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lib_mvcur.c

/****************************************************************************
 * Copyright (c) 1998-2002,2003 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>                         *
 ****************************************************************************/

/*
**    lib_mvcur.c
**
**    The routines for moving the physical cursor and scrolling:
**
**          void _nc_mvcur_init(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)
**
** 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_columns - 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)
 *#if USE_HARD_TABS
 *    int         _ht_cost;   // cost of (tab)
 *    int         _cbt_cost;  // cost of (back_tab)
 *#endif USE_HARD_TABS
 *    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 USE_HARD_TABS 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 1.97 2003/12/27 16:43:59 tom Exp $")

#define WANT_CHAR(y, x) SP->_newscr->_line[y].text[x] /* desired state */
#define BAUDRATE  cur_term->_baudrate     /* bits per second */

#if defined(MAIN) || defined(NCURSES_TEST)
#include <sys/time.h>

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

#define OPT_SIZE 512

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 = _nc_msec_cost(cap, affcnt);
    TR(TRACE_CHARPUT | TRACE_MOVE,
       ("CostOf %s %d %s", capname, result, _nc_visbuf(cap)));
    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 %s", capname, result, _nc_visbuf(cap)));
    return result;
}
#define NormalizedCost(cap,affcnt) trace_normalized_cost(#cap,cap,affcnt);

#else

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

#endif

NCURSES_EXPORT(int)
_nc_msec_cost(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 = 0.0;

      for (cp = cap; *cp; cp++) {
          /* extract padding, either mandatory or required */
          if (cp[0] == '$' && cp[1] == '<' && strchr(cp, '>')) {
            float number = 0.0;

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

#if NCURSES_NO_PADDING
            if (!(SP->_no_padding))
#endif
                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 = _nc_msec_cost(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) {
      TPUTS_TRACE("change_scroll_region");
      putp(tparm(change_scroll_region, 0, screen_lines - 1));
    }
}

NCURSES_EXPORT(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();
    SP->_cursrow = SP->_curscol = -1;

    /* restore cursor shape */
    if (SP->_cursor != -1) {
      int cursor = SP->_cursor;
      SP->_cursor = -1;
      curs_set(cursor);
    }
}

NCURSES_EXPORT(void)
_nc_mvcur_init(void)
/* initialize the cost structure */
{
    if (isatty(fileno(SP->_ofp)))
      SP->_char_padding = ((BAUDBYTE * 1000 * 10)
                       / (BAUDRATE > 0 ? BAUDRATE : 9600));
    else
      SP->_char_padding = 1;  /* must be nonzero */
    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);
#if USE_HARD_TABS
    SP->_ht_cost = CostOf(tab, 0);
    SP->_cbt_cost = CostOf(back_tab, 0);
#endif /* USE_HARD_TABS */
    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);

    SP->_smir_cost = CostOf(enter_insert_mode, 0);
    SP->_rmir_cost = CostOf(exit_insert_mode, 0);
    SP->_ip_cost = 0;
    if (insert_padding) {
      SP->_ip_cost = CostOf(insert_padding, 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);

    /*
     * If this is a bce-terminal, we want to bias the choice so we use clr_eol
     * rather than spaces at the end of a line.
     */
    if (back_color_erase)
      SP->_el_cost = 0;

    /* 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);
    SP->_cuf_ch_cost = NormalizedCost(tparm(parm_right_cursor, 23), 1);
    SP->_inline_cost = min(SP->_cup_ch_cost,
                     min(SP->_hpa_ch_cost,
                         SP->_cuf_ch_cost));

    /*
     * If save_cursor is used within enter_ca_mode, we should not use it for
     * scrolling optimization, since the corresponding restore_cursor is not
     * nested on the various terminals (vt100, xterm, etc.) which use this
     * feature.
     */
    if (save_cursor != 0
      && enter_ca_mode != 0
      && strstr(enter_ca_mode, save_cursor) != 0) {
      T(("...suppressed sc/rc capability due to conflict with smcup/rmcup"));
      save_cursor = 0;
      restore_cursor = 0;
    }

