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Diffstat (limited to 'src/rng_mt.c')
| -rw-r--r-- | src/rng_mt.c | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/src/rng_mt.c b/src/rng_mt.c new file mode 100644 index 0000000..dacc11f --- /dev/null +++ b/src/rng_mt.c @@ -0,0 +1,167 @@ +/* + 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) + + $Id$ +*/ + +#include "stdinc.h" +#include "rng_mt.h" + +/* Period parameters */ +#define N 624 +#define M 397 +#define MATRIX_A 0x9908b0dfU /* constant vector a */ +#define UPPER_MASK 0x80000000U /* most significant w-r bits */ +#define LOWER_MASK 0x7fffffffU /* least significant r bits */ + +static uint32_t mt[N]; /* the array for the state vector */ +static int mti = N + 1; /* mti==N+1 means mt[N] is not initialized */ + +/* initializes mt[N] with a seed */ +void +init_genrand(uint32_t s) +{ + mt[0] = s & 0xffffffffU; + + for (mti = 1; mti < N; mti++) + { + mt[mti] = (1812433253U * (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] &= 0xffffffffU; + /* 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 +init_by_array(uint32_t init_key[], int key_length) +{ + int i, j, k; + + init_genrand(19650218U); + + i = 1; j = 0; + k = (N > key_length ? N : key_length); + + for (; k; k--) + { + mt[i] = (mt[i] ^ ((mt[i - 1] ^ (mt[i - 1] >> 30)) * 1664525U)) + + init_key[j] + j; /* non linear */ + mt[i] &= 0xffffffffU; /* 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--) + { + mt[i] = (mt[i] ^ ((mt[i - 1] ^ (mt[i - 1] >> 30)) * 1566083941U)) + - i; /* non linear */ + mt[i] &= 0xffffffffU; /* for WORDSIZE > 32 machines */ + i++; + + if (i >= N) + { + mt[0] = mt[N - 1]; + i = 1; + } + } + + mt[0] = 0x80000000U; /* MSB is 1; assuring non-zero initial array */ +} + +/* generates a random number on [0,0xffffffff]-interval */ +uint32_t +genrand_int32(void) +{ + uint32_t y; + static uint32_t mag01[2]={ 0x0U, MATRIX_A }; + /* mag01[x] = x * MATRIX_A for x=0,1 */ + + if (mti >= N) + { /* generate N words at one time */ + int kk; + + if (mti == N + 1) /* if init_genrand() has not been called, */ + init_genrand(5489U); /* a default initial seed is used */ + + 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 & 0x1U]; + } + + 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 & 0x1U]; + } + + y = (mt[N - 1] & UPPER_MASK) | (mt[0] & LOWER_MASK); + mt[N - 1] = mt[M - 1] ^ (y >> 1) ^ mag01[y & 0x1U]; + + mti = 0; + } + + y = mt[mti++]; + + /* Tempering */ + y ^= (y >> 11); + y ^= (y << 7) & 0x9d2c5680U; + y ^= (y << 15) & 0xefc60000U; + y ^= (y >> 18); + + return y; +} |