96 lines
3.7 KiB
C
96 lines
3.7 KiB
C
/* A C-program for MT19937: Integer version */
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/* genrand() generates one pseudorandom unsigned integer (32bit) */
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/* which is uniformly distributed among 0 to 2^32-1 for each */
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/* call. sgenrand(seed) set initial values to the working area */
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/* of 624 words. Before genrand(), sgenrand(seed) must be */
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/* called once. (seed is any 32-bit integer except for 0). */
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/* Coded by Takuji Nishimura, considering the suggestions by */
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/* Topher Cooper and Marc Rieffel in July-Aug. 1997. */
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/* This library is free software; you can redistribute it and/or */
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/* modify it under the terms of the GNU Library General Public */
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/* License as published by the Free Software Foundation; either */
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/* version 2 of the License, or (at your option) any later */
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/* version. */
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/* This library is distributed in the hope that it will be useful, */
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/* but WITHOUT ANY WARRANTY; without even the implied warranty of */
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/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. */
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/* See the GNU Library General Public License for more details. */
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/* You should have received a copy of the GNU Library General */
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/* Public License along with this library; if not, write to the */
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/* Free Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA */
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/* 02111-1307 USA */
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/* Copyright (C) 1997 Makoto Matsumoto and Takuji Nishimura. */
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/* When you use this, send an email to: matumoto@math.keio.ac.jp */
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/* with an appropriate reference to your work. */
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/* Period parameters */
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#define N 624
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#define M 397
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#define MATRIX_A 0x9908b0df /* constant vector a */
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#define UPPER_MASK 0x80000000 /* most significant w-r bits */
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#define LOWER_MASK 0x7fffffff /* least significant r bits */
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/* Tempering parameters */
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#define TEMPERING_MASK_B 0x9d2c5680
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#define TEMPERING_MASK_C 0xefc60000
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#define TEMPERING_SHIFT_U(y) (y >> 11)
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#define TEMPERING_SHIFT_S(y) (y << 7)
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#define TEMPERING_SHIFT_T(y) (y << 15)
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#define TEMPERING_SHIFT_L(y) (y >> 18)
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static unsigned long mt[N]; /* the array for the state vector */
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static int mti=N+1; /* mti==N+1 means mt[N] is not initialized */
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/* initializing the array with a NONZERO seed */
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void
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sgenrand(seed)
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unsigned long seed;
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{
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/* setting initial seeds to mt[N] using */
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/* the generator Line 25 of Table 1 in */
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/* [KNUTH 1981, The Art of Computer Programming */
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/* Vol. 2 (2nd Ed.), pp102] */
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mt[0]= seed & 0xffffffff;
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for (mti=1; mti<N; mti++)
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mt[mti] = (69069 * mt[mti-1]) & 0xffffffff;
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}
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unsigned long
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genrand()
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{
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unsigned long y;
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static unsigned long mag01[2]={0x0, MATRIX_A
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};
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/* mag01[x] = x * MATRIX_A for x=0,1 */
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if (mti >= N) { /* generate N words at one time */
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int kk;
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if (mti == N+1) /* if sgenrand() has not been called, */
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sgenrand(4357); /* a default initial seed is used */
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for (kk=0;kk<N-M;kk++) {
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y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
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mt[kk] = mt[kk+M] ^ (y >> 1) ^ mag01[y & 0x1];
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}
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for (;kk<N-1;kk++) {
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y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
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mt[kk] = mt[kk+(M-N)] ^ (y >> 1) ^ mag01[y & 0x1];
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}
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y = (mt[N-1]&UPPER_MASK)|(mt[0]&LOWER_MASK);
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mt[N-1] = mt[M-1] ^ (y >> 1) ^ mag01[y & 0x1];
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mti = 0;
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}
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y = mt[mti++];
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y ^= TEMPERING_SHIFT_U(y);
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y ^= TEMPERING_SHIFT_S(y) & TEMPERING_MASK_B;
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y ^= TEMPERING_SHIFT_T(y) & TEMPERING_MASK_C;
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y ^= TEMPERING_SHIFT_L(y);
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return y;
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}
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