    /*
     * 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();
}

NCURSES_EXPORT(void)
_nc_mvcur_wrap(void)
/* wrap up cursor-addressing mode */
{
    /* leave cursor at screen bottom */
    mvcur(-1, -1, screen_lines - 1, 0);

    /* set cursor to normal mode */
    if (SP->_cursor != -1)
      curs_set(1);

    if (exit_ca_mode) {
      TPUTS_TRACE("exit_ca_mode");
      putp(exit_ca_mode);
    }
    /*
     * Reset terminal's tab counter.  There's a long-time bug that
     * if you exit a "curses" program such as vi or more, tab
     * forward, and then backspace, the cursor doesn't go to the
     * right place.  The problem is that the kernel counts the
     * escape sequences that reset things as column positions.
     * Utter a \r to reset this invisibly.
     */
    _nc_outch('\r');
}

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

/*
 * Perform repeated-append, returning cost
 */
static inline int
repeated_append(string_desc * target, int total, int num, int repeat, const char *src)
{
    size_t need = repeat * strlen(src);

    if (need < target->s_size) {
      while (repeat-- > 0) {
          if (_nc_safe_strcat(target, src)) {
            total += num;
          } else {
            total = INFINITY;
            break;
          }
      }
    } else {
      total = INFINITY;
    }
    return total;
}

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

/*
 * Assume back_tab (CBT) does not wrap backwards at the left margin, return
 * a negative value at that point to simplify the loop.
 */
#define LASTTAB(fr)     ((fr > 0) ? ((fr - 1) / init_tabs) * init_tabs : -1)

static int
relative_move(string_desc * target, 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) */
{
    string_desc save;
    int n, vcost = 0, hcost = 0;

    (void) _nc_str_copy(&save, target);

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

      if (row_address != 0
          && _nc_safe_strcat(target, 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
            && _nc_safe_strcat(_nc_str_copy(target, &save),
                           tparm(parm_down_cursor, n))) {
            vcost = SP->_cud_cost;
          }

          if (cursor_down
            && (*cursor_down != '\n' || SP->_nl)
            && (n * SP->_cud1_cost < vcost)) {
            vcost = repeated_append(_nc_str_copy(target, &save), 0,
                              SP->_cud1_cost, n, cursor_down);
          }
      } else {          /* (to_y < from_y) */
          n = (from_y - to_y);

          if (parm_up_cursor
            && SP->_cuu_cost < vcost
            && _nc_safe_strcat(_nc_str_copy(target, &save),
                           tparm(parm_up_cursor, n))) {
            vcost = SP->_cuu_cost;
          }

          if (cursor_up && (n * SP->_cuu1_cost < vcost)) {
            vcost = repeated_append(_nc_str_copy(target, &save), 0,
                              SP->_cuu1_cost, n, cursor_up);
          }
      }

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

    save = *target;

    if (to_x != from_x) {
      char str[OPT_SIZE];
      string_desc check;

      hcost = INFINITY;

      if (column_address
          && _nc_safe_strcat(_nc_str_copy(target, &save),
                         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
            && _nc_safe_strcat(_nc_str_copy(target, &save),
                           tparm(parm_right_cursor, n))) {
            hcost = SP->_cuf_cost;
          }

          if (cursor_right) {
            int lhcost = 0;

            (void) _nc_str_init(&check, str, sizeof(str));

#if USE_HARD_TABS
            /* 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(&check, lhcost,
                                     SP->_ht_cost, 1, tab);
                  if (lhcost == INFINITY)
                      break;
                }

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

            if (n <= 0 || n >= (int) check.s_size)
                ovw = FALSE;
#if BSD_TPUTS
            /*
             * If we're allowing BSD-style padding in tputs, don't generate
             * a string with a leading digit.  Otherwise, that will be
             * interpreted as a padding value rather than sent to the
             * screen.
             */
            if (ovw
                && n > 0
                && n < (int) check.s_size
                && vcost == 0
                && str[0] == '\0'
                && isdigit(CharOf(WANT_CHAR(to_y, from_x))))
                ovw = FALSE;
#endif
            /*
             * 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++) {
                  NCURSES_CH_T ch = WANT_CHAR(to_y, from_x + i);
                  if (AttrOf(ch) != SP->_current_attr
#if USE_WIDEC_SUPPORT
                      || !Charable(ch)
#endif
                      ) {
                      ovw = FALSE;
                      break;
                  }
                }
            }
            if (ovw) {
                int i;

