yac_core.F90

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! Copyright (c) 2024 The YAC Authors
!
! SPDX-License-Identifier: BSD-3-Clause
 
 
#ifdef HAVE_CONFIG_H
! Get the definition of the 'YAC_MPI_FINT_FC_KIND' macro.
#include "config.h"
#endif
 
module yac_core
  use, intrinsic :: iso_c_binding, only : c_int, c_long, &
                                        & c_long_long, c_short, c_char, &
                                        & c_size_t, c_double, c_null_char
 
  implicit none
 
  public
 
  !------------------------------------------------
  ! Constants for Fortran-C interoperability
  !------------------------------------------------
 
  integer, parameter :: yac_mpi_fint_kind = yac_mpi_fint_fc_kind
 
  !---------------
  ! Location enums
  !---------------
 
  enum, bind(c)
   enumerator :: yac_loc_cell   = 0
   enumerator :: yac_loc_corner = 1
   enumerator :: yac_loc_edge   = 2
  end enum
 
  !---------------------------
  ! Interpolation method enums
  !---------------------------
 
  enum, bind(c)
     enumerator :: yac_interp_avg_arithmetic = 0
     enumerator :: yac_interp_avg_dist       = 1
     enumerator :: yac_interp_avg_bary       = 2
  end enum
 
  enum, bind(c)
     enumerator :: yac_interp_ncc_avg  = 0
     enumerator :: yac_interp_ncc_dist = 1
  end enum
 
  enum, bind(c)
     enumerator :: yac_interp_nnn_avg    = 0
     enumerator :: yac_interp_nnn_dist   = 1
     enumerator :: yac_interp_nnn_gauss  = 2
     enumerator :: yac_interp_nnn_rbf    = 3
     enumerator :: yac_interp_nnn_zero   = 4
  end enum
 
  enum, bind(c)
     enumerator :: yac_interp_conserv_destarea = 0
     enumerator :: yac_interp_conserv_fracarea = 1
  end enum
 
  enum, bind(c)
     enumerator :: yac_interp_spmap_avg  = 0
     enumerator :: yac_interp_spmap_dist = 1
  end enum
 
  enum, bind(c)
     enumerator :: yac_interp_spmap_none       = 0
     enumerator :: yac_interp_spmap_srcarea    = 1
     enumerator :: yac_interp_spmap_invtgtarea = 2
     enumerator :: yac_interp_spmap_fracarea   = 3
  end enum
 
  !------------------------------------
  ! Interpolation method default values
  !------------------------------------
 
  ! average
  integer(kind=c_int), parameter :: yac_interp_avg_weight_type_default_f = 0_c_int
  integer(kind=c_int), parameter :: yac_interp_avg_partial_coverage_default_f = 0_c_int
 
  ! nearest corner cells
  integer(kind=c_int), parameter :: yac_interp_ncc_weight_type_default_f = 0_c_int
  integer(kind=c_int), parameter :: yac_interp_ncc_partial_coverage_default_f = 0_c_int
 
  ! conserv
  integer(kind=c_int), parameter :: yac_interp_conserv_order_default_f = 1_c_int
  integer(kind=c_int), parameter :: yac_interp_conserv_enforced_conserv_default_f = 0_c_int
  integer(kind=c_int), parameter :: yac_interp_conserv_partial_coverage_default_f = 0_c_int
  integer(kind=c_int), parameter :: yac_interp_conserv_normalisation_default_f = 0_c_int
 
  ! creep
  integer(kind=c_int), parameter :: yac_interp_creep_distance_default_f = -1_c_int
 
  ! fixed
  real(kind=c_double), parameter :: yac_interp_fixed_value_default_f = huge(1.0_c_double)
 
  ! n-nearest-neighbour
  integer(kind=c_int), parameter :: yac_interp_nnn_weighted_default_f = 0_c_int
  integer(kind=c_size_t), parameter :: yac_interp_nnn_n_default_f = 1_c_size_t
  real(kind=c_double), parameter :: yac_interp_nnn_gauss_scale_default_f = 0.1_c_double
 
