First step at speeding up io_u rand refill
Makes it 3x faster here.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/lib/rand.h b/lib/rand.h
new file mode 100644
index 0000000..363e7b6
--- /dev/null
+++ b/lib/rand.h
@@ -0,0 +1,23 @@
+#ifndef FIO_RAND_H
+#define FIO_RAND_H
+
+struct frand_state {
+ unsigned int s1, s2, s3;
+};
+
+extern struct frand_state __fio_rand_state;
+
+static inline unsigned int __rand(struct frand_state *state)
+{
+#define TAUSWORTHE(s,a,b,c,d) ((s&c)<<d) ^ (((s <<a) ^ s)>>b)
+
+ state->s1 = TAUSWORTHE(state->s1, 13, 19, 4294967294UL, 12);
+ state->s2 = TAUSWORTHE(state->s2, 2, 25, 4294967288UL, 4);
+ state->s3 = TAUSWORTHE(state->s3, 3, 11, 4294967280UL, 17);
+
+ return (state->s1 ^ state->s2 ^ state->s3);
+}
+
+extern void init_rand(struct frand_state *);
+
+#endif