--- /dev/null
+/*Written by Timothy B. Terriberry (tterribe@xiph.org) 1999-2009 public domain.
+ Based on the public domain ISAAC implementation by Robert J. Jenkins Jr.*/
+#include <float.h>
+#include <math.h>
+#include <string.h>
+#include <ccan/ilog/ilog.h>
+#include "isaac64.h"
+#if defined(__GNUC_PREREQ)
+# if __GNUC_PREREQ(4,2)
+# pragma GCC diagnostic ignored "-Wparentheses"
+# endif
+#endif
+
+
+
+#define ISAAC64_MASK ((uint64_t)0xFFFFFFFFFFFFFFFFULL)
+
+
+
+static void isaac64_update(isaac64_ctx *_ctx){
+ uint64_t *m;
+ uint64_t *r;
+ uint64_t a;
+ uint64_t b;
+ uint64_t x;
+ uint64_t y;
+ int i;
+ m=_ctx->m;
+ r=_ctx->r;
+ a=_ctx->a;
+ b=_ctx->b+(++_ctx->c)&ISAAC64_MASK;
+ for(i=0;i<ISAAC64_SZ/2;i++){
+ x=m[i];
+ a=~(a^a<<21)+m[i+ISAAC64_SZ/2]&ISAAC64_MASK;
+ m[i]=y=m[(x&ISAAC64_SZ-1<<3)>>3]+a+b&ISAAC64_MASK;
+ r[i]=b=m[y>>ISAAC64_SZ_LOG+3&ISAAC64_SZ-1]+x&ISAAC64_MASK;
+ x=m[++i];
+ a=(a^a>>5)+m[i+ISAAC64_SZ/2]&ISAAC64_MASK;
+ m[i]=y=m[(x&ISAAC64_SZ-1<<3)>>3]+a+b&ISAAC64_MASK;
+ r[i]=b=m[y>>ISAAC64_SZ_LOG+3&ISAAC64_SZ-1]+x&ISAAC64_MASK;
+ x=m[++i];
+ a=(a^a<<12)+m[i+ISAAC64_SZ/2]&ISAAC64_MASK;
+ m[i]=y=m[(x&ISAAC64_SZ-1<<3)>>3]+a+b&ISAAC64_MASK;
+ r[i]=b=m[y>>ISAAC64_SZ_LOG+3&ISAAC64_SZ-1]+x&ISAAC64_MASK;
+ x=m[++i];
+ a=(a^a>>33)+m[i+ISAAC64_SZ/2]&ISAAC64_MASK;
+ m[i]=y=m[(x&ISAAC64_SZ-1<<3)>>3]+a+b&ISAAC64_MASK;
+ r[i]=b=m[y>>ISAAC64_SZ_LOG+3&ISAAC64_SZ-1]+x&ISAAC64_MASK;
+ }
+ for(i=ISAAC64_SZ/2;i<ISAAC64_SZ;i++){
+ x=m[i];
+ a=~(a^a<<21)+m[i-ISAAC64_SZ/2]&ISAAC64_MASK;
+ m[i]=y=m[(x&ISAAC64_SZ-1<<3)>>3]+a+b&ISAAC64_MASK;
+ r[i]=b=m[y>>ISAAC64_SZ_LOG+3&ISAAC64_SZ-1]+x&ISAAC64_MASK;
+ x=m[++i];
+ a=(a^a>>5)+m[i-ISAAC64_SZ/2]&ISAAC64_MASK;
+ m[i]=y=m[(x&ISAAC64_SZ-1<<3)>>3]+a+b&ISAAC64_MASK;
+ r[i]=b=m[y>>ISAAC64_SZ_LOG+3&ISAAC64_SZ-1]+x&ISAAC64_MASK;
+ x=m[++i];
+ a=(a^a<<12)+m[i-ISAAC64_SZ/2]&ISAAC64_MASK;
+ m[i]=y=m[(x&ISAAC64_SZ-1<<3)>>3]+a+b&ISAAC64_MASK;
+ r[i]=b=m[y>>ISAAC64_SZ_LOG+3&ISAAC64_SZ-1]+x&ISAAC64_MASK;
+ x=m[++i];
+ a=(a^a>>33)+m[i-ISAAC64_SZ/2]&ISAAC64_MASK;
+ m[i]=y=m[(x&ISAAC64_SZ-1<<3)>>3]+a+b&ISAAC64_MASK;
