rand: add rand64_between()
authorJens Axboe <axboe@kernel.dk>
Tue, 12 Jun 2018 14:10:47 +0000 (08:10 -0600)
committerJens Axboe <axboe@kernel.dk>
Tue, 12 Jun 2018 14:48:55 +0000 (08:48 -0600)
For some reason we only had the 32-bit variant, and there's
a use case for the 64-bit version. Add that, and add a
32/64 agnostic helper that can be called.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
lib/rand.h

index 8832c73..6be5307 100644 (file)
@@ -127,6 +127,24 @@ static inline int rand32_between(struct frand_state *state, int start, int end)
        return start + (int) ((double)end * (r / (FRAND32_MAX + 1.0)));
 }
 
+static inline uint64_t rand64_between(struct frand_state *state, uint64_t start,
+                                     uint64_t end)
+{
+       uint64_t r;
+
+       r = __rand64(&state->state64);
+       return start + (uint64_t) ((double)end * (r / (FRAND64_MAX + 1.0)));
+}
+
+static inline uint64_t rand_between(struct frand_state *state, uint64_t start,
+                                   uint64_t end)
+{
+       if (state->use64)
+               return rand32_between(state, start, end);
+       else
+               return rand64_between(state, start, end);
+}
+
 extern void init_rand(struct frand_state *, bool);
 extern void init_rand_seed(struct frand_state *, unsigned int seed, bool);
 extern void __fill_random_buf(void *buf, unsigned int len, unsigned long seed);