src/cm.c

   1 /* Cursor motion subroutines for GNU Emacs.
   2    Copyright (C) 1985 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 1, or (at your option)
  10 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; see the file COPYING.  If not, write to
  19 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
  20
  21
  22 #include "config.h"
  23 #include <stdio.h>
  24 #include "cm.h"
  25 #include "termhooks.h"
  26
  27 #define BIG     9999            /* 9999 good on VAXen.  For 16 bit machines
  28                                    use about 2000.... */
  29
  30 char *tgoto ();
  31
  32 extern char *BC, *UP;
  33
  34 int cost;               /* sums up costs */
  35
  36 /* ARGSUSED */
  37 evalcost (c)
  38      char c;
  39 {
  40   cost++;
  41 }
  42
  43 void
  44 cmputc (c)
  45      char c;
  46 {
  47   if (termscript)
  48     fputc (c & 0177, termscript);
  49   putchar (c & 0177);
  50 }
  51
  52 /* NEXT TWO ARE DONE WITH MACROS */
  53 #if 0
  54 /*
  55  * Assume the cursor is at row row, column col.  Normally used only after
  56  * clearing the screen, when the cursor is at (0, 0), but what the heck,
  57  * let's let the guy put it anywhere.
  58  */
  59
  60 static
  61 at (row, col) {
  62     curY = row;
  63     curX = col;
  64 }
  65
  66 /*
  67  * Add n columns to the current cursor position.
  68  */
  69
  70 static
  71 addcol (n) {
  72     curX += n;
  73
  74     /*
  75      * If cursor hit edge of screen, what happened?
  76      * N.B.: DO NOT!! write past edge of screen.  If you do, you
  77      * deserve what you get.  Furthermore, on terminals with
  78      * autowrap (but not magicwrap), don't write in the last column
  79      * of the last line.
  80      */
  81
  82     if (curX == Wcm.cm_cols) {
  83         /*
  84          * Well, if magicwrap, still there, past the edge of the
  85          * screen (!).  If autowrap, on the col 0 of the next line.
  86          * Otherwise on last column.
  87          */
  88
  89         if (Wcm.cm_magicwrap)
  90             ;                   /* "limbo" */
  91         else if (Wcm.cm_autowrap) {
  92             curX = 0;
  93             curY++;             /* Beware end of screen! */
  94         }
  95         else
  96             curX--;
  97     }
  98 }
  99 #endif
 100
 101 /*
 102  * (Re)Initialize the cost factors, given the output speed of the terminal
 103  * in the variable ospeed.  (Note: this holds B300, B9600, etc -- ie stuff
 104  * out of <sgtty.h>.)
 105  */
 106
 107 cmcostinit ()
 108 {
 109     char *p;
 110
 111 #define COST(x,e)       (x ? (cost = 0, tputs (x, 1, e), cost) : BIG)
 112 #define CMCOST(x,e)     ((x == 0) ? BIG : (p = tgoto(x, 0, 0), COST(p ,e)))
 113
 114     Wcm.cc_up =         COST (Wcm.cm_up, evalcost);
 115     Wcm.cc_down =       COST (Wcm.cm_down, evalcost);
 116     Wcm.cc_left =       COST (Wcm.cm_left, evalcost);
 117     Wcm.cc_right =      COST (Wcm.cm_right, evalcost);
 118     Wcm.cc_home =       COST (Wcm.cm_home, evalcost);
 119     Wcm.cc_cr =         COST (Wcm.cm_cr, evalcost);
 120     Wcm.cc_ll =         COST (Wcm.cm_ll, evalcost);
 121     Wcm.cc_tab =        Wcm.cm_tabwidth ? COST (Wcm.cm_tab, evalcost) : BIG;
 122
 123     /*
 124      * These last three are actually minimum costs.  When (if) they are
 125      * candidates for the least-cost motion, the real cost is computed.
 126      * (Note that "0" is the assumed to generate the minimum cost.
 127      * While this is not necessarily true, I have yet to see a terminal
 128      * for which is not; all the terminals that have variable-cost
 129      * cursor motion seem to take straight numeric values.  --ACT)
 130      */
 131
 132     Wcm.cc_abs =  CMCOST (Wcm.cm_abs, evalcost);
 133     Wcm.cc_habs = CMCOST (Wcm.cm_habs, evalcost);
 134     Wcm.cc_vabs = CMCOST (Wcm.cm_vabs, evalcost);
 135
 136 #undef CMCOST
 137 #undef COST
 138 }
 139
 140 /*
 141  * Calculate the cost to move from (srcy, srcx) to (dsty, dstx) using
 142  * up and down, and left and right, motions, and tabs.  If doit is set
 143  * actually perform the motion.
