Using Explicit Offsets

include 'mpif.h'

integer status(MPI_STATUS_SIZE)

integer (kind=MPI_OFFSET_KIND) offset

C in F77, see implementation notes (might be integer*8)

call MPI_FILE_OPEN(MPI_COMM_WORLD, '/pfs/datafile', &

MPI_MODE_RDONLY, MPI_INFO_NULL, fh, ierr)

nints = FILESIZE / (nprocs*INTSIZE)

offset = rank * nints * INTSIZE

call MPI_FILE_READ_AT(fh, offset, buf, nints,

MPI_INTEGER, status, ierr)

call MPI_GET_COUNT(status, MPI_INTEGER, count, ierr)

print *, 'process ', rank, 'read ', count, 'integers'

call MPI_FILE_CLOSE(fh, ierr)

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