-/*Written by Timothy B. Terriberry (tterribe@xiph.org) 1999-2009 public domain.
+/*Written by Timothy B. Terriberry (tterribe@xiph.org) 1999-2009.
+ CC0 (Public domain) - see LICENSE file for details
Based on the public domain implementation by Robert J. Jenkins Jr.*/
#include <float.h>
#include <math.h>
#include <string.h>
#include <ccan/ilog/ilog.h>
#include "isaac.h"
-#if defined(__GNUC_PREREQ)
-# if __GNUC_PREREQ(4,2)
-# pragma GCC diagnostic ignored "-Wparentheses"
-# endif
-#endif
-
#define ISAAC_MASK (0xFFFFFFFFU)
+/* Extract ISAAC_SZ_LOG bits (starting at bit 2). */
+static inline uint32_t lower_bits(uint32_t x)
+{
+ return (x & ((ISAAC_SZ-1) << 2)) >> 2;
+}
+/* Extract next ISAAC_SZ_LOG bits (starting at bit ISAAC_SZ_LOG+2). */
+static inline uint32_t upper_bits(uint32_t y)
+{
+ return (y >> (ISAAC_SZ_LOG+2)) & (ISAAC_SZ-1);
+}
static void isaac_update(isaac_ctx *_ctx){
uint32_t *m;
m=_ctx->m;
r=_ctx->r;
a=_ctx->a;
- b=_ctx->b+(++_ctx->c)&ISAAC_MASK;
+ b=_ctx->b+(++_ctx->c);
for(i=0;i<ISAAC_SZ/2;i++){
x=m[i];
- a=(a^a<<13)+m[i+ISAAC_SZ/2]&ISAAC_MASK;
- m[i]=y=m[(x&ISAAC_SZ-1<<2)>>2]+a+b&ISAAC_MASK;
- r[i]=b=m[y>>ISAAC_SZ_LOG+2&ISAAC_SZ-1]+x&ISAAC_MASK;
+ a=(a^a<<13)+m[i+ISAAC_SZ/2];
+ m[i]=y=m[lower_bits(x)]+a+b;
+ r[i]=b=m[upper_bits(y)]+x;
x=m[++i];
- a=(a^a>>6)+m[i+ISAAC_SZ/2]&ISAAC_MASK;
- m[i]=y=m[(x&ISAAC_SZ-1<<2)>>2]+a+b&ISAAC_MASK;
- r[i]=b=m[y>>ISAAC_SZ_LOG+2&ISAAC_SZ-1]+x&ISAAC_MASK;
+ a=(a^a>>6)+m[i+ISAAC_SZ/2];
+ m[i]=y=m[lower_bits(x)]+a+b;
+ r[i]=b=m[upper_bits(y)]+x;
x=m[++i];
- a=(a^a<<2)+m[i+ISAAC_SZ/2]&ISAAC_MASK;
- m[i]=y=m[(x&ISAAC_SZ-1<<2)>>2]+a+b&ISAAC_MASK;
- r[i]=b=m[y>>ISAAC_SZ_LOG+2&ISAAC_SZ-1]+x&ISAAC_MASK;
+ a=(a^a<<2)+m[i+ISAAC_SZ/2];
+ m[i]=y=m[lower_bits(x)]+a+b;
+ r[i]=b=m[upper_bits(y)]+x;
x=m[++i];
- a=(a^a>>16)+m[i+ISAAC_SZ/2]&ISAAC_MASK;
- m[i]=y=m[(x&ISAAC_SZ-1<<2)>>2]+a+b&ISAAC_MASK;
- r[i]=b=m[y>>ISAAC_SZ_LOG+2&ISAAC_SZ-1]+x&ISAAC_MASK;
+ a=(a^a>>16)+m[i+ISAAC_SZ/2];
+ m[i]=y=m[lower_bits(x)]+a+b;
+ r[i]=b=m[upper_bits(y)]+x;
}
for(i=ISAAC_SZ/2;i<ISAAC_SZ;i++){
x=m[i];
- a=(a^a<<13)+m[i-ISAAC_SZ/2]&ISAAC_MASK;
- m[i]=y=m[(x&ISAAC_SZ-1<<2)>>2]+a+b&ISAAC_MASK;
- r[i]=b=m[y>>ISAAC_SZ_LOG+2&ISAAC_SZ-1]+x&ISAAC_MASK;
+ a=(a^a<<13)+m[i-ISAAC_SZ/2];
+ m[i]=y=m[lower_bits(x)]+a+b;
+ r[i]=b=m[upper_bits(y)]+x;
