triangular-pack.c

mpi并行计算的c++代码 可用vc或gcc编译通过 可以用来搭建并行计算试验环境

/* -*- Mode: C; c-basic-offset:4 ; -*- */
/*
 *  (C) 2001 by Argonne National Laboratory.
 *      See COPYRIGHT in top-level directory.
 */
#include <math.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include "mpi.h"

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

/* helper functions */
int parse_args(int argc, char **argv);

static int verbose = 0;

int main(int argc, char *argv[])
{
    /* Variable declarations */
    int a[100][100], b[100][100];
    int disp[100], block[100];
    MPI_Datatype ltype;
	
    int bufsize, position = 0;
    void *buffer;
	
    int i, j, errs = 0;
	
    /* Initialize a to some known values and zero out b. */
    for(i = 0; i < 100; i++) {
	for(j = 0; j < 100; j++) {
	    a[i][j] = 1000*i + j;
	    b[i][j] = 0;
	}
    }
	
    /* Initialize MPI */
    MPI_Init(&argc, &argv);
  
    parse_args(argc, argv);

    for(i = 0; i < 100; i++) {
	/* Fortran version has disp(i) = 100*(i-1) + i and block(i) = 100-i. */
	/* This code here is wrong. It compacts everything together,
	 * which isn't what we want.
	 * What we want is to put the lower triangular values into b and leave
	 * the rest of it unchanged, right?
	 */
	block[i] = i+1;
	disp[i] = 100*i;
    }
	
    /* Create datatype for lower triangular part. */
    MPI_Type_indexed(100, block, disp, MPI_INT, &ltype);
    MPI_Type_commit(&ltype);
	
    /* Pack it. */
    MPI_Pack_size(1, ltype, MPI_COMM_WORLD, &bufsize);
    buffer = (void *) malloc((unsigned) bufsize);
    MPI_Pack( a, 1, ltype, buffer, bufsize, &position, MPI_COMM_WORLD );
	
    /* Unpack the buffer into b. */
    position = 0;
    MPI_Unpack(buffer, bufsize, &position, b, 1, ltype, MPI_COMM_WORLD);
	
    for(i = 0; i < 100; i++) {
	for(j = 0; j < 100; j++) {
	    if (j > i && b[i][j] != 0) {
		errs++;
		if (verbose) fprintf(stderr, "b[%d][%d] = %d; should be %d\n",
				     i, j, b[i][j], 0);
	    }
	    else if (j <= i && b[i][j] != 1000*i + j) {
		errs++;
		if (verbose) fprintf(stderr, "b[%d][%d] = %d; should be %d\n",
				     i, j, b[i][j], 1000*i + j);
	    }
	}
    }

    /* print message and exit */
    if (errs) {
	fprintf(stderr, "Found %d errors\n", errs);
    }
    else {
	printf(" No errors\n");
    }
    MPI_Finalize();
    return 0;
}

int parse_args(int argc, char **argv)
{
    int ret;

    while ((ret = getopt(argc, argv, "v")) >= 0)
    {
	switch (ret) {
	    case 'v':
		verbose = 1;
		break;
	}
    }
    return 0;
}