src/cm.c

   1 /* Cursor motion subroutines for GNU Emacs.
   2    Copyright (C) 1985, 1995, 2001-2015 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            /* Good on 32-bit hosts.  */
  32
  33 int cost;               /* sums up costs */
  34
  35 /* ARGSUSED */
  36 int
  37 evalcost (int c)
  38 {
  39   cost++;
  40   return c;
  41 }
  42
  43 /* The terminal to use for low-level output. */
  44 struct tty_display_info *current_tty;
  45
  46 int
  47 cmputc (int c)
  48 {
  49   if (current_tty->termscript)
  50     putc (c & 0177, current_tty->termscript);
  51   putc (c & 0177, current_tty->output);
  52   return c;
  53 }
  54
  55 /* NEXT TWO ARE DONE WITH MACROS */
  56 #if 0
  57 /*
  58  * Assume the cursor is at row row, column col.  Normally used only after
  59  * clearing the screen, when the cursor is at (0, 0), but what the heck,
  60  * let's let the guy put it anywhere.
  61  */
  62
  63 static
  64 at (tty, row, col) {
  65   curY (tty) = row;
  66   curX (tty)  = col;
  67 }
  68
  69 /*
  70  * Add n columns to the current cursor position.
  71  */
  72
  73 static
  74 addcol (tty, n) {
  75   curX (tty) += n;
  76
  77     /*
  78      * If cursor hit edge of screen, what happened?
  79      * N.B.: DO NOT!! write past edge of screen.  If you do, you
  80      * deserve what you get.  Furthermore, on terminals with
  81      * autowrap (but not magicwrap), don't write in the last column
  82      * of the last line.
  83      */
  84
  85   if (curX (tty) == tty->Wcm->cm_cols) {
  86         /*
  87          * Well, if magicwrap, still there, past the edge of the
  88          * screen (!).  If autowrap, on the col 0 of the next line.
  89          * Otherwise on last column.
  90          */
  91
  92         if (tty->Wcm->cm_magicwrap)
  93             ;                   /* "limbo" */
  94         else if (tty->Wcm->cm_autowrap) {
  95           curX (tty) = 0;
  96           curY (tty) ++;                /* Beware end of screen! */
  97         }
  98         else
  99           curX (tty)--;
 100     }
 101 }
 102 #endif
 103
 104 /*
 105  * Terminals with magicwrap (xn) don't all behave identically.
 106  * The VT100 leaves the cursor in the last column but will wrap before
 107  * printing the next character.  I hear that the Concept terminal does
 108  * the wrap immediately but ignores the next newline it sees.  And some
 109  * terminals just have buggy firmware, and think that the cursor is still
 110  * in limbo if we use direct cursor addressing from the phantom column.
 111  * The only guaranteed safe thing to do is to emit a CRLF immediately
 112  * after we reach the last column; this takes us to a known state.
 113  */
 114 void
 115 cmcheckmagic (struct tty_display_info *tty)
 116 {
 117   if (curX (tty) == FrameCols (tty))
 118     {
 119       if (!MagicWrap (tty) || curY (tty) >= FrameRows (tty) - 1)
 120         emacs_abort ();
 121       if (tty->termscript)
 122         putc ('\r', tty->termscript);
 123       putc ('\r', tty->output);
 124       if (tty->termscript)
 125         putc ('\n', tty->termscript);
 126       putc ('\n', tty->output);
 127       curX (tty) = 0;
 128       curY (tty)++;
 129     }
 130 }
 131
 132
 133 /*
 134  * (Re)Initialize the cost factors, given the output speed of the terminal
 135  * in the variable ospeed.  (Note: this holds B300, B9600, etc -- ie stuff
 136  * out of <sgtty.h>.)
