src/cm.c

   1 /* Cursor motion subroutines for GNU Emacs.
   2    Copyright (C) 1985, 1995, 2001-2018 Free Software Foundation, Inc.
   3     based primarily on public domain code written by Chris Torek
   4
   5 This file is part of GNU Emacs.
   6
   7 GNU Emacs is free software: you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation, either version 3 of the License, or (at
  10 your option) any later version.
  11
  12 GNU Emacs is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
  19
  20
  21 #include <config.h>
  22
  23 #include "lisp.h"
  24 #include "cm.h"
  25 #include "sysstdio.h"
  26 #include "termchar.h"
  27 #include "tparam.h"
  28
  29 #define BIG     9999            /* Good on 32-bit hosts.  */
  30
  31 int cost;               /* sums up costs */
  32
  33 /* ARGSUSED */
  34 int
  35 evalcost (int c)
  36 {
  37   cost++;
  38   return c;
  39 }
  40
  41 /* The terminal to use for low-level output. */
  42 struct tty_display_info *current_tty;
  43
  44 int
  45 cmputc (int c)
  46 {
  47   if (current_tty->termscript)
  48     putc_unlocked (c & 0177, current_tty->termscript);
  49   putc_unlocked (c & 0177, current_tty->output);
  50   return c;
  51 }
  52
  53 /* NEXT TWO ARE DONE WITH MACROS */
  54 #if 0
  55 /*
  56  * Assume the cursor is at row row, column col.  Normally used only after
  57  * clearing the screen, when the cursor is at (0, 0), but what the heck,
  58  * let's let the guy put it anywhere.
  59  */
  60
  61 static
  62 at (tty, row, col) {
  63   curY (tty) = row;
  64   curX (tty)  = col;
  65 }
  66
  67 /*
  68  * Add n columns to the current cursor position.
  69  */
  70
  71 static
  72 addcol (tty, n) {
  73   curX (tty) += n;
  74
  75     /*
  76      * If cursor hit edge of screen, what happened?
  77      * N.B.: DO NOT!! write past edge of screen.  If you do, you
  78      * deserve what you get.  Furthermore, on terminals with
  79      * autowrap (but not magicwrap), don't write in the last column
  80      * of the last line.
  81      */
  82
  83   if (curX (tty) == tty->Wcm->cm_cols) {
  84         /*
  85          * Well, if magicwrap, still there, past the edge of the
  86          * screen (!).  If autowrap, on the col 0 of the next line.
  87          * Otherwise on last column.
  88          */
  89
  90         if (tty->Wcm->cm_magicwrap)
  91             ;                   /* "limbo" */
  92         else if (tty->Wcm->cm_autowrap) {
  93           curX (tty) = 0;
  94           curY (tty) ++;                /* Beware end of screen! */
  95         }
  96         else
  97           curX (tty)--;
  98     }
  99 }
 100 #endif
 101
 102 /*
 103  * Terminals with magicwrap (xn) don't all behave identically.
 104  * The VT100 leaves the cursor in the last column but will wrap before
 105  * printing the next character.  I hear that the Concept terminal does
 106  * the wrap immediately but ignores the next newline it sees.  And some
 107  * terminals just have buggy firmware, and think that the cursor is still
 108  * in limbo if we use direct cursor addressing from the phantom column.
 109  * The only guaranteed safe thing to do is to emit a CRLF immediately
 110  * after we reach the last column; this takes us to a known state.
 111  */
 112 void
 113 cmcheckmagic (struct tty_display_info *tty)
 114 {
 115   if (curX (tty) == FrameCols (tty))
 116     {
 117       if (!MagicWrap (tty) || curY (tty) >= FrameRows (tty) - 1)
 118         emacs_abort ();
 119       if (tty->termscript)
 120         putc_unlocked ('\r', tty->termscript);
 121       putc_unlocked ('\r', tty->output);
 122       if (tty->termscript)
 123         putc_unlocked ('\n', tty->termscript);
 124       putc_unlocked ('\n', tty->output);
 125       curX (tty) = 0;
 126       curY (tty)++;
 127     }
 128 }
 129
 130
 131 /*
 132  * (Re)Initialize the cost factors, given the output speed of the terminal
 133  * in the variable ospeed.  (Note: this holds B300, B9600, etc -- ie stuff
 134  * out of <sgtty.h>.)