+ r[i]=b=m[y>>ISAAC64_SZ_LOG+3&ISAAC64_SZ-1]+x&ISAAC64_MASK;
+ }
+ _ctx->b=b;
+ _ctx->a=a;
+ _ctx->n=ISAAC64_SZ;
+}
+
+static void isaac64_mix(uint64_t _x[8]){
+ static const unsigned char SHIFT[8]={9,9,23,15,14,20,17,14};
+ int i;
+ for(i=0;i<8;i++){
+ _x[i]-=_x[i+4&7];
+ _x[i+5&7]^=_x[i+7&7]>>SHIFT[i];
+ _x[i+7&7]+=_x[i];
+ i++;
+ _x[i]-=_x[i+4&7];
+ _x[i+5&7]^=_x[i+7&7]<<SHIFT[i];
+ _x[i+7&7]+=_x[i];
+ }
+}
+
+
+void isaac64_init(isaac64_ctx *_ctx,const unsigned char *_seed,int _nseed){
+ _ctx->a=_ctx->b=_ctx->c=0;
+ memset(_ctx->r,0,sizeof(_ctx->r));
+ isaac64_reseed(_ctx,_seed,_nseed);
+}
+
+void isaac64_reseed(isaac64_ctx *_ctx,const unsigned char *_seed,int _nseed){
+ uint64_t *m;
+ uint64_t *r;
+ uint64_t x[8];
+ int i;
+ int j;
+ m=_ctx->m;
+ r=_ctx->r;
+ if(_nseed>ISAAC64_SEED_SZ_MAX)_nseed=ISAAC64_SEED_SZ_MAX;
+ for(i=0;i<_nseed>>3;i++){
+ r[i]^=(uint64_t)_seed[i<<3|7]<<56|(uint64_t)_seed[i<<3|6]<<48|
+ (uint64_t)_seed[i<<3|5]<<40|(uint64_t)_seed[i<<3|4]<<32|
+ (uint64_t)_seed[i<<3|3]<<24|(uint64_t)_seed[i<<3|2]<<16|
+ (uint64_t)_seed[i<<3|1]<<8|_seed[i<<3];
+ }
+ _nseed-=i<<3;
+ if(_nseed>0){
+ uint64_t ri;
+ ri=_seed[i<<3];
+ for(j=1;j<_nseed;j++)ri|=(uint64_t)_seed[i<<3|j]<<(j<<3);
+ r[i++]^=ri;
+ }
+ x[0]=x[1]=x[2]=x[3]=x[4]=x[5]=x[6]=x[7]=(uint64_t)0x9E3779B97F4A7C13ULL;
+ for(i=0;i<4;i++)isaac64_mix(x);
+ for(i=0;i<ISAAC64_SZ;i+=8){
+ for(j=0;j<8;j++)x[j]+=r[i+j];
+ isaac64_mix(x);
+ memcpy(m+i,x,sizeof(x));
+ }
+ for(i=0;i<ISAAC64_SZ;i+=8){
+ for(j=0;j<8;j++)x[j]+=m[i+j];
+ isaac64_mix(x);
+ memcpy(m+i,x,sizeof(x));
+ }
+ isaac64_update(_ctx);
+}
+
+uint64_t isaac64_next_uint64(isaac64_ctx *_ctx){
+ if(!_ctx->n)isaac64_update(_ctx);
+ return _ctx->r[--_ctx->n];
+}
+
+uint64_t isaac64_next_uint(isaac64_ctx *_ctx,uint64_t _n){
+ uint64_t r;
+ uint64_t v;
+ uint64_t d;
+ do{
+ r=isaac64_next_uint64(_ctx);
+ v=r%_n;
+ d=r-v;
+ }
+ while((d+_n-1&ISAAC64_MASK)<d);
+ return v;
+}
+
+/*Returns a uniform random float.
+ The expected value is within FLT_MIN (e.g., 1E-37) of 0.5.
+ _bits: An initial set of random bits.
