expression_dirichlet.f90

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module expression_dirichlet
  use num_types, only : rp
  use bc, only : bc_t
  use coefs, only : coef_t
  use expression, only : expression_t, expression_check_finite
  use neko_config, only : neko_bcknd_device
  use device, only : device_map, device_unmap, device_memcpy, host_to_device
  use device_inhom_dirichlet, only : device_inhom_dirichlet_apply_scalar
  use json_module, only : json_file
  use json_utils, only : json_get
  use time_state, only : time_state_t
  use utils, only : neko_error
  use, intrinsic :: iso_c_binding, only : c_ptr, c_null_ptr
  implicit none
  private
 
  type, public, extends(bc_t) :: expression_dirichlet_t
     type(expression_t) :: expr
     real(kind=rp), allocatable :: g(:)
     real(kind=rp), allocatable :: xm(:)
     real(kind=rp), allocatable :: ym(:)
     real(kind=rp), allocatable :: zm(:)
     type(c_ptr) :: g_d = c_null_ptr
   contains
     procedure, pass(this) :: init => expression_dirichlet_init
     procedure, pass(this) :: init_from_components => &
          expression_dirichlet_init_from_components
     procedure, pass(this) :: free => expression_dirichlet_free
     procedure, pass(this) :: finalize => expression_dirichlet_finalize
     procedure, pass(this) :: apply_scalar => expression_dirichlet_apply_scalar
     procedure, pass(this) :: apply_vector => expression_dirichlet_apply_vector
     procedure, pass(this) :: apply_scalar_dev => &
          expression_dirichlet_apply_scalar_dev
     procedure, pass(this) :: apply_vector_dev => &
          expression_dirichlet_apply_vector_dev
     procedure, pass(this) :: update => expression_dirichlet_update
  end type expression_dirichlet_t
 
  public :: expression_mask_coords
 
contains
 
  subroutine expression_dirichlet_init(this, coef, json)
    class(expression_dirichlet_t), intent(inout), target :: this
    type(coef_t), target, intent(in) :: coef
    type(json_file), intent(inout) :: json
    character(len=:), allocatable :: str
 
    call json_get(json, "value", str)
    call this%init_from_components(coef, str)
    if (allocated(str)) deallocate(str)
 
  end subroutine expression_dirichlet_init
 
  subroutine expression_dirichlet_init_from_components(this, coef, str)
    class(expression_dirichlet_t), intent(inout), target :: this
    type(coef_t), target, intent(in) :: coef
    character(len=*), intent(in) :: str
 
    call this%free()
    call this%init_base(coef)
 
    if (len_trim(str) .eq. 0) then
       call neko_error("An expression boundary condition needs a non-empty " &
            // "expression under the value keyword")
    end if
 
    call this%expr%init(str)
 
  end subroutine expression_dirichlet_init_from_components
 
  subroutine expression_dirichlet_free(this)
    class(expression_dirichlet_t), target, intent(inout) :: this
 
    call this%free_base()
    call this%expr%free()
 
    if (allocated(this%g)) then
       if (neko_bcknd_device .eq. 1) then
          call device_unmap(this%g, this%g_d)
       end if
       deallocate(this%g)
    end if
 
    if (allocated(this%xm)) deallocate(this%xm)
    if (allocated(this%ym)) deallocate(this%ym)
    if (allocated(this%zm)) deallocate(this%zm)
 
  end subroutine expression_dirichlet_free
 
  subroutine expression_dirichlet_finalize(this, only_facets)
    class(expression_dirichlet_t), target, intent(inout) :: this
    logical, optional, intent(in) :: only_facets
    logical :: only_facets_
    integer :: m
 
    if (present(only_facets)) then
       only_facets_ = only_facets
    else
       only_facets_ = .false.
    end if
 
    call this%finalize_base(only_facets_)
 
    m = this%msk(0)
    if (m .eq. 0) return
 
    allocate(this%xm(m), this%ym(m), this%zm(m), this%g(m))
    call expression_mask_coords(this, this%xm, this%ym, this%zm)
    this%g = 0.0_rp
 
    if (neko_bcknd_device .eq. 1) then
       call device_map(this%g, this%g_d, m)
    end if
 
    if (.not. this%expr%time_dependent) then
       call this%expr%eval(this%g, m, this%xm, this%ym, this%zm)
       call expression_check_finite(this%expr%src, this%g, m, &
            "boundary condition")
       if (neko_bcknd_device .eq. 1) then
          call device_memcpy(this%g, this%g_d, m, host_to_device, &
               sync = .true.)
       end if
    end if
 
  end subroutine expression_dirichlet_finalize
 
  subroutine expression_dirichlet_update(this, time, strm)
    class(expression_dirichlet_t), intent(inout) :: this
    type(time_state_t), intent(in), optional :: time
    type(c_ptr), intent(inout), optional :: strm
    integer :: m
 
    if (.not. this%expr%time_dependent) return
    if (this%updated) return
 
    if (.not. present(time)) then
       call neko_error("The boundary condition expression '" // &
            this%expr%src // "' depends on time, but the solver did not " // &
            "provide a time state")
    end if
 
    m = this%msk(0)
    call this%expr%eval(this%g, m, this%xm, this%ym, this%zm, time%t, time%dt)
    call expression_check_finite(this%expr%src, this%g, m, &
         "boundary condition")
 
    if (neko_bcknd_device .eq. 1) then
       ! Synchronous on purpose: the host buffer is reused every timestep,
       ! and the copy is only as large as the mask.
       call device_memcpy(this%g, this%g_d, m, host_to_device, &
            sync = .true., strm = strm)
    end if
 
    this%updated = .true.
 
