src/cm.c

   1 /* Cursor motion subroutines for GNU Emacs.
   2    Copyright (C) 1985, 1995, 2001-2012  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
  10 (at 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 <http://www.gnu.org/licenses/>.  */
  19
  20
  21 #include <config.h>
  22 #include <stdio.h>
  23
  24 #include "lisp.h"
  25 #include "frame.h"
  26 #include "cm.h"
  27 #include "termhooks.h"
  28 #include "termchar.h"
  29 #include "tparam.h"
  30
  31 #define BIG     9999            /* 9999 good on VAXen.  For 16 bit machines
  32                                    use about 2000.... */
  33
  34 int cost;               /* sums up costs */
  35
  36 /* ARGSUSED */
  37 int
  38 evalcost (int c)
  39 {
  40   cost++;
  41   return c;
  42 }
  43
  44 /* The terminal to use for low-level output. */
  45 struct tty_display_info *current_tty;
  46
  47 int
  48 cmputc (int c)
  49 {
  50   if (current_tty->termscript)
  51     putc (c & 0177, current_tty->termscript);
  52   putc (c & 0177, current_tty->output);
  53   return c;
  54 }
  55
  56 /* NEXT TWO ARE DONE WITH MACROS */
  57 #if 0
  58 /*
  59  * Assume the cursor is at row row, column col.  Normally used only after
  60  * clearing the screen, when the cursor is at (0, 0), but what the heck,
  61  * let's let the guy put it anywhere.
  62  */
  63
  64 static
  65 at (tty, row, col) {
  66   curY (tty) = row;
  67   curX (tty)  = col;
  68 }
  69
  70 /*
  71  * Add n columns to the current cursor position.
  72  */
  73
  74 static
  75 addcol (tty, n) {
  76   curX (tty) += n;
  77
  78     /*
  79      * If cursor hit edge of screen, what happened?
  80      * N.B.: DO NOT!! write past edge of screen.  If you do, you
  81      * deserve what you get.  Furthermore, on terminals with
  82      * autowrap (but not magicwrap), don't write in the last column
  83      * of the last line.
  84      */
  85
  86   if (curX (tty) == tty->Wcm->cm_cols) {
  87         /*
  88          * Well, if magicwrap, still there, past the edge of the
  89          * screen (!).  If autowrap, on the col 0 of the next line.
  90          * Otherwise on last column.
  91          */
  92
  93         if (tty->Wcm->cm_magicwrap)
  94             ;                   /* "limbo" */
  95         else if (tty->Wcm->cm_autowrap) {
  96           curX (tty) = 0;
  97           curY (tty) ++;                /* Beware end of screen! */
  98         }
  99         else
 100           curX (tty)--;
 101     }
 102 }
 103 #endif
 104
 105 /*
 106  * Terminals with magicwrap (xn) don't all behave identically.
 107  * The VT100 leaves the cursor in the last column but will wrap before
 108  * printing the next character.  I hear that the Concept terminal does
 109  * the wrap immediately but ignores the next newline it sees.  And some
 110  * terminals just have buggy firmware, and think that the cursor is still
 111  * in limbo if we use direct cursor addressing from the phantom column.
 112  * The only guaranteed safe thing to do is to emit a CRLF immediately
 113  * after we reach the last column; this takes us to a known state.
 114  */
 115 void
 116 cmcheckmagic (struct tty_display_info *tty)
 117 {
 118   if (curX (tty) == FrameCols (tty))
 119     {
 120       if (!MagicWrap (tty) || curY (tty) >= FrameRows (tty) - 1)
 121         emacs_abort ();
 122       if (tty->termscript)
 123         putc ('\r', tty->termscript);
 124       putc ('\r', tty->output);
 125       if (tty->termscript)
 126         putc ('\n', tty->termscript);
 127       putc ('\n', tty->output);
 128       curX (tty) = 0;
 129       curY (tty)++;
 130     }
 131 }
 132
 133
 134 /*
 135  * (Re)Initialize the cost factors, given the output speed of the terminal
 136  * in the variable ospeed.  (Note: this holds B300, B9600, etc -- ie stuff
 137  * out of <sgtty.h>.)
