Source:SLASH'EM 0.0.7E7F2/track.c

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1.   /*	SCCS Id: @(#)track.c	3.4	87/08/08	*/ 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.   #ifdef OVLB 14.   15.   void 16.  initrack 17.  {  18.   	utcnt = utpnt = 0; 19.  }  20.    21.   #endif /* OVLB */ 22.  #ifdef OVL1 23.   24.   /* add to track */ 25.  void 26.  settrack 27.  {  28.   	if(utcnt < UTSZ) utcnt++; 29.  	if(utpnt == UTSZ) utpnt = 0; 30.  	utrack[utpnt].x = u.ux; 31.  	utrack[utpnt].y = u.uy; 32.  	utpnt++; 33.  }  34.    35.   #endif /* OVL1 */ 36.  #ifdef OVL0 37.   38.   coord * 39.  gettrack(x, y)  40. register int x, y; 41. { 42.       register int cnt, ndist; 43.      register coord *tc; 44.      cnt = utcnt; 45.      for(tc = &utrack[utpnt]; cnt--; ){ 46.  	if(tc == utrack) tc = &utrack[UTSZ-1]; 47.  	else tc--; 48.  	ndist = distmin(x,y,tc->x,tc->y); 49.   50.   	/* if far away, skip track entries til we're closer */ 51.  	if(ndist > 2) { 52.  	    ndist -= 2; /* be careful due to extra decrement at top of loop */ 53.  	    cnt -= ndist; 54.  	    if(cnt <= 0) 55.  		return (coord *) 0; /* too far away, no matches possible */ 56.  	    if(tc < &utrack[ndist]) 57.  		tc += (UTSZ-ndist); 58.  	    else 59.  		tc -= ndist; 60.  	} else if(ndist <= 1) 61.  	    return(ndist ? tc : 0); 62.      }  63.       return (coord *)0; 64.  }  65.    66.   #endif /* OVL0 */ 67.   68.   /*track.c*/