MPI Subroutine Reference

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

MPI_UNPACK