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)

       USE MPI
       ! or the older form: 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_SEQUENTIAL 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. FORTRAN 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.