/*
 *  metime.c
 *
 * Modular exponentiation timing 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 "mpi.h"
#include "mpprime.h"

double clk_to_sec(clock_t start, clock_t stop);

int
main(int argc, char *argv[])
{
    int ix, num, prec = 8;
    unsigned int seed;
    clock_t start, stop;
    double sec;

    mp_int a, m, c;

    if (PR_GetEnvSecure("SEED") != NULL)
        seed = abs(atoi(PR_GetEnvSecure("SEED")));
    else
        seed = (unsigned int)time(NULL);

    if (argc < 2) {
        fprintf(stderr, "Usage: %s <num-tests> [<nbits>]\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;
        else
            prec = (prec + (DIGIT_BIT - 1)) / DIGIT_BIT;
    }

    printf("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);

    srand(seed);

    start = clock();
    for (ix = 0; ix < num; ix++) {

        mpp_random_size(&a, prec);
        mpp_random_size(&c, prec);
        mpp_random_size(&m, prec);
        /* set msb and lsb of m */
        DIGIT(&m, 0) |= 1;
        DIGIT(&m, USED(&m) - 1) |= (mp_digit)1 << (DIGIT_BIT - 1);
        if (mp_cmp(&a, &m) > 0)
            mp_sub(&a, &m, &a);

        mp_exptmod(&a, &c, &m, &c);
    }
    stop = clock();

    sec = clk_to_sec(start, stop);

    printf("Total:      %.3f seconds\n", sec);
    printf("Individual: %.3f seconds\n", sec / num);

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

    return 0;
}

double
clk_to_sec(clock_t start, clock_t stop)
{
    return (double)(stop - start) / CLOCKS_PER_SEC;
}

/*------------------------------------------------------------------------*/
/* HERE THERE BE DRAGONS                                                  */