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