/***************************************************************************
 *   Copyright (C) 2010 by Michael Fischer                                 *
 *   fischer-michael@cs.yale.edu                                           *
 *                                                                         *
 *   For use in Yale course CPSC 467b, Spring 2010                         *
 ***************************************************************************/

// Compute a^b (mod c) using gmp library
//usage:  modexp-ssl a b c

#include <stdio.h>
#include <stdlib.h>
#include <gmp.h>
#include "stopwatch.h"

// ----------------------------------------------------------------------------
int main(int argc, char* argv[]) {
	stopwatch watch;

	if (argc != 4) {
		fprintf(stderr, "usage: %s a b c\n", argv[0]);
		return 1;
	}

	/* Start timing */
	startTime(&watch);

	mpz_t a;
	mpz_init(a);
	mpz_t b;
	mpz_init(b);
	mpz_t c;
	mpz_init(c);
	mpz_t d;
	mpz_init(d);

	mpz_set_str(a, argv[1], 10);
	mpz_set_str(b, argv[2], 10);
	mpz_set_str(c, argv[3], 10);

	mpz_powm(d, a, b, c);

	char* s = mpz_get_str(NULL, 10, d);
	puts(s);
	free(s);

	mpz_clear(a);
	mpz_clear(b);
	mpz_clear(c);
	mpz_clear(d);

	// Stop timing
	stopTime(&watch);

	// Print timing results
	printElapsedTime(&watch);
}