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 66d04729a49eaa073f822d77a93b66ae426f659d..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;
        }
@@ -91,17 +134,49 @@ unsigned long fill_random_buf(struct frand_state *fs, void *buf,
        return r;
 }
 
-unsigned long fill_random_buf_percentage(struct frand_state *fs, void *buf,
-                                        unsigned int percentage,
-                                        unsigned int segment, unsigned int len)
+void fill_pattern(void *p, unsigned int len, char *pattern,
+                 unsigned int pattern_bytes)
 {
-       unsigned int this_len, rep_len;
-       unsigned long r = __rand(fs);
+       switch (pattern_bytes) {
+       case 0:
+               assert(0);
+               break;
+       case 1:
+               memset(p, pattern[0], len);
+               break;
+       default: {
+               unsigned int i = 0, size = 0;
+               unsigned char *b = p;
+
+               while (i < len) {
+                       size = pattern_bytes;
+                       if (size > (len - i))
+                               size = len - i;
+                       memcpy(b+i, pattern, size);
+                       i += size;
+               }
+               break;
+               }
+       }
+}
 
-       assert(segment <= len);
+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 int this_len;
+
+       if (percentage == 100) {
+               if (pbytes)
+                       fill_pattern(buf, len, pattern, pbytes);
+               else
+                       memset(buf, 0, len);
+               return;
+       }
 
-       if (sizeof(int) != sizeof(long *))
-               r *= (unsigned long) __rand(fs);
+       if (segment > len)
+               segment = len;
 
        while (len) {
                /*
@@ -111,22 +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;
 
-               /*
-                * Now duplicate random chunk in rest of buf
-                */
-               rep_len = segment - this_len;
-               if (rep_len > len)
-                       rep_len = 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);
 
-               memcpy(buf, buf + rep_len, rep_len);
-               buf += rep_len;
-               len -= rep_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;
 }