursor, 23), 1);
    SP->_cuf_cost  = CostOf(tparm(parm_right_cursor, 23), 1);
    SP->_cud_cost  = CostOf(tparm(parm_down_cursor, 23), 1);
    SP->_cuu_cost  = CostOf(tparm(parm_up_cursor, 23), 1);
    SP->_hpa_cost  = CostOf(tparm(column_address, 23), 1);
    SP->_vpa_cost  = CostOf(tparm(row_address, 23), 1);

    /* non-parameterized screen-update strings */
    SP->_ed_cost   = NormalizedCost(clr_eos, 1);
    SP->_el_cost   = NormalizedCost(clr_eol, 1);
    SP->_el1_cost  = NormalizedCost(clr_bol, 1);
    SP->_dch1_cost = NormalizedCost(delete_character, 1);
    SP->_ich1_cost = NormalizedCost(insert_character, 1);

    /* parameterized screen-update strings */
    SP->_dch_cost  = NormalizedCost(tparm(parm_dch, 23), 1);
    SP->_ich_cost  = NormalizedCost(tparm(parm_ich, 23), 1);
    SP->_ech_cost  = NormalizedCost(tparm(erase_chars, 23), 1);
    SP->_rep_cost  = NormalizedCost(tparm(repeat_char, ' ', 23), 1);

    SP->_cup_ch_cost = NormalizedCost(tparm(SP->_address_cursor, 23, 23), 1);
    SP->_hpa_ch_cost = NormalizedCost(tparm(column_address, 23), 1);

    /* pre-compute some capability lengths */
    SP->_carriage_return_length = STRLEN(carriage_return);
    SP->_cursor_home_length     = STRLEN(cursor_home);
    SP->_cursor_to_ll_length    = STRLEN(cursor_to_ll);

    /*
     * A different, possibly better way to arrange this would be to set
     * SP->_endwin = TRUE at window initialization time and let this be
     * called by doupdate's return-from-shellout code.
     */
    _nc_mvcur_resume();
}

void _nc_mvcur_wrap(void)
/* wrap up cursor-addressing mode */
{
    reset_scroll_region();
    if (exit_ca_mode)
    {
        TPUTS_TRACE("exit_ca_mode");
        putp(exit_ca_mode);
    }
}

/****************************************************************************
 *
 * Optimized cursor movement
 *
 ****************************************************************************/

/*
 * Perform repeated-append, returning cost
 */
static inline int
repeated_append (int total, int num, int repeat, char *dst, const char *src)
{
        register size_t src_len = strlen(src);
        register size_t dst_len = STRLEN(dst);

        if ((dst_len + repeat * src_len) < OPT_SIZE-1) {
                total += (num * repeat);
                if (dst) {
                    dst += dst_len;
                    while (repeat-- > 0) {
                        (void) strcpy(dst, src);
                        dst += src_len;
                    }
                }
        } else {
                total = INFINITY;
        }
        return total;
}

#ifndef NO_OPTIMIZE
#define NEXTTAB(fr)     (fr + init_tabs - (fr % init_tabs))
#define LASTTAB(fr)     (fr - init_tabs + (fr % init_tabs))

/* Note: we'd like to inline this for speed, but GNU C barfs on the attempt. */

static int
relative_move(char *result, int from_y,int from_x,int to_y,int to_x, bool ovw)
/* move via local motions (cuu/cuu1/cud/cud1/cub1/cub/cuf1/cuf/vpa/hpa) */
{
    int         n, vcost = 0, hcost = 0;

    if (result)
        result[0] = '\0';

    if (to_y != from_y)
    {
        vcost = INFINITY;

        if (row_address)
        {
            if (result)
                (void) strcpy(result, tparm(row_address, to_y));
            vcost = SP->_vpa_cost;
        }

        if (to_y > from_y)
        {
            n = (to_y - from_y);

            if (parm_down_cursor && SP->_cud_cost < vcost)
            {
                if (result)
                    (void) strcpy(result, tparm(parm_down_cursor, n));
                vcost = SP->_cud_cost;
            }

            if (cursor_down && (n * SP->_cud1_cost < vcost))
            {
                if (result)
                    result[0] = '\0';
                vcost = repeated_append(vcost, SP->_cud1_cost, n, result, cursor_down);
            }
        }
        else /* (to_y < from_y) */
        {
            n = (from_y - to_y);

