src/track.c

   1 /* NetHack 3.6  track.c $NHDT-Date: 1432512769 2015/05/25 00:12:49 $  $NHDT-Branch: master $:$NHDT-Revision: 1.9 $ */
   2 /* Copyright (c) Stichting Mathematisch Centrum, Amsterdam, 1985. */
   3 /* NetHack may be freely redistributed.  See license for details. */
   4 /* track.c - version 1.0.2 */
   5
   6 #include "hack.h"
   7
   8 #define UTSZ 50
   9
  10 STATIC_VAR NEARDATA int utcnt, utpnt;
  11 STATIC_VAR NEARDATA coord utrack[UTSZ];
  12
  13 void
  14 initrack()
  15 {
  16     utcnt = utpnt = 0;
  17 }
  18
  19 /* add to track */
  20 void
  21 settrack()
  22 {
  23     if (utcnt < UTSZ)
  24         utcnt++;
  25     if (utpnt == UTSZ)
  26         utpnt = 0;
  27     utrack[utpnt].x = u.ux;
  28     utrack[utpnt].y = u.uy;
  29     utpnt++;
  30 }
  31
  32 coord *
  33 gettrack(x, y)
  34 register int x, y;
  35 {
  36     register int cnt, ndist;
  37     register coord *tc;
  38     cnt = utcnt;
  39     for (tc = &utrack[utpnt]; cnt--;) {
  40         if (tc == utrack)
  41             tc = &utrack[UTSZ - 1];
  42         else
  43             tc--;
  44         ndist = distmin(x, y, tc->x, tc->y);
  45
  46         /* if far away, skip track entries til we're closer */
  47         if (ndist > 2) {
  48             ndist -= 2; /* be careful due to extra decrement at top of loop */
  49             cnt -= ndist;
  50             if (cnt <= 0)
  51                 return (coord *) 0; /* too far away, no matches possible */
  52             if (tc < &utrack[ndist])
  53                 tc += (UTSZ - ndist);
  54             else
  55                 tc -= ndist;
  56         } else if (ndist <= 1)
  57             return (ndist ? tc : 0);
  58     }
  59     return (coord *) 0;
  60 }
  61
  62 /*track.c*/