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Source:NetHack 3.3.0/rnd.c

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Below is the full text to rnd.c from the source code of NetHack 3.3.0. To link to a particular line, write [[NetHack 3.3.0/rnd.c#line123]], for example.

Warning! This is the source code from an old release. For the latest release, see Source code

The NetHack General Public License applies to screenshots, source code and other content from NetHack.
1.    /*	SCCS Id: @(#)rnd.c	3.3	96/02/07	*/
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*/

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