Ruby: missing/mt19937.c Source File

Ruby 3.4.6p54 (2025-09-16 revision dbd83256b1cec76c69756ecb8758b9e1079833de)

mt19937.c
1/*
2This is based on trimmed version of MT19937. To get the original version,
3contact <http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html>.
4
5The original copyright notice follows.
6
7 A C-program for MT19937, with initialization improved 2002/2/10.
8 Coded by Takuji Nishimura and Makoto Matsumoto.
9 This is a faster version by taking Shawn Cokus's optimization,
10 Matthe Bellew's simplification, Isaku Wada's real version.
11
12 Before using, initialize the state by using init_genrand(mt, seed)
13 or init_by_array(mt, init_key, key_length).
14
15 Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura,
16 All rights reserved.
17
18 Redistribution and use in source and binary forms, with or without
19 modification, are permitted provided that the following conditions
20 are met:
21
22 1. Redistributions of source code must retain the above copyright
23 notice, this list of conditions and the following disclaimer.
24
25 2. Redistributions in binary form must reproduce the above copyright
26 notice, this list of conditions and the following disclaimer in the
27 documentation and/or other materials provided with the distribution.
28
29 3. The names of its contributors may not be used to endorse or promote
30 products derived from this software without specific prior written
31 permission.
32
33 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
34 "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
35 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
36 A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
37 CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
38 EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
39 PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
40 PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
41 LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
42 NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
43 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
44
45
46 Any feedback is very welcome.
47 http://www.math.keio.ac.jp/matumoto/emt.html
48 email: matumoto@math.keio.ac.jp
49*/
50
51/* Period parameters */
52#define N 624
53#define M 397
54#define MATRIX_A 0x9908b0dfU /* constant vector a */
55#define UMASK 0x80000000U /* most significant w-r bits */
56#define LMASK 0x7fffffffU /* least significant r bits */
57#define MIXBITS(u,v) ( ((u) & UMASK) | ((v) & LMASK) )
58#define TWIST(u,v) ((MIXBITS((u),(v)) >> 1) ^ ((v)&1U ? MATRIX_A : 0U))
59
60enum {MT_MAX_STATE = N};
61
62 struct MT {
63 /* assume int is enough to store 32bits */
64 uint32_t state[N]; /* the array for the state vector */
65 uint32_t *next;
66 int left;
67};
68
69#define genrand_initialized(mt) ((mt)->next != 0)
70#define uninit_genrand(mt) ((mt)->next = 0)
71
72NO_SANITIZE("unsigned-integer-overflow", static void init_genrand(struct MT *mt, unsigned int s));
73NO_SANITIZE("unsigned-integer-overflow", static void init_by_array(struct MT *mt, const uint32_t init_key[], int key_length));
74
75/* initializes state[N] with a seed */
76static void
77init_genrand(struct MT *mt, unsigned int s)
78{
79 int j;
80 mt->state[0] = s & 0xffffffffU;
81 for (j=1; j<N; j++) {
82 mt->state[j] = (1812433253U * (mt->state[j-1] ^ (mt->state[j-1] >> 30)) + j);
83 /* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */
84 /* In the previous versions, MSBs of the seed affect */
85 /* only MSBs of the array state[]. */
86 /* 2002/01/09 modified by Makoto Matsumoto */
87 mt->state[j] &= 0xffffffff; /* for >32 bit machines */
88 }
89 mt->left = 1;
90 mt->next = mt->state + N;
91}
92
93/* initialize by an array with array-length */
94/* init_key is the array for initializing keys */
95/* key_length is its length */
96/* slight change for C++, 2004/2/26 */
97static void
98init_by_array(struct MT *mt, const uint32_t init_key[], int key_length)
99{
100 int i, j, k;
101 init_genrand(mt, 19650218U);
102 i=1; j=0;
103 k = (N>key_length ? N : key_length);
104 for (; k; k--) {
105 mt->state[i] = (mt->state[i] ^ ((mt->state[i-1] ^ (mt->state[i-1] >> 30)) * 1664525U))
106 + init_key[j] + j; /* non linear */
107 mt->state[i] &= 0xffffffffU; /* for WORDSIZE > 32 machines */
108 i++; j++;
109 if (i>=N) { mt->state[0] = mt->state[N-1]; i=1; }
110 if (j>=key_length) j=0;
111 }
112 for (k=N-1; k; k--) {
113 mt->state[i] = (mt->state[i] ^ ((mt->state[i-1] ^ (mt->state[i-1] >> 30)) * 1566083941U))
114 - i; /* non linear */
115 mt->state[i] &= 0xffffffffU; /* for WORDSIZE > 32 machines */
116 i++;
117 if (i>=N) { mt->state[0] = mt->state[N-1]; i=1; }
118 }
119
120 mt->state[0] = 0x80000000U; /* MSB is 1; assuring non-zero initial array */
121}
122
123static void
124next_state(struct MT *mt)
125{
126 uint32_t *p = mt->state;
127 int j;
128
129 mt->left = N;
130 mt->next = mt->state;
131
132 for (j=N-M+1; --j; p++)
133 *p = p[M] ^ TWIST(p[0], p[1]);
134
135 for (j=M; --j; p++)
136 *p = p[M-N] ^ TWIST(p[0], p[1]);
137
138 *p = p[M-N] ^ TWIST(p[0], mt->state[0]);
139}
140
141/* generates a random number on [0,0xffffffff]-interval */
142static unsigned int
143genrand_int32(struct MT *mt)
144{
145 /* mt must be initialized */
146 unsigned int y;
147
148 if (--mt->left <= 0) next_state(mt);
149 y = *mt->next++;
150
151 /* Tempering */
152 y ^= (y >> 11);
153 y ^= (y << 7) & 0x9d2c5680;
154 y ^= (y << 15) & 0xefc60000;
155 y ^= (y >> 18);
156
157 return y;
158}
MT
Definition mt19937.c:62