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/* udns_jran.c: small non-cryptographic random number generator
* taken from http://burtleburtle.net/bob/rand/smallprng.html
* by Bob Jenkins, Public domain.
*/
#include "udns.h"
#define rot32(x,k) (((x) << (k)) | ((x) >> (32-(k))))
#define rot64(x,k) (((x) << (k)) | ((x) >> (64-(k))))
#define tr32(x) ((x)&0xffffffffu)
unsigned udns_jranval(struct udns_jranctx *x) {
/* This routine can be made to work with either 32 or 64bit words -
* if JRAN_32_64 is defined when compiling the file.
* We use if() instead of #if since there's no good
* portable way to check sizeof() in preprocessor without
* introducing some ugly configure-time checks.
* Most compilers will optimize the wrong branches away anyway.
* By default it assumes 32bit integers
*/
#ifdef JRAN_32_64
if (sizeof(unsigned) == 4) {
#endif
unsigned e = tr32(x->a - rot32(x->b, 27));
x->a = tr32(x->b ^ rot32(x->c, 17));
x->b = tr32(x->c + x->d);
x->c = tr32(x->d + e);
x->d = tr32(e + x->a);
#ifdef JRAN_32_64
}
else if (sizeof(unsigned) == 8) { /* assuming it's 64bits */
unsigned e = x->a - rot64(x->b, 7);
x->a = x->b ^ rot64(x->c, 13);
x->b = x->c + rot64(x->d, 37);
x->c = x->d + e;
x->d = e + x->a;
}
else {
unsigned e = 0;
x->d = 1/e; /* bail */
}
#endif
return x->d;
}
void udns_jraninit(struct udns_jranctx *x, unsigned seed) {
unsigned i;
x->a = 0xf1ea5eed;
x->b = x->c = x->d = seed;
for (i = 0; i < 20; ++i)
(void)udns_jranval(x);
}