  ! rbf
  integer(kind=c_int), parameter :: yac_interp_rbf_n_default_f = 9_c_int
  real(kind=c_double), parameter :: yac_interp_rbf_scale_default_f = 1.487973e+01_c_double
  integer(kind=c_int), parameter :: yac_interp_rbf_kernel_default_f = 0_c_int
 
  ! source-point mapping
  real(kind=c_double), parameter :: yac_interp_spmap_spread_distance_default_f = 0.0_c_double
  real(kind=c_double), parameter :: yac_interp_spmap_max_search_distance_default_f = 0.0_c_double
  integer(kind=c_int), parameter :: yac_interp_spmap_weighted_default_f = 0_c_int
  integer(kind=c_int), parameter :: yac_interp_spmap_scale_default_f = 0_c_int
  real(kind=c_double), parameter :: yac_interp_spmap_src_sphere_radius_default_f = 1.0_c_double
  real(kind=c_double), parameter :: yac_interp_spmap_tgt_sphere_radius_default_f = 1.0_c_double
 
  character(kind=c_char,len=*), parameter :: yac_interp_check_constructor_key_default_f = "" // c_null_char
  character(kind=c_char,len=*), parameter :: yac_interp_check_do_search_key_default_f = "" // c_null_char
 
  !---------------------------
  ! Interpolation weight enums
  !---------------------------
 
  enum, bind(c)
    enumerator :: yac_mapping_on_src = 0
    enumerator :: yac_mapping_on_tgt = 1
  end enum
 
  !------------------------------------------------
  ! Initialisation and finalization of MPI and YAXT
  !------------------------------------------------
 
  interface
 
    ! initialise MPI (if not already initialised)
    subroutine yac_mpi_init_c () &
      bind( c, name='yac_mpi_init' )
    end subroutine yac_mpi_init_c
 
    ! initialise YAXT
    subroutine yac_yaxt_init_c (comm) &
      bind( c, name='yac_yaxt_init_f2c' )
 
      import :: yac_mpi_fint_kind
 
      integer(kind=YAC_MPI_FINT_KIND), value :: comm
    end subroutine yac_yaxt_init_c
 
    ! check whether MPI is initialised
    function yac_mpi_is_initialised_c () &
      bind( c, name='yac_mpi_is_initialised' )
 
      use, intrinsic :: iso_c_binding
 
      integer(kind=c_int) :: yac_mpi_is_initialised_c
    end function yac_mpi_is_initialised_c
 
    ! free internal buffers and finalize yaxt
    subroutine yac_mpi_cleanup_c () &
      bind ( c, name="yac_mpi_cleanup" )
    end subroutine yac_mpi_cleanup_c
 
    ! finalize MPI (if initialised by YAC)
    subroutine yac_mpi_finalize_c () &
      bind( c, name='yac_mpi_finalize' )
    end subroutine yac_mpi_finalize_c
 
  end interface
 
  !-----------------------
  ! Handling of basic grid
  !-----------------------
 
  interface
 
    function yac_basic_grid_empty_new_c(name) &
      bind( c, name='yac_basic_grid_empty_new' )
 
      use, intrinsic :: iso_c_binding
 
      character(kind=c_char) :: name(*)
 
      type(c_ptr) :: yac_basic_grid_empty_new_c
    end function yac_basic_grid_empty_new_c
 
    subroutine yac_basic_grid_delete_c(grid) &
      bind( c, name='yac_basic_grid_delete' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value :: grid
    end subroutine yac_basic_grid_delete_c
 
    function yac_basic_grid_get_data_size_c(grid, location) &
      bind( c, name='yac_basic_grid_get_data_size_f2c')
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value         :: grid
      integer(kind=c_int), value :: location
 
      integer(kind=c_size_t) :: yac_basic_grid_get_data_size_c
    end function yac_basic_grid_get_data_size_c
 
