1 /*
2 ------------------------------------------------------------------------------
3 rand.h: definitions for a random number generator
4 By Bob Jenkins, 1996, Public Domain
5 MODIFIED:
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 */
23 struct randctx
24 {
25   ub4 randcnt;
26   ub4 randrsl[RANDSIZ];
27   ub4 randmem[RANDSIZ];
28   ub4 randa;
29   ub4 randb;
30   ub4 randc;
31 };
32 typedef  struct randctx  randctx;
33 
34 /*
35 ------------------------------------------------------------------------------
36  If (flag==TRUE), then use the contents of randrsl[0..RANDSIZ-1] as the seed.
37 ------------------------------------------------------------------------------
38 */
39 void randinit(randctx *r, word flag);
40 
41 void isaac(randctx *r);
42 
43 
44 /*
45 ------------------------------------------------------------------------------
46  Call rand(/o_ randctx *r _o/) to retrieve a single 32-bit random value
47 ------------------------------------------------------------------------------
48 */
49 #define 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 
57