src/cm.c

   1 /* Cursor motion subroutines for GNU Emacs.
   2    Copyright (C) 1985, 1995, 2001-2011  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 #include <setjmp.h>
  24
  25 #include "lisp.h"
  26 #include "frame.h"
  27 #include "cm.h"
  28 #include "termhooks.h"
  29 #include "termchar.h"
  30
  31
  32 /* For now, don't try to include termcap.h.  On some systems,
  33    configure finds a non-standard termcap.h that the main build
  34    won't find.  */
  35 extern void tputs (const char *, int, int (*)(int));
  36 extern char *tgoto (const char *, int, int);
  37
  38 #define BIG     9999            /* 9999 good on VAXen.  For 16 bit machines
  39                                    use about 2000.... */
  40
  41 extern char *BC, *UP;
  42
  43 int cost;               /* sums up costs */
  44
  45 /* ARGSUSED */
  46 int
  47 evalcost (int c)
  48 {
  49   cost++;
  50   return c;
  51 }
  52
  53 /* The terminal to use for low-level output. */
  54 struct tty_display_info *current_tty;
  55
  56 int
  57 cmputc (int c)
  58 {
  59   if (current_tty->termscript)
  60     putc (c & 0177, current_tty->termscript);
  61   putc (c & 0177, current_tty->output);
  62   return c;
  63 }
  64
  65 /* NEXT TWO ARE DONE WITH MACROS */
  66 #if 0
  67 /*
  68  * Assume the cursor is at row row, column col.  Normally used only after
  69  * clearing the screen, when the cursor is at (0, 0), but what the heck,
  70  * let's let the guy put it anywhere.
  71  */
  72
  73 static
  74 at (tty, row, col) {
  75   curY (tty) = row;
  76   curX (tty)  = col;
  77 }
  78
  79 /*
  80  * Add n columns to the current cursor position.
  81  */
  82
  83 static
  84 addcol (tty, n) {
  85   curX (tty) += n;
  86
  87     /*
  88      * If cursor hit edge of screen, what happened?
  89      * N.B.: DO NOT!! write past edge of screen.  If you do, you
  90      * deserve what you get.  Furthermore, on terminals with
  91      * autowrap (but not magicwrap), don't write in the last column
  92      * of the last line.
  93      */
  94
  95   if (curX (tty) == tty->Wcm->cm_cols) {
  96         /*
  97          * Well, if magicwrap, still there, past the edge of the
  98          * screen (!).  If autowrap, on the col 0 of the next line.
  99          * Otherwise on last column.
 100          */
 101
 102         if (tty->Wcm->cm_magicwrap)
 103             ;                   /* "limbo" */
 104         else if (tty->Wcm->cm_autowrap) {
 105           curX (tty) = 0;
 106           curY (tty) ++;                /* Beware end of screen! */
 107         }
 108         else
 109           curX (tty)--;
 110     }
 111 }
 112 #endif
 113
 114 /*
 115  * Terminals with magicwrap (xn) don't all behave identically.
 116  * The VT100 leaves the cursor in the last column but will wrap before
 117  * printing the next character.  I hear that the Concept terminal does
 118  * the wrap immediately but ignores the next newline it sees.  And some
 119  * terminals just have buggy firmware, and think that the cursor is still
 120  * in limbo if we use direct cursor addressing from the phantom column.
 121  * The only guaranteed safe thing to do is to emit a CRLF immediately
 122  * after we reach the last column; this takes us to a known state.
 123  */
 124 void
 125 cmcheckmagic (struct tty_display_info *tty)
 126 {
 127   if (curX (tty) == FrameCols (tty))
 128     {
 129       if (!MagicWrap (tty) || curY (tty) >= FrameRows (tty) - 1)
 130         abort ();
 131       if (tty->termscript)
 132         putc ('\r', tty->termscript);
 133       putc ('\r', tty->output);
 134       if (tty->termscript)
 135         putc ('\n', tty->termscript);
 136       putc ('\n', tty->output);
 137       curX (tty) = 0;
 138       curY (tty)++;
 139     }
 140 }
 141
 142
 143 /*
 144  * (Re)Initialize the cost factors, given the output speed of the terminal
 145  * in the variable ospeed.  (Note: this holds B300, B9600, etc -- ie stuff
 146  * out of <sgtty.h>.)
