/src/rt/isaac/randport.cpp
C++ | 134 lines | 109 code | 11 blank | 14 comment | 11 complexity | 7c5a573a1e4fc463af0bfa0ccb7aed5d MD5 | raw file
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(randctx *ctx) 29{ 30 register ub4 a,b,x,y,*m,*mm,*m2,*r,*mend; 31 mm=ctx->randmem; r=ctx->randrsl; 32 a = ctx->randa; b = (ctx->randb + (++ctx->randc)) & 0xffffffff; 33 for (m = mm, mend = m2 = m+(RANDSIZ/2); m<mend; ) 34 { 35 rngstep( a<<13, a, b, mm, m, m2, r, x); 36 rngstep( a>>6 , a, b, mm, m, m2, r, x); 37 rngstep( a<<2 , a, b, mm, m, m2, r, x); 38 rngstep( a>>16, a, b, mm, m, m2, r, x); 39 } 40 for (m2 = mm; m2<mend; ) 41 { 42 rngstep( a<<13, a, b, mm, m, m2, r, x); 43 rngstep( a>>6 , a, b, mm, m, m2, r, x); 44 rngstep( a<<2 , a, b, mm, m, m2, r, x); 45 rngstep( a>>16, a, b, mm, m, m2, r, x); 46 } 47 ctx->randb = b; ctx->randa = a; 48} 49 50 51#define mix(a,b,c,d,e,f,g,h) \ 52{ \ 53 a^=b<<11; d+=a; b+=c; \ 54 b^=c>>2; e+=b; c+=d; \ 55 c^=d<<8; f+=c; d+=e; \ 56 d^=e>>16; g+=d; e+=f; \ 57 e^=f<<10; h+=e; f+=g; \ 58 f^=g>>4; a+=f; g+=h; \ 59 g^=h<<8; b+=g; h+=a; \ 60 h^=a>>9; c+=h; a+=b; \ 61} 62 63/* if (flag==TRUE), then use the contents of randrsl[] to initialize mm[]. */ 64void randinit(randctx *ctx, word flag) 65{ 66 word i; 67 ub4 a,b,c,d,e,f,g,h; 68 ub4 *m,*r; 69 ctx->randa = ctx->randb = ctx->randc = 0; 70 m=ctx->randmem; 71 r=ctx->randrsl; 72 a=b=c=d=e=f=g=h=0x9e3779b9; /* the golden ratio */ 73 74 for (i=0; i<4; ++i) /* scramble it */ 75 { 76 mix(a,b,c,d,e,f,g,h); 77 } 78 79 if (flag) 80 { 81 /* initialize using the contents of r[] as the seed */ 82 for (i=0; i<RANDSIZ; i+=8) 83 { 84 a+=r[i ]; b+=r[i+1]; c+=r[i+2]; d+=r[i+3]; 85 e+=r[i+4]; f+=r[i+5]; g+=r[i+6]; h+=r[i+7]; 86 mix(a,b,c,d,e,f,g,h); 87 m[i ]=a; m[i+1]=b; m[i+2]=c; m[i+3]=d; 88 m[i+4]=e; m[i+5]=f; m[i+6]=g; m[i+7]=h; 89 } 90 /* do a second pass to make all of the seed affect all of m */ 91 for (i=0; i<RANDSIZ; i+=8) 92 { 93 a+=m[i ]; b+=m[i+1]; c+=m[i+2]; d+=m[i+3]; 94 e+=m[i+4]; f+=m[i+5]; g+=m[i+6]; h+=m[i+7]; 95 mix(a,b,c,d,e,f,g,h); 96 m[i ]=a; m[i+1]=b; m[i+2]=c; m[i+3]=d; 97 m[i+4]=e; m[i+5]=f; m[i+6]=g; m[i+7]=h; 98 } 99 } 100 else 101 { 102 for (i=0; i<RANDSIZ; i+=8) 103 { 104 /* fill in mm[] with messy stuff */ 105 mix(a,b,c,d,e,f,g,h); 106 m[i ]=a; m[i+1]=b; m[i+2]=c; m[i+3]=d; 107 m[i+4]=e; m[i+5]=f; m[i+6]=g; m[i+7]=h; 108 } 109 } 110 111 isaac(ctx); /* fill in the first set of results */ 112 ctx->randcnt=RANDSIZ; /* prepare to use the first set of results */ 113} 114 115 116#ifdef NEVER 117int main() 118{ 119 ub4 i,j; 120 randctx ctx; 121 ctx.randa=ctx.randb=ctx.randc=(ub4)0; 122 for (i=0; i<256; ++i) ctx.randrsl[i]=(ub4)0; 123 randinit(&ctx, TRUE); 124 for (i=0; i<2; ++i) 125 { 126 isaac(&ctx); 127 for (j=0; j<256; ++j) 128 { 129 printf("%.8lx",ctx.randrsl[j]); 130 if ((j&7)==7) printf("\n"); 131 } 132 } 133} 134#endif