1/* 2------------------------------------------------------------------------------ 3rand.c: By Bob Jenkins. My random number generator, ISAAC. Public Domain 4MODIFIED: 5 960327: Creation (addition of randinit, really) 6 970719: use context, not global variables, for internal state 7 980324: make a portable version 8 010626: Note this is public domain 9------------------------------------------------------------------------------ 10*/ 11#ifndef STANDARD 12#include "standard.h" 13#endif 14#ifndef RAND 15#include "rand.h" 16#endif 17 18 19#define ind(mm,x) ((mm)[(x>>2)&(RANDSIZ-1)]) 20#define rngstep(mix,a,b,mm,m,m2,r,x) \ 21{ \ 22 x = *m; \ 23 a = ((a^(mix)) + *(m2++)) & 0xffffffff; \ 24 *(m++) = y = (ind(mm,x) + a + b) & 0xffffffff; \ 25 *(r++) = b = (ind(mm,y>>RANDSIZL) + x) & 0xffffffff; \ 26} 27 28void isaac(ctx) 29randctx *ctx; 30{ 31 register ub4 a,b,x,y,*m,*mm,*m2,*r,*mend; 32 mm=ctx->randmem; r=ctx->randrsl; 33 a = ctx->randa; b = (ctx->randb + (++ctx->randc)) & 0xffffffff; 34 for (m = mm, mend = m2 = m+(RANDSIZ/2); m<mend; ) 35 { 36 rngstep( a<<13, a, b, mm, m, m2, r, x); 37 rngstep( a>>6 , a, b, mm, m, m2, r, x); 38 rngstep( a<<2 , a, b, mm, m, m2, r, x); 39 rngstep( a>>16, a, b, mm, m, m2, r, x); 40 } 41 for (m2 = mm; m2<mend; ) 42 { 43 rngstep( a<<13, a, b, mm, m, m2, r, x); 44 rngstep( a>>6 , a, b, mm, m, m2, r, x); 45 rngstep( a<<2 , a, b, mm, m, m2, r, x); 46 rngstep( a>>16, a, b, mm, m, m2, r, x); 47 } 48 ctx->randb = b; ctx->randa = a; 49} 50 51 52#define mix(a,b,c,d,e,f,g,h) \ 53{ \ 54 a^=b<<11; d+=a; b+=c; \ 55 b^=c>>2; e+=b; c+=d; \ 56 c^=d<<8; f+=c; d+=e; \ 57 d^=e>>16; g+=d; e+=f; \ 58 e^=f<<10; h+=e; f+=g; \ 59 f^=g>>4; a+=f; g+=h; \ 60 g^=h<<8; b+=g; h+=a; \ 61 h^=a>>9; c+=h; a+=b; \ 62} 63 64/* if (flag==TRUE), then use the contents of randrsl[] to initialize mm[]. */ 65void randinit(ctx, flag) 66randctx *ctx; 67word flag; 68{ 69 word i; 70 ub4 a,b,c,d,e,f,g,h; 71 ub4 *m,*r; 72 ctx->randa = ctx->randb = ctx->randc = 0; 73 m=ctx->randmem; 74 r=ctx->randrsl; 75 a=b=c=d=e=f=g=h=0x9e3779b9; /* the golden ratio */ 76 77 for (i=0; i<4; ++i) /* scramble it */ 78 { 79 mix(a,b,c,d,e,f,g,h); 80 } 81 82 if (flag) 83 { 84 /* initialize using the contents of r[] as the seed */ 85 for (i=0; i<RANDSIZ; i+=8) 86 { 87 a+=r[i ]; b+=r[i+1]; c+=r[i+2]; d+=r[i+3]; 88 e+=r[i+4]; f+=r[i+5]; g+=r[i+6]; h+=r[i+7]; 89 mix(a,b,c,d,e,f,g,h); 90 m[i ]=a; m[i+1]=b; m[i+2]=c; m[i+3]=d; 91 m[i+4]=e; m[i+5]=f; m[i+6]=g; m[i+7]=h; 92 } 93 /* do a second pass to make all of the seed affect all of m */ 94 for (i=0; i<RANDSIZ; i+=8) 95 { 96 a+=m[i ]; b+=m[i+1]; c+=m[i+2]; d+=m[i+3]; 97 e+=m[i+4]; f+=m[i+5]; g+=m[i+6]; h+=m[i+7]; 98 mix(a,b,c,d,e,f,g,h); 99 m[i ]=a; m[i+1]=b; m[i+2]=c; m[i+3]=d; 100 m[i+4]=e; m[i+5]=f; m[i+6]=g; m[i+7]=h; 101 } 102 } 103 else 104 { 105 for (i=0; i<RANDSIZ; i+=8) 106 { 107 /* fill in mm[] with messy stuff */ 108 mix(a,b,c,d,e,f,g,h); 109 m[i ]=a; m[i+1]=b; m[i+2]=c; m[i+3]=d; 110 m[i+4]=e; m[i+5]=f; m[i+6]=g; m[i+7]=h; 111 } 112 } 113 114 isaac(ctx); /* fill in the first set of results */ 115 ctx->randcnt=RANDSIZ; /* prepare to use the first set of results */ 116} 117 118 119#ifdef NEVER 120int main() 121{ 122 ub4 i,j; 123 randctx ctx; 124 ctx.randa=ctx.randb=ctx.randc=(ub4)0; 125 for (i=0; i<256; ++i) ctx.randrsl[i]=(ub4)0; 126 randinit(&ctx, TRUE); 127 for (i=0; i<2; ++i) 128 { 129 isaac(&ctx); 130 for (j=0; j<256; ++j) 131 { 132 printf("%.8lx",ctx.randrsl[j]); 133 if ((j&7)==7) printf("\n"); 134 } 135 } 136} 137#endif 138