    function yac_basic_grid_add_coordinates_c( &
      grid, location, coordinates, count) &
      bind( c, name='yac_basic_grid_add_coordinates_f2c')
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value            :: grid
      integer(kind=c_int), value    :: location
      real(kind=c_double)           :: coordinates(*)
      integer(kind=c_size_t), value :: count
 
      integer(kind=c_size_t) :: yac_basic_grid_add_coordinates_c
    end function yac_basic_grid_add_coordinates_c
 
    function yac_basic_grid_add_coordinates_nocpy_c( &
      grid, location, coordinates) &
      bind( c, name='yac_basic_grid_add_coordinates_nocpy_f2c')
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value            :: grid
      integer(kind=c_int), value    :: location
      real(kind=c_double)           :: coordinates(*)
 
      integer(kind=c_size_t) :: yac_basic_grid_add_coordinates_nocpy_c
    end function yac_basic_grid_add_coordinates_nocpy_c
 
    function yac_basic_grid_add_mask_c( &
      grid, location, mask, count, name) &
      bind( c, name='yac_basic_grid_add_mask_f2c')
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value            :: grid
      integer(kind=c_int), value    :: location
      integer(kind=c_int)           :: mask(*)
      integer(kind=c_size_t), value :: count
      character(kind=c_char)        :: name(*)
 
      integer(kind=c_size_t) :: yac_basic_grid_add_mask_c
    end function yac_basic_grid_add_mask_c
 
    function yac_basic_grid_add_mask_nocpy_c( &
      grid, location, mask, name) &
      bind( c, name='yac_basic_grid_add_mask_nocpy_f2c')
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value            :: grid
      integer(kind=c_int), value    :: location
      integer(kind=c_int)           :: mask(*)
      character(kind=c_char)        :: name(*)
 
      integer(kind=c_size_t) :: yac_basic_grid_add_mask_nocpy_c
    end function yac_basic_grid_add_mask_nocpy_c
 
    function yac_basic_grid_reg_2d_new_c( &
      name, nbr_vertices, cyclic, lon_vertices, lat_vertices) &
      bind( c, name='yac_basic_grid_reg_2d_new')
 
      use, intrinsic :: iso_c_binding
 
      character(kind=c_char) :: name(*)
      integer(kind=c_size_t) :: nbr_vertices(2)
      integer(kind=c_int)    :: cyclic(2)
      real(kind=c_double)    :: lon_vertices(*)
      real(kind=c_double)    :: lat_vertices(*)
 
      type(c_ptr) :: yac_basic_grid_reg_2d_new_c
    end function yac_basic_grid_reg_2d_new_c
 
    function yac_basic_grid_reg_2d_deg_new_c( &
      name, nbr_vertices, cyclic, lon_vertices, lat_vertices) &
      bind( c, name='yac_basic_grid_reg_2d_deg_new')
 
      use, intrinsic :: iso_c_binding
 
      character(kind=c_char) :: name(*)
      integer(kind=c_size_t) :: nbr_vertices(2)
      integer(kind=c_int)    :: cyclic(2)
      real(kind=c_double)    :: lon_vertices(*)
      real(kind=c_double)    :: lat_vertices(*)
 
      type(c_ptr) :: yac_basic_grid_reg_2d_deg_new_c
    end function yac_basic_grid_reg_2d_deg_new_c
 
    function yac_basic_grid_curve_2d_new_c( &
      name, nbr_vertices, cyclic, lon_vertices, lat_vertices) &
      bind( c, name='yac_basic_grid_curve_2d_new')
 
      use, intrinsic :: iso_c_binding
 
      character(kind=c_char) :: name(*)
      integer(kind=c_size_t) :: nbr_vertices(2)
      integer(kind=c_int)    :: cyclic(2)
      real(kind=c_double)    :: lon_vertices(*)
      real(kind=c_double)    :: lat_vertices(*)
 
      type(c_ptr) :: yac_basic_grid_curve_2d_new_c
    end function yac_basic_grid_curve_2d_new_c
 