 137  */
 138
 139 void
 140 cmcostinit (struct tty_display_info *tty)
 141 {
 142     char *p;
 143
 144 #define COST(x,e)       (x ? (cost = 0, tputs (x, 1, e), cost) : BIG)
 145 #define CMCOST(x,e)     ((x == 0) ? BIG : (p = tgoto(x, 0, 0), COST(p ,e)))
 146
 147     tty->Wcm->cc_up =    COST (tty->Wcm->cm_up, evalcost);
 148     tty->Wcm->cc_down =  COST (tty->Wcm->cm_down, evalcost);
 149     tty->Wcm->cc_left =  COST (tty->Wcm->cm_left, evalcost);
 150     tty->Wcm->cc_right = COST (tty->Wcm->cm_right, evalcost);
 151     tty->Wcm->cc_home =  COST (tty->Wcm->cm_home, evalcost);
 152     tty->Wcm->cc_cr =    COST (tty->Wcm->cm_cr, evalcost);
 153     tty->Wcm->cc_ll =    COST (tty->Wcm->cm_ll, evalcost);
 154     tty->Wcm->cc_tab =   tty->Wcm->cm_tabwidth ? COST (tty->Wcm->cm_tab, evalcost) : BIG;
 155
 156     /*
 157      * These last three are actually minimum costs.  When (if) they are
 158      * candidates for the least-cost motion, the real cost is computed.
 159      * (Note that "0" is the assumed to generate the minimum cost.
 160      * While this is not necessarily true, I have yet to see a terminal
 161      * for which is not; all the terminals that have variable-cost
 162      * cursor motion seem to take straight numeric values.  --ACT)
 163      */
 164
 165     tty->Wcm->cc_abs =  CMCOST (tty->Wcm->cm_abs, evalcost);
 166     tty->Wcm->cc_habs = CMCOST (tty->Wcm->cm_habs, evalcost);
 167     tty->Wcm->cc_vabs = CMCOST (tty->Wcm->cm_vabs, evalcost);
 168
 169 #undef CMCOST
 170 #undef COST
 171 }
 172
 173 /*
 174  * Calculate the cost to move from (srcy, srcx) to (dsty, dstx) using
 175  * up and down, and left and right, motions, and tabs.  If doit is set
 176  * actually perform the motion.
 177  */
 178
 179 static int
 180 calccost (struct tty_display_info *tty,
 181           int srcy, int srcx, int dsty, int dstx, int doit)
 182 {
 183     register int    deltay,
 184                     deltax,
 185                     c,
 186                     totalcost;
 187     int     ntabs,
 188             n2tabs,
 189             tabx,
 190             tab2x,
 191             tabcost;
 192     register const char *p;
 193
 194     /* If have just wrapped on a terminal with xn,
 195        don't believe the cursor position: give up here
 196        and force use of absolute positioning.  */
 197
 198     if (curX (tty) == tty->Wcm->cm_cols)
 199       goto fail;
 200
 201     totalcost = 0;
 202     if ((deltay = dsty - srcy) == 0)
 203         goto x;
 204     if (deltay < 0)
 205         p = tty->Wcm->cm_up, c = tty->Wcm->cc_up, deltay = -deltay;
 206     else
 207         p = tty->Wcm->cm_down, c = tty->Wcm->cc_down;
 208     if (c == BIG) {             /* caint get thar from here */
 209         if (doit)
 210             printf ("OOPS");
 211         return c;
 212     }
 213     totalcost = c * deltay;
 214     if (doit)
 215       do
 216           emacs_tputs (tty, p, 1, cmputc);
 217       while (--deltay > 0);
 218 x:
 219     if ((deltax = dstx - srcx) == 0)
 220         goto done;
 221     if (deltax < 0) {
 222         p = tty->Wcm->cm_left, c = tty->Wcm->cc_left, deltax = -deltax;
 223         goto dodelta;           /* skip all the tab junk */
 224     }
 225     /* Tabs (the toughie) */
 226     if (tty->Wcm->cc_tab >= BIG || !tty->Wcm->cm_usetabs)
 227         goto olddelta;          /* forget it! */
 228
 229     /*
 230      * ntabs is # tabs towards but not past dstx; n2tabs is one more
 231      * (ie past dstx), but this is only valid if that is not past the
 232      * right edge of the screen.  We can check that at the same time
 233      * as we figure out where we would be if we use the tabs (which
 234      * we will put into tabx (for ntabs) and tab2x (for n2tabs)).
