MPI_PACK, MPI_Pack

Purpose

Packs the message in the specified send buffer into the specified buffer
space.

C synopsis

#include <mpi.h>
int MPI_Pack(void* inbuf,int incount,MPI_Datatype datatype,
             void *outbuf,int outsize,int *position,MPI_Comm comm);

C++ synopsis

#include mpi.h
void MPI::Datatype::Pack(const void* inbuf, int incount, void* outbuf,
                         int outsize, int& position, const MPI::Comm& comm)
                         const;

FORTRAN synopsis

include 'mpif.h' or use mpi
MPI_PACK(CHOICE INBUF,INTEGER INCOUNT,INTEGER DATATYPE,CHOICE OUTBUF,
         INTEGER OUTSIZE,INTEGER POSITION,INTEGER COMM,INTEGER IERROR)

Parameters

inbuf
     is the input buffer start (choice) (IN)

incount
     is an integer specifying the number of input data items (IN)

datatype
     is the datatype of each input data item (handle) (IN)

outbuf
     is the output buffer start (choice) (OUT)

outsize
     is an integer specifying the output buffer size in bytes (OUT)

position
     is the current position in the output buffer counted in bytes
     (integer) (INOUT)

comm
     is the communicator for sending the packed message (handle) (IN)

IERROR
     is the FORTRAN return code. It is always the last argument.

Description

This subroutine packs the message specified by inbuf, incount, and datatype
into the buffer space specified by outbuf and outsize. The input buffer is
any communication buffer allowed in MPI_SEND. The output buffer is any
contiguous storage space containing outsize bytes and starting at the
address outbuf.

The input value of position is the beginning offset in the output buffer
that will be used for packing. The output value of position is the offset
in the output buffer following the locations occupied by the packed
message. comm is the communicator that will be used for sending the packed
message.

Notes

MPI_PACK must be used with some care in 64-bit applications because outsize
and position are integers and can be subject to overflow.

Errors

Invalid incount
     incount < 0

Invalid datatype

Type not committed

Invalid communicator

Outbuf too small

Negative length or position for buffer
     outsize < 0 or position < 0

MPI not initialized

MPI already finalized

Related information

     MPI_PACK_SIZE