            if (parm_up_cursor && SP->_cup_cost < vcost)
            {
                if (result)
                    (void) strcpy(result, tparm(parm_up_cursor, n));
                vcost = SP->_cup_cost;
            }

            if (cursor_up && (n * SP->_cuu1_cost < vcost))
            {
                if (result)
                    result[0] = '\0';
                vcost = repeated_append(vcost, SP->_cuu1_cost, n, result, cursor_up);
            }
        }

        if (vcost == INFINITY)
            return(INFINITY);
    }

    if (result)
        result += strlen(result);

    if (to_x != from_x)
    {
        char    try[OPT_SIZE];

        hcost = INFINITY;

        if (column_address)
        {
            if (result)
                (void) strcpy(result, tparm(column_address, to_x));
            hcost = SP->_hpa_cost;
        }

        if (to_x > from_x)
        {
            n = to_x - from_x;

            if (parm_right_cursor && SP->_cuf_cost < hcost)
            {
                if (result)
                    (void) strcpy(result, tparm(parm_right_cursor, n));
                hcost = SP->_cuf_cost;
            }

            if (cursor_right)
            {
                int     lhcost = 0;

                try[0] = '\0';

#ifdef TABS_OK
                /* use hard tabs, if we have them, to do as much as possible */
                if (init_tabs > 0 && tab)
                {
                    int nxt, fr;

                    for (fr = from_x; (nxt = NEXTTAB(fr)) <= to_x; fr = nxt)
                    {
                        lhcost = repeated_append(lhcost, SP->_ht_cost, 1, try, tab);
                        if (lhcost == INFINITY)
                                break;
                    }

                    n = to_x - fr;
                    from_x = fr;
                }
#endif /* TABS_OK */

#if defined(REAL_ATTR) && defined(WANT_CHAR)
                /*
                 * If we have no attribute changes, overwrite is cheaper.
                 * Note: must suppress this by passing in ovw = FALSE whenever
                 * WANT_CHAR would return invalid data.  In particular, this
                 * is true between the time a hardware scroll has been done
                 * and the time the structure WANT_CHAR would access has been
                 * updated.
                 */
                if (ovw)
                {
                    int i;

                    for (i = 0; i < n; i++)
                        if ((WANT_CHAR(to_y, from_x + i) & A_ATTRIBUTES) != CURRENT_ATTR)
                        {
                            ovw = FALSE;
                            break;
                        }
                }
                if (ovw)
                {
                    char        *sp;
                    int i;

                    sp = try + strlen(try);

                    for (i = 0; i < n; i++)
                        *sp++ = WANT_CHAR(to_y, from_x + i);
                    *sp = '\0';
                    lhcost += n * SP->_char_padding;
                }
                else
#endif /* defined(REAL_ATTR) && defined(WANT_CHAR) */
                {
                    lhcost = repeated_append(lhcost, SP->_cuf1_cost, n, try, cursor_right);
                }

                if (lhcost < hcost)
                {
                    if (result)
                        (void) strcpy(result, try);
                    hcost = lhcost;
                }
            }
        }
        else /* (to_x < from_x) */
        {
            n = from_x - to_x;

            if (parm_left_cursor && SP->_cub_cost < hcost)
            {
                if (result)
                    (void) strcpy(result, tparm(parm_left_cursor, n));
                hcost = SP->_cub_cost;
            }

            if (cursor_left)
            {
                int     lhcost = 0;

                try[0] = '\0';

#ifdef TABS_OK
                if (init_tabs > 0 && back_tab)
                {
                    int nxt, fr;

                    for (fr = from_x; (nxt = LASTTAB(fr)) >= to_x; fr = nxt)
                    {
                        lhcost = repeated_append(lhcost, SP->_cbt_cost, 1, try, back_tab);
                        if (lhcost == INFINITY)
                                break;
                    }

                    n = to_x - fr;
                }
#endif /* TABS_OK */

                lhcost = repeated_append(lhcost, SP->_cub1_cost, n, try, cursor_left);

                if (lhcost < hcost)
                {
                    if (result)
                        (void) strcpy(result, try);
                    hcost = lhcost;
                }
            }
        }

