Unpack a datatype into contiguous memory


#include "mpi.h"
int MPI_Unpack ( inbuf, insize, position, outbuf, outcount, datatype, comm )
void         *inbuf;
int           insize;
int          *position;
void         *outbuf;
int           outcount;
MPI_Datatype  datatype;
MPI_Comm      comm;

Input Parameters

inbuf - input buffer start (choice)
insize - size of input buffer, in bytes (integer)
position - current position in bytes (integer)
outcount - number of items to be unpacked (integer)
datatype - datatype of each output data item (handle)
comm - communicator for packed message (handle)

Output Parameter

outbuf - output buffer start (choice)

Notes for Fortran

All MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK) have an additional argument ierr at the end of the argument list. ierr is an integer and has the same meaning as the return value of the routine in C. In Fortran, MPI routines are subroutines, and are invoked with the call statement.

All MPI objects (e.g., MPI_Datatype, MPI_Comm) are of type INTEGER in Fortran.


All MPI routines (except MPI_Wtime and MPI_Wtick) return an error value; C routines as the value of the function and Fortran routines in the last argument. Before the value is returned, the current MPI error handler is called. By default, this error handler aborts the MPI job. The error handler may be changed with MPI_Errhandler_set; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarentee that an MPI program can continue past an error.

MPI_SUCCESS - No error; MPI routine completed successfully.
MPI_ERR_COMM - Invalid communicator. A common error is to use a null communicator in a call (not even allowed in MPI_Comm_rank).
MPI_ERR_COUNT - Invalid count argument. Count arguments must be non-negative; a count of zero is often valid.
MPI_ERR_TYPE - Invalid datatype argument. May be an uncommitted
MPI_Datatype (see MPI_Type_commit).
MPI_ERR_ARG - Invalid argument. Some argument is invalid and is not identified by a specific error class (e.g., MPI_ERR_RANK).

See Also

MPI_Pack, MPI_Pack_size