  end subroutine expression_dirichlet_update
 
  subroutine expression_dirichlet_apply_scalar(this, x, n, time, strong)
    class(expression_dirichlet_t), intent(inout) :: this
    integer, intent(in) :: n
    real(kind=rp), intent(inout), dimension(n) :: x
    type(time_state_t), intent(in), optional :: time
    logical, intent(in), optional :: strong
    integer :: i, m
    logical :: strong_
 
    if (present(strong)) then
       strong_ = strong
    else
       strong_ = .true.
    end if
 
    m = this%msk(0)
    if (.not. strong_ .or. m .eq. 0) return
 
    ! The bc list applies the host conditions from inside an OpenMP parallel
    ! region, and evaluating an expression mutates the shared evaluation stack
    ! of `expr`, so only one thread may run the update. The implicit barrier of
    ! `single` also makes `g` visible to every thread before the loop below.
    !$omp single
    call this%update(time)
    !$omp end single
 
    !$omp do
    do i = 1, m
       x(this%msk(i)) = this%g(i)
    end do
    !$omp end do
 
  end subroutine expression_dirichlet_apply_scalar
 
  subroutine expression_dirichlet_apply_vector(this, x, y, z, n, time, strong)
    class(expression_dirichlet_t), intent(inout) :: this
    integer, intent(in) :: n
    real(kind=rp), intent(inout), dimension(n) :: x
    real(kind=rp), intent(inout), dimension(n) :: y
    real(kind=rp), intent(inout), dimension(n) :: z
    type(time_state_t), intent(in), optional :: time
    logical, intent(in), optional :: strong
  end subroutine expression_dirichlet_apply_vector
 
  subroutine expression_dirichlet_apply_scalar_dev(this, x_d, time, strong, &
       strm)
    class(expression_dirichlet_t), intent(inout), target :: this
    type(c_ptr), intent(inout) :: x_d
    type(time_state_t), intent(in), optional :: time
    logical, intent(in), optional :: strong
    type(c_ptr), intent(inout) :: strm
    integer :: m
    logical :: strong_
 
    if (present(strong)) then
       strong_ = strong
    else
       strong_ = .true.
    end if
 
    m = this%msk(0)
    if (.not. strong_ .or. m .eq. 0) return
 
    call this%update(time, strm)
 
    call device_inhom_dirichlet_apply_scalar(this%msk_d, x_d, this%g_d, m, strm)
 
  end subroutine expression_dirichlet_apply_scalar_dev
 
  subroutine expression_dirichlet_apply_vector_dev(this, x_d, y_d, z_d, &
       time, strong, strm)
    class(expression_dirichlet_t), intent(inout), target :: this
    type(c_ptr), intent(inout) :: x_d
    type(c_ptr), intent(inout) :: y_d
    type(c_ptr), intent(inout) :: z_d
    type(time_state_t), intent(in), optional :: time
    logical, intent(in), optional :: strong
    type(c_ptr), intent(inout) :: strm
  end subroutine expression_dirichlet_apply_vector_dev
 
  subroutine expression_mask_coords(bc, xm, ym, zm)
    class(bc_t), intent(in) :: bc
    real(kind=rp), intent(inout) :: xm(:)
    real(kind=rp), intent(inout) :: ym(:)
    real(kind=rp), intent(inout) :: zm(:)
 
    call gather_coords(bc%msk, bc%msk(0), bc%dof%x, bc%dof%y, bc%dof%z, &
         size(bc%dof%x), xm, ym, zm)
 
  end subroutine expression_mask_coords
 
  subroutine gather_coords(msk, m, x, y, z, n, xm, ym, zm)
    integer, intent(in) :: m
    integer, intent(in) :: n
    integer, intent(in) :: msk(0:m)
    real(kind=rp), intent(in) :: x(n)
    real(kind=rp), intent(in) :: y(n)
    real(kind=rp), intent(in) :: z(n)
    real(kind=rp), intent(inout) :: xm(m)
    real(kind=rp), intent(inout) :: ym(m)
    real(kind=rp), intent(inout) :: zm(m)
    integer :: i, k
 
    do i = 1, m
       k = msk(i)
       xm(i) = x(k)
       ym(i) = y(k)
       zm(i) = z(k)
    end do
 
  end subroutine gather_coords
 
end module expression_dirichlet