 135  */
 136
 137 void
 138 cmcostinit (struct tty_display_info *tty)
 139 {
 140     char *p;
 141
 142 #define COST(x,e)       (x ? (cost = 0, tputs (x, 1, e), cost) : BIG)
 143 #define CMCOST(x,e)     ((x == 0) ? BIG : (p = tgoto(x, 0, 0), COST(p ,e)))
 144
 145     tty->Wcm->cc_up =    COST (tty->Wcm->cm_up, evalcost);
 146     tty->Wcm->cc_down =  COST (tty->Wcm->cm_down, evalcost);
 147     tty->Wcm->cc_left =  COST (tty->Wcm->cm_left, evalcost);
 148     tty->Wcm->cc_right = COST (tty->Wcm->cm_right, evalcost);
 149     tty->Wcm->cc_home =  COST (tty->Wcm->cm_home, evalcost);
 150     tty->Wcm->cc_cr =    COST (tty->Wcm->cm_cr, evalcost);
 151     tty->Wcm->cc_ll =    COST (tty->Wcm->cm_ll, evalcost);
 152     tty->Wcm->cc_tab =   tty->Wcm->cm_tabwidth ? COST (tty->Wcm->cm_tab, evalcost) : BIG;
 153
 154     /*
 155      * These last three are actually minimum costs.  When (if) they are
 156      * candidates for the least-cost motion, the real cost is computed.
 157      * (Note that "0" is the assumed to generate the minimum cost.
 158      * While this is not necessarily true, I have yet to see a terminal
 159      * for which is not; all the terminals that have variable-cost
 160      * cursor motion seem to take straight numeric values.  --ACT)
 161      */
 162
 163     tty->Wcm->cc_abs =  CMCOST (tty->Wcm->cm_abs, evalcost);
 164     tty->Wcm->cc_habs = CMCOST (tty->Wcm->cm_habs, evalcost);
 165     tty->Wcm->cc_vabs = CMCOST (tty->Wcm->cm_vabs, evalcost);
 166
 167 #undef CMCOST
 168 #undef COST
 169 }
 170
 171 /*
 172  * Calculate the cost to move from (srcy, srcx) to (dsty, dstx) using
 173  * up and down, and left and right, motions, and tabs.  If doit is set
 174  * actually perform the motion.
 175  */
 176
 177 static int
 178 calccost (struct tty_display_info *tty,
 179           int srcy, int srcx, int dsty, int dstx, int doit)
 180 {
 181     register int    deltay,
 182                     deltax,
 183                     c,
 184                     totalcost;
 185     int     ntabs,
 186             n2tabs,
 187             tabx,
 188             tab2x,
 189             tabcost;
 190     register const char *p;
 191
 192     /* If have just wrapped on a terminal with xn,
 193        don't believe the cursor position: give up here
 194        and force use of absolute positioning.  */
 195
 196     if (curX (tty) == tty->Wcm->cm_cols)
 197       goto fail;
 198
 199     totalcost = 0;
 200     if ((deltay = dsty - srcy) == 0)
 201         goto x;
 202     if (deltay < 0)
 203         p = tty->Wcm->cm_up, c = tty->Wcm->cc_up, deltay = -deltay;
 204     else
 205         p = tty->Wcm->cm_down, c = tty->Wcm->cc_down;
 206     if (c == BIG) {             /* caint get thar from here */
 207         if (doit)
 208             printf ("OOPS");
 209         return c;
 210     }
 211     totalcost = c * deltay;
 212     if (doit)
 213       do
 214           emacs_tputs (tty, p, 1, cmputc);
 215       while (--deltay > 0);
 216 x:
 217     if ((deltax = dstx - srcx) == 0)
 218         goto done;
 219     if (deltax < 0) {
 220         p = tty->Wcm->cm_left, c = tty->Wcm->cc_left, deltax = -deltax;
 221         goto dodelta;           /* skip all the tab junk */
 222     }
 223     /* Tabs (the toughie) */
 224     if (tty->Wcm->cc_tab >= BIG || !tty->Wcm->cm_usetabs)
 225         goto olddelta;          /* forget it! */
 226
 227     /*
 228      * ntabs is # tabs towards but not past dstx; n2tabs is one more
 229      * (ie past dstx), but this is only valid if that is not past the
 230      * right edge of the screen.  We can check that at the same time
 231      * as we figure out where we would be if we use the tabs (which
 232      * we will put into tabx (for ntabs) and tab2x (for n2tabs)).
