2 A C-program for MT19937, with initialization improved 2002/1/26.
3 Coded by Takuji Nishimura and Makoto Matsumoto.
5 Before using, initialize the state by using init_genrand(seed)
6 or init_by_array(init_key, key_length).
8 Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura,
11 Redistribution and use in source and binary forms, with or without
12 modification, are permitted provided that the following conditions
15 1. Redistributions of source code must retain the above copyright
16 notice, this list of conditions and the following disclaimer.
18 2. Redistributions in binary form must reproduce the above copyright
19 notice, this list of conditions and the following disclaimer in the
20 documentation and/or other materials provided with the distribution.
22 3. The names of its contributors may not be used to endorse or promote
23 products derived from this software without specific prior written
26 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
27 "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
28 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
29 A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
30 CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
31 EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
32 PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
33 PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
34 LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
35 NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
36 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
39 Any feedback is very welcome.
40 http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html
41 email: m-mat @ math.sci.hiroshima-u.ac.jp (remove space)
51 const unsigned long MATRIX_A = 0x9908b0dfUL; // Constant vector a
52 const unsigned long UPPER_MASK = 0x80000000UL; // Most significant w-r bits
53 const unsigned long LOWER_MASK = 0x7fffffffUL; // Least significant r bits
55 unsigned long mt[N]; // The array for the state vector
56 int mti = N + 1; // mti == N+1 means mt[N] is not initialized
58 // Initializes mt[N] with a seed
59 void init_genrand(unsigned long s) {
61 mt[0]= s & 0xffffffffUL;
62 for (mti = 1; mti < N; mti++)
64 // See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier.
65 // In the previous versions, MSBs of the seed affect
66 // only MSBs of the array mt[].
67 // 2002/01/09 modified by Makoto Matsumoto
68 mt[mti] = 1812433253UL * (mt[mti-1] ^ (mt[mti-1] >> 30)) + mti;
69 mt[mti] &= 0xffffffffUL; // For > 32 bit machines
73 // Initialize by an array with array-length
74 // init_key is the array for initializing keys
75 // key_length is its length
76 // slight change for C++, 2004/2/26
77 void init_by_array(unsigned long init_key[], int key_length) {
81 int k = (N > key_length ? N : key_length);
83 init_genrand(19650218UL);
87 mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * 1664525UL)) + init_key[j] + j; // Non linear
88 mt[i] &= 0xffffffffUL; // For WORDSIZE > 32 machines
100 mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * 1566083941UL)) - i; // Non linear
101 mt[i] &= 0xffffffffUL; // For WORDSIZE > 32 machines
109 mt[0] = 0x80000000UL; // MSB is 1; assuring non-zero initial array
115 // Generates a random number on [0,0xffffffff]-interval
116 uint32_t genrand_int32() {
119 static unsigned long mag01[2] = {0x0UL, MATRIX_A};
120 /* mag01[x] = x * MATRIX_A for x=0,1 */
122 // Generate N words at one time
127 if (mti == N+1) // If init_genrand() has not been called,
128 init_genrand(5489UL); // a default initial seed is used.
130 for (kk = 0; kk < N-M; kk++)
132 y = (mt[kk] & UPPER_MASK) | (mt[kk+1] & LOWER_MASK);
133 mt[kk] = mt[kk+M] ^ (y >> 1) ^ mag01[y & 0x1UL];
135 for ( ; kk < N-1; kk++)
137 y = (mt[kk] & UPPER_MASK) | (mt[kk+1] & LOWER_MASK);
138 mt[kk] = mt[kk+(M-N)] ^ (y >> 1) ^ mag01[y & 0x1UL];
140 y = (mt[N-1] & UPPER_MASK) | (mt[0] & LOWER_MASK);
141 mt[N-1] = mt[M-1] ^ (y >> 1) ^ mag01[y & 0x1UL];
149 y ^= (y << 7) & 0x9d2c5680UL;
150 y ^= (y << 15) & 0xefc60000UL;
156 uint64_t genrand_int64() {
162 return (x << 32) | y;
165 void init_mersenne() {
167 unsigned long init[4] = {0x123, 0x234, 0x345, 0x456};
168 unsigned long length = 4;
170 init_by_array(init, length);