Merge branch 'dedupe_bugfix' of https://github.com/bardavid/fio
[fio.git] / lib / rand.c
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1/*
2 This is a maximally equidistributed combined Tausworthe generator
3 based on code from GNU Scientific Library 1.5 (30 Jun 2004)
4
5 x_n = (s1_n ^ s2_n ^ s3_n)
6
7 s1_{n+1} = (((s1_n & 4294967294) <<12) ^ (((s1_n <<13) ^ s1_n) >>19))
8 s2_{n+1} = (((s2_n & 4294967288) << 4) ^ (((s2_n << 2) ^ s2_n) >>25))
9 s3_{n+1} = (((s3_n & 4294967280) <<17) ^ (((s3_n << 3) ^ s3_n) >>11))
10
11 The period of this generator is about 2^88.
12
13 From: P. L'Ecuyer, "Maximally Equidistributed Combined Tausworthe
14 Generators", Mathematics of Computation, 65, 213 (1996), 203--213.
15
16 This is available on the net from L'Ecuyer's home page,
17
18 http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme.ps
19 ftp://ftp.iro.umontreal.ca/pub/simulation/lecuyer/papers/tausme.ps
20
21 There is an erratum in the paper "Tables of Maximally
22 Equidistributed Combined LFSR Generators", Mathematics of
23 Computation, 68, 225 (1999), 261--269:
24 http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme2.ps
25
26 ... the k_j most significant bits of z_j must be non-
27 zero, for each j. (Note: this restriction also applies to the
28 computer code given in [4], but was mistakenly not mentioned in
29 that paper.)
30
31 This affects the seeding procedure by imposing the requirement
32 s1 > 1, s2 > 7, s3 > 15.
33
34*/
35
9c42684e 36#include <string.h>
1fbbf72e 37#include "rand.h"
ad8b6a2f 38#include "pattern.h"
637ef8d9 39#include "../hash.h"
1fbbf72e 40
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41int arch_random;
42
c3546b53 43static inline uint64_t __seed(uint64_t x, uint64_t m)
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44{
45 return (x < m) ? x + m : x;
46}
47
5f2f3569 48static void __init_rand32(struct taus88_state *state, unsigned int seed)
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49{
50 int cranks = 6;
51
52#define LCG(x, seed) ((x) * 69069 ^ (seed))
53
54 state->s1 = __seed(LCG((2^31) + (2^17) + (2^7), seed), 1);
55 state->s2 = __seed(LCG(state->s1, seed), 7);
56 state->s3 = __seed(LCG(state->s2, seed), 15);
57
58 while (cranks--)
c3546b53 59 __rand32(state);
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60}
61
5f2f3569 62static void __init_rand64(struct taus258_state *state, uint64_t seed)
1fbbf72e 63{
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64 int cranks = 6;
65
66#define LCG64(x, seed) ((x) * 6906969069ULL ^ (seed))
67
68 state->s1 = __seed(LCG64((2^31) + (2^17) + (2^7), seed), 1);
69 state->s2 = __seed(LCG64(state->s1, seed), 7);
70 state->s3 = __seed(LCG64(state->s2, seed), 15);
71 state->s4 = __seed(LCG64(state->s3, seed), 33);
72 state->s5 = __seed(LCG64(state->s4, seed), 49);
73
74 while (cranks--)
75 __rand64(state);
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76}
77
de4096e8 78void init_rand(struct frand_state *state, bool use64)
2615cc4b 79{
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80 state->use64 = use64;
81
82 if (!use64)
83 __init_rand32(&state->state32, 1);
84 else
85 __init_rand64(&state->state64, 1);
86}
87
eda99d55 88void init_rand_seed(struct frand_state *state, uint64_t seed, bool use64)
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89{
90 state->use64 = use64;
91
92 if (!use64)
eda99d55 93 __init_rand32(&state->state32, (unsigned int) seed);
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94 else
95 __init_rand64(&state->state64, seed);
1fbbf72e 96}
637ef8d9 97
9781c080 98void __fill_random_buf(void *buf, unsigned int len, uint64_t seed)
637ef8d9 99{
6780906f 100 void *ptr = buf;
637ef8d9 101
6780906f 102 while (len) {
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103 int this_len;
104
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105 if (len >= sizeof(int64_t)) {
106 *((int64_t *) ptr) = seed;
74a92cdd 107 this_len = sizeof(int64_t);
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108 } else if (len >= sizeof(int32_t)) {
109 *((int32_t *) ptr) = seed;
74a92cdd 110 this_len = sizeof(int32_t);
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111 } else if (len >= sizeof(int16_t)) {
112 *((int16_t *) ptr) = seed;
74a92cdd 113 this_len = sizeof(int16_t);
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114 } else {
115 *((int8_t *) ptr) = seed;
74a92cdd 116 this_len = sizeof(int8_t);
6780906f 117 }
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118 ptr += this_len;
119 len -= this_len;
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120 seed *= GOLDEN_RATIO_PRIME;
121 seed >>= 3;
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122 }
123}
7d9fb455 124
9781c080
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125uint64_t fill_random_buf(struct frand_state *fs, void *buf,
126 unsigned int len)
7d9fb455 127{
9781c080 128 uint64_t r = __rand(fs);
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129
130 if (sizeof(int) != sizeof(long *))
3545a109 131 r *= (unsigned long) __rand(fs);
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132
133 __fill_random_buf(buf, len, r);
134 return r;
135}
9c42684e 136
9781c080 137void __fill_random_buf_percentage(uint64_t seed, void *buf,
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138 unsigned int percentage,
139 unsigned int segment, unsigned int len,
140 char *pattern, unsigned int pbytes)
9c42684e 141{
811ac503 142 unsigned int this_len;
9c42684e 143
811ac503 144 if (percentage == 100) {
d1af2894 145 if (pbytes)
2cac8fcb 146 (void)cpy_pattern(pattern, pbytes, buf, len);
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147 else
148 memset(buf, 0, len);
bc769898 149 return;
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150 }
151
152 if (segment > len)
153 segment = len;
9c42684e 154
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155 while (len) {
156 /*
157 * Fill random chunk
158 */
2474b06d 159 this_len = ((unsigned long long)segment * (100 - percentage)) / 100;
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160 if (this_len > len)
161 this_len = len;
162
bc769898 163 __fill_random_buf(buf, this_len, seed);
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164
165 len -= this_len;
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166 if (!len)
167 break;
9c42684e 168 buf += this_len;
3363fa44 169 this_len = segment - this_len;
9c42684e 170
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171 if (this_len > len)
172 this_len = len;
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173 else if (len - this_len <= sizeof(long))
174 this_len = len;
9c42684e 175
d1af2894 176 if (pbytes)
2cac8fcb 177 (void)cpy_pattern(pattern, pbytes, buf, this_len);
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178 else
179 memset(buf, 0, this_len);
bc769898 180
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181 len -= this_len;
182 buf += this_len;
9c42684e 183 }
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184}
185
9781c080
MHT
186uint64_t fill_random_buf_percentage(struct frand_state *fs, void *buf,
187 unsigned int percentage,
188 unsigned int segment, unsigned int len,
189 char *pattern, unsigned int pbytes)
bc769898 190{
9781c080 191 uint64_t r = __rand(fs);
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192
193 if (sizeof(int) != sizeof(long *))
194 r *= (unsigned long) __rand(fs);
9c42684e 195
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196 __fill_random_buf_percentage(r, buf, percentage, segment, len,
197 pattern, pbytes);
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198 return r;
199}