        if (hcost == INFINITY)
            return(INFINITY);
    }

    return(vcost + hcost);
}
#endif /* !NO_OPTIMIZE */

/*
 * With the machinery set up above, it's conceivable that
 * onscreen_mvcur could be modified into a recursive function that does
 * an alpha-beta search of motion space, as though it were a chess
 * move tree, with the weight function being boolean and the search
 * depth equated to length of string.  However, this would jack up the
 * computation cost a lot, especially on terminals without a cup
 * capability constraining the search tree depth.  So we settle for
 * the simpler method below.
 */

static inline int
onscreen_mvcur(int yold,int xold,int ynew,int xnew, bool ovw)
/* onscreen move from (yold, xold) to (ynew, xnew) */
{
    char        use[OPT_SIZE], *sp;
    int         tactic = 0, newcost, usecost = INFINITY;

#ifdef MAIN
    struct timeval before, after;

    gettimeofday(&before, NULL);
#endif /* MAIN */

    /* tactic #0: use direct cursor addressing */
    sp = tparm(SP->_address_cursor, ynew, xnew);
    if (sp)
    {
        tactic = 0;
        (void) strcpy(use, sp);
        usecost = SP->_cup_cost;

#if defined(TRACE) || defined(NCURSES_TEST)
        if (!(_nc_optimize_enable & OPTIMIZE_MVCUR))
            goto nonlocal;
#endif /* TRACE */

        /*
         * We may be able to tell in advance that the full optimization
         * will probably not be worth its overhead.  Also, don't try to
         * use local movement if the current attribute is anything but
         * A_NORMAL...there are just too many ways this can screw up
         * (like, say, local-movement \n getting mapped to some obscure
         * character because A_ALTCHARSET is on).
         */
        if (yold == -1 || xold == -1  ||
            REAL_ATTR != A_NORMAL || NOT_LOCAL(yold, xold, ynew, xnew))
        {
#ifdef MAIN
            if (!profiling)
            {
                (void) fputs("nonlocal\n", stderr);
                goto nonlocal;  /* always run the optimizer if profiling */
            }
#else
            goto nonlocal;
#endif /* MAIN */
        }
    }

#ifndef NO_OPTIMIZE
    /* tactic #1: use local movement */
    if (yold != -1 && xold != -1
                && ((newcost=relative_move(NULL, yold, xold, ynew, xnew, ovw))!=INFINITY)
                && newcost < usecost)
    {
        tactic = 1;
        usecost = newcost;
    }

    /* tactic #2: use carriage-return + local movement */
    if (yold < screen_lines - 1 && xold < screen_columns - 1)
    {
        if (carriage_return
                && ((newcost=relative_move(NULL, yold,0,ynew,xnew, ovw)) != INFINITY)
                && SP->_cr_cost + newcost < usecost)
        {
            tactic = 2;
            usecost = SP->_cr_cost + newcost;
        }
    }

    /* tactic #3: use home-cursor + local movement */
    if (cursor_home
        && ((newcost=relative_move(NULL, 0, 0, ynew, xnew, ovw)) != INFINITY)
        && SP->_home_cost + newcost < usecost)
    {
        tactic = 3;
        usecost = SP->_home_cost + newcost;
    }

    /* tactic #4: use home-down + local movement */
    if (cursor_to_ll
        && ((newcost=relative_move(NULL, screen_lines-1, 0, ynew, xnew, ovw)) != INFINITY)
        && SP->_ll_cost + newcost < usecost)
    {
        tactic = 4;
        usecost = SP->_ll_cost + newcost;
    }

    /*
     * tactic #5: use left margin for wrap to right-hand side,
     * unless strange wrap behavior indicated by xenl might hose us.
     */
    if (auto_left_margin && !eat_newline_glitch
        && yold > 0 && yold < screen_lines - 1 && cursor_left
        && ((newcost=relative_move(NULL, yold-1, screen_columns-1, ynew, xnew, ovw)) != INFINITY)
        && SP->_cr_cost + SP->_cub1_cost + newcost + newcost < usecost)
    {
        tactic = 5;
        usecost = SP->_cr_cost + SP->_cub1_cost + newcost;
    }

