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/*
------------------------------------------------------------------------------
isaac64.c: My random number generator for 64-bit machines.
By Bob Jenkins, 1996. Public Domain.
------------------------------------------------------------------------------
*/
#ifndef STANDARD
#include "isaac_standard.h"
#endif
#ifndef ISAAC64
#include "isaac64.h"
#endif
#define ind(mm,x) (*(ub8 *)((ub1 *)(mm) + ((x) & ((RANDSIZ-1)<<3))))
#define rngstep(mix,a,b,mm,m,m2,r,x) \
{ \
x = *m; \
a = (mix) + *(m2++); \
*(m++) = y = ind(mm,x) + a + b; \
*(r++) = b = ind(mm,y>>RANDSIZL) + x; \
}
void isaac64(rand64ctx *ctx)
{
register ub8 a,b,x,y,*m,*mm,*m2,*r,*mend;
mm=ctx->mm; r=ctx->randrsl;
a = ctx->aa; b = ctx->bb + (++ctx->cc);
for (m = mm, mend = m2 = m+(RANDSIZ/2); m<mend; )
{
rngstep(~(a^(a<<21)), a, b, mm, m, m2, r, x);
rngstep( a^(a>>5) , a, b, mm, m, m2, r, x);
rngstep( a^(a<<12) , a, b, mm, m, m2, r, x);
rngstep( a^(a>>33) , a, b, mm, m, m2, r, x);
}
for (m2 = mm; m2<mend; )
{
rngstep(~(a^(a<<21)), a, b, mm, m, m2, r, x);
rngstep( a^(a>>5) , a, b, mm, m, m2, r, x);
rngstep( a^(a<<12) , a, b, mm, m, m2, r, x);
rngstep( a^(a>>33) , a, b, mm, m, m2, r, x);
}
ctx->bb = b; ctx->aa = a;
}
#define mix(a,b,c,d,e,f,g,h) \
{ \
a-=e; f^=h>>9; h+=a; \
b-=f; g^=a<<9; a+=b; \
c-=g; h^=b>>23; b+=c; \
d-=h; a^=c<<15; c+=d; \
e-=a; b^=d>>14; d+=e; \
f-=b; c^=e<<20; e+=f; \
g-=c; d^=f>>17; f+=g; \
h-=d; e^=g<<14; g+=h; \
}
void rand64init(rand64ctx *ctx, word flag)
{
word i;
ub8 a,b,c,d,e,f,g,h;
ub8 *mm, *randrsl;
ctx->aa = ctx->bb = ctx->cc = (ub8)0;
mm=ctx->mm;
randrsl=ctx->randrsl;
a=b=c=d=e=f=g=h=0x9e3779b97f4a7c13LL; /* the golden ratio */
for (i=0; i<4; ++i) /* scramble it */
{
mix(a,b,c,d,e,f,g,h);
}
for (i=0; i<RANDSIZ; i+=8) /* fill in mm[] with messy stuff */
{
if (flag) /* use all the information in the seed */
{
a+=randrsl[i ]; b+=randrsl[i+1]; c+=randrsl[i+2]; d+=randrsl[i+3];
e+=randrsl[i+4]; f+=randrsl[i+5]; g+=randrsl[i+6]; h+=randrsl[i+7];
}
mix(a,b,c,d,e,f,g,h);
mm[i ]=a; mm[i+1]=b; mm[i+2]=c; mm[i+3]=d;
mm[i+4]=e; mm[i+5]=f; mm[i+6]=g; mm[i+7]=h;
}
if (flag)
{ /* do a second pass to make all of the seed affect all of mm */
for (i=0; i<RANDSIZ; i+=8)
{
a+=mm[i ]; b+=mm[i+1]; c+=mm[i+2]; d+=mm[i+3];
e+=mm[i+4]; f+=mm[i+5]; g+=mm[i+6]; h+=mm[i+7];
mix(a,b,c,d,e,f,g,h);
mm[i ]=a; mm[i+1]=b; mm[i+2]=c; mm[i+3]=d;
mm[i+4]=e; mm[i+5]=f; mm[i+6]=g; mm[i+7]=h;
}
}
isaac64(ctx); /* fill in the first set of results */
ctx->randcnt=RANDSIZ; /* prepare to use the first set of results */
}
#ifdef NEVER
int main()
{
ub8 i,j;
rand64ctx ctx;
ctx.aa=ctx.bb=ctx.cc=(ub8)0;
for (i=0; i<RANDSIZ; ++i) ctx.mm[i]=(ub8)0;
rand64init(&ctx, TRUE);
for (i=0; i<2; ++i)
{
isaac64(&ctx);
for (j=0; j<RANDSIZ; ++j)
{
printf("%.8lx%.8lx",(ub4)(ctx.randrsl[j]>>32),(ub4)ctx.randrsl[j]);
if ((j&3)==3) printf("\n");
}
}
}
#endif
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