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00028 #include <stdio.h>
00029 #include "random.h"
00030
00031
00032
00033 #ifdef DEBUG
00034 #include "common.h"
00035 #include "log.h"
00036 #endif
00037
00038
00039
00040 #define M 397
00041 #define A 0x9908b0df
00042 #define UPPER_MASK 0x80000000
00043 #define LOWER_MASK 0x7fffffff
00044
00046 void av_init_random(unsigned int seed, AVRandomState *state)
00047 {
00048 int index;
00049
00050
00051
00052
00053
00054
00055
00056
00057 state->mt[0] = seed & 0xffffffff;
00058 for (index = 1; index < AV_RANDOM_N; index++) {
00059 unsigned int prev= state->mt[index - 1];
00060 state->mt[index] = (1812433253UL * (prev ^ (prev>>30)) + index) & 0xffffffff;
00061 }
00062 state->index= index;
00063 }
00064
00066 void av_random_generate_untempered_numbers(AVRandomState *state)
00067 {
00068 int kk;
00069 unsigned int y;
00070
00071 for (kk = 0; kk < AV_RANDOM_N - M; kk++) {
00072 y = (state->mt[kk] & UPPER_MASK) | (state->mt[kk + 1] & LOWER_MASK);
00073 state->mt[kk] = state->mt[kk + M] ^ (y >> 1) ^ ((y&1)*A);
00074 }
00075 for (; kk < AV_RANDOM_N - 1; kk++) {
00076 y = (state->mt[kk] & UPPER_MASK) | (state->mt[kk + 1] & LOWER_MASK);
00077 state->mt[kk] = state->mt[kk + (M - AV_RANDOM_N)] ^ (y >> 1) ^ ((y&1)*A);
00078 }
00079 y = (state->mt[AV_RANDOM_N - 1] & UPPER_MASK) | (state->mt[0] & LOWER_MASK);
00080 state->mt[AV_RANDOM_N - 1] = state->mt[M - 1] ^ (y >> 1) ^ ((y&1)*A);
00081 state->index = 0;
00082 }
00083
00084 #ifdef DEBUG
00085 void av_benchmark_random(void)
00086 {
00087 int x=0;
00088 int i, j;
00089 AVRandomState state;
00090
00091 av_init_random(0xdeadbeef, &state);
00092 for (j = 0; j < 100; j++) {
00093 START_TIMER;
00094 x+= av_random(&state);
00095 STOP_TIMER("first call to av_random");
00096 for (i = 1; i < AV_RANDOM_N; i++) {
00097 START_TIMER;
00098 x+= av_random(&state);
00099 STOP_TIMER("AV_RANDOM_N calls of av_random");
00100 }
00101 }
00102 av_log(NULL, AV_LOG_ERROR, "final value:%X\n", x);
00103 }
00104 #endif