1 /*
2 A C-program for MT19937, with initialization improved 2002/1/26.
3 Coded by Takuji Nishimura and Makoto Matsumoto.
4
5 Before using, initialize the state by using init_genrand(seed)
6 or init_by_array(init_key, key_length).
7
8 Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura,
9 All rights reserved.
10
11 Redistribution and use in source and binary forms, with or without
12 modification, are permitted provided that the following conditions
13 are met:
14
15 1. Redistributions of source code must retain the above copyright
16 notice, this list of conditions and the following disclaimer.
17
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.
21
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
24 permission.
25
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.
37
38
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)
42 */
43
44 #include "mt19937ar.h"
45
46 /* Period parameters */
47 #define N 624
48 #define M 397
49 #define MATRIX_A 0x9908b0dfUL /* constant vector a */
50 #define UPPER_MASK 0x80000000UL /* most significant w-r bits */
51 #define LOWER_MASK 0x7fffffffUL /* least significant r bits */
52
MersenneTwister()53 MersenneTwister::MersenneTwister() : mt(N), mti(N+1) {
54 }
55
~MersenneTwister()56 MersenneTwister::~MersenneTwister() {
57 }
58
59 /* initializes mt[N] with a seed */
init_genrand(uint32 s)60 void MersenneTwister::init_genrand(uint32 s)
61 {
62 mt[0]= s & 0xffffffffUL;
63 for (mti=1; mti<N; mti++) {
64 mt[mti] =
65 (1812433253UL * (mt[mti-1] ^ (mt[mti-1] >> 30)) + mti);
66 /* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */
67 /* In the previous versions, MSBs of the seed affect */
68 /* only MSBs of the array mt[]. */
69 /* 2002/01/09 modified by Makoto Matsumoto */
70 mt[mti] &= 0xffffffffUL;
71 /* for >32 bit machines */
72 }
73 }
74
75 /* initialize by an array with array-length */
76 /* init_key is the array for initializing keys */
77 /* key_length is its length */
78 /* slight change for C++, 2004/2/26 */
init_by_array(uint32 init_key[],int key_length)79 void MersenneTwister::init_by_array(uint32 init_key[], int key_length)
80 {
81 int i, j, k;
82 init_genrand(19650218UL);
83 i=1; j=0;
84 k = (N>key_length ? N : key_length);
85 for (; k; k--) {
86 mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * 1664525UL))
87 + init_key[j] + j; /* non linear */
88 mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
89 i++; j++;
90 if (i>=N) { mt[0] = mt[N-1]; i=1; }
91 if (j>=key_length) j=0;
92 }
93 for (k=N-1; k; k--) {
94 mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * 1566083941UL))
95 - i; /* non linear */
96 mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
97 i++;
98 if (i>=N) { mt[0] = mt[N-1]; i=1; }
99 }
100
101 mt[0] = 0x80000000UL; /* MSB is 1; assuring non-zero initial array */
102 }
103
104 /* generates a random number on [0,0xffffffff]-interval */
genrand_int32(void)105 uint32 MersenneTwister::genrand_int32(void)
106 {
107 uint32 y;
108 static uint32 mag01[2]={0x0UL, MATRIX_A};
109 /* mag01[x] = x * MATRIX_A for x=0,1 */
110
111 if (mti >= N) { /* generate N words at one time */
112 int kk;
113
114 if (mti == N+1) /* if init_genrand() has not been called, */
115 init_genrand(5489UL); /* a default initial seed is used */
116
117 for (kk=0;kk<N-M;kk++) {
118 y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
119 mt[kk] = mt[kk+M] ^ (y >> 1) ^ mag01[y & 0x1UL];
120 }
121 for (;kk<N-1;kk++) {
122 y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
123 mt[kk] = mt[kk+(M-N)] ^ (y >> 1) ^ mag01[y & 0x1UL];
124 }
125 y = (mt[N-1]&UPPER_MASK)|(mt[0]&LOWER_MASK);
126 mt[N-1] = mt[M-1] ^ (y >> 1) ^ mag01[y & 0x1UL];
127
128 mti = 0;
129 }
130
131 y = mt[mti++];
132
133 /* Tempering */
134 y ^= (y >> 11);
135 y ^= (y << 7) & 0x9d2c5680UL;
136 y ^= (y << 15) & 0xefc60000UL;
137 y ^= (y >> 18);
138
139 return y;
140 }
141