                for (i = 0; i < n; i++)
                  *check.s_tail++ = CharOf(WANT_CHAR(to_y, from_x + i));
                *check.s_tail = '\0';
                check.s_size -= n;
                lhcost += n * SP->_char_padding;
            } else {
                lhcost = repeated_append(&check, lhcost, SP->_cuf1_cost,
                                   n, cursor_right);
            }

            if (lhcost < hcost
                && _nc_safe_strcat(_nc_str_copy(target, &save), str)) {
                hcost = lhcost;
            }
          }
      } else {          /* (to_x < from_x) */
          n = from_x - to_x;

          if (parm_left_cursor
            && SP->_cub_cost < hcost
            && _nc_safe_strcat(_nc_str_copy(target, &save),
                           tparm(parm_left_cursor, n))) {
            hcost = SP->_cub_cost;
          }

          if (cursor_left) {
            int lhcost = 0;

            (void) _nc_str_init(&check, str, sizeof(str));

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

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

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

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

            if (lhcost < hcost
                && _nc_safe_strcat(_nc_str_copy(target, &save), str)) {
                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) */
{
    string_desc result;
    char buffer[OPT_SIZE];
    int tactic = 0, newcost, usecost = INFINITY;
    int t5_cr_cost;

#if defined(MAIN) || defined(NCURSES_TEST)
    struct timeval before, after;

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

#define NullResult _nc_str_null(&result, sizeof(buffer))
#define InitResult _nc_str_init(&result, buffer, sizeof(buffer))

    /* tactic #0: use direct cursor addressing */
    if (_nc_safe_strcpy(InitResult, tparm(SP->_address_cursor, ynew, xnew))) {
      tactic = 0;
      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 || NOT_LOCAL(yold, xold, ynew, xnew)) {
#if defined(MAIN) || defined(NCURSES_TEST)
          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(NullResult, yold, xold, ynew, xnew,
                             ovw)) != INFINITY)
      && newcost < usecost) {
      tactic = 1;
      usecost = newcost;
    }

    /* tactic #2: use carriage-return + local movement */
    if (yold != -1 && carriage_return
      && ((newcost = relative_move(NullResult, 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(NullResult, 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(NullResult, 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.
     */
    t5_cr_cost = (xold > 0 ? SP->_cr_cost : 0);
    if (auto_left_margin && !eat_newline_glitch
      && yold > 0 && cursor_left
      && ((newcost = relative_move(NullResult, yold - 1, screen_columns -
                             1, ynew, xnew, ovw)) != INFINITY)
      && t5_cr_cost + SP->_cub1_cost + newcost < usecost) {
      tactic = 5;
      usecost = t5_cr_cost + SP->_cub1_cost + newcost;
    }

    /*
     * These cases are ordered by estimated relative frequency.
     */
    if (tactic)
      InitResult;
    switch (tactic) {
    case 1:
      (void) relative_move(&result, yold, xold, ynew, xnew, ovw);
      break;
    case 2:
      (void) _nc_safe_strcpy(&result, carriage_return);
      (void) relative_move(&result, yold, 0, ynew, xnew, ovw);
      break;
    case 3:
      (void) _nc_safe_strcpy(&result, cursor_home);
      (void) relative_move(&result, 0, 0, ynew, xnew, ovw);
      break;
    case 4:
      (void) _nc_safe_strcpy(&result, cursor_to_ll);
      (void) relative_move(&result, screen_lines - 1, 0, ynew, xnew, ovw);
      break;
    case 5:
      if (xold > 0)
          (void) _nc_safe_strcat(&result, carriage_return);
      (void) _nc_safe_strcat(&result, cursor_left);
      (void) relative_move(&result, yold - 1, screen_columns - 1, ynew,
                       xnew, ovw);
      break;
    }
#endif /* !NO_OPTIMIZE */

