isprime.c
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上传日期:2007-01-12
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文件大小:3k
- /*
- * isprime.c
- *
- * Probabilistic primality tester command-line tool
- *
- * 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 Michael J. Fromberger are
- * Copyright (C) 1998, 1999, 2000 Michael J. Fromberger.
- * All Rights Reserved.
- *
- * Contributor(s):
- *
- * Alternatively, the contents of this file may be used under the
- * terms of the GNU General Public License Version 2 or later (the
- * "GPL"), in which case the provisions of the GPL are applicable
- * instead of those above. If you wish to allow use of your
- * version of this file only under the terms of the GPL and not to
- * allow others to use your version of this file under the MPL,
- * indicate your decision by deleting the provisions above and
- * replace them with the notice and other provisions required by
- * the GPL. If you do not delete the provisions above, a recipient
- * may use your version of this file under either the MPL or the GPL.
- *
- * $Id: isprime.c,v 1.1 2000/07/14 00:44:58 nelsonb%netscape.com Exp $
- */
- #include <stdio.h>
- #include <stdlib.h>
- #include <string.h>
- #include "mpi.h"
- #include "mpprime.h"
- #define RM_TESTS 15 /* how many iterations of Rabin-Miller? */
- #define MINIMUM 1024 /* don't bother us with a < this */
- int g_tests = RM_TESTS;
- char *g_prog = NULL;
- int main(int argc, char *argv[])
- {
- mp_int a;
- mp_digit np = prime_tab_size; /* from mpprime.h */
- int res = 0;
- g_prog = argv[0];
- if(argc < 2) {
- fprintf(stderr, "Usage: %s <a>, where <a> is a decimal integern"
- "Use '0x' prefix for a hexadecimal valuen", g_prog);
- return 1;
- }
- /* Read number of tests from environment, if present */
- {
- char *tmp;
- if((tmp = getenv("RM_TESTS")) != NULL) {
- if((g_tests = atoi(tmp)) <= 0)
- g_tests = RM_TESTS;
- }
- }
- mp_init(&a);
- if(argv[1][0] == '0' && argv[1][1] == 'x')
- mp_read_radix(&a, argv[1] + 2, 16);
- else
- mp_read_radix(&a, argv[1], 10);
- if(mp_cmp_d(&a, MINIMUM) <= 0) {
- fprintf(stderr, "%s: please use a value greater than %dn",
- g_prog, MINIMUM);
- mp_clear(&a);
- return 1;
- }
- /* Test for divisibility by small primes */
- if(mpp_divis_primes(&a, &np) != MP_NO) {
- printf("Not prime (divisible by small prime %d)n", np);
- res = 2;
- goto CLEANUP;
- }
- /* Test with Fermat's test, using 2 as a witness */
- if(mpp_fermat(&a, 2) != MP_YES) {
- printf("Not prime (failed Fermat test)n");
- res = 2;
- goto CLEANUP;
- }
-
- /* Test with Rabin-Miller probabilistic test */
- if(mpp_pprime(&a, g_tests) == MP_NO) {
- printf("Not prime (failed pseudoprime test)n");
- res = 2;
- goto CLEANUP;
- }
- printf("Probably prime, 1 in 4^%d chance of false positiven", g_tests);
- CLEANUP:
- mp_clear(&a);
-
- return res;
- }