/* ------------------------------------------------------------------------------ rand.c: By Bob Jenkins. My random number generator, ISAAC. Public Domain. MODIFIED: 960327: Creation (addition of randinit, really) 970719: use context, not global variables, for internal state 980324: added main (ifdef'ed out), also rearranged randinit() 010626: Note that this is public domain ------------------------------------------------------------------------------ */ #ifndef STANDARD #include "standard.h" #endif #ifndef RAND #include "rand.h" #endif #define ind(mm,x) (*(ub4 *)((ub1 *)(mm) + ((x) & ((RANDSIZ-1)<<2)))) #define rngstep(mix,a,b,mm,m,m2,r,x) \ { \ x = *m; \ a = (a^(mix)) + *(m2++); \ *(m++) = y = ind(mm,x) + a + b; \ *(r++) = b = ind(mm,y>>RANDSIZL) + x; \ } void isaac(ctx) randctx *ctx; { register ub4 a,b,x,y,*m,*mm,*m2,*r,*mend; mm=ctx->randmem; r=ctx->randrsl; a = ctx->randa; b = ctx->randb + (++ctx->randc); for (m = mm, mend = m2 = m+(RANDSIZ/2); m>6 , a, b, mm, m, m2, r, x); rngstep( a<<2 , a, b, mm, m, m2, r, x); rngstep( a>>16, a, b, mm, m, m2, r, x); } for (m2 = mm; m2>6 , a, b, mm, m, m2, r, x); rngstep( a<<2 , a, b, mm, m, m2, r, x); rngstep( a>>16, a, b, mm, m, m2, r, x); } ctx->randb = b; ctx->randa = a; } #define mix(a,b,c,d,e,f,g,h) \ { \ a^=b<<11; d+=a; b+=c; \ b^=c>>2; e+=b; c+=d; \ c^=d<<8; f+=c; d+=e; \ d^=e>>16; g+=d; e+=f; \ e^=f<<10; h+=e; f+=g; \ f^=g>>4; a+=f; g+=h; \ g^=h<<8; b+=g; h+=a; \ h^=a>>9; c+=h; a+=b; \ } /* if (flag==TRUE), then use the contents of randrsl[] to initialize mm[]. */ void randinit(ctx, flag) randctx *ctx; word flag; { word i; ub4 a,b,c,d,e,f,g,h; ub4 *m,*r; ctx->randa = ctx->randb = ctx->randc = 0; m=ctx->randmem; r=ctx->randrsl; a=b=c=d=e=f=g=h=0x9e3779b9; /* the golden ratio */ for (i=0; i<4; ++i) /* scramble it */ { mix(a,b,c,d,e,f,g,h); } if (flag) { /* initialize using the contents of r[] as the seed */ for (i=0; irandcnt=RANDSIZ; /* prepare to use the first set of results */ } #ifdef NEVER int main() { ub4 i,j; randctx ctx; ctx.randa=ctx.randb=ctx.randc=(ub4)0; for (i=0; i<256; ++i) ctx.randrsl[i]=(ub4)0; randinit(&ctx, TRUE); for (i=0; i<2; ++i) { isaac(&ctx); for (j=0; j<256; ++j) { printf("%.8lx",ctx.randrsl[j]); if ((j&7)==7) printf("\n"); } } } #endif