 147  */
 148
 149 void
 150 cmcostinit (struct tty_display_info *tty)
 151 {
 152     char *p;
 153
 154 #define COST(x,e)       (x ? (cost = 0, tputs (x, 1, e), cost) : BIG)
 155 #define CMCOST(x,e)     ((x == 0) ? BIG : (p = tgoto(x, 0, 0), COST(p ,e)))
 156
 157     tty->Wcm->cc_up =    COST (tty->Wcm->cm_up, evalcost);
 158     tty->Wcm->cc_down =  COST (tty->Wcm->cm_down, evalcost);
 159     tty->Wcm->cc_left =  COST (tty->Wcm->cm_left, evalcost);
 160     tty->Wcm->cc_right = COST (tty->Wcm->cm_right, evalcost);
 161     tty->Wcm->cc_home =  COST (tty->Wcm->cm_home, evalcost);
 162     tty->Wcm->cc_cr =    COST (tty->Wcm->cm_cr, evalcost);
 163     tty->Wcm->cc_ll =    COST (tty->Wcm->cm_ll, evalcost);
 164     tty->Wcm->cc_tab =   tty->Wcm->cm_tabwidth ? COST (tty->Wcm->cm_tab, evalcost) : BIG;
 165
 166     /*
 167      * These last three are actually minimum costs.  When (if) they are
 168      * candidates for the least-cost motion, the real cost is computed.
 169      * (Note that "0" is the assumed to generate the minimum cost.
 170      * While this is not necessarily true, I have yet to see a terminal
 171      * for which is not; all the terminals that have variable-cost
 172      * cursor motion seem to take straight numeric values.  --ACT)
 173      */
 174
 175     tty->Wcm->cc_abs =  CMCOST (tty->Wcm->cm_abs, evalcost);
 176     tty->Wcm->cc_habs = CMCOST (tty->Wcm->cm_habs, evalcost);
 177     tty->Wcm->cc_vabs = CMCOST (tty->Wcm->cm_vabs, evalcost);
 178
 179 #undef CMCOST
 180 #undef COST
 181 }
 182
 183 /*
 184  * Calculate the cost to move from (srcy, srcx) to (dsty, dstx) using
 185  * up and down, and left and right, motions, and tabs.  If doit is set
 186  * actually perform the motion.
 187  */
 188
 189 static int
 190 calccost (struct tty_display_info *tty,
 191           int srcy, int srcx, int dsty, int dstx, int doit)
 192 {
 193     register int    deltay,
 194                     deltax,
 195                     c,
 196                     totalcost;
 197     int     ntabs,
 198             n2tabs,
 199             tabx,
 200             tab2x,
 201             tabcost;
 202     register char  *p;
 203
 204     /* If have just wrapped on a terminal with xn,
 205        don't believe the cursor position: give up here
 206        and force use of absolute positioning.  */
 207
 208     if (curX (tty) == tty->Wcm->cm_cols)
 209       goto fail;
 210
 211     totalcost = 0;
 212     if ((deltay = dsty - srcy) == 0)
 213         goto x;
 214     if (deltay < 0)
 215         p = tty->Wcm->cm_up, c = tty->Wcm->cc_up, deltay = -deltay;
 216     else
 217         p = tty->Wcm->cm_down, c = tty->Wcm->cc_down;
 218     if (c == BIG) {             /* caint get thar from here */
 219         if (doit)
 220             printf ("OOPS");
 221         return c;
 222     }
 223     totalcost = c * deltay;
 224     if (doit)
 225         while (--deltay >= 0)
 226           emacs_tputs (tty, p, 1, cmputc);
 227 x:
 228     if ((deltax = dstx - srcx) == 0)
 229         goto done;
 230     if (deltax < 0) {
 231         p = tty->Wcm->cm_left, c = tty->Wcm->cc_left, deltax = -deltax;
 232         goto dodelta;           /* skip all the tab junk */
 233     }
 234     /* Tabs (the toughie) */
 235     if (tty->Wcm->cc_tab >= BIG || !tty->Wcm->cm_usetabs)
 236         goto olddelta;          /* forget it! */
 237
 238     /*
 239      * ntabs is # tabs towards but not past dstx; n2tabs is one more
 240      * (ie past dstx), but this is only valid if that is not past the
 241      * right edge of the screen.  We can check that at the same time
 242      * as we figure out where we would be if we use the tabs (which
 243      * we will put into tabx (for ntabs) and tab2x (for n2tabs)).
