RetroZilla/security/nss/lib/freebl/mpi/utils/gcd.c

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2015-10-21 05:03:22 +02:00
/*
* gcd.c
*
* Greatest common divisor
*
* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is the MPI Arbitrary Precision Integer Arithmetic library.
*
* The Initial Developer of the Original Code is
* Michael J. Fromberger.
* Portions created by the Initial Developer are Copyright (C) 1998
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
/* $Id: gcd.c,v 1.3 2004/04/27 23:04:37 gerv%gerv.net Exp $ */
#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);
}