40 lines
887 B
C
40 lines
887 B
C
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#include <stdio.h>
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#include <math.h>
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#include <stdlib.h>
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#include <time.h>
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#define RNG_M 2147483647L /* m = 2^31 - 1 */
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#define RNG_A 16807L
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#define RNG_Q 127773L /* m div a */
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#define RNG_R 2836L /* m mod a */
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/* 32 bit seed */
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static long rnd_seed;
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void set_rnd_seed (long seedval)
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{
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/* set seed to value between 1 and m-1 */
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rnd_seed = (seedval % (RNG_M - 1)) + 1;
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}
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/* returns a pseudo-random number from set 1, 2, ..., RNG_M - 1 */
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long rnd()
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{
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register long low, high, test;
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set_rnd_seed( (unsigned int) time(0) + getpid());
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high = rnd_seed / RNG_Q;
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low = rnd_seed % RNG_Q;
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test = RNG_A * low - RNG_R * high;
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if (test > 0)
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rnd_seed = test;
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else
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rnd_seed = test + RNG_M;
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return rnd_seed;
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}
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int main(void)
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{
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printf("Random number generated is %d\n", rnd());
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return 0;
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}
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