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