 138  */
 139
 140 void
 141 cmcostinit (struct tty_display_info *tty)
 142 {
 143     char *p;
 144
 145 #define COST(x,e)       (x ? (cost = 0, tputs (x, 1, e), cost) : BIG)
 146 #define CMCOST(x,e)     ((x == 0) ? BIG : (p = tgoto(x, 0, 0), COST(p ,e)))
 147
 148     tty->Wcm->cc_up =    COST (tty->Wcm->cm_up, evalcost);
 149     tty->Wcm->cc_down =  COST (tty->Wcm->cm_down, evalcost);
 150     tty->Wcm->cc_left =  COST (tty->Wcm->cm_left, evalcost);
 151     tty->Wcm->cc_right = COST (tty->Wcm->cm_right, evalcost);
 152     tty->Wcm->cc_home =  COST (tty->Wcm->cm_home, evalcost);
 153     tty->Wcm->cc_cr =    COST (tty->Wcm->cm_cr, evalcost);
 154     tty->Wcm->cc_ll =    COST (tty->Wcm->cm_ll, evalcost);
 155     tty->Wcm->cc_tab =   tty->Wcm->cm_tabwidth ? COST (tty->Wcm->cm_tab, evalcost) : BIG;
 156
 157     /*
 158      * These last three are actually minimum costs.  When (if) they are
 159      * candidates for the least-cost motion, the real cost is computed.
 160      * (Note that "0" is the assumed to generate the minimum cost.
 161      * While this is not necessarily true, I have yet to see a terminal
 162      * for which is not; all the terminals that have variable-cost
 163      * cursor motion seem to take straight numeric values.  --ACT)
 164      */
 165
 166     tty->Wcm->cc_abs =  CMCOST (tty->Wcm->cm_abs, evalcost);
 167     tty->Wcm->cc_habs = CMCOST (tty->Wcm->cm_habs, evalcost);
 168     tty->Wcm->cc_vabs = CMCOST (tty->Wcm->cm_vabs, evalcost);
 169
 170 #undef CMCOST
 171 #undef COST
 172 }
 173
 174 /*
 175  * Calculate the cost to move from (srcy, srcx) to (dsty, dstx) using
 176  * up and down, and left and right, motions, and tabs.  If doit is set
 177  * actually perform the motion.
 178  */
 179
 180 static int
 181 calccost (struct tty_display_info *tty,
 182           int srcy, int srcx, int dsty, int dstx, int doit)
 183 {
 184     register int    deltay,
 185                     deltax,
 186                     c,
 187                     totalcost;
 188     int     ntabs,
 189             n2tabs,
 190             tabx,
 191             tab2x,
 192             tabcost;
 193     register const char *p;
 194
 195     /* If have just wrapped on a terminal with xn,
 196        don't believe the cursor position: give up here
 197        and force use of absolute positioning.  */
 198
 199     if (curX (tty) == tty->Wcm->cm_cols)
 200       goto fail;
 201
 202     totalcost = 0;
 203     if ((deltay = dsty - srcy) == 0)
 204         goto x;
 205     if (deltay < 0)
 206         p = tty->Wcm->cm_up, c = tty->Wcm->cc_up, deltay = -deltay;
 207     else
 208         p = tty->Wcm->cm_down, c = tty->Wcm->cc_down;
 209     if (c == BIG) {             /* caint get thar from here */
 210         if (doit)
 211             printf ("OOPS");
 212         return c;
 213     }
 214     totalcost = c * deltay;
 215     if (doit)
 216       do
 217           emacs_tputs (tty, p, 1, cmputc);
 218       while (0 < --deltay);
 219 x:
 220     if ((deltax = dstx - srcx) == 0)
 221         goto done;
 222     if (deltax < 0) {
 223         p = tty->Wcm->cm_left, c = tty->Wcm->cc_left, deltax = -deltax;
 224         goto dodelta;           /* skip all the tab junk */
 225     }
 226     /* Tabs (the toughie) */
 227     if (tty->Wcm->cc_tab >= BIG || !tty->Wcm->cm_usetabs)
 228         goto olddelta;          /* forget it! */
 229
 230     /*
 231      * ntabs is # tabs towards but not past dstx; n2tabs is one more
 232      * (ie past dstx), but this is only valid if that is not past the
 233      * right edge of the screen.  We can check that at the same time
 234      * as we figure out where we would be if we use the tabs (which
 235      * we will put into tabx (for ntabs) and tab2x (for n2tabs)).
