source: CIVL/examples/contracts/contractsMPI/broadcast.c@ 3c8cc6c

#include<mpi.h>
#include<civlc.cvh>
#pragma PARSE_ACSL
/*@ 
  @ \mpi_collective(comm, P2P):
  @   requires 0 <= root && root < \mpi_comm_size;
  @   requires \mpi_agree(root) && \mpi_agree(count * \mpi_extent(datatype));
  @   requires 0 < count && count * \mpi_extent(datatype) < 10;
  @   requires \mpi_valid(buf, count, datatype);
  @   assigns  \mpi_region(buf, count, datatype);
  @   ensures \mpi_equals(\mpi_region(buf, count, datatype), 
  @                       \mpi_region(\on(root, buf), count, datatype));
  @   waitsfor root;
  @*/
int broadcast(void * buf, int count, 
              MPI_Datatype datatype, int root, MPI_Comm comm) {
  int nprocs, rank;
  int tag = 999;

  MPI_Comm_size(comm, &nprocs);
  MPI_Comm_rank(comm, &rank);
  if (rank == root) {
    for (int i = 0; i < nprocs; i++)
      if (i != root)
        MPI_Send(buf, count, datatype, i, tag, comm);
  } else
    MPI_Recv(buf, count, datatype, root, tag, comm,
             MPI_STATUS_IGNORE);
  return 0;
}