1 /*
2 A C-program for MT19937, with initialisation improved 2002/1/26.
3 Coded by Takuji Nishimura and Makoto Matsumoto.
4
5 Before using, initialise the state by using csoundSeedRandMT().
6
7 Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura,
8 All rights reserved.
9
10 Redistribution and use in source and binary forms, with or without
11 modification, are permitted provided that the following conditions
12 are met:
13
14 1. Redistributions of source code must retain the above copyright
15 notice, this list of conditions and the following disclaimer.
16
17 2. Redistributions in binary form must reproduce the above copyright
18 notice, this list of conditions and the following disclaimer in the
19 documentation and/or other materials provided with the distribution.
20
21 3. The names of its contributors may not be used to endorse or promote
22 products derived from this software without specific prior written
23 permission.
24
25 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
26 "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
27 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
28 A PARTICULAR PURPOSE ARE DISCLAIMED.
29 IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
30 ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
34 STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
35 IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
36 POSSIBILITY OF SUCH DAMAGE.
37
38 Any feedback is very welcome.
39 http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html
40 email: m-mat @ math.sci.hiroshima-u.ac.jp (remove space)
41 */
42
43 #include "csoundCore.h"
44
45 /* simple linear congruential generator */
46
csoundRand31(int32_t * seedVal)47 PUBLIC int32_t csoundRand31(int32_t *seedVal)
48 {
49 uint64_t tmp1;
50 uint32_t tmp2;
51
52 /* x = (742938285 * x) % 0x7FFFFFFF */
53 tmp1 = (uint64_t) ((int32_t) (*seedVal) * (int64_t) 742938285);
54 tmp2 = (uint32_t) tmp1 & (uint32_t) 0x7FFFFFFF;
55 tmp2 += (uint32_t) (tmp1 >> 31);
56 tmp2 = (tmp2 & (uint32_t) 0x7FFFFFFF) + (tmp2 >> 31);
57 (*seedVal) = (int32_t) tmp2;
58 return (int32_t) tmp2;
59 }
60
61 /* Period parameters */
62
63 #define N (624)
64 #define M (397)
65 #define MATRIX_A 0x9908B0DFU /* constant vector a */
66 #define UPPER_MASK 0x80000000U /* most significant w-r bits */
67 #define LOWER_MASK 0x7FFFFFFFU /* least significant r bits */
68
MT_update_state(uint32_t * mt)69 static CS_NOINLINE void MT_update_state(uint32_t *mt)
70 {
71 /* mag01[x] = x * MATRIX_A for x=0,1 */
72 const uint32_t mag01[2] = { (uint32_t) 0, (uint32_t) MATRIX_A };
73 int32_t i;
74 uint32_t y;
75
76 for (i = 0; i < (N - M); i++) {
77 y = (mt[i] & UPPER_MASK) | (mt[i + 1] & LOWER_MASK);
78 mt[i] = mt[i + M] ^ (y >> 1) ^ mag01[y & (uint32_t) 1];
79 }
80 for ( ; i < (N - 1); i++) {
81 y = (mt[i] & UPPER_MASK) | (mt[i + 1] & LOWER_MASK);
82 mt[i] = mt[i + (M - N)] ^ (y >> 1) ^ mag01[y & (uint32_t) 1];
83 }
84 y = (mt[N - 1] & UPPER_MASK) | (mt[0] & LOWER_MASK);
85 mt[N - 1] = mt[M - 1] ^ (y >> 1) ^ mag01[y & (uint32_t) 1];
86 }
87
88 /* generates a random number on [0,0xffffffff]-interval */
89
csoundRandMT(CsoundRandMTState * p)90 PUBLIC uint32_t csoundRandMT(CsoundRandMTState *p)
91 {
92 int32_t i = p->mti;
93 uint32_t y;
94
95 if (i >= N) { /* generate N words at one time */
96 MT_update_state(&(p->mt[0]));
97 i = 0;
98 }
99 y = p->mt[i];
100 p->mti = i + 1;
101 /* Tempering */
102 y ^= (y >> 11);
103 y ^= (y << 7) & (uint32_t) 0x9D2C5680U;
104 y ^= (y << 15) & (uint32_t) 0xEFC60000U;
105 y ^= (y >> 18);
106
107 return y;
108 }
109
110 /* initialise by an array with array-length */
111 /* init_key is the array for initialising keys */
112 /* key_length is its length */
113 /* slight change for C++, 2004/2/26 */
114
csoundSeedRandMT(CsoundRandMTState * p,const uint32_t * initKey,uint32_t keyLength)115 PUBLIC void csoundSeedRandMT(CsoundRandMTState *p,
116 const uint32_t *initKey, uint32_t keyLength)
117 {
118 int32_t i, j, k;
119 uint32_t x;
120
121 /* if array is NULL, use length parameter as simple 32 bit seed */
122 x = (initKey == NULL ? keyLength : (uint32_t) 19650218);
123 p->mt[0] = x;
124 for (i = 1; i < N; i++) {
125 /* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */
126 /* In the previous versions, MSBs of the seed affect */
127 /* only MSBs of the array mt[]. */
128 /* 2002/01/09 modified by Makoto Matsumoto */
129 x = ((uint32_t) 1812433253 * (x ^ (x >> 30)) + (uint32_t) i);
130 p->mt[i] = x;
131 }
132 p->mti = N;
133 if (initKey == NULL)
134 return;
135 i = 0; j = 0;
136 k = (N > (int32_t) keyLength ? N : (int32_t) keyLength);
137 for ( ; k; k--) {
138 x = p->mt[i++];
139 p->mt[i] = (p->mt[i] ^ ((x ^ (x >> 30)) * (uint32_t) 1664525))
140 + initKey[j] + (uint32_t) j; /* non linear */
141 if (i == (N - 1)) {
142 p->mt[0] = p->mt[N - 1];
143 i = 0;
144 }
145 if (++j >= (int32_t) keyLength)
146 j = 0;
147 }
148 for (k = (N - 1); k; k--) {
149 x = p->mt[i++];
150 p->mt[i] = (p->mt[i] ^ ((x ^ (x >> 30)) * (uint32_t) 1566083941))
151 - (uint32_t) i; /* non linear */
152 if (i == (N - 1)) {
153 p->mt[0] = p->mt[N - 1];
154 i = 0;
155 }
156 }
157 /* MSB is 1; assuring non-zero initial array */
158 p->mt[0] = (uint32_t) 0x80000000U;
159 }
160
161 /* called from csoundPreCompile() */
162
csound_init_rand(CSOUND * csound)163 void csound_init_rand(CSOUND *csound)
164 {
165 uint32_t tmp;
166
167 csound->csRandState = &(csound->randState_);
168 csound->randSeed1 = 15937;
169 tmp = (uint32_t) csound->GetRandomSeedFromTime();
170 while (tmp >= (uint32_t) 0x7FFFFFFE)
171 tmp -= (uint32_t) 0x7FFFFFFE;
172 csound->randSeed2 = ((int) tmp + 1);
173 csound->SeedRandMT(&(csound->randState_), NULL, (uint32_t) 5489);
174 }
175
176