#include "tommath_private.h"
#ifdef MP_INVMOD_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis */
/* SPDX-License-Identifier: Unlicense */
/* hac 14.61, pp608 */
mp_err mp_invmod(const mp_int *a, const mp_int *b, mp_int *c)
{
/* b cannot be negative and has to be >1 */
if ((b->sign == MP_NEG) || (mp_cmp_d(b, 1uL) != MP_GT)) {
return MP_VAL;
}
/* if the modulus is odd we can use a faster routine instead */
if (MP_HAS(S_MP_INVMOD_FAST) && mp_isodd(b)) {
return s_mp_invmod_fast(a, b, c);
}
return MP_HAS(S_MP_INVMOD_SLOW)
? s_mp_invmod_slow(a, b, c)
: MP_VAL;
}
#endif