    function yac_basic_grid_curve_2d_deg_new_c( &
      name, nbr_vertices, cyclic, lon_vertices, lat_vertices) &
      bind( c, name='yac_basic_grid_curve_2d_deg_new')
 
      use, intrinsic :: iso_c_binding
 
      character(kind=c_char) :: name(*)
      integer(kind=c_size_t) :: nbr_vertices(2)
      integer(kind=c_int)    :: cyclic(2)
      real(kind=c_double)    :: lon_vertices(*)
      real(kind=c_double)    :: lat_vertices(*)
 
      type(c_ptr) :: yac_basic_grid_curve_2d_deg_new_c
    end function yac_basic_grid_curve_2d_deg_new_c
 
    function yac_basic_grid_unstruct_new_c( &
      name, nbr_vertices, nbr_cells, num_vertices_per_cell, &
      x_vertices, y_vertices, cell_to_vertex) &
      bind( c, name='yac_basic_grid_unstruct_new')
 
      use, intrinsic :: iso_c_binding
 
      character(kind=c_char)        :: name(*)
      integer(kind=c_size_t), value :: nbr_vertices
      integer(kind=c_size_t), value :: nbr_cells
      integer(kind=c_int)           :: num_vertices_per_cell(*)
      real(kind=c_double)           :: x_vertices(*)
      real(kind=c_double)           :: y_vertices(*)
      integer(kind=c_int)           :: cell_to_vertex(*)
 
      type(c_ptr) :: yac_basic_grid_unstruct_new_c
    end function yac_basic_grid_unstruct_new_c
 
    function yac_basic_grid_unstruct_deg_new_c( &
      name, nbr_vertices, nbr_cells, num_vertices_per_cell, &
      x_vertices, y_vertices, cell_to_vertex) &
      bind( c, name='yac_basic_grid_unstruct_deg_new')
 
      use, intrinsic :: iso_c_binding
 
      character(kind=c_char)        :: name(*)
      integer(kind=c_size_t), value :: nbr_vertices
      integer(kind=c_size_t), value :: nbr_cells
      integer(kind=c_int)           :: num_vertices_per_cell(*)
      real(kind=c_double)           :: x_vertices(*)
      real(kind=c_double)           :: y_vertices(*)
      integer(kind=c_int)           :: cell_to_vertex(*)
 
      type(c_ptr) :: yac_basic_grid_unstruct_deg_new_c
    end function yac_basic_grid_unstruct_deg_new_c
 
    function yac_basic_grid_unstruct_ll_new_c( &
      name, nbr_vertices, nbr_cells, num_vertices_per_cell, &
      x_vertices, y_vertices, cell_to_vertex) &
      bind( c, name='yac_basic_grid_unstruct_ll_new')
 
      use, intrinsic :: iso_c_binding
 
      character(kind=c_char)        :: name(*)
      integer(kind=c_size_t), value :: nbr_vertices
      integer(kind=c_size_t), value :: nbr_cells
      integer(kind=c_int)           :: num_vertices_per_cell(*)
      real(kind=c_double)           :: x_vertices(*)
      real(kind=c_double)           :: y_vertices(*)
      integer(kind=c_int)           :: cell_to_vertex(*)
 
      type(c_ptr) :: yac_basic_grid_unstruct_ll_new_c
    end function yac_basic_grid_unstruct_ll_new_c
 
    function yac_basic_grid_unstruct_ll_deg_new_c( &
      name, nbr_vertices, nbr_cells, num_vertices_per_cell, &
      x_vertices, y_vertices, cell_to_vertex) &
      bind( c, name='yac_basic_grid_unstruct_ll_deg_new')
 
      use, intrinsic :: iso_c_binding
 
      character(kind=c_char)        :: name(*)
      integer(kind=c_size_t), value :: nbr_vertices
      integer(kind=c_size_t), value :: nbr_cells
      integer(kind=c_int)           :: num_vertices_per_cell(*)
      real(kind=c_double)           :: x_vertices(*)
      real(kind=c_double)           :: y_vertices(*)
      integer(kind=c_int)           :: cell_to_vertex(*)
 
