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author | Thomas Martitz <kugel@rockbox.org> | 2010-05-06 21:04:40 +0000 |
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committer | Thomas Martitz <kugel@rockbox.org> | 2010-05-06 21:04:40 +0000 |
commit | 50a6ca39ad4ed01922aa4f755f0ca579788226cf (patch) | |
tree | c7881b015b220558167310345b162324c96be15a /firmware/libc/random.c | |
parent | adb506df14aded06ed6e9ebf8540e6fd383ffd6a (diff) | |
download | rockbox-50a6ca39ad4ed01922aa4f755f0ca579788226cf.tar.gz rockbox-50a6ca39ad4ed01922aa4f755f0ca579788226cf.zip |
Move c/h files implementing/defining standard library stuff into a new libc directory, also standard'ify some parts of the code base (almost entirely #include fixes).
This is to a) to cleanup firmware/common and firmware/include a bit, but also b) for Rockbox as an application which should use the host system's c library and headers, separating makes it easy to exclude our files from the build.
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@25850 a1c6a512-1295-4272-9138-f99709370657
Diffstat (limited to 'firmware/libc/random.c')
-rw-r--r-- | firmware/libc/random.c | 119 |
1 files changed, 119 insertions, 0 deletions
diff --git a/firmware/libc/random.c b/firmware/libc/random.c new file mode 100644 index 0000000000..f3efe89351 --- /dev/null +++ b/firmware/libc/random.c | |||
@@ -0,0 +1,119 @@ | |||
1 | /* | ||
2 | A C-program for MT19937, with initialization improved 2002/2/10. | ||
3 | Coded by Takuji Nishimura and Makoto Matsumoto. | ||
4 | This is a faster version by taking Shawn Cokus's optimization, | ||
5 | Matthe Bellew's simplification. | ||
6 | |||
7 | Before using, initialize the state by using srand(seed). | ||
8 | |||
9 | Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura, | ||
10 | All rights reserved. | ||
11 | |||
12 | Redistribution and use in source and binary forms, with or without | ||
13 | modification, are permitted provided that the following conditions | ||
14 | are met: | ||
15 | |||
16 | 1. Redistributions of source code must retain the above copyright | ||
17 | notice, this list of conditions and the following disclaimer. | ||
18 | |||
19 | 2. Redistributions in binary form must reproduce the above copyright | ||
20 | notice, this list of conditions and the following disclaimer in the | ||
21 | documentation and/or other materials provided with the distribution. | ||
22 | |||
23 | 3. The names of its contributors may not be used to endorse or promote | ||
24 | products derived from this software without specific prior written | ||
25 | permission. | ||
26 | |||
27 | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | ||
28 | "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | ||
29 | LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR | ||
30 | A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR | ||
31 | CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, | ||
32 | EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, | ||
33 | PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR | ||
34 | PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF | ||
35 | LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING | ||
36 | NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS | ||
37 | SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | ||
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 | /* | ||
45 | Adapted to Rockbox by Jens Arnold | ||
46 | */ | ||
47 | |||
48 | #include <stdlib.h> | ||
49 | |||
50 | /* Period parameters */ | ||
51 | #define N 624 | ||
52 | #define M 397 | ||
53 | #define MATRIX_A 0x9908b0dfUL /* constant vector a */ | ||
54 | #define UMASK 0x80000000UL /* most significant w-r bits */ | ||
55 | #define LMASK 0x7fffffffUL /* least significant r bits */ | ||
56 | #define MIXBITS(u,v) ( ((u) & UMASK) | ((v) & LMASK) ) | ||
57 | #define TWIST(u,v) ((MIXBITS(u,v) >> 1) ^ ((v)&1UL ? MATRIX_A : 0UL)) | ||
58 | |||
59 | static unsigned long state[N]; /* the array for the state vector */ | ||
60 | static int left = 0; | ||
61 | static unsigned long *next; | ||
62 | |||
63 | /* initializes state[N] with a seed */ | ||
64 | void srand(unsigned int seed) | ||
65 | { | ||
66 | unsigned long x = seed & 0xffffffffUL; | ||
67 | unsigned long *s = state; | ||
68 | int j; | ||
69 | |||
70 | for (*s++ = x, j = 1; j < N; j++) { | ||
71 | x = (1812433253UL * (x ^ (x >> 30)) + j) & 0xffffffffUL; | ||
72 | *s++ = x; | ||
73 | /* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */ | ||
74 | /* In the previous versions, MSBs of the seed affect */ | ||
75 | /* only MSBs of the array state[]. */ | ||
76 | /* 2002/01/09 modified by Makoto Matsumoto */ | ||
77 | } | ||
78 | left = 1; | ||
79 | } | ||
80 | |||
81 | static void next_state(void) | ||
82 | { | ||
83 | unsigned long *p = state; | ||
84 | int j; | ||
85 | |||
86 | /* if srand() has not been called, */ | ||
87 | /* a default initial seed is used */ | ||
88 | if (left < 0) | ||
89 | srand(5489UL); | ||
90 | |||
91 | left = N; | ||
92 | next = state; | ||
93 | |||
94 | for (j = N - M + 1; --j; p++) | ||
95 | *p = p[M] ^ TWIST(p[0], p[1]); | ||
96 | |||
97 | for (j = M; --j; p++) | ||
98 | *p = p[M-N] ^ TWIST(p[0], p[1]); | ||
99 | |||
100 | *p = p[M-N] ^ TWIST(p[0], state[0]); | ||
101 | } | ||
102 | |||
103 | /* generates a random number on [0,RAND_MAX]-interval */ | ||
104 | int rand(void) | ||
105 | { | ||
106 | unsigned long y; | ||
107 | |||
108 | if (--left <= 0) | ||
109 | next_state(); | ||
110 | y = *next++; | ||
111 | |||
112 | /* Tempering */ | ||
113 | y ^= (y >> 11); | ||
114 | y ^= (y << 7) & 0x9d2c5680UL; | ||
115 | y ^= (y << 15) & 0xefc60000UL; | ||
116 | y ^= (y >> 18); | ||
117 | |||
118 | return ((unsigned int)y) >> 1; | ||
119 | } | ||