 236      */
 237
 238     ntabs = (deltax + srcx % tty->Wcm->cm_tabwidth) / tty->Wcm->cm_tabwidth;
 239     n2tabs = ntabs + 1;
 240     tabx = (srcx / tty->Wcm->cm_tabwidth + ntabs) * tty->Wcm->cm_tabwidth;
 241     tab2x = tabx + tty->Wcm->cm_tabwidth;
 242
 243     if (tab2x >= tty->Wcm->cm_cols)     /* too far (past edge) */
 244         n2tabs = 0;
 245
 246     /*
 247      * Now set tabcost to the cost for using ntabs, and c to the cost
 248      * for using n2tabs, then pick the minimum.
 249      */
 250
 251                    /* cost for ntabs           +    cost for right motion */
 252     tabcost = ntabs ? ntabs * tty->Wcm->cc_tab + (dstx - tabx) * tty->Wcm->cc_right
 253                     : BIG;
 254
 255                    /* cost for n2tabs          +    cost for left motion */
 256     c = n2tabs  ?    n2tabs * tty->Wcm->cc_tab + (tab2x - dstx) * tty->Wcm->cc_left
 257                 : BIG;
 258
 259     if (c < tabcost)            /* then cheaper to overshoot & back up */
 260         ntabs = n2tabs, tabcost = c, tabx = tab2x;
 261
 262     if (tabcost >= BIG)         /* caint use tabs */
 263         goto newdelta;
 264
 265     /*
 266      * See if tabcost is less than just moving right
 267      */
 268
 269     if (tabcost < (deltax * tty->Wcm->cc_right)) {
 270         totalcost += tabcost;   /* use the tabs */
 271         if (doit)
 272             while (--ntabs >= 0)
 273               emacs_tputs (tty, tty->Wcm->cm_tab, 1, cmputc);
 274         srcx = tabx;
 275     }
 276
 277     /*
 278      * Now might as well just recompute the delta.
 279      */
 280
 281 newdelta:
 282     if ((deltax = dstx - srcx) == 0)
 283         goto done;
 284 olddelta:
 285     if (deltax > 0)
 286         p = tty->Wcm->cm_right, c = tty->Wcm->cc_right;
 287     else
 288         p = tty->Wcm->cm_left, c = tty->Wcm->cc_left, deltax = -deltax;
 289
 290 dodelta:
 291     if (c == BIG) {             /* caint get thar from here */
 292 fail:
 293         if (doit)
 294             printf ("OOPS");
 295         return BIG;
 296     }
 297     totalcost += c * deltax;
 298     if (doit)
 299       do
 300           emacs_tputs (tty, p, 1, cmputc);
 301       while (0 < --deltax);
 302 done:
 303     return totalcost;
 304 }
 305
 306 #if 0
 307 void
 308 losecursor (void)
 309 {
 310   curY = -1;
 311 }
 312 #endif
 313
 314 #define USEREL  0
 315 #define USEHOME 1
 316 #define USELL   2
 317 #define USECR   3
 318
 319 void
 320 cmgoto (struct tty_display_info *tty, int row, int col)
 321 {
 322     int     homecost,
 323             crcost,
 324             llcost,
 325             relcost,
 326             directcost;
 327     int     use IF_LINT (= 0);
 328     char *p;
 329     const char *dcm;
 330
 331   /* First the degenerate case */
 332     if (row == curY (tty) && col == curX (tty)) /* already there */
 333     return;
 334
 335     if (curY (tty) >= 0 && curX (tty) >= 0)
 336     {
 337       /* We may have quick ways to go to the upper-left, bottom-left,
 338        * start-of-line, or start-of-next-line.  Or it might be best to
 339        * start where we are.  Examine the options, and pick the cheapest.