    /*
     * These cases are ordered by estimated relative frequency.
     */
    if (tactic)
    {
        if (tactic == 1)
            (void) relative_move(use, yold, xold, ynew, xnew, ovw);
        else if (tactic == 2)
        {
            (void) strcpy(use, carriage_return);
            (void) relative_move(use + SP->_carriage_return_length,
                                 yold,0,ynew,xnew, ovw);
        }
        else if (tactic == 3)
        {
            (void) strcpy(use, cursor_home);
            (void) relative_move(use + SP->_cursor_home_length,
                                 0, 0, ynew, xnew, ovw);
        }
        else if (tactic == 4)
        {
            (void) strcpy(use, cursor_to_ll);
            (void) relative_move(use + SP->_cursor_to_ll_length,
                                 screen_lines-1, 0, ynew, xnew, ovw);
        }
        else /* if (tactic == 5) */
        {
            use[0] = '\0';
            if (xold > 0)
                (void) strcat(use, carriage_return);
            (void) strcat(use, cursor_left);
            (void) relative_move(use + strlen(use),
                                 yold-1, screen_columns-1, ynew, xnew, ovw);
        }
    }
#endif /* !NO_OPTIMIZE */

#ifdef MAIN
    gettimeofday(&after, NULL);
    diff = after.tv_usec - before.tv_usec
        + (after.tv_sec - before.tv_sec) * 1000000;
    if (!profiling)
        (void) fprintf(stderr, "onscreen: %d msec, %f 28.8Kbps char-equivalents\n",
                       (int)diff, diff/288);
#endif /* MAIN */

 nonlocal:
    if (usecost != INFINITY)
    {
        TPUTS_TRACE("mvcur");
        tputs(use, 1, _nc_outch);
        return(OK);
    }
    else
        return(ERR);
}

int mvcur(int yold, int xold, int ynew, int xnew)
/* optimized cursor move from (yold, xold) to (ynew, xnew) */
{
    TR(TRACE_MOVE, ("mvcur(%d,%d,%d,%d) called", yold, xold, ynew, xnew));

    if (yold == ynew && xold == xnew)
        return(OK);

    /*
     * Most work here is rounding for terminal boundaries getting the
     * column position implied by wraparound or the lack thereof and
     * rolling up the screen to get ynew on the screen.
     */

    if (xnew >= screen_columns)
    {
        ynew += xnew / screen_columns;
        xnew %= screen_columns;
    }
    if (xold >= screen_columns)
    {
        int     l;

        l = (xold + 1) / screen_columns;
        yold += l;
        if (yold >= screen_lines)
                l -= (yold - screen_lines - 1);

        while (l > 0) {
                if (newline)
                {
                        TPUTS_TRACE("newline");
                        tputs(newline, 0, _nc_outch);
                }
                else
                        putchar('\n');
                l--;
                if (xold > 0)
                {
                        if (carriage_return)
                        {
                                TPUTS_TRACE("carriage_return");
                                tputs(carriage_return, 0, _nc_outch);
                        }
                        else
                                putchar('\r');
                        xold = 0;
                }
        }
    }

    if (yold > screen_lines - 1)
        yold = screen_lines - 1;
    if (ynew > screen_lines - 1)
        ynew = screen_lines - 1;

    /* destination location is on screen now */
    return(onscreen_mvcur(yold, xold, ynew, xnew, TRUE));
}


/****************************************************************************
 *
 * Cursor save_restore
 *
 ****************************************************************************/

/* assumption: sc/rc is faster than cursor addressing */

static int      oy, ox;         /* ugh, mvcur_scrolln() needs to see this */

static void save_curs(void)
{
    if (save_cursor && restore_cursor)
    {
        TPUTS_TRACE("save_cursor");
        putp(save_cursor);
    }

    oy = CURRENT_ROW;
    ox = CURRENT_COLUMN;
}

static void restore_curs(void)
{
    if (save_cursor && restore_cursor)
    {
        TPUTS_TRACE("restore_cursor");
        putp(restore_cursor);
    }
    else
        onscreen_mvcur(-1, -1, oy, ox, FALSE);
}

/****************************************************************************
 *
 * Physical-scrolling support
 *
 ****************************************************************************/

static int DoTheScrolling(int n, int top, int bot, int maxy)
/* scroll region from top to bot by n lines */
{
    int i;