 144  */
 145
 146 static
 147 calccost (srcy, srcx, dsty, dstx, doit)
 148 {
 149     register int    deltay,
 150                     deltax,
 151                     c,
 152                     totalcost;
 153     int     ntabs,
 154             n2tabs,
 155             tabx,
 156             tab2x,
 157             tabcost;
 158     register char  *p;
 159
 160     /* If have just wrapped on a terminal with xn,
 161        don't believe the cursor position: give up here
 162        and force use of absolute positioning.  */
 163
 164     if (curX == Wcm.cm_cols)
 165       goto fail;
 166
 167     totalcost = 0;
 168     if ((deltay = dsty - srcy) == 0)
 169         goto x;
 170     if (deltay < 0)
 171         p = Wcm.cm_up, c = Wcm.cc_up, deltay = -deltay;
 172     else
 173         p = Wcm.cm_down, c = Wcm.cc_down;
 174     if (c == BIG) {             /* caint get thar from here */
 175         if (doit)
 176             printf ("OOPS");
 177         return c;
 178     }
 179     totalcost = c * deltay;
 180     if (doit)
 181         while (--deltay >= 0)
 182             tputs (p, 1, cmputc);
 183 x:
 184     if ((deltax = dstx - srcx) == 0)
 185         goto done;
 186     if (deltax < 0) {
 187         p = Wcm.cm_left, c = Wcm.cc_left, deltax = -deltax;
 188         goto dodelta;           /* skip all the tab junk */
 189     }
 190     /* Tabs (the toughie) */
 191     if (Wcm.cc_tab >= BIG || !Wcm.cm_usetabs)
 192         goto olddelta;          /* forget it! */
 193
 194     /*
 195      * ntabs is # tabs towards but not past dstx; n2tabs is one more
 196      * (ie past dstx), but this is only valid if that is not past the
 197      * right edge of the screen.  We can check that at the same time
 198      * as we figure out where we would be if we use the tabs (which
 199      * we will put into tabx (for ntabs) and tab2x (for n2tabs)).
 200      */
 201
 202     ntabs = (deltax + srcx % Wcm.cm_tabwidth) / Wcm.cm_tabwidth;
 203     n2tabs = ntabs + 1;
 204     tabx = (srcx / Wcm.cm_tabwidth + ntabs) * Wcm.cm_tabwidth;
 205     tab2x = tabx + Wcm.cm_tabwidth;
 206
 207     if (tab2x >= Wcm.cm_cols)   /* too far (past edge) */
 208         n2tabs = 0;
 209
 210     /*
 211      * Now set tabcost to the cost for using ntabs, and c to the cost
 212      * for using n2tabs, then pick the minimum.
 213      */
 214
 215                    /* cost for ntabs     +    cost for right motion */
 216     tabcost = ntabs ? ntabs * Wcm.cc_tab + (dstx - tabx) * Wcm.cc_right
 217                     : BIG;
 218
 219                    /* cost for n2tabs    +    cost for left motion */
 220     c = n2tabs  ?    n2tabs * Wcm.cc_tab + (tab2x - dstx) * Wcm.cc_left
 221                 : BIG;
 222
 223     if (c < tabcost)            /* then cheaper to overshoot & back up */
 224         ntabs = n2tabs, tabcost = c, tabx = tab2x;
 225
 226     if (tabcost >= BIG)         /* caint use tabs */
 227         goto newdelta;
 228
 229     /*
 230      * See if tabcost is less than just moving right
 231      */
 232
 233     if (tabcost < (deltax * Wcm.cc_right)) {
 234         totalcost += tabcost;   /* use the tabs */
 235         if (doit)
 236             while (--ntabs >= 0)
 237                 tputs (Wcm.cm_tab, 1, cmputc);
 238         srcx = tabx;
 239     }
 240
 241     /*
 242      * Now might as well just recompute the delta.
 243      */
 244
 245 newdelta:
 246     if ((deltax = dstx - srcx) == 0)
 247         goto done;
 248 olddelta:
 249     if (deltax > 0)
 250         p = Wcm.cm_right, c = Wcm.cc_right;
 251     else
 252         p = Wcm.cm_left, c = Wcm.cc_left, deltax = -deltax;
 253
 254 dodelta:
 255     if (c == BIG) {             /* caint get thar from here */
 256 fail:
 257         if (doit)
 258             printf ("OOPS");
 259         return BIG;
 260     }
 261     totalcost += c * deltax;
 262     if (doit)
 263         while (--deltax >= 0)
 264             tputs (p, 1, cmputc);
 265 done:
 266     return totalcost;
 267 }
 268
 269 #if 0
 270 losecursor ()
 271 {
 272   curY = -1;
 273 }
 274 #endif
 275
 276 #define USEREL  0
 277 #define USEHOME 1
 278 #define USELL   2
 279 #define USECR   3
 280
 281 cmgoto (row, col)
 282 {
 283     int     homecost,
 284             crcost,
 285             llcost,
 286             relcost,
 287             directcost;
 288     int     use;
 289     char   *p,
 290            *dcm;
 291
 292   /* First the degenerate case */
 293   if (row == curY && col == curX) /* already there */
 294     return;
 295
 296   if (curY >= 0 && curX >= 0)
 297     {
 298       /* We may have quick ways to go to the upper-left, bottom-left,
 299        * start-of-line, or start-of-next-line.  Or it might be best to
 300        * start where we are.  Examine the options, and pick the cheapest.
