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
__seed(uint64_t x,uint64_t m)44 static inline uint64_t __seed(uint64_t x, uint64_t m)
45 {
46 return (x < m) ? x + m : x;
47 }
48
__init_rand32(struct taus88_state * state,unsigned int seed)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
__init_rand64(struct taus258_state * state,uint64_t seed)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
init_rand(struct frand_state * state,bool use64)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
init_rand_seed(struct frand_state * state,unsigned int seed,bool use64)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
__fill_random_buf(void * buf,unsigned int len,unsigned long seed)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
fill_random_buf(struct frand_state * fs,void * buf,unsigned int len)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
__fill_random_buf_percentage(unsigned long seed,void * buf,unsigned int percentage,unsigned int segment,unsigned int len,char * pattern,unsigned int pbytes)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
fill_random_buf_percentage(struct frand_state * fs,void * buf,unsigned int percentage,unsigned int segment,unsigned int len,char * pattern,unsigned int pbytes)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