/src/rt/isaac/rand.h

 1/*
 2------------------------------------------------------------------------------
 3rand.h: definitions for a random number generator
 4By Bob Jenkins, 1996, Public Domain
 5MODIFIED:
 6  960327: Creation (addition of randinit, really)
 7  970719: use context, not global variables, for internal state
 8  980324: renamed seed to flag
 9  980605: recommend RANDSIZL=4 for noncryptography.
10  010626: note this is public domain
11------------------------------------------------------------------------------
12*/
13#ifndef STANDARD
14#include "standard.h"
15#endif
16
17#ifndef RAND
18#define RAND
19#define RANDSIZL   (8)  /* I recommend 8 for crypto, 4 for simulations */
20#define RANDSIZ    (1<<RANDSIZL)
21
22/* context of random number generator */
23struct randctx
24{
25  ub4 randcnt;
26  ub4 randrsl[RANDSIZ];
27  ub4 randmem[RANDSIZ];
28  ub4 randa;
29  ub4 randb;
30  ub4 randc;
31};
32typedef  struct randctx  randctx;
33
34/*
35------------------------------------------------------------------------------
36 If (flag==TRUE), then use the contents of randrsl[0..RANDSIZ-1] as the seed.
37------------------------------------------------------------------------------
38*/
39void randinit(randctx *r, word flag);
40
41void isaac(randctx *r);
42
43
44/*
45------------------------------------------------------------------------------
46 Call isaac_rand(/o_ randctx *r _o/) to retrieve a single 32-bit random value
47------------------------------------------------------------------------------
48*/
49#define isaac_rand(r) \
50   (!(r)->randcnt-- ? \
51     (isaac(r), (r)->randcnt=RANDSIZ-1, (r)->randrsl[(r)->randcnt]) : \
52     (r)->randrsl[(r)->randcnt])
53
54#endif  /* RAND */
55
56