 301        */
 302
 303       relcost = calccost (curY, curX, row, col, 0);
 304       use = USEREL;
 305       if ((homecost = Wcm.cc_home) < BIG)
 306           homecost += calccost (0, 0, row, col, 0);
 307       if (homecost < relcost)
 308           relcost = homecost, use = USEHOME;
 309       if ((llcost = Wcm.cc_ll) < BIG)
 310           llcost += calccost (Wcm.cm_rows - 1, 0, row, col, 0);
 311       if (llcost < relcost)
 312           relcost = llcost, use = USELL;
 313       if ((crcost = Wcm.cc_cr) < BIG) {
 314           if (Wcm.cm_autolf)
 315               if (curY + 1 >= Wcm.cm_rows)
 316                   crcost = BIG;
 317               else
 318                   crcost += calccost (curY + 1, 0, row, col, 0);
 319           else
 320               crcost += calccost (curY, 0, row, col, 0);
 321       }
 322       if (crcost < relcost)
 323           relcost = crcost, use = USECR;
 324       directcost = Wcm.cc_abs, dcm = Wcm.cm_abs;
 325       if (row == curY && Wcm.cc_habs < BIG)
 326           directcost = Wcm.cc_habs, dcm = Wcm.cm_habs;
 327       else if (col == curX && Wcm.cc_vabs < BIG)
 328           directcost = Wcm.cc_vabs, dcm = Wcm.cm_vabs;
 329     }
 330   else
 331     {
 332       directcost = 0, relcost = 100000;
 333       dcm = Wcm.cm_abs;
 334     }
 335
 336   /*
 337    * In the following comparison, the = in <= is because when the costs
 338    * are the same, it looks nicer (I think) to move directly there.
 339    */
 340   if (directcost <= relcost)
 341     {
 342       /* compute REAL direct cost */
 343       cost = 0;
 344       p = dcm == Wcm.cm_habs ? tgoto (dcm, row, col) :
 345                                tgoto (dcm, col, row);
 346       tputs (p, 1, evalcost);
 347       if (cost <= relcost)
 348         {       /* really is cheaper */
 349           tputs (p, 1, cmputc);
 350           curY = row, curX = col;
 351           return;
 352         }
 353     }
 354
 355   switch (use)
 356     {
 357     case USEHOME:
 358       tputs (Wcm.cm_home, 1, cmputc);
 359       curY = 0, curX = 0;
 360       break;
 361
 362     case USELL:
 363       tputs (Wcm.cm_ll, 1, cmputc);
 364       curY = Wcm.cm_rows - 1, curX = 0;
 365       break;
 366
 367     case USECR:
 368       tputs (Wcm.cm_cr, 1, cmputc);
 369       if (Wcm.cm_autolf)
 370         curY++;
 371       curX = 0;
 372       break;
 373     }
 374
 375   (void) calccost (curY, curX, row, col, 1);
 376   curY = row, curX = col;
 377 }
 378
 379 /* Clear out all terminal info.
 380    Used before copying into it the info on the actual terminal.
 381  */
 382
 383 Wcm_clear ()
 384 {
 385   bzero (&Wcm, sizeof Wcm);
 386   UP = 0;
 387   BC = 0;
 388 }
 389
 390 /*
 391  * Initialized stuff
 392  * Return 0 if can do CM.
 393  * Return -1 if cannot.
 394  * Return -2 if size not specified.
 395  */
 396
 397 Wcm_init ()
 398 {
 399 #if 0
 400   if (Wcm.cm_abs && !Wcm.cm_ds)
 401     return 0;
 402 #endif
 403   if (Wcm.cm_abs)
 404     return 0;
 405   /* Require up and left, and, if no absolute, down and right */
 406   if (!Wcm.cm_up || !Wcm.cm_left)
 407     return - 1;
 408   if (!Wcm.cm_abs && (!Wcm.cm_down || !Wcm.cm_right))
 409     return - 1;
 410   /* Check that we know the size of the screen.... */
 411   if (Wcm.cm_rows <= 0 || Wcm.cm_cols <= 0)
 412     return - 2;
 413   return 0;
 414 }