 244      */
 245
 246     ntabs = (deltax + srcx % tty->Wcm->cm_tabwidth) / tty->Wcm->cm_tabwidth;
 247     n2tabs = ntabs + 1;
 248     tabx = (srcx / tty->Wcm->cm_tabwidth + ntabs) * tty->Wcm->cm_tabwidth;
 249     tab2x = tabx + tty->Wcm->cm_tabwidth;
 250
 251     if (tab2x >= tty->Wcm->cm_cols)     /* too far (past edge) */
 252         n2tabs = 0;
 253
 254     /*
 255      * Now set tabcost to the cost for using ntabs, and c to the cost
 256      * for using n2tabs, then pick the minimum.
 257      */
 258
 259                    /* cost for ntabs           +    cost for right motion */
 260     tabcost = ntabs ? ntabs * tty->Wcm->cc_tab + (dstx - tabx) * tty->Wcm->cc_right
 261                     : BIG;
 262
 263                    /* cost for n2tabs          +    cost for left motion */
 264     c = n2tabs  ?    n2tabs * tty->Wcm->cc_tab + (tab2x - dstx) * tty->Wcm->cc_left
 265                 : BIG;
 266
 267     if (c < tabcost)            /* then cheaper to overshoot & back up */
 268         ntabs = n2tabs, tabcost = c, tabx = tab2x;
 269
 270     if (tabcost >= BIG)         /* caint use tabs */
 271         goto newdelta;
 272
 273     /*
 274      * See if tabcost is less than just moving right
 275      */
 276
 277     if (tabcost < (deltax * tty->Wcm->cc_right)) {
 278         totalcost += tabcost;   /* use the tabs */
 279         if (doit)
 280             while (--ntabs >= 0)
 281               emacs_tputs (tty, tty->Wcm->cm_tab, 1, cmputc);
 282         srcx = tabx;
 283     }
 284
 285     /*
 286      * Now might as well just recompute the delta.
 287      */
 288
 289 newdelta:
 290     if ((deltax = dstx - srcx) == 0)
 291         goto done;
 292 olddelta:
 293     if (deltax > 0)
 294         p = tty->Wcm->cm_right, c = tty->Wcm->cc_right;
 295     else
 296         p = tty->Wcm->cm_left, c = tty->Wcm->cc_left, deltax = -deltax;
 297
 298 dodelta:
 299     if (c == BIG) {             /* caint get thar from here */
 300 fail:
 301         if (doit)
 302             printf ("OOPS");
 303         return BIG;
 304     }
 305     totalcost += c * deltax;
 306     if (doit)
 307         while (--deltax >= 0)
 308           emacs_tputs (tty, p, 1, cmputc);
 309 done:
 310     return totalcost;
 311 }
 312
 313 #if 0
 314 losecursor ()
 315 {
 316   curY = -1;
 317 }
 318 #endif
 319
 320 #define USEREL  0
 321 #define USEHOME 1
 322 #define USELL   2
 323 #define USECR   3
 324
 325 void
 326 cmgoto (struct tty_display_info *tty, int row, int col)
 327 {
 328     int     homecost,
 329             crcost,
 330             llcost,
 331             relcost,
 332             directcost;
 333     int     use;
 334     char   *p,
 335            *dcm;
 336
 337   /* First the degenerate case */
 338     if (row == curY (tty) && col == curX (tty)) /* already there */
 339     return;
 340
 341     if (curY (tty) >= 0 && curX (tty) >= 0)
 342     {
 343       /* We may have quick ways to go to the upper-left, bottom-left,
 344        * start-of-line, or start-of-next-line.  Or it might be best to
 345        * start where we are.  Examine the options, and pick the cheapest.
