/*
 *  mptest4a - modular exponentiation speed test
 *
 * 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 <limits.h>
#include <time.h>

#include <sys/time.h>

#include "mpi.h"
#include "mpprime.h"

typedef struct {
    unsigned int sec;
    unsigned int usec;
} instant_t;

instant_t
now(void)
{
    struct timeval clk;
    instant_t res;

    res.sec = res.usec = 0;

    if (gettimeofday(&clk, NULL) != 0)
        return res;

    res.sec = clk.tv_sec;
    res.usec = clk.tv_usec;

    return res;
}

extern mp_err s_mp_pad();

int
main(int argc, char *argv[])
{
    int ix, num, prec = 8;
    unsigned int d;
    instant_t start, finish;
    time_t seed;
    mp_int a, m, c;

    seed = time(NULL);

    if (argc < 2) {
        fprintf(stderr, "Usage: %s <num-tests> [<precision>]\n", argv[0]);
        return 1;
    }

    if ((num = atoi(argv[1])) < 0)
        num = -num;

    if (!num) {
        fprintf(stderr, "%s: must perform at least 1 test\n", argv[0]);
        return 1;
    }

    if (argc > 2) {
        if ((prec = atoi(argv[2])) <= 0)
            prec = 8;
    }

    printf("Test 3a: Modular exponentiation timing test\n"
           "Precision:  %d digits (%d bits)\n"
           "# of tests: %d\n\n",
           prec, prec * DIGIT_BIT, num);

    mp_init_size(&a, prec);
    mp_init_size(&m, prec);
    mp_init_size(&c, prec);
    s_mp_pad(&a, prec);
    s_mp_pad(&m, prec);
    s_mp_pad(&c, prec);

    printf("Testing modular exponentiation ... \n");
    srand((unsigned int)seed);

    start = now();
    for (ix = 0; ix < num; ix++) {
        mpp_random(&a);
        mpp_random(&c);
        mpp_random(&m);
        mp_exptmod(&a, &c, &m, &c);
    }
    finish = now();

    d = (finish.sec - start.sec) * 1000000;
    d -= start.usec;
    d += finish.usec;

    printf("Total time elapsed:        %u usec\n", d);
    printf("Time per exponentiation:   %u usec (%.3f sec)\n",
           (d / num), (double)(d / num) / 1000000);

    mp_clear(&c);
    mp_clear(&a);
    mp_clear(&m);

    return 0;
}