Source:NetHack 3.1.0/rnd.c

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1.    /*	SCCS Id: @(#)rnd.c	3.1	90/22/02
2.    /* NetHack may be freely redistributed.  See license for details. */
3.    
4.    #include	"hack.h"
5.    
6.    #if defined(LINT) && defined(UNIX)	/* rand() is long... */
7.    extern int NDECL(rand);
8.    #define RND(x)	(rand() % x)
9.    #else /* LINT */
10.   /* rand() is either random() or lrand48() - see config.h. */
11.   #ifdef UNIX
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(0) attempted");
28.   		return(0);
29.   	}
30.   #endif
31.   	return(RND(x));
32.   }
33.   
34.   #endif /* OVL0 */
35.   #ifdef OVLB
36.   
37.   int
38.   rnl(x)		/* 0 <= rnl(x) < x; sometimes subtracting Luck */
39.   register int x;	/* good luck approaches 0, bad luck approaches (x-1) */
40.   {
41.   	register int i;
42.   
43.   #ifdef DEBUG
44.   	if (x == 0) {
45.   		impossible("rnl(0) attempted");
46.   		return(0);
47.   	}
48.   #endif
49.   	i = RND(x);
50.   
51.   	if (Luck && rn2(50 - Luck)) {
52.   	    i -= (x <= 15 && Luck >= -5 ? Luck/3 : Luck);
53.   	    if (i < 0) i = 0;
54.   	    else if (i >= x) i = x-1;
55.   	}
56.   
57.   	return i;
58.   }
59.   
60.   #endif /* OVLB */
61.   #ifdef OVL0
62.   
63.   int
64.   rnd(x)		/* 1 <= rnd(x) <= x */
65.   register int x;
66.   {
67.   #ifdef DEBUG
68.   	if (x == 0) {
69.   		impossible("rnd(0) attempted");
70.   		return(1);
71.   	}
72.   #endif
73.   	return(RND(x)+1);
74.   }
75.   
76.   #endif /* OVL0 */
77.   #ifdef OVL1
78.   
79.   int
80.   d(n,x)		/* n <= d(n,x) <= (n*x) */
81.   register int n, x;
82.   {
83.   	register int tmp = n;
84.   
85.   #ifdef DEBUG
86.   	if (x == 0) {
87.   		impossible("d(n,0) attempted");
88.   		return(1);
89.   	}
90.   #endif
91.   	while(n--) tmp += RND(x);
92.   	return(tmp); /* Alea iacta est. -- J.C. */
93.   }
94.   
95.   #endif /* OVL1 */
96.   #ifdef OVLB
97.   
98.   int
99.   rne(x)	  /* by stewr 870807 */
100.  register int x;
101.  {
102.  	register int tmp = 1;
103.  	while(!rn2(x)) tmp++;
104.  	return(min(tmp,(u.ulevel < 15) ? 5 : (int)u.ulevel/3));
105.  }
106.  
107.  int
108.  rnz(i)
109.  int i;
110.  {
111.  #ifdef LINT
112.  	int x = i;
113.  	int tmp = 1000;
114.  #else
115.  	register long x = i;
116.  	register long tmp = 1000;
117.  #endif
118.  	tmp += rn2(1000);
119.  	tmp *= rne(4);
120.  	if (rn2(2)) { x *= tmp; x /= 1000; }
121.  	else { x *= 1000; x /= tmp; }
122.  	return((int)x);
123.  }
124.  
125.  #endif /* OVLB */
126.  
127.  /*rnd.c*/