src/cm.c

   1 /* Cursor motion subroutines for GNU Emacs.
   2    Copyright (C) 1985, 1995, 2001, 2002, 2003, 2004,
   3                  2005, 2006, 2007, 2008  Free Software Foundation, Inc.
   4     based primarily on public domain code written by Chris Torek
   5
   6 This file is part of GNU Emacs.
   7
   8 GNU Emacs is free software; you can redistribute it and/or modify
   9 it under the terms of the GNU General Public License as published by
  10 the Free Software Foundation; either version 3, or (at your option)
  11 any later version.
  12
  13 GNU Emacs is distributed in the hope that it will be useful,
  14 but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 GNU General Public License for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GNU Emacs; see the file COPYING.  If not, write to
  20 the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  21 Boston, MA 02110-1301, USA.  */
  22
  23
  24 #include <config.h>
  25 #include <stdio.h>
  26 #include "cm.h"
  27 #include "termhooks.h"
  28
  29 /* For now, don't try to include termcap.h.  On some systems,
  30    configure finds a non-standard termcap.h that the main build
  31    won't find.  */
  32
  33 #if defined HAVE_TERMCAP_H && 0
  34 #include <termcap.h>
  35 #else
  36 extern void tputs P_ ((const char *, int, int (*)(int)));
  37 extern char *tgoto P_ ((const char *, int, int));
  38 #endif
  39
  40 #define BIG     9999            /* 9999 good on VAXen.  For 16 bit machines
  41                                    use about 2000.... */
  42
  43 extern char *BC, *UP;
  44
  45 int cost;               /* sums up costs */
  46
  47 /* ARGSUSED */
  48 int
  49 evalcost (c)
  50      char c;
  51 {
  52   cost++;
  53   return c;
  54 }
  55
  56 int
  57 cmputc (c)
  58      char c;
  59 {
  60   if (termscript)
  61     fputc (c & 0177, termscript);
  62   putchar (c & 0177);
  63   return c;
  64 }
  65
  66 /* NEXT TWO ARE DONE WITH MACROS */
  67 #if 0
  68 /*
  69  * Assume the cursor is at row row, column col.  Normally used only after
  70  * clearing the screen, when the cursor is at (0, 0), but what the heck,
  71  * let's let the guy put it anywhere.
  72  */
  73
  74 static
  75 at (row, col) {
  76     curY = row;
  77     curX = col;
  78 }
  79
  80 /*
  81  * Add n columns to the current cursor position.
  82  */
  83
  84 static
  85 addcol (n) {
  86     curX += n;
  87
  88     /*
  89      * If cursor hit edge of screen, what happened?
  90      * N.B.: DO NOT!! write past edge of screen.  If you do, you
  91      * deserve what you get.  Furthermore, on terminals with
  92      * autowrap (but not magicwrap), don't write in the last column
  93      * of the last line.
  94      */
  95
  96     if (curX == Wcm.cm_cols) {
  97         /*
  98          * Well, if magicwrap, still there, past the edge of the
  99          * screen (!).  If autowrap, on the col 0 of the next line.
 100          * Otherwise on last column.
 101          */
 102
 103         if (Wcm.cm_magicwrap)
 104             ;                   /* "limbo" */
 105         else if (Wcm.cm_autowrap) {
 106             curX = 0;
 107             curY++;             /* Beware end of screen! */
 108         }
 109         else
 110             curX--;
 111     }
 112 }
 113 #endif
 114
 115 /*
 116  * Terminals with magicwrap (xn) don't all behave identically.
 117  * The VT100 leaves the cursor in the last column but will wrap before
 118  * printing the next character.  I hear that the Concept terminal does
 119  * the wrap immediately but ignores the next newline it sees.  And some
 120  * terminals just have buggy firmware, and think that the cursor is still
 121  * in limbo if we use direct cursor addressing from the phantom column.
 122  * The only guaranteed safe thing to do is to emit a CRLF immediately
 123  * after we reach the last column; this takes us to a known state.