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

    if (usecost != INFINITY) {
      TPUTS_TRACE("mvcur");
      tputs(buffer, 1, _nc_outch);
      SP->_cursrow = ynew;
      SP->_curscol = xnew;
      return (OK);
    } else
      return (ERR);
}

NCURSES_EXPORT(int)
mvcur(int yold, int xold, int ynew, int xnew)
/* optimized cursor move from (yold, xold) to (ynew, xnew) */
{
    attr_t oldattr;
    int code;

    TR(TRACE_CALLS | TRACE_MOVE, (T_CALLED("mvcur(%d,%d,%d,%d)"),
                          yold, xold, ynew, xnew));

    if (SP == 0) {
      code = ERR;
    } else if (yold == ynew && xold == xnew) {
      code = OK;
    } else {

      /*
       * 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;
      }

      /*
       * Force restore even if msgr is on when we're in an alternate
       * character set -- these have a strong tendency to screw up the CR &
       * LF used for local character motions!
       */
      oldattr = SP->_current_attr;
      if ((oldattr & A_ALTCHARSET)
          || (oldattr && !move_standout_mode)) {
          TR(TRACE_CHARPUT, ("turning off (%#lx) %s before move",
                         oldattr, _traceattr(oldattr)));
          (void) vidattr(A_NORMAL);
      }

      if (xold >= screen_columns) {
          int l;

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

            if (l > 0) {
                if (carriage_return) {
                  TPUTS_TRACE("carriage_return");
                  putp(carriage_return);
                } else
                  _nc_outch('\r');
                xold = 0;

                while (l > 0) {
                  if (newline) {
                      TPUTS_TRACE("newline");
                      putp(newline);
                  } else
                      _nc_outch('\n');
                  l--;
                }
            }
          } else {
            /*
             * If caller set nonl(), we cannot really use newlines to
             * position to the next row.
             */
            xold = -1;
            yold = -1;
          }
      }

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

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

      /*
       * Restore attributes if we disabled them before moving.
       */
      if (oldattr != SP->_current_attr) {
          TR(TRACE_CHARPUT, ("turning on (%#lx) %s after move",
                         oldattr, _traceattr(oldattr)));
          (void) vidattr(oldattr);
      }
    }
    returnCode(code);
}

#if defined(TRACE) || defined(NCURSES_TEST)
NCURSES_EXPORT_VAR(int) _nc_optimize_enable = OPTIMIZE_ALL;
#endif

#if defined(MAIN) || defined(NCURSES_TEST)
/****************************************************************************
 *
 * Movement optimizer test code
 *
 ****************************************************************************/

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

NCURSES_EXPORT_VAR(const char *) _nc_progname = "mvcur";

static unsigned long xmits;

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

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

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

NCURSES_EXPORT(int)
delay_output(int ms GCC_UNUSED)
{
    return OK;
}

static char tname[PATH_MAX];

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 GCC_UNUSED, char *argv[]GCC_UNUSED)
{
    (void) strcpy(tname, termname());
    load_term();
    _nc_setupscreen(lines, columns, stdout);
    baudrate();

    _nc_mvcur_init();
    NC_BUFFERED(FALSE);

    (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",
                   termname());
          (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",
               (long) (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_scrolln(fy, fx, ty, tx);
          gettimeofday(&after, NULL);

          printf("\" (%ld msec)\n",
               (long) (after.tv_usec - before.tv_usec + (after.tv_sec -
                                               before.tv_sec)
                     * 1000000));
      } else if (buf[0] == 'r') {
          (void) strcpy(tname, termname());
          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] = ABSENT_NUMERIC;
                (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] = ABSENT_STRING;
                (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, FALSE);
          dump_entry(&cur_term->type, FALSE, TRUE, 0, 0, 0);
          putchar('\n');
      } else if (buf[0] == 'o') {
          if (_nc_optimize_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 = 0.0, 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);
#if USE_HARD_TABS
          (void) printf("ht cost: %d\n", SP->_ht_cost);
          (void) printf("cbt cost: %d\n", SP->_cbt_cost);
#endif /* USE_HARD_TABS */
          (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 */

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