 233      */
 234
 235     ntabs = (deltax + srcx % tty->Wcm->cm_tabwidth) / tty->Wcm->cm_tabwidth;
 236     n2tabs = ntabs + 1;
 237     tabx = (srcx / tty->Wcm->cm_tabwidth + ntabs) * tty->Wcm->cm_tabwidth;
 238     tab2x = tabx + tty->Wcm->cm_tabwidth;
 239
 240     if (tab2x >= tty->Wcm->cm_cols)     /* too far (past edge) */
 241         n2tabs = 0;
 242
 243     /*
 244      * Now set tabcost to the cost for using ntabs, and c to the cost
 245      * for using n2tabs, then pick the minimum.
 246      */
 247
 248                    /* cost for ntabs           +    cost for right motion */
 249     tabcost = ntabs ? ntabs * tty->Wcm->cc_tab + (dstx - tabx) * tty->Wcm->cc_right
 250                     : BIG;
 251
 252                    /* cost for n2tabs          +    cost for left motion */
 253     c = n2tabs  ?    n2tabs * tty->Wcm->cc_tab + (tab2x - dstx) * tty->Wcm->cc_left
 254                 : BIG;
 255
 256     if (c < tabcost)            /* then cheaper to overshoot & back up */
 257         ntabs = n2tabs, tabcost = c, tabx = tab2x;
 258
 259     if (tabcost >= BIG)         /* caint use tabs */
 260         goto newdelta;
 261
 262     /*
 263      * See if tabcost is less than just moving right
 264      */
 265
 266     if (tabcost < (deltax * tty->Wcm->cc_right)) {
 267         totalcost += tabcost;   /* use the tabs */
 268         if (doit)
 269             while (--ntabs >= 0)
 270               emacs_tputs (tty, tty->Wcm->cm_tab, 1, cmputc);
 271         srcx = tabx;
 272     }
 273
 274     /*
 275      * Now might as well just recompute the delta.
 276      */
 277
 278 newdelta:
 279     if ((deltax = dstx - srcx) == 0)
 280         goto done;
 281 olddelta:
 282     if (deltax > 0)
 283         p = tty->Wcm->cm_right, c = tty->Wcm->cc_right;
 284     else
 285         p = tty->Wcm->cm_left, c = tty->Wcm->cc_left, deltax = -deltax;
 286
 287 dodelta:
 288     if (c == BIG) {             /* caint get thar from here */
 289 fail:
 290         if (doit)
 291             printf ("OOPS");
 292         return BIG;
 293     }
 294     totalcost += c * deltax;
 295     if (doit)
 296       do
 297           emacs_tputs (tty, p, 1, cmputc);
 298       while (--deltax > 0);
 299 done:
 300     return totalcost;
 301 }
 302
 303 #if 0
 304 void
 305 losecursor (void)
 306 {
 307   curY = -1;
 308 }
 309 #endif
 310
 311 #define USEREL  0
 312 #define USEHOME 1
 313 #define USELL   2
 314 #define USECR   3
 315
 316 void
 317 cmgoto (struct tty_display_info *tty, int row, int col)
 318 {
 319     int     homecost,
 320             crcost,
 321             llcost,
 322             relcost,
 323             directcost;
 324     int use UNINIT;
 325     char *p;
 326     const char *dcm;
 327
 328   /* First the degenerate case */
 329     if (row == curY (tty) && col == curX (tty)) /* already there */
 330     return;
 331
 332     if (curY (tty) >= 0 && curX (tty) >= 0)
 333     {
 334       /* We may have quick ways to go to the upper-left, bottom-left,
 335        * start-of-line, or start-of-next-line.  Or it might be best to
 336        * start where we are.  Examine the options, and pick the cheapest.