 340        */
 341
 342       relcost = calccost (tty, curY (tty), curX (tty), row, col, 0);
 343       use = USEREL;
 344       if ((homecost = tty->Wcm->cc_home) < BIG)
 345           homecost += calccost (tty, 0, 0, row, col, 0);
 346       if (homecost < relcost)
 347           relcost = homecost, use = USEHOME;
 348       if ((llcost = tty->Wcm->cc_ll) < BIG)
 349           llcost += calccost (tty, tty->Wcm->cm_rows - 1, 0, row, col, 0);
 350       if (llcost < relcost)
 351           relcost = llcost, use = USELL;
 352       if ((crcost = tty->Wcm->cc_cr) < BIG) {
 353           if (tty->Wcm->cm_autolf)
 354             if (curY (tty) + 1 >= tty->Wcm->cm_rows)
 355                 crcost = BIG;
 356               else
 357                 crcost += calccost (tty, curY (tty) + 1, 0, row, col, 0);
 358           else
 359             crcost += calccost (tty, curY (tty), 0, row, col, 0);
 360       }
 361       if (crcost < relcost)
 362           relcost = crcost, use = USECR;
 363       directcost = tty->Wcm->cc_abs, dcm = tty->Wcm->cm_abs;
 364       if (row == curY (tty) && tty->Wcm->cc_habs < BIG)
 365           directcost = tty->Wcm->cc_habs, dcm = tty->Wcm->cm_habs;
 366       else if (col == curX (tty) && tty->Wcm->cc_vabs < BIG)
 367           directcost = tty->Wcm->cc_vabs, dcm = tty->Wcm->cm_vabs;
 368     }
 369   else
 370     {
 371       directcost = 0, relcost = 100000;
 372       dcm = tty->Wcm->cm_abs;
 373     }
 374
 375   /*
 376    * In the following comparison, the = in <= is because when the costs
 377    * are the same, it looks nicer (I think) to move directly there.
 378    */
 379   if (directcost <= relcost)
 380     {
 381       /* compute REAL direct cost */
 382       cost = 0;
 383       p = (dcm == tty->Wcm->cm_habs
 384            ? tgoto (dcm, row, col)
 385            : tgoto (dcm, col, row));
 386       emacs_tputs (tty, p, 1, evalcost);
 387       if (cost <= relcost)
 388         {       /* really is cheaper */
 389           emacs_tputs (tty, p, 1, cmputc);
 390           curY (tty) = row, curX (tty) = col;
 391           return;
 392         }
 393     }
 394
 395   switch (use)
 396     {
 397     case USEHOME:
 398       emacs_tputs (tty, tty->Wcm->cm_home, 1, cmputc);
 399       curY (tty) = 0, curX (tty) = 0;
 400       break;
 401
 402     case USELL:
 403       emacs_tputs (tty, tty->Wcm->cm_ll, 1, cmputc);
 404       curY (tty) = tty->Wcm->cm_rows - 1, curX (tty) = 0;
 405       break;
 406
 407     case USECR:
 408       emacs_tputs (tty, tty->Wcm->cm_cr, 1, cmputc);
 409       if (tty->Wcm->cm_autolf)
 410         curY (tty)++;
 411       curX (tty) = 0;
 412       break;
 413     }
 414
 415   (void) calccost (tty, curY (tty), curX (tty), row, col, 1);
 416   curY (tty) = row, curX (tty) = col;
 417 }
 418
 419 /* Clear out all terminal info.
 420    Used before copying into it the info on the actual terminal.
 421  */
 422
 423 void
 424 Wcm_clear (struct tty_display_info *tty)
 425 {
 426   memset (tty->Wcm, 0, sizeof (struct cm));
 427   UP = 0;
 428   BC = 0;
 429 }
 430
 431 /*
 432  * Initialized stuff
 433  * Return 0 if can do CM.
 434  * Return -1 if cannot.
 435  * Return -2 if size not specified.
 436  */
 437
 438 int
 439 Wcm_init (struct tty_display_info *tty)
 440 {
 441 #if 0
 442   if (tty->Wcm->cm_abs && !tty->Wcm->cm_ds)
 443     return 0;
 444 #endif
 445   if (tty->Wcm->cm_abs)
 446     return 0;
 447   /* Require up and left, and, if no absolute, down and right */
 448   if (!tty->Wcm->cm_up || !tty->Wcm->cm_left)
 449     return - 1;
 450   if (!tty->Wcm->cm_abs && (!tty->Wcm->cm_down || !tty->Wcm->cm_right))
 451     return - 1;
 452   /* Check that we know the size of the screen.... */
 453   if (tty->Wcm->cm_rows <= 0 || tty->Wcm->cm_cols <= 0)
 454     return - 2;
 455   return 0;
 456 }