/**
* scryptenc_cpuperf(opps):
* Estimate the number of salsa20/8 cores which can be executed per second,
* and return the value via opps.
*/
int
scryptenc_cpuperf(double * opps)
{
struct timespec st;
double resd, diffd;
uint64_t i = 0;
/* Get the clock resolution. */
if (getclockres(&resd))
return (2);
#ifdef DEBUG
fprintf(stderr, "Clock resolution is %f\n", resd);
#endif
/* Loop until the clock ticks. */
if (getclocktime(&st))
return (2);
do {
/* Do an scrypt. */
if (crypto_scrypt(NULL, 0, NULL, 0, 16, 1, 1, NULL, 0))
return (3);
/* Has the clock ticked? */
if (getclockdiff(&st, &diffd))
return (2);
if (diffd > 0)
break;
} while (1);
/* Could how many scryps we can do before the next tick. */
if (getclocktime(&st))
return (2);
do {
/* Do an scrypt. */
if (crypto_scrypt(NULL, 0, NULL, 0, 128, 1, 1, NULL, 0))
return (3);
/* We invoked the salsa20/8 core 512 times. */
i += 512;
/* Check if we have looped for long enough. */
if (getclockdiff(&st, &diffd))
return (2);
if (diffd > resd)
break;
} while (1);
#ifdef DEBUG
fprintf(stderr, "%u salsa20/8 cores performed in %f seconds\n",
(uintmax_t)i, diffd);
#endif
/* We can do approximately i salsa20/8 cores per diffd seconds. */
*opps = i / diffd;
return (0);
}
static int getclockdiff(struct timespec * st, double * diffd)
{
struct timespec en;
if (getclocktime(&en))
return (1);
*diffd = (en.tv_nsec - st->tv_nsec) * 0.000000001 +
(en.tv_sec - st->tv_sec);
return (0);
}