+ _base: This should be -(the number of bits in _bits), up to -64.
+ Return: A float uniformly distributed between 0 (inclusive) and 1
+ (exclusive).
+ The average value was measured over 2**32 samples to be
+ 0.499991407275206357.*/
+static float isaac64_float_bits(isaac64_ctx *_ctx,uint64_t _bits,int _base){
+ float ret;
+ int nbits_needed;
+ while(!_bits){
+ if(_base+FLT_MANT_DIG<FLT_MIN_EXP)return 0;
+ _base-=64;
+ _bits=isaac64_next_uint64(_ctx);
+ }
+ nbits_needed=FLT_MANT_DIG-ILOGNZ_64(_bits);
+#if FLT_MANT_DIG>64
+ ret=ldexpf((float)_bits,_base);
+# if FLT_MANT_DIG>129
+ while(64-nbits_needed<0){
+# else
+ if(64-nbits_needed<0){
+# endif
+ _base-=64;
+ nbits_needed-=64;
+ ret+=ldexpf((float)isaac64_next_uint64(_ctx),_base);
+ }
+ _bits=isaac64_next_uint64(_ctx)>>64-nbits_needed;
+ ret+=ldexpf((float)_bits,_base-nbits_needed);
+#else
+ if(nbits_needed>0){
+ _bits=_bits<<nbits_needed|isaac64_next_uint64(_ctx)>>64-nbits_needed;
+ }
+# if FLT_MANT_DIG<64
+ else _bits>>=-nbits_needed;
+# endif
+ ret=ldexpf((float)_bits,_base-nbits_needed);
+#endif
+ return ret;
+}
+
+float isaac64_next_float(isaac64_ctx *_ctx){
+ return isaac64_float_bits(_ctx,0,0);
+}
+
+float isaac64_next_signed_float(isaac64_ctx *_ctx){
+ uint64_t bits;
+ bits=isaac64_next_uint64(_ctx);
+ return (1|-((int)bits&1))*isaac64_float_bits(_ctx,bits>>1,-63);
+}
+
+/*Returns a uniform random double.
+ _bits: An initial set of random bits.
+ _base: This should be -(the number of bits in _bits), up to -64.
+ Return: A double uniformly distributed between 0 (inclusive) and 1
+ (exclusive).
+ The average value was measured over 2**32 samples to be
+ 0.499990992392019273.*/
+static double isaac64_double_bits(isaac64_ctx *_ctx,uint64_t _bits,int _base){
+ double ret;
+ int nbits_needed;
+ while(!_bits){
+ if(_base+DBL_MANT_DIG<DBL_MIN_EXP)return 0;
+ _base-=64;
+ _bits=isaac64_next_uint64(_ctx);
+ }
+ nbits_needed=DBL_MANT_DIG-ILOGNZ_64(_bits);
+#if DBL_MANT_DIG>64
+ ret=ldexp((double)_bits,_base);
+# if DBL_MANT_DIG>129
+ while(64-nbits_needed<0){
+# else
+ if(64-nbits_needed<0){
+# endif
+ _base-=64;
+ nbits_needed-=64;
+ ret+=ldexp((double)isaac64_next_uint64(_ctx),_base);
+ }
+ _bits=isaac64_next_uint64(_ctx)>>64-nbits_needed;
+ ret+=ldexp((double)_bits,_base-nbits_needed);
+#else
+ if(nbits_needed>0){
+ _bits=_bits<<nbits_needed|isaac64_next_uint64(_ctx)>>64-nbits_needed;
+ }
+# if DBL_MANT_DIG<64
+ else _bits>>=-nbits_needed;
+# endif
+ ret=ldexp((double)_bits,_base-nbits_needed);
+#endif
+ return ret;
+}
+
+double isaac64_next_double(isaac64_ctx *_ctx){
+ return isaac64_double_bits(_ctx,0,0);
+}
+
+double isaac64_next_signed_double(isaac64_ctx *_ctx){
+ uint64_t bits;
+ bits=isaac64_next_uint64(_ctx);
+ return (1|-((int)bits&1))*isaac64_double_bits(_ctx,bits>>1,-63);
+}
projects / ccan / blobdiff