Changes to Random Number Generation between r2 and r8
'''Using a Computer to Generate Random Numbers'''
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My algorithm: Uses low-order bits from high precision of timing trivial programs to frequently seed the [Psuedo-Random Number Generator]. The low-order bits are high in entropy and affected by external sources such things as CPU load, CPU temperature (CPU speed varies slightly with CPU temperature), clock variance, and other unpredictable stimulus.
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There is no seed (or rather, it is self-seeding) needed to prime the routines, and the results are not predictable given previous results.
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Sample C implementation: --> Sample C implementation [http://www.rkeene.org/projects/info/resources/rng/rng.c]
#include <sys/time.h>
#include <inttypes.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
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uint32_t ms_to_run(const char *pathname) {
struct timeval start, finish;
uint32_t ret;
gettimeofday(&start, NULL);
system(pathname);
gettimeofday(&finish, NULL);
if (finish.tv_usec < start.tv_usec) {
ret = finish.tv_usec + 1000000 - start.tv_usec;
} else {
ret = finish.tv_usec - start.tv_usec;
} --> ----
return(ret);
}
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int generate_random_values(unsigned char *destarray, int destarray_len, int freq) {
uint32_t x;
unsigned char val;
int i;
for (i = 0; i < destarray_len; i++) {
if ((i % freq) == 0) {
x = ms_to_run("/bin/true");
srand((x << 14) + rand());
}
if (destarray) {
val = (int) (256.0 * rand() / (RAND_MAX + 1.0));
destarray[i] = val;
}
}
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return(0);
}
int main(void) {
char buf[1024 * 4];
int ret;
ret = generate_random_values(buf, sizeof(buf), 3);
if (ret < 0) {
fprintf(stderr, "Error generating random numbers, aborting.\n");
return(EXIT_FAILURE);
}
fwrite(buf, sizeof(buf), sizeof(buf[0]), stdout);
return(EXIT_SUCCESS);
}
Diehard Battery of Tests [http://www.stat.fsu.edu/pub/diehard/] for determining the quality of random numbers.
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"ENT" random number testing program [http://www.fourmilab.ch/random/] [http://www.rkeene.org/projects/info/resources/rng/ent-0.0.0.tar.gz]
Only in r2
Only in r8 --> Modified slightly between r2 and r8