diff options
Diffstat (limited to 'gl/lib/rand-isaac.c')
| -rw-r--r-- | gl/lib/rand-isaac.c | 24 |
1 files changed, 17 insertions, 7 deletions
diff --git a/gl/lib/rand-isaac.c b/gl/lib/rand-isaac.c index defd21778..04af2e782 100644 --- a/gl/lib/rand-isaac.c +++ b/gl/lib/rand-isaac.c @@ -58,16 +58,26 @@ just (isaac_word a) return a & desired_bits; } -/* The index operation. On typical machines whose words are exactly - the right size, this is optimized to a mask, an addition, and an - indirect load. Atypical machines need more work. */ +/* The index operation. */ static inline isaac_word ind (isaac_word const *m, isaac_word x) { - return (sizeof *m * CHAR_BIT == ISAAC_BITS - ? (* (isaac_word *) ((char *) m - + (x & ((ISAAC_WORDS - 1) * sizeof *m)))) - : m[(x / (ISAAC_BITS / CHAR_BIT)) & (ISAAC_WORDS - 1)]); + if (sizeof *m * CHAR_BIT == ISAAC_BITS) + { + /* The typical case, where words are exactly the right size. + Optimize this to a mask, an addition, and an indirect + load. */ + void const *void_m = m; + char const *base_p = void_m; + void const *word_p = base_p + (x & ((ISAAC_WORDS - 1) * sizeof *m)); + isaac_word const *p = word_p; + return *p; + } + else + { + /* Atypical machines need more work. */ + return m[(x / (ISAAC_BITS / CHAR_BIT)) & (ISAAC_WORDS - 1)]; + } } /* Use and update *S to generate random data to fill RESULT. */ |