Source:Rnd.c

Below is the full text to src/rnd.c from NetHack 3.4.3. To link to a particular line, write [[rnd.c#line123 ]], for example. 1.   /*	SCCS Id: @(#)rnd.c	3.4	1996/02/07	*/ 2.   /* NetHack may be freely redistributed. See license for details. */ 3.     4.    #include "hack.h"

5.    6.    /* "Rand"s definition is determined by [OS]conf.h */ 7.   #if defined(LINT) && defined(UNIX)	/* rand is long... */ 8.    extern int NDECL(rand); 9.   #define RND(x)	(rand % x)  10. #else /* LINT */ 11.  # if defined(UNIX) || defined(RANDOM) 12.  #define RND(x)	(int)(Rand % (long)(x)) 13.  # else 14.  /* Good luck: the bottom order bits are cyclic. */ 15.   #define RND(x)	(int)((Rand>>3) % (x)) 16.  # endif 17.  #endif /* LINT */ 18.   19.   #ifdef OVL0 20.   21.   int 22.  rn2(x)		/* 0 <= rn2(x) < x */ 23.  register int x;  24. { 25.   #ifdef DEBUG 26.  	if (x <= 0) { 27.  		impossible("rn2(%d) attempted", x); 28.  		return(0); 29.  	}  30.   	x = RND(x); 31.  	return(x); 32.  #else 33.  	return(RND(x)); 34.  #endif 35.  }  36.    37.   #endif /* OVL0 */ 38.  #ifdef OVLB 39.   40.   int 41.  rnl(x)		/* 0 <= rnl(x) < x; sometimes subtracting Luck */ 42.  register int x;	/* good luck approaches 0, bad luck approaches (x-1) */ 43.  {  44.   	register int i;  45. 46.  #ifdef DEBUG 47.  	if (x <= 0) { 48.  		impossible("rnl(%d) attempted", x); 49.  		return(0); 50.  	}  51.   #endif 52.  	i = RND(x); 53.   54.   	if (Luck && rn2(50 - Luck)) { 55.  	    i -= (x <= 15 && Luck >= -5 ? Luck/3 : Luck); 56.  	    if (i < 0) i = 0; 57.  	    else if (i >= x) i = x-1; 58.  	}  59.    60.   	return i;  61. } 62.    63.   #endif /* OVLB */ 64.  #ifdef OVL0 65.   66.   int 67.  rnd(x)		/* 1 <= rnd(x) <= x */ 68.  register int x;  69. { 70.   #ifdef DEBUG 71.  	if (x <= 0) { 72.  		impossible("rnd(%d) attempted", x); 73.  		return(1); 74.  	}  75.   	x = RND(x)+1; 76.  	return(x); 77.  #else 78.  	return(RND(x)+1); 79.  #endif 80.  }  81.    82.   #endif /* OVL0 */ 83.  #ifdef OVL1 84.   85.   int 86.  d(n,x)		/* n <= d(n,x) <= (n*x) */ 87.  register int n, x;  88. { 89.   	register int tmp = n;  90. 91.  #ifdef DEBUG 92.  	if (x < 0 || n < 0 || (x == 0 && n != 0)) { 93.  		impossible("d(%d,%d) attempted", n, x); 94.  		return(1); 95.  	}  96.   #endif 97.  	while(n--) tmp += RND(x); 98.  	return(tmp); /* Alea iacta est. -- J.C. */ 99.  }  100.   101.  #endif /* OVL1 */ 102. #ifdef OVLB 103.  104.  int 105. rne(x) 106. register int x;  107. { 108.  	register int tmp, utmp; 109.  110.  	utmp = (u.ulevel < 15) ? 5 : u.ulevel/3; 111. 	tmp = 1; 112. 	while (tmp < utmp && !rn2(x)) 113. 		tmp++; 114. 	return tmp; 115.  116.  	/* was: 117. 	 *	tmp = 1; 118. 	 *	while(!rn2(x)) tmp++; 119. 	 *	return(min(tmp,(u.ulevel < 15) ? 5 : u.ulevel/3)); 120. 	 * which is clearer but less efficient and stands a vanishingly 121. 	 * small chance of overflowing tmp 122. 	 */  123.  }  124.   125.  int 126. rnz(i) 127. int i;  128. { 129.  #ifdef LINT 130. 	int x = i;  131. int tmp = 1000; 132. #else 133. 	register long x = i;  134. register long tmp = 1000; 135. #endif 136. 	tmp += rn2(1000); 137. 	tmp *= rne(4); 138. 	if (rn2(2)) { x *= tmp; x /= 1000; } 139. 	else { x *= 1000; x /= tmp; } 140. 	return((int)x); 141. }  142.   143.  #endif /* OVLB */ 144.  145.  /*rnd.c*/