/*
This program demonstrate the issue of message matchiong and mismatching. 
*/

/* Compile : mpicc -o message_match message_match.c */
/* Run     : mpirun -np 2 message_match      */

#include "mpi.h"
#include <stdio.h>
#define SIZE 15

int main(int argc,char *argv[]) {
        int pid, np, i, count, element,flag;
        int a[SIZE],b[SIZE];
        MPI_Status stat;
        MPI_Datatype MPI_2D_POINTs;
        MPI_Datatype MPI_3D_POINTs;

MPI_Init(&argc,&argv);
MPI_Comm_rank(MPI_COMM_WORLD, &pid);
MPI_Comm_size(MPI_COMM_WORLD, &np);
   
for (i=0;i<SIZE;i++)    a[i]=i;

MPI_Type_contiguous(2, MPI_DOUBLE, &MPI_2D_POINTs);
MPI_Type_commit(&MPI_2D_POINTs);

MPI_Type_contiguous(3, MPI_DOUBLE, &MPI_3D_POINTs);
MPI_Type_commit(&MPI_3D_POINTs);

if (np == 2)
   if (pid == 0) {
       MPI_Send(a, 4, MPI_3D_POINTs, 1, 1, MPI_COMM_WORLD);
       printf("(%d)Case 1: Send 4 units of MPI_3D_POINTs.\n",pid);
       MPI_Send(a, 5, MPI_3D_POINTs, 1, 2, MPI_COMM_WORLD);
       printf("(%d)Case 2: Send 5 units of MPI_3D_POINTs.\n",pid);
   }
   else {
       MPI_Recv(b, 10, MPI_2D_POINTs, 0, 1, MPI_COMM_WORLD, &stat); 
       MPI_Get_count(&stat,MPI_2D_POINTs,&count);
       MPI_Get_elements(&stat,MPI_2D_POINTs,&element);
       printf("(%d)Case 1: MPI_2D_POINTs:- count= %d, element= %d\n",pid,count,element);
       MPI_Recv(b, 10, MPI_2D_POINTs, 0, 2, MPI_COMM_WORLD, &stat); 
       flag=MPI_Get_count(&stat,MPI_2D_POINTs,&count);
       MPI_Get_elements(&stat,MPI_2D_POINTs,&element);
       printf("(%d)Case 2: MPI_2D_POINTs:- count= %d, element= %d, flag= %d.\n",
                pid,count,element,flag);
   }
else
  printf("Must specify 2 processors. Terminating.\n");
   
MPI_Finalize();
}