Source:NetHack 2.3e/rnd.c

Below is the full text to rnd.c from the source code of NetHack 2.3e.

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1.    /*	SCCS Id: @(#)rnd.c	2.3	87/12/12
2.     */
3.    #include	"config.h"
4.    /* rand() is either random() or lrand48() - see config.h. */
5.    #ifdef UNIX
6.    #define RND(x)	(rand() % (x))
7.    #else
8.    /* Good luck: the bottom order bits are cyclic. */
9.    #define RND(x)	((rand()>>3) % (x))
10.   #endif
11.   
12.   rn1(x,y)	/* y <= rn1(x,y) < (y+x) */ 
13.   register x,y;
14.   {
15.   	return(RND(x)+y);
16.   }
17.   
18.   rn2(x)		/* 0 <= rn2(x) < x */
19.   register x;
20.   {
21.   	return(RND(x));
22.   }
23.   
24.   rnd(x)		/* 1 <= rnd(x) <= x */
25.   register x;
26.   {
27.   	return(RND(x)+1);
28.   }
29.   
30.   d(n,x)		/* n <= d(n,x) <= (n*x) */
31.   register n,x;
32.   {
33.   	register tmp = n;
34.   
35.   	while(n--) tmp += RND(x);
36.   	return(tmp);
37.   }
38.   
39.   rne(x)          /* by stewr 870807 */
40.   register x;
41.   {
42.           register tmp = 1;
43.   	while(!rn2(x)) tmp++;
44.   	return(tmp);
45.   }
46.   
47.   rnz(i)
48.   int i;
49.   {
50.   	register long x = i;
51.           register long tmp = 1000;
52.   	tmp += rn2(1000);
53.   	tmp *= rne(4);
54.   	if (rn2(2)) { x *= tmp; x /= 1000; }
55.   	else { x *= 1000; x /= tmp; }
56.   	return((int)x);
57.   }