Substitute for native MPI collectives

Substitute for native MPI collective operations in parallel applications

• add -I$(MPIBlib-dir)/include to CPPFLAGS
• add -L$(MPIBlib-dir)/lib -lmpib_coll to LDFLAGS
• replace #include <mpi.h> by #include "mpib_coll.h"
• define macro substitutes for native MPI collective operations #define MPI_Scatter MPIB_Scatter_flat

//#include <mpi.h>
#include "mpib_coll.h"
#define MPI_Scatter MPIB_Scatter_flat_nb
#define MPI_Gather MPIB_Gather_flat_nb

#include <malloc.h>

int main(int argc, char** argv)
{
    MPI_Init(&argc, &argv);
    int rank;
    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
    int size;
    MPI_Comm_size(MPI_COMM_WORLD, &size);
    int M = 1024;
    char* buffer = rank == 0 ? (char*)malloc(sizeof(char) * M * size) : (char*)malloc(sizeof(char) * M);
    MPI_Scatter(buffer, M, MPI_CHAR, buffer, M, MPI_CHAR, 0, MPI_COMM_WORLD);
    MPI_Gather(buffer, M, MPI_CHAR, buffer, M, MPI_CHAR, 0, MPI_COMM_WORLD);
    free(buffer);
    MPI_Finalize();
    return 0;
}