| /* |
| This is a maximally equidistributed combined Tausworthe generator |
| based on code from GNU Scientific Library 1.5 (30 Jun 2004) |
| |
| x_n = (s1_n ^ s2_n ^ s3_n) |
| |
| s1_{n+1} = (((s1_n & 4294967294) <<12) ^ (((s1_n <<13) ^ s1_n) >>19)) |
| s2_{n+1} = (((s2_n & 4294967288) << 4) ^ (((s2_n << 2) ^ s2_n) >>25)) |
| s3_{n+1} = (((s3_n & 4294967280) <<17) ^ (((s3_n << 3) ^ s3_n) >>11)) |
| |
| The period of this generator is about 2^88. |
| |
| From: P. L'Ecuyer, "Maximally Equidistributed Combined Tausworthe |
| Generators", Mathematics of Computation, 65, 213 (1996), 203--213. |
| |
| This is available on the net from L'Ecuyer's home page, |
| |
| http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme.ps |
| ftp://ftp.iro.umontreal.ca/pub/simulation/lecuyer/papers/tausme.ps |
| |
| There is an erratum in the paper "Tables of Maximally |
| Equidistributed Combined LFSR Generators", Mathematics of |
| Computation, 68, 225 (1999), 261--269: |
| http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme2.ps |
| |
| ... the k_j most significant bits of z_j must be non- |
| zero, for each j. (Note: this restriction also applies to the |
| computer code given in [4], but was mistakenly not mentioned in |
| that paper.) |
| |
| This affects the seeding procedure by imposing the requirement |
| s1 > 1, s2 > 7, s3 > 15. |
| |
| */ |
| |
| #include <string.h> |
| #include <assert.h> |
| #include "rand.h" |
| #include "../hash.h" |
| |
| static inline int __seed(unsigned int x, unsigned int m) |
| { |
| return (x < m) ? x + m : x; |
| } |
| |
| static void __init_rand(struct frand_state *state, unsigned int seed) |
| { |
| int cranks = 6; |
| |
| #define LCG(x, seed) ((x) * 69069 ^ (seed)) |
| |
| state->s1 = __seed(LCG((2^31) + (2^17) + (2^7), seed), 1); |
| state->s2 = __seed(LCG(state->s1, seed), 7); |
| state->s3 = __seed(LCG(state->s2, seed), 15); |
| |
| while (cranks--) |
| __rand(state); |
| } |
| |
| void init_rand(struct frand_state *state) |
| { |
| __init_rand(state, 1); |
| } |
| |
| void init_rand_seed(struct frand_state *state, unsigned int seed) |
| { |
| __init_rand(state, seed); |
| } |
| |
| void __fill_random_buf(void *buf, unsigned int len, unsigned long seed) |
| { |
| void *ptr = buf; |
| |
| 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; |
| } |
| } |
| |
| unsigned long fill_random_buf(struct frand_state *fs, void *buf, |
| unsigned int len) |
| { |
| unsigned long r = __rand(fs); |
| |
| if (sizeof(int) != sizeof(long *)) |
| r *= (unsigned long) __rand(fs); |
| |
| __fill_random_buf(buf, len, r); |
| return r; |
| } |
| |
| void fill_pattern(void *p, unsigned int len, char *pattern, |
| unsigned int pattern_bytes) |
| { |
| 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; |
| } |
| } |
| } |
| |
| 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 (segment > len) |
| segment = len; |
| |
| while (len) { |
| /* |
| * Fill random chunk |
| */ |
| this_len = (segment * (100 - percentage)) / 100; |
| if (this_len > len) |
| this_len = len; |
| |
| __fill_random_buf(buf, this_len, seed); |
| |
| len -= this_len; |
| if (!len) |
| break; |
| buf += this_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); |
| |
| 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; |
| } |