 124  */
 125 void
 126 cmcheckmagic ()
 127 {
 128   if (curX == FrameCols)
 129     {
 130       if (!MagicWrap || curY >= FrameRows - 1)
 131         abort ();
 132       if (termscript)
 133         putc ('\r', termscript);
 134       putchar ('\r');
 135       if (termscript)
 136         putc ('\n', termscript);
 137       putchar ('\n');
 138       curX = 0;
 139       curY++;
 140     }
 141 }
 142
 143
 144 /*
 145  * (Re)Initialize the cost factors, given the output speed of the terminal
 146  * in the variable ospeed.  (Note: this holds B300, B9600, etc -- ie stuff
 147  * out of <sgtty.h>.)
 148  */
 149
 150 void
 151 cmcostinit ()
 152 {
 153     char *p;
 154
 155 #define COST(x,e)       (x ? (cost = 0, tputs (x, 1, e), cost) : BIG)
 156 #define CMCOST(x,e)     ((x == 0) ? BIG : (p = tgoto(x, 0, 0), COST(p ,e)))
 157
 158     Wcm.cc_up =         COST (Wcm.cm_up, evalcost);
 159     Wcm.cc_down =       COST (Wcm.cm_down, evalcost);
 160     Wcm.cc_left =       COST (Wcm.cm_left, evalcost);
 161     Wcm.cc_right =      COST (Wcm.cm_right, evalcost);
 162     Wcm.cc_home =       COST (Wcm.cm_home, evalcost);
 163     Wcm.cc_cr =         COST (Wcm.cm_cr, evalcost);
 164     Wcm.cc_ll =         COST (Wcm.cm_ll, evalcost);
 165     Wcm.cc_tab =        Wcm.cm_tabwidth ? COST (Wcm.cm_tab, evalcost) : BIG;
 166
 167     /*
 168      * These last three are actually minimum costs.  When (if) they are
 169      * candidates for the least-cost motion, the real cost is computed.
 170      * (Note that "0" is the assumed to generate the minimum cost.
 171      * While this is not necessarily true, I have yet to see a terminal
 172      * for which is not; all the terminals that have variable-cost
 173      * cursor motion seem to take straight numeric values.  --ACT)
 174      */
 175
 176     Wcm.cc_abs =  CMCOST (Wcm.cm_abs, evalcost);
 177     Wcm.cc_habs = CMCOST (Wcm.cm_habs, evalcost);
 178     Wcm.cc_vabs = CMCOST (Wcm.cm_vabs, evalcost);
 179
 180 #undef CMCOST
 181 #undef COST
 182 }
 183
 184 /*
 185  * Calculate the cost to move from (srcy, srcx) to (dsty, dstx) using
 186  * up and down, and left and right, motions, and tabs.  If doit is set
 187  * actually perform the motion.
 188  */
 189
 190 static int
 191 calccost (srcy, srcx, dsty, dstx, doit)
 192      int srcy, srcx, dsty, dstx, doit;
 193 {
 194     register int    deltay,
 195                     deltax,
 196                     c,
 197                     totalcost;
 198     int     ntabs,
 199             n2tabs,
 200             tabx,
 201             tab2x,
 202             tabcost;
 203     register char  *p;
 204
 205     /* If have just wrapped on a terminal with xn,
 206        don't believe the cursor position: give up here
 207        and force use of absolute positioning.  */
 208
 209     if (curX == Wcm.cm_cols)
 210       goto fail;
 211
 212     totalcost = 0;
 213     if ((deltay = dsty - srcy) == 0)
 214         goto x;
 215     if (deltay < 0)
 216         p = Wcm.cm_up, c = Wcm.cc_up, deltay = -deltay;
 217     else
 218         p = Wcm.cm_down, c = Wcm.cc_down;
 219     if (c == BIG) {             /* caint get thar from here */
 220         if (doit)
 221             printf ("OOPS");
 222         return c;
 223     }
 224     totalcost = c * deltay;
 225     if (doit)
 226         while (--deltay >= 0)
 227             tputs (p, 1, cmputc);
 228 x:
 229     if ((deltax = dstx - srcx) == 0)
 230         goto done;
 231     if (deltax < 0) {
 232         p = Wcm.cm_left, c = Wcm.cc_left, deltax = -deltax;
 233         goto dodelta;           /* skip all the tab junk */
 234     }
 235     /* Tabs (the toughie) */
 236     if (Wcm.cc_tab >= BIG || !Wcm.cm_usetabs)
 237         goto olddelta;          /* forget it! */
 238
 239     /*
 240      * ntabs is # tabs towards but not past dstx; n2tabs is one more
 241      * (ie past dstx), but this is only valid if that is not past the
 242      * right edge of the screen.  We can check that at the same time
 243      * as we figure out where we would be if we use the tabs (which
 244      * we will put into tabx (for ntabs) and tab2x (for n2tabs)).
