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Diffstat (limited to 'src/isaac_rand/isaac_rand.c')
| -rw-r--r-- | src/isaac_rand/isaac_rand.c | 169 |
1 files changed, 169 insertions, 0 deletions
diff --git a/src/isaac_rand/isaac_rand.c b/src/isaac_rand/isaac_rand.c new file mode 100644 index 0000000..c9220e0 --- /dev/null +++ b/src/isaac_rand/isaac_rand.c @@ -0,0 +1,169 @@ +/* +------------------------------------------------------------------------------ +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 "isaac_standard.h" +#endif +#ifndef RAND +#include "isaac_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<mend; ) + { + rngstep( a<<13, a, b, mm, m, m2, r, x); + rngstep( a>>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<mend; ) + { + rngstep( a<<13, a, b, mm, m, m2, r, x); + rngstep( a>>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; i<RANDSIZ; i+=8) + { + a+=r[i ]; + b+=r[i+1]; + c+=r[i+2]; + d+=r[i+3]; + e+=r[i+4]; + f+=r[i+5]; + g+=r[i+6]; + h+=r[i+7]; + mix(a,b,c,d,e,f,g,h); + m[i ]=a; + m[i+1]=b; + m[i+2]=c; + m[i+3]=d; + m[i+4]=e; + m[i+5]=f; + m[i+6]=g; + m[i+7]=h; + } + /* do a second pass to make all of the seed affect all of m */ + for (i=0; i<RANDSIZ; i+=8) + { + a+=m[i ]; + b+=m[i+1]; + c+=m[i+2]; + d+=m[i+3]; + e+=m[i+4]; + f+=m[i+5]; + g+=m[i+6]; + h+=m[i+7]; + mix(a,b,c,d,e,f,g,h); + m[i ]=a; + m[i+1]=b; + m[i+2]=c; + m[i+3]=d; + m[i+4]=e; + m[i+5]=f; + m[i+6]=g; + m[i+7]=h; + } + } + else + { + /* fill in m[] with messy stuff */ + for (i=0; i<RANDSIZ; i+=8) + { + mix(a,b,c,d,e,f,g,h); + m[i ]=a; + m[i+1]=b; + m[i+2]=c; + m[i+3]=d; + m[i+4]=e; + m[i+5]=f; + m[i+6]=g; + m[i+7]=h; + } + } + + isaac(ctx); /* fill in the first set of results */ + ctx->randcnt=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 |