/*
 *  lap.c
 *
 *  Find least annihilating power of a mod m
 *
 * 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 <signal.h>

#include "mpi.h"

void sig_catch(int ign);

int g_quit = 0;

int
main(int argc, char *argv[])
{
    mp_int a, m, p, k;

    if (argc < 3) {
        fprintf(stderr, "Usage: %s <a> <m>\n", argv[0]);
        return 1;
    }

    mp_init(&a);
    mp_init(&m);
    mp_init(&p);
    mp_add_d(&p, 1, &p);

    mp_read_radix(&a, argv[1], 10);
    mp_read_radix(&m, argv[2], 10);

    mp_init_copy(&k, &a);

    signal(SIGINT, sig_catch);
#ifndef __OS2__
    signal(SIGHUP, sig_catch);
#endif
    signal(SIGTERM, sig_catch);

    while (mp_cmp(&p, &m) < 0) {
        if (g_quit) {
            int len;
            char *buf;

            len = mp_radix_size(&p, 10);
            buf = malloc(len);
            mp_toradix(&p, buf, 10);

            fprintf(stderr, "Terminated at: %s\n", buf);
            free(buf);
            return 1;
        }
        if (mp_cmp_d(&k, 1) == 0) {
            int len;
            char *buf;

            len = mp_radix_size(&p, 10);
            buf = malloc(len);
            mp_toradix(&p, buf, 10);

            printf("%s\n", buf);

            free(buf);
            break;
        }

        mp_mulmod(&k, &a, &m, &k);
        mp_add_d(&p, 1, &p);
    }

    if (mp_cmp(&p, &m) >= 0)
        printf("No annihilating power.\n");

    mp_clear(&p);
    mp_clear(&m);
    mp_clear(&a);
    return 0;
}

void
sig_catch(int ign)
{
    g_quit = 1;
}