 337        */
 338
 339       relcost = calccost (tty, curY (tty), curX (tty), row, col, 0);
 340       use = USEREL;
 341       if ((homecost = tty->Wcm->cc_home) < BIG)
 342           homecost += calccost (tty, 0, 0, row, col, 0);
 343       if (homecost < relcost)
 344           relcost = homecost, use = USEHOME;
 345       if ((llcost = tty->Wcm->cc_ll) < BIG)
 346           llcost += calccost (tty, tty->Wcm->cm_rows - 1, 0, row, col, 0);
 347       if (llcost < relcost)
 348           relcost = llcost, use = USELL;
 349       if ((crcost = tty->Wcm->cc_cr) < BIG) {
 350           if (tty->Wcm->cm_autolf)
 351             if (curY (tty) + 1 >= tty->Wcm->cm_rows)
 352                 crcost = BIG;
 353               else
 354                 crcost += calccost (tty, curY (tty) + 1, 0, row, col, 0);
 355           else
 356             crcost += calccost (tty, curY (tty), 0, row, col, 0);
 357       }
 358       if (crcost < relcost)
 359           relcost = crcost, use = USECR;
 360       directcost = tty->Wcm->cc_abs, dcm = tty->Wcm->cm_abs;
 361       if (row == curY (tty) && tty->Wcm->cc_habs < BIG)
 362           directcost = tty->Wcm->cc_habs, dcm = tty->Wcm->cm_habs;
 363       else if (col == curX (tty) && tty->Wcm->cc_vabs < BIG)
 364           directcost = tty->Wcm->cc_vabs, dcm = tty->Wcm->cm_vabs;
 365     }
 366   else
 367     {
 368       directcost = 0, relcost = 100000;
 369       dcm = tty->Wcm->cm_abs;
 370     }
 371
 372   /*
 373    * In the following comparison, the = in <= is because when the costs
 374    * are the same, it looks nicer (I think) to move directly there.
 375    */
 376   if (directcost <= relcost)
 377     {
 378       /* compute REAL direct cost */
 379       cost = 0;
 380       p = (dcm == tty->Wcm->cm_habs
 381            ? tgoto (dcm, row, col)
 382            : tgoto (dcm, col, row));
 383       emacs_tputs (tty, p, 1, evalcost);
 384       if (cost <= relcost)
 385         {       /* really is cheaper */
 386           emacs_tputs (tty, p, 1, cmputc);
 387           curY (tty) = row, curX (tty) = col;
 388           return;
 389         }
 390     }
 391
 392   switch (use)
 393     {
 394     case USEHOME:
 395       emacs_tputs (tty, tty->Wcm->cm_home, 1, cmputc);
 396       curY (tty) = 0, curX (tty) = 0;
 397       break;
 398
 399     case USELL:
 400       emacs_tputs (tty, tty->Wcm->cm_ll, 1, cmputc);
 401       curY (tty) = tty->Wcm->cm_rows - 1, curX (tty) = 0;
 402       break;
 403
 404     case USECR:
 405       emacs_tputs (tty, tty->Wcm->cm_cr, 1, cmputc);
 406       if (tty->Wcm->cm_autolf)
 407         curY (tty)++;
 408       curX (tty) = 0;
 409       break;
 410     }
 411
 412   (void) calccost (tty, curY (tty), curX (tty), row, col, 1);
 413   curY (tty) = row, curX (tty) = col;
 414 }
 415
 416 /* Clear out all terminal info.
 417    Used before copying into it the info on the actual terminal.
 418  */
 419
 420 void
 421 Wcm_clear (struct tty_display_info *tty)
 422 {
 423   memset (tty->Wcm, 0, sizeof (struct cm));
 424   UP = 0;
 425   BC = 0;
 426 }
 427
 428 /*
 429  * Initialized stuff
 430  * Return 0 if can do CM.
 431  * Return -1 if cannot.
 432  * Return -2 if size not specified.
 433  */
 434
 435 int
 436 Wcm_init (struct tty_display_info *tty)
 437 {
 438 #if 0
 439   if (tty->Wcm->cm_abs && !tty->Wcm->cm_ds)
 440     return 0;
 441 #endif
 442   if (tty->Wcm->cm_abs)
 443     return 0;
 444   /* Require up and left, and, if no absolute, down and right */
 445   if (!tty->Wcm->cm_up || !tty->Wcm->cm_left)
 446     return - 1;
 447   if (!tty->Wcm->cm_abs && (!tty->Wcm->cm_down || !tty->Wcm->cm_right))
 448     return - 1;
 449   /* Check that we know the size of the screen.... */
 450   if (tty->Wcm->cm_rows <= 0 || tty->Wcm->cm_cols <= 0)
 451     return - 2;
 452   return 0;
 453 }