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/*
* gcd.c
*
* Greatest common divisor
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "mpi.h"
char *g_prog = NULL;
void print_mp_int(mp_int *mp, FILE *ofp);
int
main(int argc, char *argv[])
{
mp_int a, b, x, y;
mp_err res;
int ext = 0;
g_prog = argv[0];
if (argc < 3) {
fprintf(stderr, "Usage: %s <a> <b>\n", g_prog);
return 1;
}
mp_init(&a);
mp_read_radix(&a, argv[1], 10);
mp_init(&b);
mp_read_radix(&b, argv[2], 10);
/* If we were called 'xgcd', compute x, y so that g = ax + by */
if (strcmp(g_prog, "xgcd") == 0) {
ext = 1;
mp_init(&x);
mp_init(&y);
}
if (ext) {
if ((res = mp_xgcd(&a, &b, &a, &x, &y)) != MP_OKAY) {
fprintf(stderr, "%s: error: %s\n", g_prog, mp_strerror(res));
mp_clear(&a);
mp_clear(&b);
mp_clear(&x);
mp_clear(&y);
return 1;
}
} else {
if ((res = mp_gcd(&a, &b, &a)) != MP_OKAY) {
fprintf(stderr, "%s: error: %s\n", g_prog,
mp_strerror(res));
mp_clear(&a);
mp_clear(&b);
return 1;
}
}
print_mp_int(&a, stdout);
if (ext) {
fputs("x = ", stdout);
print_mp_int(&x, stdout);
fputs("y = ", stdout);
print_mp_int(&y, stdout);
}
mp_clear(&a);
mp_clear(&b);
if (ext) {
mp_clear(&x);
mp_clear(&y);
}
return 0;
}
void
print_mp_int(mp_int *mp, FILE *ofp)
{
char *buf;
int len;
len = mp_radix_size(mp, 10);
buf = calloc(len, sizeof(char));
mp_todecimal(mp, buf);
fprintf(ofp, "%s\n", buf);
free(buf);
}
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