pack_unpack.cc
5454280b8282master

pack_unpack.cc
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			#include <assert.h>
			#include <iostream>
			#include <mpi.h>
			#include <vector>

			void fill_buffer(std::vector<int> &buf) {
			for (auto &v : buf) {
			v = 0;
			}
			}

			int main() {
			int rank, size;
			std::vector<char> buf(100);
			int position{0}, count;
			MPI_Status status;

			int a;
			double d[10];

			MPI_Init(NULL, NULL);
			MPI_Comm_rank(MPI_COMM_WORLD, &rank);
			MPI_Comm_size(MPI_COMM_WORLD, &size);

			assert(size == 2 && "Works only with 2 procs");

			if (rank == 0) {
			a = 0xcafe;
			MPI_Pack(&a, 1, MPI_INT, buf.data(), buf.size(), &position, MPI_COMM_WORLD);
			MPI_Pack(d, 10, MPI_DOUBLE, buf.data(), buf.size(), &position,
			MPI_COMM_WORLD);
			MPI_Send(buf.data(), position, MPI_PACKED, 1, 0, MPI_COMM_WORLD);
			} else if (rank == 1) {
			MPI_Recv(buf.data(), buf.size(), MPI_PACKED, 0, 0, MPI_COMM_WORLD, &status);
			MPI_Unpack(buf.data(), buf.size(), &position, &a, 1, MPI_INT,
			MPI_COMM_WORLD);
			MPI_Unpack(buf.data(), buf.size(), &position, d, 10, MPI_DOUBLE,
			MPI_COMM_WORLD);
			}

			if (rank == 1) {
			MPI_Get_count(&status, MPI_PACKED, &count);
			std::cout << " position: " << position << " count: " << count << " - a: 0x"
			<< std::hex << a << std::endl;
			}

			MPI_Finalize();

			return 0;
			}