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#include "tommath_private.h"
#ifdef BN_MP_EXTEUCLID_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis
/* LibTomMath, multiple-precision integer library -- Tom St Denis */
*
* LibTomMath is a library that provides multiple-precision
* integer arithmetic as well as number theoretic functionality.
*
* The library was designed directly after the MPI library by
* Michael Fromberger but has been written from scratch with
* additional optimizations in place.
*
* SPDX-License-Identifier: Unlicense
/* SPDX-License-Identifier: Unlicense */
*/
/* Extended euclidean algorithm of (a, b) produces
a*u1 + b*u2 = u3
*/
int mp_exteuclid(const mp_int *a, const mp_int *b, mp_int *U1, mp_int *U2, mp_int *U3)
mp_err mp_exteuclid(const mp_int *a, const mp_int *b, mp_int *U1, mp_int *U2, mp_int *U3)
{
mp_int u1, u2, u3, v1, v2, v3, t1, t2, t3, q, tmp;
int err;
mp_err err;
if ((err = mp_init_multi(&u1, &u2, &u3, &v1, &v2, &v3, &t1, &t2, &t3, &q, &tmp, NULL)) != MP_OKAY) {
return err;
}
/* initialize, (u1,u2,u3) = (1,0,a) */
mp_set(&u1, 1uL);
if ((err = mp_copy(a, &u3)) != MP_OKAY) {
goto LBL_ERR;
}
/* initialize, (v1,v2,v3) = (0,1,b) */
mp_set(&v2, 1uL);
if ((err = mp_copy(b, &v3)) != MP_OKAY) {
goto LBL_ERR;
}
/* loop while v3 != 0 */
while (mp_iszero(&v3) == MP_NO) {
while (!MP_IS_ZERO(&v3)) {
/* q = u3/v3 */
if ((err = mp_div(&u3, &v3, &q, NULL)) != MP_OKAY) {
goto LBL_ERR;
}
/* (t1,t2,t3) = (u1,u2,u3) - (v1,v2,v3)q */
if ((err = mp_mul(&v1, &q, &tmp)) != MP_OKAY) {
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err = MP_OKAY;
LBL_ERR:
mp_clear_multi(&u1, &u2, &u3, &v1, &v2, &v3, &t1, &t2, &t3, &q, &tmp, NULL);
return err;
}
#endif
/* ref: $Format:%D$ */
/* git commit: $Format:%H$ */
/* commit time: $Format:%ai$ */
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