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Remove deprecated and now unused Mersenne Twister PRNG. 

Originally committed as revision 18116 to svn://svn.ffmpeg.org/ffmpeg/trunk
tags/v0.6
Diego Biurrun 17 years ago
parent
6a03a34b01
commit
ee6624ef4a
3 changed files with 1 additions and 177 deletions
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  1. +1
    -2
      libavutil/Makefile
  2. +0
    -99
      libavutil/random.c
  3. +0
    -76
      libavutil/random.h

+ 1
- 2
libavutil/Makefile View File

@@ -34,7 +34,6 @@ OBJS = adler32.o \
mathematics.o \
md5.o \
mem.o \
random.o \
random_seed.o \
rational.o \
rc4.o \
@@ -42,7 +41,7 @@ OBJS = adler32.o \
tree.o \
utils.o \

TESTS = $(addsuffix -test$(EXESUF), adler32 aes base64 crc des lls md5 pca random sha1 softfloat tree)
TESTS = $(addsuffix -test$(EXESUF), adler32 aes base64 crc des lls md5 pca sha1 softfloat tree)

DIRS = arm bfin sh4 x86



+ 0
- 99
libavutil/random.c View File

@@ -1,99 +0,0 @@
/*
* Mersenne Twister PRNG algorithm
* Copyright (c) 2006 Ryan Martell
* Based on a C program for MT19937, with initialization improved 2002/1/26.
* Coded by Takuji Nishimura and Makoto Matsumoto.
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/


/**
* See http://en.wikipedia.org/wiki/Mersenne_twister
* for an explanation of this algorithm.
*/
#include <stdio.h>
#include "random.h"


/* period parameters */
#define M 397
#define A 0x9908b0df /* constant vector a */
#define UPPER_MASK 0x80000000 /* most significant w-r bits */
#define LOWER_MASK 0x7fffffff /* least significant r bits */

/** Initializes mt[AV_RANDOM_N] with a seed. */
void av_random_init(AVRandomState *state, unsigned int seed)
{
int index;

/*
This differs from the Wikipedia article. Source is from the
Makoto Matsumoto and Takuji Nishimura code, with the following comment:
*/
/* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */
/* In the previous versions, MSBs of the seed affect */
/* only MSBs of the array mt[]. */
state->mt[0] = seed & 0xffffffff;
for (index = 1; index < AV_RANDOM_N; index++) {
unsigned int prev= state->mt[index - 1];
state->mt[index] = (1812433253UL * (prev ^ (prev>>30)) + index) & 0xffffffff;
}
state->index= index; // Will cause it to generate untempered numbers in the first iteration.
}

/** Generates AV_RANDOM_N words at one time (which will then be tempered later).
* av_random calls this; you shouldn't. */
void av_random_generate_untempered_numbers(AVRandomState *state)
{
int kk;
unsigned int y;

for (kk = 0; kk < AV_RANDOM_N - M; kk++) {
y = (state->mt[kk] & UPPER_MASK) | (state->mt[kk + 1] & LOWER_MASK);
state->mt[kk] = state->mt[kk + M] ^ (y >> 1) ^ ((y&1)*A);
}
for (; kk < AV_RANDOM_N - 1; kk++) {
y = (state->mt[kk] & UPPER_MASK) | (state->mt[kk + 1] & LOWER_MASK);
state->mt[kk] = state->mt[kk + (M - AV_RANDOM_N)] ^ (y >> 1) ^ ((y&1)*A);
}
y = (state->mt[AV_RANDOM_N - 1] & UPPER_MASK) | (state->mt[0] & LOWER_MASK);
state->mt[AV_RANDOM_N - 1] = state->mt[M - 1] ^ (y >> 1) ^ ((y&1)*A);
state->index = 0;
}

#ifdef TEST
#include "common.h"
#include "log.h"
int main(void)
{
int x=0;
int i, j;
AVRandomState state;

av_random_init(&state, 0xdeadbeef);
for (j = 0; j < 10000; j++) {
START_TIMER
for (i = 0; i < 624; i++) {
x+= av_random(&state);
}
STOP_TIMER("624 calls of av_random");
}
av_log(NULL, AV_LOG_ERROR, "final value:%X\n", x);
return 0;
}
#endif

+ 0
- 76
libavutil/random.h View File

@@ -1,76 +0,0 @@
/*
* Mersenne Twister PRNG algorithm
* Copyright (c) 2006 Ryan Martell
* Based on a C program for MT19937, with initialization improved 2002/1/26.
* Coded by Takuji Nishimura and Makoto Matsumoto.
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/

#ifndef AVUTIL_RANDOM_H
#define AVUTIL_RANDOM_H

#define AV_RANDOM_N 624

#include "avutil.h"
#include "common.h"

typedef struct {
unsigned int mt[AV_RANDOM_N]; ///< the array for the state vector
int index; ///< Current untempered value we use as the base.
} AVRandomState;


attribute_deprecated void av_random_init(AVRandomState *state, unsigned int seed); ///< To be inlined, the struct must be visible. So it does not make sense to try and keep it opaque with malloc/free-like calls.
attribute_deprecated void av_random_generate_untempered_numbers(AVRandomState *state); ///< Regenerate the untempered numbers (must be done every 624 iterations, or it will loop).

/**
* Generates a random number from the interval [0,0xffffffff].
*
* Please do NOT use the Mersenne Twister, it is slow. Use the random number
* generator from lfg.c/h or a simple LCG like state = state*1664525+1013904223.
* If you still choose to use MT, expect that you will have to provide
* some evidence that it makes a difference for the case where you use it.
*/
attribute_deprecated static inline unsigned int av_random(AVRandomState *state)
{
unsigned int y;

// Regenerate the untempered numbers if we should...
if (state->index >= AV_RANDOM_N)
av_random_generate_untempered_numbers(state);

// Grab one...
y = state->mt[state->index++];

/* Now temper (Mersenne Twister coefficients). The coefficients for MT19937 are.. */
y ^= (y >> 11);
y ^= (y << 7) & 0x9d2c5680;
y ^= (y << 15) & 0xefc60000;
y ^= (y >> 18);

return y;
}

/** Returns a random number in the range [0-1] as double. */
attribute_deprecated static inline double av_random_real1(AVRandomState *state)
{
/* divided by 2^32-1 */
return av_random(state) * (1.0 / 4294967296.0);
}

#endif /* AVUTIL_RANDOM_H */

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