    /*
     * 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
     * happen.
     *
     * 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.
     */
    if (n > 0)
    {
        /*
         * Explicitly clear if stuff pushed off top of region might
         * be saved by the terminal.
         */
        if (non_dest_scroll_region || (memory_above && top == 0)) {
            for (i = 0; i < n; i++)
            {
                mvcur(-1, -1, i, 0);
                TPUTS_TRACE("clr_eol");
                tputs(clr_eol, n, _nc_outch);
            }
        }

        if (change_scroll_region && (scroll_forward || parm_index))
        {
            TPUTS_TRACE("change_scroll_region");
            tputs(tparm(change_scroll_region, top, bot), 0, _nc_outch);

            onscreen_mvcur(-1, -1, bot, 0, TRUE);

            if (parm_index != NULL)
            {
                TPUTS_TRACE("parm_index");
                tputs(tparm(parm_index, n, 0), n, _nc_outch);
            }
            else
            {
                for (i = 0; i < n; i++)
                {
                    TPUTS_TRACE("scroll_forward");
                    tputs(scroll_forward, 0, _nc_outch);
                }
            }
            TPUTS_TRACE("change_scroll_region");
            tputs(tparm(change_scroll_region, 0, maxy), 0, _nc_outch);
        }
        else if (parm_index && top == 0 && bot == maxy)
        {
            onscreen_mvcur(oy, ox, bot, 0, TRUE);
            TPUTS_TRACE("parm_index");
            tputs(tparm(parm_index, n, 0), n, _nc_outch);
        }
        else if (scroll_forward && top == 0 && bot == maxy)
        {
            onscreen_mvcur(oy, ox, bot, 0, TRUE);
            for (i = 0; i < n; i++)
            {
                TPUTS_TRACE("scroll_forward");
                tputs(scroll_forward, 0, _nc_outch);
            }
        }
        else if (_nc_idlok
         && (parm_delete_line || delete_line)
         && (parm_insert_line || insert_line))
        {
            onscreen_mvcur(oy, ox, top, 0, TRUE);

            if (parm_delete_line)
            {
                TPUTS_TRACE("parm_delete_line");
                tputs(tparm(parm_delete_line, n, 0), n, _nc_outch);
            }
            else
            {
                for (i = 0; i < n; i++)
                {
                    TPUTS_TRACE("parm_index");
                    tputs(delete_line, 0, _nc_outch);
                }
            }

            onscreen_mvcur(top, 0, bot - n + 1, 0, FALSE);

            /* Push down the bottom region. */
            if (parm_insert_line)
            {
                TPUTS_TRACE("parm_insert_line");
                tputs(tparm(parm_insert_line, n, 0), n, _nc_outch);
            }
            else
            {
                for (i = 0; i < n; i++)
                {
                    TPUTS_TRACE("insert_line");
                    tputs(insert_line, 0, _nc_outch);
                }
            }
        }
        else
            return(ERR);
    }
    else /* (n < 0) */
    {
        /*
         * Do explicit clear to end of region if it's possible that the
         * terminal might hold on to stuff we push off the end.
         */
        if (non_dest_scroll_region || (memory_below && bot == maxy))
        {
            if (bot == maxy && clr_eos)
            {
                mvcur(-1, -1, lines + n, 0);
                TPUTS_TRACE("clr_eos");
                tputs(clr_eos, n, _nc_outch);
            }
            else if (clr_eol)
            {
                for (i = 0; i < -n; i++)
                {
                    mvcur(-1, -1, lines + n + i, 0);
                    TPUTS_TRACE("clr_eol");
                    tputs(clr_eol, n, _nc_outch);
                }
            }
        }

        if (change_scroll_region && (scroll_reverse || parm_rindex))
        {
            TPUTS_TRACE("change_scroll_region");
            tputs(tparm(change_scroll_region, top, bot), 0, _nc_outch);

            onscreen_mvcur(-1, -1, top, 0, TRUE);

            if (parm_rindex)
            {
                TPUTS_TRACE("parm_rindex");
                tputs(tparm(parm_rindex, -n, 0), -n, _nc_outch);
            }
            else
            {
                for (i = n; i < 0; i++)
                {
                    TPUTS_TRACE("scroll_reverse");
                    tputs(scroll_reverse, 0, _nc_outch);
                }
            }
            TPUTS_TRACE("change_scroll_region");
            tputs(tparm(change_scroll_region, 0, maxy), 0, _nc_outch);
        }
        else if (parm_rindex && top == 0 && bot == maxy)
        {
            onscreen_mvcur(oy, ox, bot + n + 1, 0, TRUE);

