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/*
* isprime.c
*
* Probabilistic primality tester command-line tool
*
* 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"
#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 integer\n"
"Use '0x' prefix for a hexadecimal value\n", 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 %d\n",
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 positive\n", g_tests);
CLEANUP:
mp_clear(&a);
return res;
}
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