      type(c_ptr) :: yac_basic_grid_unstruct_ll_deg_new_c
    end function yac_basic_grid_unstruct_ll_deg_new_c
 
  end interface
 
  !------------------------------
  ! Handling of distributed grids
  !------------------------------
 
  interface
 
    function yac_dist_grid_pair_new_c(grid_a, grid_b, comm) &
      bind( c, name='yac_dist_grid_pair_new_f2c' )
 
      use, intrinsic :: iso_c_binding
      import :: yac_mpi_fint_kind
 
      type(c_ptr), value                     :: grid_a
      type(c_ptr), value                     :: grid_b
      integer(kind=YAC_MPI_FINT_KIND), value :: comm
 
      type(c_ptr) :: yac_dist_grid_pair_new_c
    end function yac_dist_grid_pair_new_c
 
    subroutine yac_dist_grid_pair_delete_c(grid_pair) &
      bind( c, name='yac_dist_grid_pair_delete' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value :: grid_pair
    end subroutine yac_dist_grid_pair_delete_c
 
  end interface
 
  !-------------------------------
  ! Handling of interpolation grid
  !-------------------------------
 
  interface
 
    function yac_interp_grid_new_c( dist_grid_pair,            &
                                    src_grid_name,             &
                                    tgt_grid_name,             &
                                    num_src_fields,            &
                                    src_field_locations,       &
                                    src_field_coordinate_idxs, &
                                    src_field_masks_idxs,      &
                                    tgt_field_location,        &
                                    tgt_field_coordinate_idx,  &
                                    tgt_field_masks_idx)        &
      bind( c, name='yac_interp_grid_new_f2c' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value            :: dist_grid_pair
      character(kind=c_char)        :: src_grid_name(*)
      character(kind=c_char)        :: tgt_grid_name(*)
      integer(kind=c_size_t), value :: num_src_fields
      integer(kind=c_int)           :: src_field_locations(*)
      integer(kind=c_size_t)        :: src_field_coordinate_idxs(*)
      integer(kind=c_size_t)        :: src_field_masks_idxs(*)
      integer(kind=c_int), value    :: tgt_field_location
      integer(kind=c_size_t), value :: tgt_field_coordinate_idx
      integer(kind=c_size_t), value :: tgt_field_masks_idx
 
      type(c_ptr) :: yac_interp_grid_new_c
    end function yac_interp_grid_new_c
 
    subroutine yac_interp_grid_delete_c(interp_grid) &
      bind( c, name='yac_interp_grid_delete' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value :: interp_grid
    end subroutine yac_interp_grid_delete_c
 
  end interface
 
  !--------------------------------
  ! Handling of interpolation stack
  !--------------------------------
 
  interface
 
    function yac_interp_stack_config_new_c() &
      bind( c, name='yac_interp_stack_config_new' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr) :: yac_interp_stack_config_new_c
    end function yac_interp_stack_config_new_c
 
    function yac_interp_stack_config_copy_c(interp_stack_config) &
      bind( c, name='yac_interp_stack_config_copy' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value :: interp_stack_config
 
      type(c_ptr) :: yac_interp_stack_config_copy_c
    end function yac_interp_stack_config_copy_c
 
    subroutine yac_interp_stack_config_delete_c(interp_stack_config) &
      bind( c, name='yac_interp_stack_config_delete' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value :: interp_stack_config
    end subroutine yac_interp_stack_config_delete_c
 
    subroutine yac_interp_stack_config_add_average_c( &
      interp_stack_config, reduction_type, partial_coverage) &
      bind( c, name='yac_interp_stack_config_add_average_f2c' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value         :: interp_stack_config
      integer(kind=c_int), value :: reduction_type
      integer(kind=c_int), value :: partial_coverage
    end subroutine yac_interp_stack_config_add_average_c
 