 245      */
 246
 247     ntabs = (deltax + srcx % Wcm.cm_tabwidth) / Wcm.cm_tabwidth;
 248     n2tabs = ntabs + 1;
 249     tabx = (srcx / Wcm.cm_tabwidth + ntabs) * Wcm.cm_tabwidth;
 250     tab2x = tabx + Wcm.cm_tabwidth;
 251
 252     if (tab2x >= Wcm.cm_cols)   /* too far (past edge) */
 253         n2tabs = 0;
 254
 255     /*
 256      * Now set tabcost to the cost for using ntabs, and c to the cost
 257      * for using n2tabs, then pick the minimum.
 258      */
 259
 260                    /* cost for ntabs     +    cost for right motion */
 261     tabcost = ntabs ? ntabs * Wcm.cc_tab + (dstx - tabx) * Wcm.cc_right
 262                     : BIG;
 263
 264                    /* cost for n2tabs    +    cost for left motion */
 265     c = n2tabs  ?    n2tabs * Wcm.cc_tab + (tab2x - dstx) * Wcm.cc_left
 266                 : BIG;
 267
 268     if (c < tabcost)            /* then cheaper to overshoot & back up */
 269         ntabs = n2tabs, tabcost = c, tabx = tab2x;
 270
 271     if (tabcost >= BIG)         /* caint use tabs */
 272         goto newdelta;
 273
 274     /*
 275      * See if tabcost is less than just moving right
 276      */
 277
 278     if (tabcost < (deltax * Wcm.cc_right)) {
 279         totalcost += tabcost;   /* use the tabs */
 280         if (doit)
 281             while (--ntabs >= 0)
 282                 tputs (Wcm.cm_tab, 1, cmputc);
 283         srcx = tabx;
 284     }
 285
 286     /*
 287      * Now might as well just recompute the delta.
 288      */
 289
 290 newdelta:
 291     if ((deltax = dstx - srcx) == 0)
 292         goto done;
 293 olddelta:
 294     if (deltax > 0)
 295         p = Wcm.cm_right, c = Wcm.cc_right;
 296     else
 297         p = Wcm.cm_left, c = Wcm.cc_left, deltax = -deltax;
 298
 299 dodelta:
 300     if (c == BIG) {             /* caint get thar from here */
 301 fail:
 302         if (doit)
 303             printf ("OOPS");
 304         return BIG;
 305     }
 306     totalcost += c * deltax;
 307     if (doit)
 308         while (--deltax >= 0)
 309             tputs (p, 1, cmputc);
 310 done:
 311     return totalcost;
 312 }
 313
 314 #if 0
 315 losecursor ()
 316 {
 317   curY = -1;
 318 }
 319 #endif
 320
 321 #define USEREL  0
 322 #define USEHOME 1
 323 #define USELL   2
 324 #define USECR   3
 325
 326 void
 327 cmgoto (row, col)
 328      int row, col;
 329 {
 330     int     homecost,
 331             crcost,
 332             llcost,
 333             relcost,
 334             directcost;
 335     int     use;
 336     char   *p,
 337            *dcm;
 338
 339   /* First the degenerate case */
 340   if (row == curY && col == curX) /* already there */
 341     return;
 342
 343   if (curY >= 0 && curX >= 0)
 344     {
 345       /* We may have quick ways to go to the upper-left, bottom-left,
 346        * start-of-line, or start-of-next-line.  Or it might be best to
 347        * start where we are.  Examine the options, and pick the cheapest.
