io_read_plane.f90

!=======================================================================
! This is part of the 2DECOMP&FFT library
! 
! 2DECOMP&FFT is a software framework for general-purpose 2D (pencil) 
! decomposition. It also implements a highly scalable distributed
! three-dimensional Fast Fourier Transform (FFT).
!
! Copyright (C) 2009-2011 Ning Li, the Numerical Algorithms Group (NAG)
!
!=======================================================================

! This file contain common code to be included by subroutines 
! 'mpiio_read_one_...' in io.f90

    ! Using MPI-IO to read a 2D array from a file
    if (present(opt_decomp)) then
       decomp = opt_decomp
    else
       call get_decomp_info(decomp)
    end if
 

!    if (iplane==1) then
       allocate(wk2d(decomp%xsz(2),decomp%xsz(3)))

       sizes(1) = 1
       sizes(2) = decomp%ysz(2)
       sizes(3) = decomp%zsz(3)

       subsizes(1) = 1
       subsizes(2) = decomp%xsz(2)
       subsizes(3) = decomp%xsz(3)
       starts(1) = 0
       starts(2) = decomp%xst(2)-1
       starts(3) = decomp%xst(3)-1
!    end if)

    call MPI_TYPE_CREATE_SUBARRAY(3, sizes, subsizes, starts,  &
         MPI_ORDER_FORTRAN, data_type, newtype, ierror)
    call MPI_TYPE_COMMIT(newtype,ierror)
    call MPI_FILE_OPEN(MPI_COMM_WORLD, filename, &
         MPI_MODE_RDONLY, MPI_INFO_NULL, &
         fh, ierror)
    disp = 0_MPI_OFFSET_KIND
    call MPI_FILE_SET_VIEW(fh,disp,data_type, &
         newtype,'native',MPI_INFO_NULL,ierror)
    call MPI_FILE_READ_ALL(fh, wk2d, &
         subsizes(1)*subsizes(2)*subsizes(3), &
         data_type, MPI_STATUS_IGNORE, ierror)
    call MPI_FILE_CLOSE(fh,ierror)
    call MPI_TYPE_FREE(newtype,ierror)
  !  do k=1,decomp%xsz(3)
  !        do j=1,decomp%xsz(2)
  !           wk(n,j,k)=wk2d(1,j,k)
  !        end do
  !     end do
     var=wk2d
    deallocate(wk2d)

!    if ( any(isnan(var)) ) then
!      print*,'ERROR in read_plane : NaN after reading.'
!      return
!    endif