Commit | Line | Data |
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79c94bd3 JA |
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> |
d1af2894 | 37 | #include <assert.h> |
1fbbf72e | 38 | #include "rand.h" |
637ef8d9 | 39 | #include "../hash.h" |
1fbbf72e | 40 | |
1fbbf72e JA |
41 | static inline int __seed(unsigned int x, unsigned int m) |
42 | { | |
43 | return (x < m) ? x + m : x; | |
44 | } | |
45 | ||
2615cc4b JA |
46 | static void __init_rand(struct frand_state *state, unsigned int seed) |
47 | { | |
48 | int cranks = 6; | |
49 | ||
50 | #define LCG(x, seed) ((x) * 69069 ^ (seed)) | |
51 | ||
52 | state->s1 = __seed(LCG((2^31) + (2^17) + (2^7), seed), 1); | |
53 | state->s2 = __seed(LCG(state->s1, seed), 7); | |
54 | state->s3 = __seed(LCG(state->s2, seed), 15); | |
55 | ||
56 | while (cranks--) | |
57 | __rand(state); | |
58 | } | |
59 | ||
1fbbf72e JA |
60 | void init_rand(struct frand_state *state) |
61 | { | |
2615cc4b JA |
62 | __init_rand(state, 1); |
63 | } | |
64 | ||
65 | void init_rand_seed(struct frand_state *state, unsigned int seed) | |
66 | { | |
67 | __init_rand(state, seed); | |
1fbbf72e | 68 | } |
637ef8d9 | 69 | |
7d9fb455 | 70 | void __fill_random_buf(void *buf, unsigned int len, unsigned long seed) |
637ef8d9 | 71 | { |
6780906f | 72 | void *ptr = buf; |
637ef8d9 | 73 | |
6780906f | 74 | while (len) { |
74a92cdd JA |
75 | int this_len; |
76 | ||
6780906f JA |
77 | if (len >= sizeof(int64_t)) { |
78 | *((int64_t *) ptr) = seed; | |
74a92cdd | 79 | this_len = sizeof(int64_t); |
6780906f JA |
80 | } else if (len >= sizeof(int32_t)) { |
81 | *((int32_t *) ptr) = seed; | |
74a92cdd | 82 | this_len = sizeof(int32_t); |
6780906f JA |
83 | } else if (len >= sizeof(int16_t)) { |
84 | *((int16_t *) ptr) = seed; | |
74a92cdd | 85 | this_len = sizeof(int16_t); |
6780906f JA |
86 | } else { |
87 | *((int8_t *) ptr) = seed; | |
74a92cdd | 88 | this_len = sizeof(int8_t); |
6780906f | 89 | } |
74a92cdd JA |
90 | ptr += this_len; |
91 | len -= this_len; | |
7d9fb455 JA |
92 | seed *= GOLDEN_RATIO_PRIME; |
93 | seed >>= 3; | |
637ef8d9 JA |
94 | } |
95 | } | |
7d9fb455 | 96 | |
3545a109 JA |
97 | unsigned long fill_random_buf(struct frand_state *fs, void *buf, |
98 | unsigned int len) | |
7d9fb455 | 99 | { |
3545a109 | 100 | unsigned long r = __rand(fs); |
7d9fb455 JA |
101 | |
102 | if (sizeof(int) != sizeof(long *)) | |
3545a109 | 103 | r *= (unsigned long) __rand(fs); |
7d9fb455 JA |
104 | |
105 | __fill_random_buf(buf, len, r); | |
106 | return r; | |
107 | } | |
9c42684e | 108 | |
d1af2894 JA |
109 | void fill_pattern(void *p, unsigned int len, char *pattern, |
110 | unsigned int pattern_bytes) | |
111 | { | |
112 | switch (pattern_bytes) { | |
113 | case 0: | |
114 | assert(0); | |
115 | break; | |
116 | case 1: | |
117 | memset(p, pattern[0], len); | |
118 | break; | |
119 | default: { | |
120 | unsigned int i = 0, size = 0; | |
121 | unsigned char *b = p; | |
122 | ||
123 | while (i < len) { | |
124 | size = pattern_bytes; | |
125 | if (size > (len - i)) | |
126 | size = len - i; | |
127 | memcpy(b+i, pattern, size); | |
128 | i += size; | |
129 | } | |
130 | break; | |
131 | } | |
132 | } | |
133 | } | |
134 | ||
bc769898 JA |
135 | void __fill_random_buf_percentage(unsigned long seed, void *buf, |
136 | unsigned int percentage, | |
137 | unsigned int segment, unsigned int len, | |
138 | char *pattern, unsigned int pbytes) | |
9c42684e | 139 | { |
811ac503 | 140 | unsigned int this_len; |
9c42684e | 141 | |
811ac503 | 142 | if (percentage == 100) { |
d1af2894 JA |
143 | if (pbytes) |
144 | fill_pattern(buf, len, pattern, pbytes); | |
145 | else | |
146 | memset(buf, 0, len); | |
bc769898 | 147 | return; |
811ac503 JA |
148 | } |
149 | ||
150 | if (segment > len) | |
151 | segment = len; | |
9c42684e | 152 | |
9c42684e JA |
153 | while (len) { |
154 | /* | |
155 | * Fill random chunk | |
156 | */ | |
157 | this_len = (segment * (100 - percentage)) / 100; | |
158 | if (this_len > len) | |
159 | this_len = len; | |
160 | ||
bc769898 | 161 | __fill_random_buf(buf, this_len, seed); |
9c42684e JA |
162 | |
163 | len -= this_len; | |
6780906f JA |
164 | if (!len) |
165 | break; | |
9c42684e JA |
166 | buf += this_len; |
167 | ||
811ac503 JA |
168 | if (this_len > len) |
169 | this_len = len; | |
6780906f JA |
170 | else if (len - this_len <= sizeof(long)) |
171 | this_len = len; | |
9c42684e | 172 | |
d1af2894 JA |
173 | if (pbytes) |
174 | fill_pattern(buf, this_len, pattern, pbytes); | |
175 | else | |
176 | memset(buf, 0, this_len); | |
bc769898 | 177 | |
98836539 JA |
178 | len -= this_len; |
179 | buf += this_len; | |
9c42684e | 180 | } |
bc769898 JA |
181 | } |
182 | ||
183 | unsigned long fill_random_buf_percentage(struct frand_state *fs, void *buf, | |
184 | unsigned int percentage, | |
185 | unsigned int segment, unsigned int len, | |
186 | char *pattern, unsigned int pbytes) | |
187 | { | |
188 | unsigned long r = __rand(fs); | |
189 | ||
190 | if (sizeof(int) != sizeof(long *)) | |
191 | r *= (unsigned long) __rand(fs); | |
9c42684e | 192 | |
bc769898 JA |
193 | __fill_random_buf_percentage(r, buf, percentage, segment, len, |
194 | pattern, pbytes); | |
9c42684e JA |
195 | return r; |
196 | } |