    subroutine yac_interp_stack_config_add_ncc_c( &
      interp_stack_config, weight_type, partial_coverage) &
      bind( c, name='yac_interp_stack_config_add_ncc_f2c' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value         :: interp_stack_config
      integer(kind=c_int), value :: weight_type
      integer(kind=c_int), value :: partial_coverage
    end subroutine yac_interp_stack_config_add_ncc_c
 
    subroutine yac_interp_stack_config_add_nnn_c( &
      interp_stack_config, type, n, scale) &
      bind( c, name='yac_interp_stack_config_add_nnn_f2c' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value            :: interp_stack_config
      integer(kind=c_int), value    :: type
      integer(kind=c_size_t), value :: n
      real(kind=c_double), value    :: scale
    end subroutine yac_interp_stack_config_add_nnn_c
 
    subroutine yac_interp_stack_config_add_conservative_c(            &
      interp_stack_config, order, enforced_conserv, partial_coverage, &
      normalisation) &
      bind( c, name='yac_interp_stack_config_add_conservative_f2c' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value         :: interp_stack_config
      integer(kind=c_int), value :: order
      integer(kind=c_int), value :: enforced_conserv
      integer(kind=c_int), value :: partial_coverage
      integer(kind=c_int), value :: normalisation
    end subroutine yac_interp_stack_config_add_conservative_c
 
    subroutine yac_interp_stack_config_add_spmap_c( &
      interp_stack_config, spread_distance, max_search_distance, &
      weight_type, scale_type, src_sphere_radius, tgt_sphere_radius) &
      bind( c, name='yac_interp_stack_config_add_spmap_f2c' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value         :: interp_stack_config
      real(kind=c_double), value :: spread_distance
      real(kind=c_double), value :: max_search_distance
      integer(kind=c_int), value :: weight_type
      integer(kind=c_int), value :: scale_type
      real(kind=c_double), value :: src_sphere_radius
      real(kind=c_double), value :: tgt_sphere_radius
    end subroutine yac_interp_stack_config_add_spmap_c
 
    subroutine yac_interp_stack_config_add_hcsbb_c(interp_stack_config) &
      bind( c, name='yac_interp_stack_config_add_hcsbb' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value :: interp_stack_config
    end subroutine yac_interp_stack_config_add_hcsbb_c
 
    subroutine yac_interp_stack_config_add_user_file_c( &
      interp_stack_config, filename, src_grid_name, tgt_grid_name) &
      bind( c, name='yac_interp_stack_config_add_user_file' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value     :: interp_stack_config
      character(kind=c_char) :: filename(*)
      character(kind=c_char) :: src_grid_name(*)
      character(kind=c_char) :: tgt_grid_name(*)
    end subroutine yac_interp_stack_config_add_user_file_c
 
    subroutine yac_interp_stack_config_add_fixed_c( &
      interp_stack_config, value) &
      bind( c, name='yac_interp_stack_config_add_fixed' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value         :: interp_stack_config
      real(kind=c_double), value :: value
    end subroutine yac_interp_stack_config_add_fixed_c
 
    subroutine yac_interp_stack_config_add_creep_c( &
      interp_stack_config, n) &
      bind( c, name='yac_interp_stack_config_add_creep' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value         :: interp_stack_config
      integer(kind=c_int), value :: n
    end subroutine yac_interp_stack_config_add_creep_c
 
    subroutine yac_interp_stack_config_add_check_c( &
      interp_stack_config, constructor_key, do_search_key) &
      bind( c, name='yac_interp_stack_config_add_check' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value     :: interp_stack_config
      character(kind=c_char) :: constructor_key(*)
      character(kind=c_char) :: do_search_key(*)
    end subroutine yac_interp_stack_config_add_check_c
 
    function yac_interp_stack_config_compare_c(a, b) &
      bind( c, name='yac_interp_stack_config_compare' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value :: a
      type(c_ptr), value :: b
 
      integer(kind=c_int) :: yac_interp_stack_config_compare_c
    end function yac_interp_stack_config_compare_c
 
