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Diffstat (limited to 'src/base/random_mt.cc')
| -rw-r--r-- | src/base/random_mt.cc | 149 |
1 files changed, 149 insertions, 0 deletions
diff --git a/src/base/random_mt.cc b/src/base/random_mt.cc new file mode 100644 index 000000000..1492240ee --- /dev/null +++ b/src/base/random_mt.cc @@ -0,0 +1,149 @@ +/* + * A C-program for MT19937, with initialization improved 2002/1/26. + * Coded by Takuji Nishimura and Makoto Matsumoto. + * + * Before using, initialize the state by using init_genrand(seed) + * or init_by_array(init_key, key_length). + * + * Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura, + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * + * 2. Redistributions in binary form must reproduce the above + * copyright notice, this list of conditions and the following + * disclaimer in the documentation and/or other materials provided + * with the distribution. + * + * 3. The names of its contributors may not be used to endorse or + * promote products derived from this software without specific + * prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR + * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, + * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED + * OF THE POSSIBILITY OF SUCH DAMAGE. + * + * + * Any feedback is very welcome. + * http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html + * email: m-mat @ math.sci.hiroshima-u.ac.jp (remove space) + */ + +#include "base/random.hh" + +/* initializes mt[N] with a seed */ +void +Random::init(uint32_t s) +{ + mti = N + 1; + mt[0] = s & (uint32_t)0xffffffff; + + for (mti = 1; mti < N; mti++) { + mt[mti] = 1812433253UL * (mt[mti-1] ^ (mt[mti-1] >> 30)) + mti; + /* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */ + /* In the previous versions, MSBs of the seed affect */ + /* only MSBs of the array mt[]. */ + /* 2002/01/09 modified by Makoto Matsumoto */ + mt[mti] &= (uint32_t)0xffffffff; + /* for >32 bit machines */ + } +} + +/* initialize by an array with array-length */ +/* init_key is the array for initializing keys */ +/* key_length is its length */ +/* slight change for C++, 2004/2/26 */ +void +Random::init(uint32_t init_key[], int key_length) +{ + int i = 1; + int j = 0; + int k = (N > key_length) ? N : key_length; + + init(19650218); + + for (; k; k--) { + mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * (uint32_t)1664525)) + + init_key[j] + j; /* non linear */ + + mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */ + + i++; + j++; + + if (i >= N) { + mt[0] = mt[N - 1]; + i = 1; + } + + if (j >= key_length) + j = 0; + } + + for (k = N - 1; k; k--) { + /* non linear */ + mt[i] = (mt[i] ^ ((mt[i - 1] ^ (mt[i - 1] >> 30)) * 1566083941UL)) - i; + + /* for WORDSIZE > 32 machines */ + mt[i] &= (uint32_t)0xffffffff; + i++; + + if (i >= N) { + mt[0] = mt[N - 1]; + i = 1; + } + } + + /* MSB is 1; assuring non-zero initial array */ + mt[0] = (uint32_t)0x80000000; +} + +/* generates a random number on [0,0xffffffff]-interval */ +uint32_t +Random::genrand() +{ + uint32_t y; + static uint32_t mag01[2] = { 0, MATRIX_A}; + + if (mti >= N) { /* generate N words at one time */ + int kk; + + for (kk = 0; kk < N - M; kk++) { + y = mt[kk] & UPPER_MASK | mt[kk+1] & LOWER_MASK; + mt[kk] = mt[kk + M] ^ (y >> 1) ^ mag01[y & 0x1UL]; + } + for (; kk < N - 1; kk++) { + y = mt[kk] & UPPER_MASK | mt[kk+1] & LOWER_MASK; + mt[kk] = mt[kk + (M - N)] ^ (y >> 1) ^ mag01[y & 0x1UL]; + } + + y = mt[N - 1] & UPPER_MASK | mt[0] & LOWER_MASK; + mt[N - 1] = mt[M - 1] ^ (y >> 1) ^ mag01[y & 0x1UL]; + + mti = 0; + } + + y = mt[mti++]; + + /* Tempering */ + y ^= (y >> 11); + y ^= (y << 7) & (uint32_t)0x9d2c5680; + y ^= (y << 15) & (uint32_t)0xefc60000; + y ^= (y >> 18); + + return y; +} |