x=m[++i];
- a=(a^a>>6)+m[i-ISAAC_SZ/2]&ISAAC_MASK;
- m[i]=y=m[(x&ISAAC_SZ-1<<2)>>2]+a+b&ISAAC_MASK;
- r[i]=b=m[y>>ISAAC_SZ_LOG+2&ISAAC_SZ-1]+x&ISAAC_MASK;
+ a=(a^a>>6)+m[i-ISAAC_SZ/2];
+ m[i]=y=m[lower_bits(x)]+a+b;
+ r[i]=b=m[upper_bits(y)]+x;
x=m[++i];
- a=(a^a<<2)+m[i-ISAAC_SZ/2]&ISAAC_MASK;
- m[i]=y=m[(x&ISAAC_SZ-1<<2)>>2]+a+b&ISAAC_MASK;
- r[i]=b=m[y>>ISAAC_SZ_LOG+2&ISAAC_SZ-1]+x&ISAAC_MASK;
+ a=(a^a<<2)+m[i-ISAAC_SZ/2];
+ m[i]=y=m[lower_bits(x)]+a+b;
+ r[i]=b=m[upper_bits(y)]+x;
x=m[++i];
- a=(a^a>>16)+m[i-ISAAC_SZ/2]&ISAAC_MASK;
- m[i]=y=m[(x&ISAAC_SZ-1<<2)>>2]+a+b&ISAAC_MASK;
- r[i]=b=m[y>>ISAAC_SZ_LOG+2&ISAAC_SZ-1]+x&ISAAC_MASK;
+ a=(a^a>>16)+m[i-ISAAC_SZ/2];
+ m[i]=y=m[lower_bits(x)]+a+b;
+ r[i]=b=m[upper_bits(y)]+x;
}
_ctx->b=b;
_ctx->a=a;
static const unsigned char SHIFT[8]={11,2,8,16,10,4,8,9};
int i;
for(i=0;i<8;i++){
- _x[i]^=_x[i+1&7]<<SHIFT[i];
- _x[i+3&7]+=_x[i];
- _x[i+1&7]+=_x[i+2&7];
+ _x[i]^=_x[(i+1)&7]<<SHIFT[i];
+ _x[(i+3)&7]+=_x[i];
+ _x[(i+1)&7]+=_x[(i+2)&7];
i++;
- _x[i]^=_x[i+1&7]>>SHIFT[i];
- _x[i+3&7]+=_x[i];
- _x[i+1&7]+=_x[i+2&7];
+ _x[i]^=_x[(i+1)&7]>>SHIFT[i];
+ _x[(i+3)&7]+=_x[i];
+ _x[(i+1)&7]+=_x[(i+2)&7];
}
}
v=r%_n;
d=r-v;
}
- while((d+_n-1&ISAAC_MASK)<d);
+ while(((d+_n-1)&ISAAC_MASK)<d);
return v;
}
FLT_MANT_DIG+1 consecutive one bits.
Even the fallback C implementation of ILOGNZ_32() yields an implementation
25% faster than the frexp() method.*/
- nbits_needed=FLT_MANT_DIG-ILOGNZ_32(_bits);
+ nbits_needed=FLT_MANT_DIG-ilog32_nz(_bits);
#if FLT_MANT_DIG>32
ret=ldexpf((float)_bits,_base);
# if FLT_MANT_DIG>65
ret+=ldexpf((float)_bits,_base-nbits_needed);
#else
if(nbits_needed>0){
- _bits=_bits<<nbits_needed|isaac_next_uint32(_ctx)>>32-nbits_needed;
+ _bits=_bits<<nbits_needed|isaac_next_uint32(_ctx)>>(32-nbits_needed);
}
# if FLT_MANT_DIG<32
else _bits>>=-nbits_needed;
_base-=32;
_bits=isaac_next_uint32(_ctx);
}
- nbits_needed=DBL_MANT_DIG-ILOGNZ_32(_bits);
+ nbits_needed=DBL_MANT_DIG-ilog32_nz(_bits);
#if DBL_MANT_DIG>32
ret=ldexp((double)_bits,_base);
# if DBL_MANT_DIG>65
nbits_needed-=32;
ret+=ldexp((double)isaac_next_uint32(_ctx),_base);
}
- _bits=isaac_next_uint32(_ctx)>>32-nbits_needed;
+ _bits=isaac_next_uint32(_ctx)>>(32-nbits_needed);
ret+=ldexp((double)_bits,_base-nbits_needed);
#else
if(nbits_needed>0){