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MPI_File_read_at_all(3OpenMPI)                                                MPI_File_read_at_all(3OpenMPI)



NAME
       MPI_File_read_at_all - Reads a file at explicitly specified offsets (blocking, collective).


SYNTAX
       C Syntax
           #include <mpi.h>
           int MPI_File_read_at_all(MPI_File fh, MPI_Offset offset,
            void *buf, int count, MPI_Datatype datatype,
            MPI_Status *status)

       Fortran Syntax (see FORTRAN 77 NOTES)
           INCLUDE 'mpif.h'
           MPI_FILE_READ_AT_ALL(FH,  OFFSET,  BUF, COUNT,
                   DATATYPE, STATUS,  IERROR)
             <type> BUF(*)
             INTEGER FH, COUNT, DATATYPE, STATUS(MPI_STATUS_SIZE), IERROR
             INTEGER(KIND=MPI_OFFSET_KIND) OFFSET


C++ Syntax
       #include <mpi.h>
       void MPI::File::Read_at_all(MPI::Offset offset, void* buf,
            int count, const MPI::Datatype& datatype, MPI::Status& status)

       void MPI::File::Read_at_all(MPI::Offset offset, void* buf,
            int count, const MPI::Datatype& datatype)


INPUT PARAMETERS
       fh        File handle (handle).

       offset    File offset (integer).

       count     Number of elements in buffer (integer).

       datatype  Data type of each buffer element (handle).


OUTPUT PARAMETERS
       buf       Initial address of buffer (choice).

       status    Status object (status).

       IERROR    Fortran only: Error status (integer).


DESCRIPTION
       MPI_File_read_at_all  is  a collective routine that attempts to read from the file associated with fh
       (at the offset position) a total number of count data items having  datatype  type  into  the  user's
       buffer  buf.   The  offset  is  in  etype  units relative to the current view. That is, holes are not
       counted when locating an offset. The data is taken out of those parts of the file  specified  by  the
       current  view.  MPI_File_read_at_all  stores the number of datatype elements actually read in status.
       All other fields of status are undefined. It is erroneous to call this function  if  MPI_MODE_SEQUEN-TIAL MPI_MODE_SEQUENTIAL
       TIAL mode was specified when the file was opened.


FORTRAN 77 NOTES
       The MPI standard prescribes portable Fortran syntax for the OFFSET argument only for Fortran 90. FOR-TRAN FORTRAN
       TRAN 77 users may use the non-portable syntax

            INTEGER*MPI_OFFSET_KIND OFFSET

       where MPI_OFFSET_KIND is a constant defined in mpif.h and gives the length of the declared integer in
       bytes.


ERRORS
       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.  For  MPI  I/O  function
       errors,  the default error handler is set to MPI_ERRORS_RETURN. The error handler may be changed with
       MPI_File_set_errhandler; the predefined error handler MPI_ERRORS_ARE_FATAL may be used  to  make  I/O
       errors fatal. Note that MPI does not guarantee that an MPI program can continue past an error.




Open MPI 1.2                                   September 2006                 MPI_File_read_at_all(3OpenMPI)