    function yac_interp_stack_config_generate_c(interp_stack_config) &
      bind( c, name='yac_interp_stack_config_generate' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value :: interp_stack_config
 
      type(c_ptr) :: yac_interp_stack_config_generate_c
    end function yac_interp_stack_config_generate_c
 
  end interface
 
  !----------------------------------
  ! Handling of interpolation methods
  !----------------------------------
 
  interface
 
    function yac_interp_method_do_search_c(interp_method_stack, interp_grid) &
      bind( c, name='yac_interp_method_do_search' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value :: interp_method_stack
      type(c_ptr), value :: interp_grid
 
      type(c_ptr) :: yac_interp_method_do_search_c
    end function yac_interp_method_do_search_c
 
    subroutine yac_interp_method_delete_c(interp_method_stack) &
      bind( c, name='yac_interp_method_delete' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value :: interp_method_stack
    end subroutine yac_interp_method_delete_c
 
  end interface
 
  !----------------------------------
  ! Handling of interpolation weights
  !----------------------------------
 
  interface
 
    subroutine yac_interp_weights_delete_c(interp_weights) &
      bind( c, name='yac_interp_weights_delete' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value :: interp_weights
    end subroutine yac_interp_weights_delete_c
 
    subroutine yac_interp_weights_write_to_file_c(interp_weights, &
                                                  filename,       &
                                                  src_grid_name,  &
                                                  tgt_grid_name,  &
                                                  src_grid_size,  &
                                                  tgt_grid_size)  &
      bind( c, name='yac_interp_weights_write_to_file' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value            :: interp_weights
      character(kind=c_char)        :: filename(*)
      character(kind=c_char)        :: src_grid_name(*)
      character(kind=c_char)        :: tgt_grid_name(*)
      integer(kind=c_size_t), value :: src_grid_size
      integer(kind=c_size_t), value :: tgt_grid_size
    end subroutine yac_interp_weights_write_to_file_c
 
    function yac_interp_weights_get_interpolation_c( &
      interp_weights, reorder, collection_size, frac_mask_fallback_value, &
      scaling_factor, scaling_summand) &
      bind( c, name='yac_interp_weights_get_interpolation_f2c' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value            :: interp_weights
      integer(kind=c_int), value    :: reorder
      integer(kind=c_size_t), value :: collection_size
      real(kind=c_double), value    :: frac_mask_fallback_value
      real(kind=c_double), value    :: scaling_factor
      real(kind=c_double), value    :: scaling_summand
 
      type(c_ptr) :: yac_interp_weights_get_interpolation_c
    end function yac_interp_weights_get_interpolation_c
 
  end interface
 
  !---------------------------
  ! Handling of interpolations
  !---------------------------
 
  interface
 
    subroutine yac_interpolation_delete_c(interp) &
      bind( c, name='yac_interpolation_delete' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value :: interp
    end subroutine yac_interpolation_delete_c
 
    subroutine yac_interpolation_execute_c( &
      interp, src_fields, tgt_field) &
      bind( c, name='yac_interpolation_execute' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value :: interp
      type(c_ptr), value :: src_fields
      type(c_ptr), value :: tgt_field
    end subroutine yac_interpolation_execute_c
 
    subroutine yac_interpolation_execute_frac_c( &
      interp, src_fields, src_frac_masks, tgt_field) &
      bind( c, name='yac_interpolation_execute_frac' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value :: interp
      type(c_ptr), value :: src_fields
      type(c_ptr), value :: src_frac_masks
      type(c_ptr), value :: tgt_field
    end subroutine yac_interpolation_execute_frac_c
 
    subroutine yac_interpolation_execute_put_c(interp, src_fields) &
      bind( c, name='yac_interpolation_execute_put' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value :: interp
      type(c_ptr), value :: src_fields
    end subroutine yac_interpolation_execute_put_c
 
    subroutine yac_interpolation_execute_put_frac_c( &
      interp, src_fields, src_frac_masks) &
      bind( c, name='yac_interpolation_execute_put_frac' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value :: interp
      type(c_ptr), value :: src_fields
      type(c_ptr), value :: src_frac_masks
    end subroutine yac_interpolation_execute_put_frac_c
 