 235      */
 236
 237     ntabs = (deltax + srcx % tty->Wcm->cm_tabwidth) / tty->Wcm->cm_tabwidth;
 238     n2tabs = ntabs + 1;
 239     tabx = (srcx / tty->Wcm->cm_tabwidth + ntabs) * tty->Wcm->cm_tabwidth;
 240     tab2x = tabx + tty->Wcm->cm_tabwidth;
 241
 242     if (tab2x >= tty->Wcm->cm_cols)     /* too far (past edge) */
 243         n2tabs = 0;
 244
 245     /*
 246      * Now set tabcost to the cost for using ntabs, and c to the cost
 247      * for using n2tabs, then pick the minimum.
 248      */
 249
 250                    /* cost for ntabs           +    cost for right motion */
 251     tabcost = ntabs ? ntabs * tty->Wcm->cc_tab + (dstx - tabx) * tty->Wcm->cc_right
 252                     : BIG;
 253
 254                    /* cost for n2tabs          +    cost for left motion */
 255     c = n2tabs  ?    n2tabs * tty->Wcm->cc_tab + (tab2x - dstx) * tty->Wcm->cc_left
 256                 : BIG;
 257
 258     if (c < tabcost)            /* then cheaper to overshoot & back up */
 259         ntabs = n2tabs, tabcost = c, tabx = tab2x;
 260
 261     if (tabcost >= BIG)         /* caint use tabs */
 262         goto newdelta;
 263
 264     /*
 265      * See if tabcost is less than just moving right
 266      */
 267
 268     if (tabcost < (deltax * tty->Wcm->cc_right)) {
 269         totalcost += tabcost;   /* use the tabs */
 270         if (doit)
 271             while (--ntabs >= 0)
 272               emacs_tputs (tty, tty->Wcm->cm_tab, 1, cmputc);
 273         srcx = tabx;
 274     }
 275
 276     /*
 277      * Now might as well just recompute the delta.
 278      */
 279
 280 newdelta:
 281     if ((deltax = dstx - srcx) == 0)
 282         goto done;
 283 olddelta:
 284     if (deltax > 0)
 285         p = tty->Wcm->cm_right, c = tty->Wcm->cc_right;
 286     else
 287         p = tty->Wcm->cm_left, c = tty->Wcm->cc_left, deltax = -deltax;
 288
 289 dodelta:
 290     if (c == BIG) {             /* caint get thar from here */
 291 fail:
 292         if (doit)
 293             printf ("OOPS");
 294         return BIG;
 295     }
 296     totalcost += c * deltax;
 297     if (doit)
 298       do
 299           emacs_tputs (tty, p, 1, cmputc);
 300       while (--deltax > 0);
 301 done:
 302     return totalcost;
 303 }
 304
 305 #if 0
 306 void
 307 losecursor (void)
 308 {
 309   curY = -1;
 310 }
 311 #endif
 312
 313 #define USEREL  0
 314 #define USEHOME 1
 315 #define USELL   2
 316 #define USECR   3
 317
 318 void
 319 cmgoto (struct tty_display_info *tty, int row, int col)
 320 {
 321     int     homecost,
 322             crcost,
 323             llcost,
 324             relcost,
 325             directcost;
 326     int     use IF_LINT (= 0);
 327     char *p;
 328     const char *dcm;
 329
 330   /* First the degenerate case */
 331     if (row == curY (tty) && col == curX (tty)) /* already there */
 332     return;
 333
 334     if (curY (tty) >= 0 && curX (tty) >= 0)
 335     {
 336       /* We may have quick ways to go to the upper-left, bottom-left,
 337        * start-of-line, or start-of-next-line.  Or it might be best to
 338        * start where we are.  Examine the options, and pick the cheapest.
