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 36 #include <string.h> 37 #include <assert.h> 38 #include "rand.h" 39 #include "pattern.h" 40 #include "../hash.h" 41 42 int arch_random; 43 44 static inline uint64_t __seed(uint64_t x, uint64_t m) 45 { 46 return (x < m) ? x + m : x; 47 } 48 49 static void __init_rand32(struct taus88_state *state, unsigned int seed) 50 { 51 int cranks = 6; 52 53 #define LCG(x, seed) ((x) * 69069 ^ (seed)) 54 55 state->s1 = __seed(LCG((2^31) + (2^17) + (2^7), seed), 1); 56 state->s2 = __seed(LCG(state->s1, seed), 7); 57 state->s3 = __seed(LCG(state->s2, seed), 15); 58 59 while (cranks--) 60 __rand32(state); 61 } 62 63 static void __init_rand64(struct taus258_state *state, uint64_t seed) 64 { 65 int cranks = 6; 66 67 #define LCG64(x, seed) ((x) * 6906969069ULL ^ (seed)) 68 69 state->s1 = __seed(LCG64((2^31) + (2^17) + (2^7), seed), 1); 70 state->s2 = __seed(LCG64(state->s1, seed), 7); 71 state->s3 = __seed(LCG64(state->s2, seed), 15); 72 state->s4 = __seed(LCG64(state->s3, seed), 33); 73 state->s5 = __seed(LCG64(state->s4, seed), 49); 74 75 while (cranks--) 76 __rand64(state); 77 } 78 79 void init_rand(struct frand_state *state, bool use64) 80 { 81 state->use64 = use64; 82 83 if (!use64) 84 __init_rand32(&state->state32, 1); 85 else 86 __init_rand64(&state->state64, 1); 87 } 88 89 void init_rand_seed(struct frand_state *state, unsigned int seed, bool use64) 90 { 91 state->use64 = use64; 92 93 if (!use64) 94 __init_rand32(&state->state32, seed); 95 else 96 __init_rand64(&state->state64, seed); 97 } 98 99 void __fill_random_buf(void *buf, unsigned int len, unsigned long seed) 100 { 101 void *ptr = buf; 102 103 while (len) { 104 int this_len; 105 106 if (len >= sizeof(int64_t)) { 107 *((int64_t *) ptr) = seed; 108 this_len = sizeof(int64_t); 109 } else if (len >= sizeof(int32_t)) { 110 *((int32_t *) ptr) = seed; 111 this_len = sizeof(int32_t); 112 } else if (len >= sizeof(int16_t)) { 113 *((int16_t *) ptr) = seed; 114 this_len = sizeof(int16_t); 115 } else { 116 *((int8_t *) ptr) = seed; 117 this_len = sizeof(int8_t); 118 } 119 ptr += this_len; 120 len -= this_len; 121 seed *= GOLDEN_RATIO_PRIME; 122 seed >>= 3; 123 } 124 } 125 126 unsigned long fill_random_buf(struct frand_state *fs, void *buf, 127 unsigned int len) 128 { 129 unsigned long r = __rand(fs); 130 131 if (sizeof(int) != sizeof(long *)) 132 r *= (unsigned long) __rand(fs); 133 134 __fill_random_buf(buf, len, r); 135 return r; 136 } 137 138 void __fill_random_buf_percentage(unsigned long seed, void *buf, 139 unsigned int percentage, 140 unsigned int segment, unsigned int len, 141 char *pattern, unsigned int pbytes) 142 { 143 unsigned int this_len; 144 145 if (percentage == 100) { 146 if (pbytes) 147 (void)cpy_pattern(pattern, pbytes, buf, len); 148 else 149 memset(buf, 0, len); 150 return; 151 } 152 153 if (segment > len) 154 segment = len; 155 156 while (len) { 157 /* 158 * Fill random chunk 159 */ 160 this_len = (segment * (100 - percentage)) / 100; 161 if (this_len > len) 162 this_len = len; 163 164 __fill_random_buf(buf, this_len, seed); 165 166 len -= this_len; 167 if (!len) 168 break; 169 buf += this_len; 170 171 if (this_len > len) 172 this_len = len; 173 else if (len - this_len <= sizeof(long)) 174 this_len = len; 175 176 if (pbytes) 177 (void)cpy_pattern(pattern, pbytes, buf, this_len); 178 else 179 memset(buf, 0, this_len); 180 181 len -= this_len; 182 buf += this_len; 183 } 184 } 185 186 unsigned long 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) 190 { 191 unsigned long r = __rand(fs); 192 193 if (sizeof(int) != sizeof(long *)) 194 r *= (unsigned long) __rand(fs); 195 196 __fill_random_buf_percentage(r, buf, percentage, segment, len, 197 pattern, pbytes); 198 return r; 199 } 200
