lib/prng.h

   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 # define STANDARD
  15 # ifndef STDIO
  16 #  include <stdio.h>
  17 #  define STDIO
  18 # endif
  19 # ifndef STDDEF
  20 #  include <stddef.h>
  21 #  define STDDEF
  22 # endif
  23 typedef  unsigned long long  ub8;
  24 #define UB8MAXVAL 0xffffffffffffffffLL
  25 #define UB8BITS 64
  26 typedef    signed long long  sb8;
  27 #define SB8MAXVAL 0x7fffffffffffffffLL
  28 typedef  unsigned long  int  ub4;   /* unsigned 4-byte quantities */
  29 #define UB4MAXVAL 0xffffffff
  30 typedef    signed long  int  sb4;
  31 #define UB4BITS 32
  32 #define SB4MAXVAL 0x7fffffff
  33 typedef  unsigned short int  ub2;
  34 #define UB2MAXVAL 0xffff
  35 #define UB2BITS 16
  36 typedef    signed short int  sb2;
  37 #define SB2MAXVAL 0x7fff
  38 typedef  unsigned       char ub1;
  39 #define UB1MAXVAL 0xff
  40 #define UB1BITS 8
  41 typedef    signed       char sb1;   /* signed 1-byte quantities */
  42 #define SB1MAXVAL 0x7f
  43 typedef                 int  word;  /* fastest type available */
  44
  45 #define bis(target,mask)  ((target) |=  (mask))
  46 #define bic(target,mask)  ((target) &= ~(mask))
  47 #define bit(target,mask)  ((target) &   (mask))
  48 #ifndef min
  49 # define min(a,b) (((a)<(b)) ? (a) : (b))
  50 #endif /* min */
  51 #ifndef max
  52 # define max(a,b) (((a)<(b)) ? (b) : (a))
  53 #endif /* max */
  54 #ifndef align
  55 # define align(a) (((ub4)a+(sizeof(void *)-1))&(~(sizeof(void *)-1)))
  56 #endif /* align */
  57 #ifndef abs
  58 # define abs(a)   (((a)>0) ? (a) : -(a))
  59 #endif
  60 #define TRUE  1
  61 #define FALSE 0
  62 #define SUCCESS 0  /* 1 on VAX */
  63
  64 #endif /* STANDARD */
  65
  66 #ifndef PRNG
  67 #define PRNG
  68 #define RANDSIZL   (8)  /* I recommend 8 for crypto, 4 for simulations */
  69 #define RANDSIZ    (1<<RANDSIZL)
  70
  71 /* context of random number generator */
  72 struct prngctx
  73 {
  74   ub4 randcnt;
  75   ub4 randrsl[RANDSIZ];
  76   ub4 randmem[RANDSIZ];
  77   ub4 randa;
  78   ub4 randb;
  79   ub4 randc;
  80 };
  81 typedef  struct prngctx  prngctx;
  82
  83 /*
  84 ------------------------------------------------------------------------------
  85  If (flag==TRUE), then use the contents of randrsl[0..RANDSIZ-1] as the seed.
  86 ------------------------------------------------------------------------------
  87 */
  88 void prnginit(/*_ prngctx *r, word flag _*/);
  89
  90 void isaac(/*_ prngctx *r _*/);
  91
  92
  93 /*
  94 ------------------------------------------------------------------------------
  95  Call rand(/o_ prngctx *r _o/) to retrieve a single 32-bit random value
  96 ------------------------------------------------------------------------------
  97 */
  98 #define prng(r) \
  99    (!(r)->randcnt-- ? \
 100      (isaac(r), (r)->randcnt=RANDSIZ-1, (r)->randrsl[(r)->randcnt]) : \
 101      (r)->randrsl[(r)->randcnt])
 102
 103 #endif  /* RAND */
 104
 105