    subroutine yac_interpolation_execute_get_c(interp, tgt_field) &
      bind( c, name='yac_interpolation_execute_get' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value :: interp
      type(c_ptr), value :: tgt_field
    end subroutine yac_interpolation_execute_get_c
 
    subroutine yac_interpolation_execute_get_async_c(interp, tgt_field) &
      bind( c, name='yac_interpolation_execute_get_async' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value :: interp
      type(c_ptr), value :: tgt_field
    end subroutine yac_interpolation_execute_get_async_c
 
    function yac_interpolation_execute_put_test_c(interp) &
      bind( c, name='yac_interpolation_execute_put_test' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value :: interp
 
      integer(kind=c_int) :: yac_interpolation_execute_put_test_c
    end function yac_interpolation_execute_put_test_c
 
    function yac_interpolation_execute_get_test_c(interp) &
      bind( c, name='yac_interpolation_execute_get_test' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value :: interp
 
      integer(kind=c_int) :: yac_interpolation_execute_get_test_c
    end function yac_interpolation_execute_get_test_c
 
    subroutine yac_interpolation_execute_wait_c(interp) &
      bind( c, name='yac_interpolation_execute_wait' )
 
      use, intrinsic :: iso_c_binding
 
      type(c_ptr), value :: interp
    end subroutine yac_interpolation_execute_wait_c
 
    function yac_interpolation_get_const_frac_mask_no_value_c() &
      bind( c, name='yac_interpolation_get_const_frac_mask_no_value_c2f' )
 
      use, intrinsic :: iso_c_binding
 
      real(kind=c_double) :: &
        yac_interpolation_get_const_frac_mask_no_value_c
    end function yac_interpolation_get_const_frac_mask_no_value_c
 
    function yac_interpolation_get_const_frac_mask_undef_c() &
      bind( c, name='yac_interpolation_get_const_frac_mask_undef_c2f' )
 
      use, intrinsic :: iso_c_binding
 
      real(kind=c_double) :: &
        yac_interpolation_get_const_frac_mask_undef_c
    end function yac_interpolation_get_const_frac_mask_undef_c
 
  end interface
 
  !--------------------
  ! Abort functionality
  !--------------------
 
  interface
 
     subroutine yac_abort_message_c ( text, file, line ) &
           bind( c, name='yac_abort_message' )
 
       use, intrinsic :: iso_c_binding, only : c_int, c_char
 
       character ( kind=c_char ), dimension(*) :: text
       character ( kind=c_char ), dimension(*) :: file
       integer ( kind=c_int ), value           :: line
 
     end subroutine yac_abort_message_c
 
  end interface
 
  !---------------------------------
  ! Setting of callback routines for
  ! check interpolation method
  !---------------------------------
 
  interface
 
     subroutine yac_interp_method_check_add_constructor_callback_c ( &
       constructor_callback, user_data, key ) &
       bind( c, name='yac_interp_method_check_add_constructor_callback' )
 
       use, intrinsic :: iso_c_binding, only : c_funptr, c_ptr, c_char
 
       type(c_funptr), value                   :: constructor_callback
       type(c_ptr), value                      :: user_data
       character ( kind=c_char ), dimension(*) :: key
 
     end subroutine yac_interp_method_check_add_constructor_callback_c
 
     subroutine yac_interp_method_check_add_do_search_callback_c ( &
       do_search_callback, user_data, key ) &
       bind( c, name='yac_interp_method_check_add_do_search_callback' )
 
       use, intrinsic :: iso_c_binding, only : c_funptr, c_ptr, c_char
 
       type(c_funptr), value                   :: do_search_callback
       type(c_ptr), value                      :: user_data
       character ( kind=c_char ), dimension(*) :: key
 
     end subroutine yac_interp_method_check_add_do_search_callback_c
 
  end interface
 
end module yac_core