 348        */
 349
 350       relcost = calccost (curY, curX, row, col, 0);
 351       use = USEREL;
 352       if ((homecost = Wcm.cc_home) < BIG)
 353           homecost += calccost (0, 0, row, col, 0);
 354       if (homecost < relcost)
 355           relcost = homecost, use = USEHOME;
 356       if ((llcost = Wcm.cc_ll) < BIG)
 357           llcost += calccost (Wcm.cm_rows - 1, 0, row, col, 0);
 358       if (llcost < relcost)
 359           relcost = llcost, use = USELL;
 360       if ((crcost = Wcm.cc_cr) < BIG) {
 361           if (Wcm.cm_autolf)
 362               if (curY + 1 >= Wcm.cm_rows)
 363                   crcost = BIG;
 364               else
 365                   crcost += calccost (curY + 1, 0, row, col, 0);
 366           else
 367               crcost += calccost (curY, 0, row, col, 0);
 368       }
 369       if (crcost < relcost)
 370           relcost = crcost, use = USECR;
 371       directcost = Wcm.cc_abs, dcm = Wcm.cm_abs;
 372       if (row == curY && Wcm.cc_habs < BIG)
 373           directcost = Wcm.cc_habs, dcm = Wcm.cm_habs;
 374       else if (col == curX && Wcm.cc_vabs < BIG)
 375           directcost = Wcm.cc_vabs, dcm = Wcm.cm_vabs;
 376     }
 377   else
 378     {
 379       directcost = 0, relcost = 100000;
 380       dcm = Wcm.cm_abs;
 381     }
 382
 383   /*
 384    * In the following comparison, the = in <= is because when the costs
 385    * are the same, it looks nicer (I think) to move directly there.
 386    */
 387   if (directcost <= relcost)
 388     {
 389       /* compute REAL direct cost */
 390       cost = 0;
 391       p = dcm == Wcm.cm_habs ? tgoto (dcm, row, col) :
 392                                tgoto (dcm, col, row);
 393       tputs (p, 1, evalcost);
 394       if (cost <= relcost)
 395         {       /* really is cheaper */
 396           tputs (p, 1, cmputc);
 397           curY = row, curX = col;
 398           return;
 399         }
 400     }
 401
 402   switch (use)
 403     {
 404     case USEHOME:
 405       tputs (Wcm.cm_home, 1, cmputc);
 406       curY = 0, curX = 0;
 407       break;
 408
 409     case USELL:
 410       tputs (Wcm.cm_ll, 1, cmputc);
 411       curY = Wcm.cm_rows - 1, curX = 0;
 412       break;
 413
 414     case USECR:
 415       tputs (Wcm.cm_cr, 1, cmputc);
 416       if (Wcm.cm_autolf)
 417         curY++;
 418       curX = 0;
 419       break;
 420     }
 421
 422   (void) calccost (curY, curX, row, col, 1);
 423   curY = row, curX = col;
 424 }
 425
 426 /* Clear out all terminal info.
 427    Used before copying into it the info on the actual terminal.
 428  */
 429
 430 void
 431 Wcm_clear ()
 432 {
 433   bzero (&Wcm, sizeof Wcm);
 434   UP = 0;
 435   BC = 0;
 436 }
 437
 438 /*
 439  * Initialized stuff
 440  * Return 0 if can do CM.
 441  * Return -1 if cannot.
 442  * Return -2 if size not specified.
 443  */
 444
 445 int
 446 Wcm_init ()
 447 {
 448 #if 0
 449   if (Wcm.cm_abs && !Wcm.cm_ds)
 450     return 0;
 451 #endif
 452   if (Wcm.cm_abs)
 453     return 0;
 454   /* Require up and left, and, if no absolute, down and right */
 455   if (!Wcm.cm_up || !Wcm.cm_left)
 456     return - 1;
 457   if (!Wcm.cm_abs && (!Wcm.cm_down || !Wcm.cm_right))
 458     return - 1;
 459   /* Check that we know the size of the screen.... */
 460   if (Wcm.cm_rows <= 0 || Wcm.cm_cols <= 0)
 461     return - 2;
 462   return 0;
 463 }
 464
 465 /* arch-tag: bcf64c02-00f6-44ef-94b6-c56eab5b3dc4
 466    (do not change this comment) */