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MPI_Pack_external_size - Calculates upper bound on space needed
to write to a portable format
#include <mpi.h>
int MPI_Pack_external_size(char *datarep, int incount,
MPI_Datatype datatype, MPI_Aint *size)
INCLUDE ’mpif.h’
MPI_PACK_EXTERNAL_SIZE(DATAREP, INCOUNT, DATATYPE, SIZE, IERROR)
INTEGER INCOUNT, DATATYPE, IERROR
INTEGER (KIND=MPI_ADDRESS_KIND) SIZE
CHARACTER*(*) DATAREP
#include <mpi.h>
MPI::Aint MPI::Datatype::Pack_external_size(const char* datarep,
int incount) const
- datarep
- Data representation (string).
- incount
- Number of
input data items (integer).
- datatype
- Datatype of each input data item (handle).
- size
- Upper bound on size of packed message, in bytes
(integer).
- IERROR
- Fortran only: Error status (integer).
MPI_Pack_external_size
allows the application to find out how much space is needed to pack a message
in the portable format defined by the MPI Forum. It returns in size an upper
bound on the increment in position that would occur in a call to MPI_Pack_external
with the same values for datarep, incount, and datatype.
The call returns
an upper bound, rather than an exact bound, as the exact amount of space
needed to pack the message may depend on context and alignment (e.g., the
first message packed in a packing unit may take more space).
The datarep
argument specifies the data format. The only valid value in the current
version of MPI is "external32". The argument is provided for future extensibility.
Almost all MPI routines return an error value; C routines as the
value of the function and Fortran routines in the last argument. C++ functions
do not return errors. If the default error handler is set to MPI::ERRORS_THROW_EXCEPTIONS,
then on error the C++ exception mechanism will be used to throw an MPI::Exception
object.
Before the error value is returned, the current MPI error handler
is called. By default, this error handler aborts the MPI job, except for
I/O function errors. The error handler may be changed with MPI_Comm_set_errhandler;
the predefined error handler MPI_ERRORS_RETURN may be used to cause error
values to be returned. Note that MPI does not guarantee that an MPI program
can continue past an error.
See the MPI man page for a full list of MPI
error codes.
MPI_Pack_external
MPI_Unpack_external
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