            TPUTS_TRACE("parm_rindex");
            tputs(tparm(parm_rindex, -n, 0), -n, _nc_outch);
        }
        else if (scroll_reverse && top == 0 && bot == maxy)
        {
            onscreen_mvcur(-1, -1, 0, 0, TRUE);
            for (i = n; i < 0; i++)
            {
                TPUTS_TRACE("scroll_reverse");
                tputs(scroll_reverse, 0, _nc_outch);
            }
        }
        else if (_nc_idlok
         && (parm_delete_line || delete_line)
         && (parm_insert_line || insert_line))
        {
            onscreen_mvcur(oy, ox, bot + n + 1, 0, TRUE);

            if (parm_delete_line)
            {
                TPUTS_TRACE("parm_delete_line");
                tputs(tparm(parm_delete_line, -n, 0), -n, _nc_outch);
            }
            else
            {
                for (i = n; i < 0; i++)
                {
                    TPUTS_TRACE("delete_line");
                    tputs(delete_line, 0, _nc_outch);
                }
            }

            onscreen_mvcur(bot + n + 1, 0, top, 0, FALSE);

            /* Scroll the block down. */
            if (parm_insert_line)
            {
                TPUTS_TRACE("parm_insert_line");
                tputs(tparm(parm_insert_line, -n, 0), -n, _nc_outch);
            }
            else
            {
                for (i = n; i < 0; i++)
                {
                    TPUTS_TRACE("insert_line");
                    tputs(insert_line, 0, _nc_outch);
                }
            }
        }
        else
            return(ERR);
    }

    return(OK);
}

int _nc_mvcur_scrolln(int n, int top, int bot, int maxy)
/* scroll region from top to bot by n lines */
{
    int code;

    TR(TRACE_MOVE, ("mvcur_scrolln(%d, %d, %d, %d)", n, top, bot, maxy));

    save_curs();
    code = DoTheScrolling(n, top, bot, maxy);
    restore_curs();
    return(code);
}

#ifdef MAIN
/****************************************************************************
 *
 * Movement optimizer test code
 *
 ****************************************************************************/

#include <tic.h>
#include <dump_entry.h>

char *_nc_progname = "mvcur";

static unsigned long xmits;

int tputs(const char *string, int affcnt, int (*outc)(int))
/* stub tputs() that dumps sequences in a visible form */
{
    if (profiling)
        xmits += strlen(string);
    else
        (void) fputs(_nc_visbuf(string), stdout);
    return(OK);
}

int putp(const char *string)
{
    return(tputs(string, 1, _nc_outch));
}

int _nc_outch(int ch)
{
    putc(ch, stdout);
    return OK;
}

static char     tname[BUFSIZ];

static void load_term(void)
{
    (void) setupterm(tname, STDOUT_FILENO, NULL);
}

static int roll(int n)
{
    int i, j;

    i = (RAND_MAX / n) * n;
    while ((j = rand()) >= i)
        continue;
    return (j % n);
}

int main(int argc, char *argv[])
{
    (void) strcpy(tname, getenv("TERM"));
    load_term();
    _nc_setupscreen(lines, columns, stdout);
    baudrate();

    _nc_mvcur_init();
#if HAVE_SETVBUF || HAVE_SETBUFFER
    /*
     * Undo the effects of our optimization hack, otherwise our interactive
     * prompts don't flush properly.
     */
#if HAVE_SETVBUF
    (void) setvbuf(SP->_ofp, malloc(BUFSIZ), _IOLBF, BUFSIZ);
#elif HAVE_SETBUFFER
    (void) setbuffer(SP->_ofp, malloc(BUFSIZ), BUFSIZ);
#endif
#endif /* HAVE_SETVBUF || HAVE_SETBUFFER */

