mirror of https://codeberg.org/grunfink/snac2.git
88 lines
1.8 KiB
C
88 lines
1.8 KiB
C
/* copyright (c) 2022 - 2024 grunfink et al. / MIT license */
|
|
|
|
#ifndef _XS_RANDOM_H
|
|
|
|
#define _XS_RANDOM_H
|
|
|
|
unsigned int xs_rnd_int32_d(unsigned int *seed);
|
|
void *xs_rnd_buf(void *buf, int size);
|
|
|
|
#ifdef XS_IMPLEMENTATION
|
|
|
|
#include <stdio.h>
|
|
#include <sys/time.h>
|
|
#include <unistd.h>
|
|
#include <stdlib.h>
|
|
|
|
unsigned int xs_rnd_int32_d(unsigned int *seed)
|
|
/* returns a deterministic random integer. If seed is NULL, uses a static one */
|
|
{
|
|
static unsigned int s = 0;
|
|
|
|
if (seed == NULL)
|
|
seed = &s;
|
|
|
|
if (*seed == 0) {
|
|
struct timeval tv;
|
|
|
|
gettimeofday(&tv, NULL);
|
|
*seed = tv.tv_sec ^ tv.tv_usec ^ getpid();
|
|
}
|
|
|
|
/* Linear congruential generator by Numerical Recipes */
|
|
*seed = (*seed * 1664525) + 1013904223;
|
|
|
|
return *seed;
|
|
}
|
|
|
|
|
|
void *xs_rnd_buf(void *buf, int size)
|
|
/* fills buf with random data */
|
|
{
|
|
#ifdef __OpenBSD__
|
|
|
|
/* available since OpenBSD 2.2 */
|
|
arc4random_buf(buf, size);
|
|
|
|
#else
|
|
|
|
FILE *f;
|
|
int done = 0;
|
|
|
|
if ((f = fopen("/dev/urandom", "r")) != NULL) {
|
|
/* fill with great random data from the system */
|
|
if (fread(buf, size, 1, f) == 1)
|
|
done = 1;
|
|
|
|
fclose(f);
|
|
}
|
|
|
|
if (!done) {
|
|
/* fill the buffer with poor quality, deterministic data */
|
|
unsigned int s = 0;
|
|
unsigned char *p = (unsigned char *)buf;
|
|
int n = size / sizeof(s);
|
|
|
|
/* fill with full integers */
|
|
while (n--) {
|
|
xs_rnd_int32_d(&s);
|
|
p = memcpy(p, &s, sizeof(s)) + sizeof(s);
|
|
}
|
|
|
|
if ((n = size % sizeof(s))) {
|
|
/* fill the remaining */
|
|
xs_rnd_int32_d(&s);
|
|
memcpy(p, &s, n);
|
|
}
|
|
}
|
|
|
|
#endif /* __OpenBSD__ */
|
|
|
|
return buf;
|
|
}
|
|
|
|
|
|
#endif /* XS_IMPLEMENTATION */
|
|
|
|
#endif /* XS_RANDOM_H */
|