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LAYOUT("0DHPF_ARRAY"0D) and PASS_BY("0DHPF_HANDLE"0D)

This example performs only the initialization of the above example. It illustrates use of the LAYOUT("0DF77_ARRAY"0D) attribute to pass an HPF distributed array without remapping, as well as use of PASS_BY("0DHPF_HANDLE"0D) to pass an HPF-style descriptor or handle for use in the F77_LOCAL subgrid inquiry function. It also illustrates the addressing of data in terms of ``embedding arrays.''

• HPF caller

        PROGRAM EXAMPLE
  
        INTEGER, PARAMETER :: NX = 100, NY = 100
        REAL, DIMENSION(NX,NY) :: Y
  !HPF$ DISTRIBUTE(BLOCK,BLOCK) :: Y
  
  ! Local subgrid parameters are declared per processor
  ! for a rank-two array
        INTEGER, DIMENSION(NUMBER_OF PROCESSORS(),2) ::
       & LB, UB, LB_EMBED, UB_EMBED
  !HPF$ DISTRIBUTE(BLOCK,*) :: LB, UB, LB_EMBED, UB_EMBED
  
  ! Define interfaces
  
        INTERFACE
  
          EXTRINSIC(F77_LOCAL) SUBROUTINE LOCAL1(
       &   LB1, UB1, LB_EMBED1, UB_EMBED1,
       &   LB2, UB2, LB_EMBED2, UB_EMBED2, X, X_DESC )
          INTEGER, DIMENSION(:) ::
       &   LB1, UB1, LB_EMBED1, UB_EMBED1,
       &   LB2, UB2, LB_EMBED2, UB_EMBED2
   !             By default, X is passed by reference
          REAL, DIMENSION(:,:), LAYOUT('HPF_ARRAY') :: X
   !             X_DESC is passed by its descriptor or 'handle'
          REAL, DIMENSION(:,:), LAYOUT('HPF_ARRAY'),
       &                    PASS_BY('HPF_HANDLE') :: X_DESC
  !HPF$ DISTRIBUTE(BLOCK) :: LB1, UB1, LB_EMBED1, UB_EMBED1
  !HPF$ DISTRIBUTE(BLOCK) :: LB2, UB2, LB_EMBED2, UB_EMBED2
  !HPF$ DISTRIBUTE(BLOCK,BLOCK) :: X
          END
  
        END INTERFACE
  
  ! Initialize values
  ! ( Assume stride = 1 and no axis permutation )
  
        CALL HPF_SUBGRID_INFO( Y, IERR,
       & LB=LB, LB_EMBED=LB_EMBED,
       & UB=UB, UB_EMBED=UB_EMBED)
        IF (IERR.NE.0) STOP 'ERROR!'
  
        CALL LOCAL1(
       & LB(:,1), UB(:,1), LB_EMBED(:,1), UB_EMBED(:,1),
       & LB(:,2), UB(:,2), LB_EMBED(:,2), UB_EMBED(:,2), Y, Y )
  
        END
  

• Fortran 77 callee

        SUBROUTINE LOCAL1(
       & LB1, UB1, LB_EMBED1, UB_EMBED1,
       & LB2, UB2, LB_EMBED2, UB_EMBED2, X, X_DESC )
  
  ! The subgrid has been passed in its 'embedded' form
        REAL X ( LB_EMBED1 : UB_EMBED1 , LB_EMBED2 : UB_EMBED2 )
  
  ! This argument is used only as input to inquiry functions
        INTEGER X_DESC
  
  ! Get the global extent of the first axis
  ! This is an HPF_LOCAL type of inquiry routine with an 'F77_' prefix
        CALL F77_GLOBAL_SIZE(NX,X_DESC,1)
  
  ! Otherwise, initialize elements of the array
  ! Loop only over actual array elements
        DO J = LB2, UB2
          DO I = LB2, UB2
            X(I,J) = I + (J-1) * NX
          END DO
        END DO
  
        END