docs: Added note to curvetun doc
[netsniff-ng.git] / src / mtrand.c
blob67b4e3372bdca7aecc6f29e47f0cc623e8d22007
1 /*
2 * netsniff-ng - the packet sniffing beast
3 * By Daniel Borkmann <daniel@netsniff-ng.org>
4 * Copyright 2009, 2010 Daniel Borkmann.
5 * Subject to the GPL, version 2.
6 */
8 /*
9 * Copyright (C) 1997-2004, Makoto Matsumoto, Takuji Nishimura, and
10 * Eric Landry; All rights reserved.
11 * Daniel Borkmann: Refactored, added initialization functions.
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
15 * are met:
17 * 1. Redistributions of source code must retain the above copyright
18 * notice, this list of conditions and the following disclaimer.
20 * 2. Redistributions in binary form must reproduce the above copyright
21 * notice, this list of conditions and the following disclaimer
22 * in the documentation and/or other materials provided with the
23 * distribution.
25 * 3. The names of its contributors may not be used to endorse or
26 * promote products derived from this software without specific
27 * prior written permission.
29 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
30 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
31 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
32 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
33 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
34 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
35 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
36 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
37 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
38 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
39 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
41 * Any feedback is very welcome.
42 * http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html
43 * email: m-mat @ math.sci.hiroshima-u.ac.jp (remove space)
45 * Reference: M. Matsumoto and T. Nishimura, "Mersenne Twister:
46 * A 623-Dimensionally Equidistributed Uniform Pseudo-Random Number
47 * Generator", ACM Transactions on Modeling and Computer Simulation,
48 * Vol. 8, No. 1, January 1998, pp 3--30.
51 #include <stdio.h>
52 #include <stdlib.h>
53 #include <time.h>
54 #include <fcntl.h>
55 #include <unistd.h>
57 #include "mtrand.h"
58 #include "xio.h"
60 #define N 624
61 #define M 397
62 #define LEN_INIT 256
64 #define MATRIX_A 0x9908b0dfUL
65 #define UPPER_MASK 0x80000000UL
66 #define LOWER_MASK 0x7fffffffUL
68 static unsigned long x[N];
69 static unsigned long *p0, *p1, *pm;
72 * Initialize with a seed.
74 * See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier.
75 * In the previous versions, MSBs of the seed affect only MSBs of
76 * the state.
77 * 2002-01-09 modified by Makoto Matsumoto
79 void mt_init_by_seed_rand(unsigned long s)
81 int i;
83 x[0] = s & 0xffffffffUL;
85 for (i = 1; i < N; ++i) {
86 x[i] = (1812433253UL * (x[i - 1] ^ (x[i - 1] >> 30)) + i) &
87 0xffffffffUL;
90 p0 = x;
91 p1 = x + 1;
92 pm = x + M;
96 * Initialize with time as seed.
98 void mt_init_by_seed_time(void)
100 int i;
102 x[0] = ((unsigned long) time(NULL)) & 0xffffffffUL;
104 for (i = 1; i < N; ++i) {
105 x[i] = (1812433253UL * (x[i - 1] ^ (x[i - 1] >> 30)) + i) &
106 0xffffffffUL;
109 p0 = x;
110 p1 = x + 1;
111 pm = x + M;
115 * Initialize by an array with array-length.
117 void mt_init_by_seed_array(unsigned long key[], int len)
119 int i, j, k;
121 mt_init_by_seed_rand(19650218UL);
123 i = 1;
124 j = 0;
126 for (k = (N > len ? N : len); k; --k) {
127 /* Non linear */
128 x[i] = ((x[i] ^ ((x[i - 1] ^ (x[i - 1] >> 30)) *
129 1664525UL)) + key[j] + j) & 0xffffffffUL;
131 if (++i >= N) {
132 x[0] = x[N - 1];
133 i = 1;
136 if (++j >= len)
137 j = 0;
140 for (k = N - 1; k; --k) {
141 /* Non linear */
142 x[i] = ((x[i] ^ ((x[i - 1] ^ (x[i - 1] >> 30)) *
143 1566083941UL)) - i) & 0xffffffffUL;
145 if (++i >= N) {
146 x[0] = x[N - 1];
147 i = 1;
151 x[0] = 0x80000000UL;
155 * Initialize by an random array.
157 void mt_init_by_seed_rand_array(void)
159 int i;
160 unsigned long k[LEN_INIT];
162 srand((unsigned int) time(NULL));
163 for (i = 0; i < LEN_INIT; i++)
164 k[i] = rand();
166 mt_init_by_seed_array(k, LEN_INIT);
170 * Initialize by an random array read from /dev/random
172 void mt_init_by_random_device(void)
174 int fd;
175 unsigned long k[LEN_INIT];
177 fd = open_or_die("/dev/random", O_RDONLY);
178 read_or_die(fd, k, sizeof(unsigned long) * LEN_INIT);
179 close(fd);
181 mt_init_by_seed_array(k, LEN_INIT);
185 * Generates a random number on the interval [0,0xffffffff]
187 unsigned long mt_rand_int32(void)
189 unsigned long y;
191 /* Default seed */
192 if (p0 == NULL)
193 mt_init_by_seed_rand(5489UL);
195 /* Twisted feedback */
196 y = *p0 = *pm++ ^ (((*p0 & UPPER_MASK) | (*p1 & LOWER_MASK)) >> 1) ^
197 (-(*p1 & 1) & MATRIX_A);
199 p0 = p1++;
201 if (pm == x + N)
202 pm = x;
203 if (p1 == x + N)
204 p1 = x;
206 /* Temper */
207 y ^= y >> 11;
208 y ^= y << 7 & 0x9d2c5680UL;
209 y ^= y << 15 & 0xefc60000UL;
210 y ^= y >> 18;
212 return y;
216 * Generates a random number on the interval [0,0x7fffffff]
218 long mt_rand_int31(void)
220 return (long) mt_rand_int32() >> 1;
224 * Generates a random number on the real interval [0,1]
226 double mt_rand_real1(void)
228 return mt_rand_int32() * (1.0 / 4294967295.0);
229 /* Divided by 2^32-1 */
233 * Generates a random number on the real interval [0,1)
235 double mt_rand_real2(void)
237 return mt_rand_int32() * (1.0 / 4294967296.0);
238 /* Divided by 2^32 */
242 * Generates a random number on the real interval (0,1)
244 double mt_rand_real3(void)
246 return (((double) mt_rand_int32()) + 0.5) * (1.0 / 4294967296.0);
247 /* Divided by 2^32 */
251 * Generates a 53-bit random number on the real interval [0,1)
253 double mt_rand_res53(void)
255 unsigned long a = mt_rand_int32() >> 5, b = mt_rand_int32() >> 6;
256 return (a * 67108864.0 + b) * (1.0 / 9007199254740992.0);