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/* See LICENSE file for copyright and license details. */
#include "internals.h"
#define tb libzahl_tmp_pow_b
#define td libzahl_tmp_pow_d
void
zmodpowu(z_t a, z_t b, unsigned long long int c, z_t d)
{
if (!c) {
if (zzero(b))
FAILURE(EDOM); /* Indeterminate form: 0:th power of 0 */
else if (zzero(d))
FAILURE(EDOM); /* Undefined form: Division by 0 */
else
zsetu(a, 1);
return;
} else if (zzero(d)) {
FAILURE(EDOM); /* Undefined form: Division by 0 */
} else if (zzero(b)) {
SET_SIGNUM(a, 0);
return;
}
zmod(tb, b, d);
zset(td, d);
zsetu(a, 1);
for (; c; c >>= 1) {
if (c & 1)
zmodmul(a, a, tb, td);
zmodsqr(tb, tb, td);
}
}
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