 346        */
 347
 348       relcost = calccost (tty, curY (tty), curX (tty), row, col, 0);
 349       use = USEREL;
 350       if ((homecost = tty->Wcm->cc_home) < BIG)
 351           homecost += calccost (tty, 0, 0, row, col, 0);
 352       if (homecost < relcost)
 353           relcost = homecost, use = USEHOME;
 354       if ((llcost = tty->Wcm->cc_ll) < BIG)
 355           llcost += calccost (tty, tty->Wcm->cm_rows - 1, 0, row, col, 0);
 356       if (llcost < relcost)
 357           relcost = llcost, use = USELL;
 358       if ((crcost = tty->Wcm->cc_cr) < BIG) {
 359           if (tty->Wcm->cm_autolf)
 360             if (curY (tty) + 1 >= tty->Wcm->cm_rows)
 361                 crcost = BIG;
 362               else
 363                 crcost += calccost (tty, curY (tty) + 1, 0, row, col, 0);
 364           else
 365             crcost += calccost (tty, curY (tty), 0, row, col, 0);
 366       }
 367       if (crcost < relcost)
 368           relcost = crcost, use = USECR;
 369       directcost = tty->Wcm->cc_abs, dcm = tty->Wcm->cm_abs;
 370       if (row == curY (tty) && tty->Wcm->cc_habs < BIG)
 371           directcost = tty->Wcm->cc_habs, dcm = tty->Wcm->cm_habs;
 372       else if (col == curX (tty) && tty->Wcm->cc_vabs < BIG)
 373           directcost = tty->Wcm->cc_vabs, dcm = tty->Wcm->cm_vabs;
 374     }
 375   else
 376     {
 377       directcost = 0, relcost = 100000;
 378       dcm = tty->Wcm->cm_abs;
 379     }
 380
 381   /*
 382    * In the following comparison, the = in <= is because when the costs
 383    * are the same, it looks nicer (I think) to move directly there.
 384    */
 385   if (directcost <= relcost)
 386     {
 387       /* compute REAL direct cost */
 388       cost = 0;
 389       p = (dcm == tty->Wcm->cm_habs
 390            ? tgoto (dcm, row, col)
 391            : tgoto (dcm, col, row));
 392       emacs_tputs (tty, p, 1, evalcost);
 393       if (cost <= relcost)
 394         {       /* really is cheaper */
 395           emacs_tputs (tty, p, 1, cmputc);
 396           curY (tty) = row, curX (tty) = col;
 397           return;
 398         }
 399     }
 400
 401   switch (use)
 402     {
 403     case USEHOME:
 404       emacs_tputs (tty, tty->Wcm->cm_home, 1, cmputc);
 405       curY (tty) = 0, curX (tty) = 0;
 406       break;
 407
 408     case USELL:
 409       emacs_tputs (tty, tty->Wcm->cm_ll, 1, cmputc);
 410       curY (tty) = tty->Wcm->cm_rows - 1, curX (tty) = 0;
 411       break;
 412
 413     case USECR:
 414       emacs_tputs (tty, tty->Wcm->cm_cr, 1, cmputc);
 415       if (tty->Wcm->cm_autolf)
 416         curY (tty)++;
 417       curX (tty) = 0;
 418       break;
 419     }
 420
 421   (void) calccost (tty, curY (tty), curX (tty), row, col, 1);
 422   curY (tty) = row, curX (tty) = col;
 423 }
 424
 425 /* Clear out all terminal info.
 426    Used before copying into it the info on the actual terminal.
 427  */
 428
 429 void
 430 Wcm_clear (struct tty_display_info *tty)
 431 {
 432   memset (tty->Wcm, 0, sizeof (struct cm));
 433   UP = 0;
 434   BC = 0;
 435 }
 436
 437 /*
 438  * Initialized stuff
 439  * Return 0 if can do CM.
 440  * Return -1 if cannot.
 441  * Return -2 if size not specified.
 442  */
 443
 444 int
 445 Wcm_init (struct tty_display_info *tty)
 446 {
 447 #if 0
 448   if (tty->Wcm->cm_abs && !tty->Wcm->cm_ds)
 449     return 0;
 450 #endif
 451   if (tty->Wcm->cm_abs)
 452     return 0;
 453   /* Require up and left, and, if no absolute, down and right */
 454   if (!tty->Wcm->cm_up || !tty->Wcm->cm_left)
 455     return - 1;
 456   if (!tty->Wcm->cm_abs && (!tty->Wcm->cm_down || !tty->Wcm->cm_right))
 457     return - 1;
 458   /* Check that we know the size of the screen.... */
 459   if (tty->Wcm->cm_rows <= 0 || tty->Wcm->cm_cols <= 0)
 460     return - 2;
 461   return 0;
 462 }
 463