rand: add 64-bit tausworthe variant with a 2^258 cycle

[fio.git] / lib / rand.c

diff --git a/lib/rand.c b/lib/rand.c
index e5332bfe792492651e7685c4cd35595ca981ddf0..2e4c66e144b5cc56a04ec8c4747e435368b68a3a 100644 (file)
--- a/lib/rand.c
+++ b/lib/rand.c
@@ -38,12 +38,14 @@
 #include "rand.h"
 #include "../hash.h"
 
-static inline int __seed(unsigned int x, unsigned int m)
+int arch_random;
+
+static inline uint64_t __seed(uint64_t x, uint64_t m)
 {
        return (x < m) ? x + m : x;
 }
 
-static void __init_rand(struct frand_state *state, unsigned int seed)
+static void __init_rand32(struct taus88_state *state, unsigned int seed)
 {
        int cranks = 6;
 
@@ -54,26 +56,67 @@ static void __init_rand(struct frand_state *state, unsigned int seed)
        state->s3 = __seed(LCG(state->s2, seed), 15);
 
        while (cranks--)
-               __rand(state);
+               __rand32(state);
+}
+
+static void __init_rand64(struct taus258_state *state, uint64_t seed)
+{
+       int cranks = 6;
+
+#define LCG64(x, seed)  ((x) * 6906969069ULL ^ (seed))
+
+       state->s1 = __seed(LCG64((2^31) + (2^17) + (2^7), seed), 1);
+       state->s2 = __seed(LCG64(state->s1, seed), 7);
+       state->s3 = __seed(LCG64(state->s2, seed), 15);
+       state->s4 = __seed(LCG64(state->s3, seed), 33);
+       state->s5 = __seed(LCG64(state->s4, seed), 49);
+
+       while (cranks--)
+               __rand64(state);
 }
 
-void init_rand(struct frand_state *state)
+void init_rand(struct frand_state *state, int use64)
 {
-       __init_rand(state, 1);
+       state->use64 = use64;
+
+       if (!use64)
+               __init_rand32(&state->state32, 1);
+       else
+               __init_rand64(&state->state64, 1);
 }
 
-void init_rand_seed(struct frand_state *state, unsigned int seed)
+void init_rand_seed(struct frand_state *state, unsigned int seed, int use64)
 {
-       __init_rand(state, seed);
+       state->use64 = use64;
+
+       if (!use64)
+               __init_rand32(&state->state32, seed);
+       else
+               __init_rand64(&state->state64, seed);
 }
 
 void __fill_random_buf(void *buf, unsigned int len, unsigned long seed)
 {
-       long *ptr = buf;
+       void *ptr = buf;
 
-       while ((void *) ptr - buf < len) {
-               *ptr = seed;
-               ptr++;
+       while (len) {
+               int this_len;
+
+               if (len >= sizeof(int64_t)) {
+                       *((int64_t *) ptr) = seed;
+                       this_len = sizeof(int64_t);
+               } else if (len >= sizeof(int32_t)) {
+                       *((int32_t *) ptr) = seed;
+                       this_len = sizeof(int32_t);
+               } else if (len >= sizeof(int16_t)) {
+                       *((int16_t *) ptr) = seed;
+                       this_len = sizeof(int16_t);
+               } else {
+                       *((int8_t *) ptr) = seed;
+                       this_len = sizeof(int8_t);
+               }
+               ptr += this_len;
+               len -= this_len;
                seed *= GOLDEN_RATIO_PRIME;
                seed >>= 3;
        }
@@ -117,12 +160,11 @@ void fill_pattern(void *p, unsigned int len, char *pattern,
        }
 }
 
-unsigned long fill_random_buf_percentage(struct frand_state *fs, void *buf,
-                                        unsigned int percentage,
-                                        unsigned int segment, unsigned int len,
-                                        char *pattern, unsigned int pbytes)
+void __fill_random_buf_percentage(unsigned long seed, void *buf,
+                                 unsigned int percentage,
+                                 unsigned int segment, unsigned int len,
+                                 char *pattern, unsigned int pbytes)
 {
-       unsigned long r = __rand(fs);
        unsigned int this_len;
 
        if (percentage == 100) {
@@ -130,15 +172,12 @@ unsigned long fill_random_buf_percentage(struct frand_state *fs, void *buf,
                        fill_pattern(buf, len, pattern, pbytes);
                else
                        memset(buf, 0, len);
-               return 0;
+               return;
        }
 
        if (segment > len)
                segment = len;
 
-       if (sizeof(int) != sizeof(long *))
-               r *= (unsigned long) __rand(fs);
-
        while (len) {
                /*
                 * Fill random chunk
@@ -147,21 +186,39 @@ unsigned long fill_random_buf_percentage(struct frand_state *fs, void *buf,
                if (this_len > len)
                        this_len = len;
 
-               __fill_random_buf(buf, this_len, r);
+               __fill_random_buf(buf, this_len, seed);
 
                len -= this_len;
+               if (!len)
+                       break;
                buf += this_len;
 
                if (this_len > len)
                        this_len = len;
+               else if (len - this_len <= sizeof(long))
+                       this_len = len;
 
                if (pbytes)
                        fill_pattern(buf, this_len, pattern, pbytes);
                else
                        memset(buf, 0, this_len);
+
                len -= this_len;
                buf += this_len;
        }
+}
+
+unsigned long fill_random_buf_percentage(struct frand_state *fs, void *buf,
+                                        unsigned int percentage,
+                                        unsigned int segment, unsigned int len,
+                                        char *pattern, unsigned int pbytes)
+{
+       unsigned long r = __rand(fs);
+
+       if (sizeof(int) != sizeof(long *))
+               r *= (unsigned long) __rand(fs);
 
+       __fill_random_buf_percentage(r, buf, percentage, segment, len,
+                                       pattern, pbytes);
        return r;
 }