    (void) puts("The mvcur tester.  Type ? for help");

    fputs("smcup:", stdout);
    putchar('\n');

    for (;;)
    {
        int     fy, fx, ty, tx, n, i;
        char    buf[BUFSIZ], capname[BUFSIZ];

        (void) fputs("> ", stdout);
        (void) fgets(buf, sizeof(buf), stdin);

        if (buf[0] == '?')
        {
(void) puts("?                -- display this help message");
(void) puts("fy fx ty tx      -- (4 numbers) display (fy,fx)->(ty,tx) move");
(void) puts("s[croll] n t b m -- display scrolling sequence");
(void) printf("r[eload]         -- reload terminal info for %s\n",
              getenv("TERM"));
(void) puts("l[oad] <term>    -- load terminal info for type <term>");
(void) puts("d[elete] <cap>   -- delete named capability");
(void) puts("i[nspect]        -- display terminal capabilities");
(void) puts("c[ost]           -- dump cursor-optimization cost table");
(void) puts("o[optimize]      -- toggle movement optimization");
(void) puts("t[orture] <num>  -- torture-test with <num> random moves");
(void) puts("q[uit]           -- quit the program");
        }
        else if (sscanf(buf, "%d %d %d %d", &fy, &fx, &ty, &tx) == 4)
        {
            struct timeval before, after;

            putchar('"');

            gettimeofday(&before, NULL);
            mvcur(fy, fx, ty, tx);
            gettimeofday(&after, NULL);

            printf("\" (%ld msec)\n",
                after.tv_usec - before.tv_usec + (after.tv_sec - before.tv_sec) * 1000000);
        }
        else if (sscanf(buf, "s %d %d %d %d", &fy, &fx, &ty, &tx) == 4)
        {
            struct timeval before, after;

            putchar('"');

            gettimeofday(&before, NULL);
            _nc_mvcur_scrolln(fy, fx, ty, tx);
            gettimeofday(&after, NULL);

            printf("\" (%ld msec)\n",
                after.tv_usec - before.tv_usec + (after.tv_sec - before.tv_sec) * 1000000);
        }
        else if (buf[0] == 'r')
        {
            (void) strcpy(tname, getenv("TERM"));
            load_term();
        }
        else if (sscanf(buf, "l %s", tname) == 1)
        {
            load_term();
        }
        else if (sscanf(buf, "d %s", capname) == 1)
        {
            struct name_table_entry const       *np = _nc_find_entry(capname,
                                                         _nc_info_hash_table);

            if (np == NULL)
                (void) printf("No such capability as \"%s\"\n", capname);
            else
            {
                switch(np->nte_type)
                {
                case BOOLEAN:
                    cur_term->type.Booleans[np->nte_index] = FALSE;
                    (void) printf("Boolean capability `%s' (%d) turned off.\n",
                                  np->nte_name, np->nte_index);
                    break;

                case NUMBER:
                    cur_term->type.Numbers[np->nte_index] = -1;
                    (void) printf("Number capability `%s' (%d) set to -1.\n",
                                  np->nte_name, np->nte_index);
                    break;

                case STRING:
                    cur_term->type.Strings[np->nte_index] = (char *)NULL;
                    (void) printf("String capability `%s' (%d) deleted.\n",
                                  np->nte_name, np->nte_index);
                    break;
                }
            }
        }
        else if (buf[0] == 'i')
        {
             dump_init((char *)NULL, F_TERMINFO, S_TERMINFO, 70, 0);
             dump_entry(&cur_term->type, NULL);
             putchar('\n');
        }
        else if (buf[0] == 'o')
        {
             if (_nc_optime_enable & OPTIMIZE_MVCUR)
             {
                 _nc_optimize_enable &=~ OPTIMIZE_MVCUR;
                 (void) puts("Optimization is now off.");
             }
             else
             {
                 _nc_optimize_enable |= OPTIMIZE_MVCUR;
                 (void) puts("Optimization is now on.");
             }
        }
        /*
         * You can use the `t' test to profile and tune the movement
         * optimizer.  Use iteration values in three digits or more.
         * At above 5000 iterations the profile timing averages are stable
         * to within a millisecond or three.
         *
         * The `overhead' field of the report will help you pick a
         * COMPUTE_OVERHEAD figure appropriate for your processor and
         * expected line speed.  The `total estimated time' is
         * computation time plus a character-transmission time
         * estimate computed from the number of transmits and the baud
         * rate.
         *
         * Use this together with the `o' command to get a read on the
         * optimizer's effectiveness.  Compare the total estimated times
         * for `t' runs of the same length in both optimized and un-optimized
         * modes.  As long as the optimized times are less, the optimizer
         * is winning.
         */
        else if (sscanf(buf, "t %d", &n) == 1)
        {
            float cumtime = 0, perchar;
            int speeds[] = {2400, 9600, 14400, 19200, 28800, 38400, 0};