 339        */
 340
 341       relcost = calccost (tty, curY (tty), curX (tty), row, col, 0);
 342       use = USEREL;
 343       if ((homecost = tty->Wcm->cc_home) < BIG)
 344           homecost += calccost (tty, 0, 0, row, col, 0);
 345       if (homecost < relcost)
 346           relcost = homecost, use = USEHOME;
 347       if ((llcost = tty->Wcm->cc_ll) < BIG)
 348           llcost += calccost (tty, tty->Wcm->cm_rows - 1, 0, row, col, 0);
 349       if (llcost < relcost)
 350           relcost = llcost, use = USELL;
 351       if ((crcost = tty->Wcm->cc_cr) < BIG) {
 352           if (tty->Wcm->cm_autolf)
 353             if (curY (tty) + 1 >= tty->Wcm->cm_rows)
 354                 crcost = BIG;
 355               else
 356                 crcost += calccost (tty, curY (tty) + 1, 0, row, col, 0);
 357           else
 358             crcost += calccost (tty, curY (tty), 0, row, col, 0);
 359       }
 360       if (crcost < relcost)
 361           relcost = crcost, use = USECR;
 362       directcost = tty->Wcm->cc_abs, dcm = tty->Wcm->cm_abs;
 363       if (row == curY (tty) && tty->Wcm->cc_habs < BIG)
 364           directcost = tty->Wcm->cc_habs, dcm = tty->Wcm->cm_habs;
 365       else if (col == curX (tty) && tty->Wcm->cc_vabs < BIG)
 366           directcost = tty->Wcm->cc_vabs, dcm = tty->Wcm->cm_vabs;
 367     }
 368   else
 369     {
 370       directcost = 0, relcost = 100000;
 371       dcm = tty->Wcm->cm_abs;
 372     }
 373
 374   /*
 375    * In the following comparison, the = in <= is because when the costs
 376    * are the same, it looks nicer (I think) to move directly there.
 377    */
 378   if (directcost <= relcost)
 379     {
 380       /* compute REAL direct cost */
 381       cost = 0;
 382       p = (dcm == tty->Wcm->cm_habs
 383            ? tgoto (dcm, row, col)
 384            : tgoto (dcm, col, row));
 385       emacs_tputs (tty, p, 1, evalcost);
 386       if (cost <= relcost)
 387         {       /* really is cheaper */
 388           emacs_tputs (tty, p, 1, cmputc);
 389           curY (tty) = row, curX (tty) = col;
 390           return;
 391         }
 392     }
 393
 394   switch (use)
 395     {
 396     case USEHOME:
 397       emacs_tputs (tty, tty->Wcm->cm_home, 1, cmputc);
 398       curY (tty) = 0, curX (tty) = 0;
 399       break;
 400
 401     case USELL:
 402       emacs_tputs (tty, tty->Wcm->cm_ll, 1, cmputc);
 403       curY (tty) = tty->Wcm->cm_rows - 1, curX (tty) = 0;
 404       break;
 405
 406     case USECR:
 407       emacs_tputs (tty, tty->Wcm->cm_cr, 1, cmputc);
 408       if (tty->Wcm->cm_autolf)
 409         curY (tty)++;
 410       curX (tty) = 0;
 411       break;
 412     }
 413
 414   (void) calccost (tty, curY (tty), curX (tty), row, col, 1);
 415   curY (tty) = row, curX (tty) = col;
 416 }
 417
 418 /* Clear out all terminal info.
 419    Used before copying into it the info on the actual terminal.
 420  */
 421
 422 void
 423 Wcm_clear (struct tty_display_info *tty)
 424 {
 425   memset (tty->Wcm, 0, sizeof (struct cm));
 426   UP = 0;
 427   BC = 0;
 428 }
 429
 430 /*
 431  * Initialized stuff
 432  * Return 0 if can do CM.
 433  * Return -1 if cannot.
 434  * Return -2 if size not specified.
 435  */
 436
 437 int
 438 Wcm_init (struct tty_display_info *tty)
 439 {
 440 #if 0
 441   if (tty->Wcm->cm_abs && !tty->Wcm->cm_ds)
 442     return 0;
 443 #endif
 444   if (tty->Wcm->cm_abs)
 445     return 0;
 446   /* Require up and left, and, if no absolute, down and right */
 447   if (!tty->Wcm->cm_up || !tty->Wcm->cm_left)
 448     return - 1;
 449   if (!tty->Wcm->cm_abs && (!tty->Wcm->cm_down || !tty->Wcm->cm_right))
 450     return - 1;
 451   /* Check that we know the size of the screen.... */
 452   if (tty->Wcm->cm_rows <= 0 || tty->Wcm->cm_cols <= 0)
 453     return - 2;
 454   return 0;
 455 }