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mpi-genesis             1 /* mpi-gcd.c  -  MPI functions
mpi_second_cut 2 * Modified by No Such Labs. (C) 2015. See README.
mpi-genesis 3 *
mpi_second_cut 4 * This file was originally part of Gnu Privacy Guard (GPG), ver. 1.4.10,
mpi_second_cut 5 * SHA256(gnupg-1.4.10.tar.gz):
mpi_second_cut 6 * 0bfd74660a2f6cedcf7d8256db4a63c996ffebbcdc2cf54397bfb72878c5a85a
mpi_second_cut 7 * (C) 1994-2005 Free Software Foundation, Inc.
mpi-genesis 8 *
mpi_second_cut 9 * This program is free software: you can redistribute it and/or modify
mpi-genesis 10 * it under the terms of the GNU General Public License as published by
mpi_second_cut 11 * the Free Software Foundation, either version 3 of the License, or
mpi-genesis 12 * (at your option) any later version.
mpi-genesis 13 *
mpi_second_cut 14 * This program is distributed in the hope that it will be useful,
mpi-genesis 15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
mpi-genesis 16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
mpi-genesis 17 * GNU General Public License for more details.
mpi-genesis 18 *
mpi-genesis 19 * You should have received a copy of the GNU General Public License
mpi_second_cut 20 * along with this program. If not, see <http://www.gnu.org/licenses/>.
mpi-genesis 21 */
mpi-genesis 22
mpi-genesis 23 #include <stdio.h>
mpi-genesis 24 #include <stdlib.h>
mpi_second_cut 25
mpi_second_cut 26 #include "knobs.h"
mpi-genesis 27 #include "mpi-internal.h"
mpi-genesis 28
mpi-genesis 29 /****************
mpi-genesis 30 * Find the greatest common divisor G of A and B.
mpi-genesis 31 * Return: true if this 1, false in all other cases
mpi-genesis 32 */
mpi-genesis 33 int
mpi-genesis 34 mpi_gcd( MPI g, MPI xa, MPI xb )
mpi-genesis 35 {
mpi-genesis 36 MPI a, b;
mpi-genesis 37
mpi-genesis 38 a = mpi_copy(xa);
mpi-genesis 39 b = mpi_copy(xb);
mpi-genesis 40
mpi-genesis 41 /* TAOCP Vol II, 4.5.2, Algorithm A */
mpi-genesis 42 a->sign = 0;
mpi-genesis 43 b->sign = 0;
mpi-genesis 44 while( mpi_cmp_ui( b, 0 ) ) {
mpi-genesis 45 mpi_fdiv_r( g, a, b ); /* g used as temorary variable */
mpi-genesis 46 mpi_set(a,b);
mpi-genesis 47 mpi_set(b,g);
mpi-genesis 48 }
mpi-genesis 49 mpi_set(g, a);
mpi-genesis 50
mpi-genesis 51 mpi_free(a);
mpi-genesis 52 mpi_free(b);
mpi-genesis 53 return !mpi_cmp_ui( g, 1);
mpi-genesis 54 }
mpi-genesis 55
mpi-genesis 56
mpi-genesis 57