            srand((unsigned)(getpid() + time((time_t *)0)));
            profiling = TRUE;
            xmits = 0;
            for (i = 0; i < n; i++)
            {
                /*
                 * This does a move test between two random locations,
                 * Random moves probably short-change the optimizer,
                 * which will work better on the short moves probably
                 * typical of doupdate()'s usage pattern.  Still,
                 * until we have better data...
                 */
#ifdef FIND_COREDUMP
                int from_y = roll(lines);
                int to_y = roll(lines);
                int from_x = roll(columns);
                int to_x = roll(columns);

                printf("(%d,%d) -> (%d,%d)\n", from_y, from_x, to_y, to_x);
                mvcur(from_y, from_x, to_y, to_x);
#else
                mvcur(roll(lines), roll(columns), roll(lines), roll(columns));
#endif /* FIND_COREDUMP */
                if (diff)
                    cumtime += diff;
            }
            profiling = FALSE;

            /*
             * Average milliseconds per character optimization time.
             * This is the key figure to watch when tuning the optimizer.
             */
            perchar = cumtime / n;

            (void) printf("%d moves (%ld chars) in %d msec, %f msec each:\n",
                          n, xmits, (int)cumtime, perchar);

            for (i = 0; speeds[i]; i++)
            {
                /*
                 * Total estimated time for the moves, computation and
                 * transmission both. Transmission time is an estimate
                 * assuming 9 bits/char, 8 bits + 1 stop bit.
                 */
                float totalest = cumtime + xmits * 9 * 1e6 / speeds[i];

                /*
                 * Per-character optimization overhead in character transmits
                 * at the current speed.  Round this to the nearest integer
                 * to figure COMPUTE_OVERHEAD for the speed.
                 */
                float overhead = speeds[i] * perchar / 1e6;

                (void) printf("%6d bps: %3.2f char-xmits overhead; total estimated time %15.2f\n",
                              speeds[i], overhead, totalest);
            }
        }
        else if (buf[0] == 'c')
        {
            (void) printf("char padding: %d\n", SP->_char_padding);
            (void) printf("cr cost: %d\n", SP->_cr_cost);
            (void) printf("cup cost: %d\n", SP->_cup_cost);
            (void) printf("home cost: %d\n", SP->_home_cost);
            (void) printf("ll cost: %d\n", SP->_ll_cost);
#ifdef TABS_OK
            (void) printf("ht cost: %d\n", SP->_ht_cost);
            (void) printf("cbt cost: %d\n", SP->_cbt_cost);
#endif /* TABS_OK */
            (void) printf("cub1 cost: %d\n", SP->_cub1_cost);
            (void) printf("cuf1 cost: %d\n", SP->_cuf1_cost);
            (void) printf("cud1 cost: %d\n", SP->_cud1_cost);
            (void) printf("cuu1 cost: %d\n", SP->_cuu1_cost);
            (void) printf("cub cost: %d\n", SP->_cub_cost);
            (void) printf("cuf cost: %d\n", SP->_cuf_cost);
            (void) printf("cud cost: %d\n", SP->_cud_cost);
            (void) printf("cuu cost: %d\n", SP->_cuu_cost);
            (void) printf("hpa cost: %d\n", SP->_hpa_cost);
            (void) printf("vpa cost: %d\n", SP->_vpa_cost);
        }
        else if (buf[0] == 'x' || buf[0] == 'q')
            break;
        else
            (void) puts("Invalid command.");
    }

    (void) fputs("rmcup:", stdout);
    _nc_mvcur_wrap();
    putchar('\n');

    return(0);
}

#endif /* MAIN */

/* lib_mvcur.c ends here */