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 #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         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         while (--deltay >= 0)
 218           emacs_tputs (tty, p, 1, cmputc);
 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         while (--deltax >= 0)
 300           emacs_tputs (tty, p, 1, cmputc);
 301 done:
 302     return totalcost;
 303 }
 304
 305 #if 0
 306 losecursor ()
 307 {
 308   curY = -1;
 309 }
 310 #endif
 311
 312 #define USEREL  0
 313 #define USEHOME 1
 314 #define USELL   2
 315 #define USECR   3
 316
 317 void
 318 cmgoto (struct tty_display_info *tty, int row, int col)
 319 {
 320     int     homecost,
 321             crcost,
 322             llcost,
 323             relcost,
 324             directcost;
 325     int     use IF_LINT (= 0);
 326     char *p;
 327     const char *dcm;
 328
 329   /* First the degenerate case */
 330     if (row == curY (tty) && col == curX (tty)) /* already there */
 331     return;
 332
 333     if (curY (tty) >= 0 && curX (tty) >= 0)
 334     {
 335       /* We may have quick ways to go to the upper-left, bottom-left,
 336        * start-of-line, or start-of-next-line.  Or it might be best to
 337        * start where we are.  Examine the options, and pick the cheapest.
 338        */
 339
 340       relcost = calccost (tty, curY (tty), curX (tty), row, col, 0);
 341       use = USEREL;
 342       if ((homecost = tty->Wcm->cc_home) < BIG)
 343           homecost += calccost (tty, 0, 0, row, col, 0);
 344       if (homecost < relcost)
 345           relcost = homecost, use = USEHOME;
 346       if ((llcost = tty->Wcm->cc_ll) < BIG)
 347           llcost += calccost (tty, tty->Wcm->cm_rows - 1, 0, row, col, 0);
 348       if (llcost < relcost)
 349           relcost = llcost, use = USELL;
 350       if ((crcost = tty->Wcm->cc_cr) < BIG) {
 351           if (tty->Wcm->cm_autolf)
 352             if (curY (tty) + 1 >= tty->Wcm->cm_rows)
 353                 crcost = BIG;
 354               else
 355                 crcost += calccost (tty, curY (tty) + 1, 0, row, col, 0);
 356           else
 357             crcost += calccost (tty, curY (tty), 0, row, col, 0);
 358       }
 359       if (crcost < relcost)
 360           relcost = crcost, use = USECR;
 361       directcost = tty->Wcm->cc_abs, dcm = tty->Wcm->cm_abs;
 362       if (row == curY (tty) && tty->Wcm->cc_habs < BIG)
 363           directcost = tty->Wcm->cc_habs, dcm = tty->Wcm->cm_habs;
 364       else if (col == curX (tty) && tty->Wcm->cc_vabs < BIG)
 365           directcost = tty->Wcm->cc_vabs, dcm = tty->Wcm->cm_vabs;
 366     }
 367   else
 368     {
 369       directcost = 0, relcost = 100000;
 370       dcm = tty->Wcm->cm_abs;
 371     }
 372
 373   /*
 374    * In the following comparison, the = in <= is because when the costs
 375    * are the same, it looks nicer (I think) to move directly there.
 376    */
 377   if (directcost <= relcost)
 378     {
 379       /* compute REAL direct cost */
 380       cost = 0;
 381       p = (dcm == tty->Wcm->cm_habs
 382            ? tgoto (dcm, row, col)
 383            : tgoto (dcm, col, row));
 384       emacs_tputs (tty, p, 1, evalcost);
 385       if (cost <= relcost)
 386         {       /* really is cheaper */
 387           emacs_tputs (tty, p, 1, cmputc);
 388           curY (tty) = row, curX (tty) = col;
 389           return;
 390         }
 391     }
 392
 393   switch (use)
 394     {
 395     case USEHOME:
 396       emacs_tputs (tty, tty->Wcm->cm_home, 1, cmputc);
 397       curY (tty) = 0, curX (tty) = 0;
 398       break;
 399
 400     case USELL:
 401       emacs_tputs (tty, tty->Wcm->cm_ll, 1, cmputc);
 402       curY (tty) = tty->Wcm->cm_rows - 1, curX (tty) = 0;
 403       break;
 404
 405     case USECR:
 406       emacs_tputs (tty, tty->Wcm->cm_cr, 1, cmputc);
 407       if (tty->Wcm->cm_autolf)
 408         curY (tty)++;
 409       curX (tty) = 0;
 410       break;
 411     }
 412
 413   (void) calccost (tty, curY (tty), curX (tty), row, col, 1);
 414   curY (tty) = row, curX (tty) = col;
 415 }
 416
 417 /* Clear out all terminal info.
 418    Used before copying into it the info on the actual terminal.
 419  */
 420
 421 void
 422 Wcm_clear (struct tty_display_info *tty)
 423 {
 424   memset (tty->Wcm, 0, sizeof (struct cm));
 425   UP = 0;
 426   BC = 0;
 427 }
 428
 429 /*
 430  * Initialized stuff
 431  * Return 0 if can do CM.
 432  * Return -1 if cannot.
 433  * Return -2 if size not specified.
 434  */
 435
 436 int
 437 Wcm_init (struct tty_display_info *tty)
 438 {
 439 #if 0
 440   if (tty->Wcm->cm_abs && !tty->Wcm->cm_ds)
 441     return 0;
 442 #endif
 443   if (tty->Wcm->cm_abs)
 444     return 0;
 445   /* Require up and left, and, if no absolute, down and right */
 446   if (!tty->Wcm->cm_up || !tty->Wcm->cm_left)
 447     return - 1;
 448   if (!tty->Wcm->cm_abs && (!tty->Wcm->cm_down || !tty->Wcm->cm_right))
 449     return - 1;
 450   /* Check that we know the size of the screen.... */
 451   if (tty->Wcm->cm_rows <= 0 || tty->Wcm->cm_cols <= 0)
 452     return - 2;
 453   return 0;
 454 }