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/*******************************************************************************

 * proj1-parallel.c - implement a simple program that will find the minimum

 *                    and maximum numbers out of a randomly generated list of

 *                    integers, using MPI to parallelize the operation.

 *

 * Copyright (c) 2006, Ira W. Snyder (devel@irasnyder.com)

 * All rights reserved.

 *

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to

 * deal in the Software without restriction, including without limitation the

 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or

 * sell copies of the Software, and to permit persons to whom the Software is

 * furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS

 * IN THE SOFTWARE.

 ******************************************************************************/

#include <limits.h>

#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <mpi.h>

#define ROOT_NODE 0

#define TAG_MAX  0x1010

#define TAG_MIN  0x0101

#define TAG_SIZE 0x0808

#define TAG_DATA 0x0c0c

void find_max_and_min (const int *numbers, const int size, int *max, int *min)

{

    int i;

    *max = INT_MIN;

    *min = INT_MAX;

    for (i=0; i<size; i++)

    {

        if (numbers[i] > *max)

            *max = numbers[i];

        if (numbers[i] < *min)

            *min = numbers[i];

    }

}

int main (int argc, char *argv[])

{

    int numprocs, myid, i;

    int n = -1;

    int c = -1;

    int size;

    int *numbers;

    int max = INT_MIN;

    int min = INT_MAX;

    int temp;

    MPI_Status status;

    MPI_Init (&argc, &argv);

    MPI_Comm_size (MPI_COMM_WORLD, &numprocs);

    MPI_Comm_rank (MPI_COMM_WORLD, &myid);

    if (myid == ROOT_NODE)

    {

        /* Parse the command line options */

        opterr = 0;

        while ((c = getopt (argc, argv, "n:")) != -1)

        {

            switch (c)

            {

                /* Try to get -n option */

                case 'n':

                    n = atoi (optarg);

                    break;

                /* Catch bad options */

                case '?':

                    if (isprint (optopt))

                        fprintf (stderr, "Unknown option '-%c'.\n", optopt);

                    else

                        fprintf (stderr, "Unknown option character '\\x%x'.\n", optopt);

                    return 1;

                    break;

                default:

                    abort ();

            }

        }

        /* Seed the random number generator */

        srand (time(NULL));

        /* Check if the n value is valid */

        if (n<=0)

        {

            fprintf (stderr, "Bad value for n, must be greater than 0\n");

            fprintf (stderr, "Please specify the '-n NUMBER' option\n");

            return 1;

        }

        /* Allocate memory for the random number array */

        if ((numbers = (int*) malloc (n * sizeof(int))) == NULL)

        {

            puts ("Out of memory");

            return 1;

        }

        /* Generate random numbers, staying in the range [0,10n) */

        for (i=0; i<n; i++)

            numbers[i] = (int) ((n*10.0) * rand() / (RAND_MAX + 1.0));

        /* Calculate slice size */

        size = n/numprocs;

        /* Send out n to everyone */

        for (i=1; i<numprocs; i++)

            MPI_Send (&size, 1, MPI_INT, i, TAG_SIZE, MPI_COMM_WORLD);

        /* Send out data to everyone */

        for (i=1; i<numprocs; i++)

            MPI_Send (numbers+(size*i), size, MPI_INT, i, TAG_DATA, MPI_COMM_WORLD);

        /* Calculate my part of the data */

        find_max_and_min (numbers, size, &max, &min);

        /* Recieve data back */

        for (i=1; i<numprocs; i++)

        {

            /* Find actual max */

            MPI_Recv (&temp, 1, MPI_INT, i, TAG_MAX, MPI_COMM_WORLD, &status);

            if (temp > max)

                max = temp;

            /* Find actual min */

            MPI_Recv (&temp, 1, MPI_INT, i, TAG_MIN, MPI_COMM_WORLD, &status);

            if (temp < min)

                min = temp;

        }

        printf ("final max: %d\n", max);

        printf ("final min: %d\n", min);

    }

    else // not ROOT_NODE

    {

        /* Recieve size of the data */

        MPI_Recv (&size, 1, MPI_INT, ROOT_NODE, TAG_SIZE, MPI_COMM_WORLD, &status);

        /* Allocate memory to store the data */

        if ((numbers = (int*) malloc (size * sizeof(int))) == NULL)

        {

            puts ("Out of memory");

            return 1;

        }

        /* Recieve the data */

        MPI_Recv (numbers, size, MPI_INT, ROOT_NODE, TAG_DATA, MPI_COMM_WORLD, &status);

        /* Calculate the max and min of my part of the data */

        find_max_and_min (numbers, size, &max, &min);

        /* Send the max and min back to the root node */

        MPI_Send (&max, 1, MPI_INT, ROOT_NODE, TAG_MAX, MPI_COMM_WORLD);

        MPI_Send (&min, 1, MPI_INT, ROOT_NODE, TAG_MIN, MPI_COMM_WORLD);

        free (numbers);

    }

    MPI_Finalize ();

    return 0;

}