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-rw-r--r--lib/rand.h10
1 files changed, 6 insertions, 4 deletions
diff --git a/lib/rand.h b/lib/rand.h
index 2ccc1b37..46c1c5e0 100644
--- a/lib/rand.h
+++ b/lib/rand.h
@@ -6,7 +6,9 @@
#include "types.h"
#define FRAND32_MAX (-1U)
+#define FRAND32_MAX_PLUS_ONE (1.0 * (1ULL << 32))
#define FRAND64_MAX (-1ULL)
+#define FRAND64_MAX_PLUS_ONE (1.0 * (1ULL << 32) * (1ULL << 32))
struct taus88_state {
unsigned int s1, s2, s3;
@@ -106,11 +108,11 @@ static inline double __rand_0_1(struct frand_state *state)
if (state->use64) {
uint64_t val = __rand64(&state->state64);
- return (val + 1.0) / (FRAND64_MAX + 1.0);
+ return (val + 1.0) / FRAND64_MAX_PLUS_ONE;
} else {
uint32_t val = __rand32(&state->state32);
- return (val + 1.0) / (FRAND32_MAX + 1.0);
+ return (val + 1.0) / FRAND32_MAX_PLUS_ONE;
}
}
@@ -122,7 +124,7 @@ static inline uint32_t rand32_upto(struct frand_state *state, uint32_t end)
r = __rand32(&state->state32);
end++;
- return (int) ((double)end * (r / (FRAND32_MAX + 1.0)));
+ return (int) ((double)end * (r / FRAND32_MAX_PLUS_ONE));
}
static inline uint64_t rand64_upto(struct frand_state *state, uint64_t end)
@@ -133,7 +135,7 @@ static inline uint64_t rand64_upto(struct frand_state *state, uint64_t end)
r = __rand64(&state->state64);
end++;
- return (uint64_t) ((double)end * (r / (FRAND64_MAX + 1.0)));
+ return (uint64_t) ((double)end * (r / FRAND64_MAX_PLUS_ONE));
}
/*