SELF_MappedVector_2D.f90 Source File


This file depends on

sourcefile~~self_mappedvector_2d.f90~2~~EfferentGraph sourcefile~self_mappedvector_2d.f90~2 SELF_MappedVector_2D.f90 sourcefile~self_mappedvector_2d_t.f90 SELF_MappedVector_2D_t.f90 sourcefile~self_mappedvector_2d.f90~2->sourcefile~self_mappedvector_2d_t.f90 sourcefile~self_gpuinterfaces.f90 SELF_GPUInterfaces.f90 sourcefile~self_mappedvector_2d.f90~2->sourcefile~self_gpuinterfaces.f90 sourcefile~self_gpu.f90 SELF_GPU.f90 sourcefile~self_mappedvector_2d.f90~2->sourcefile~self_gpu.f90 sourcefile~self_mesh_2d.f90 SELF_Mesh_2D.f90 sourcefile~self_mappedvector_2d_t.f90->sourcefile~self_mesh_2d.f90 sourcefile~self_domaindecomposition.f90 SELF_DomainDecomposition.f90 sourcefile~self_mappedvector_2d_t.f90->sourcefile~self_domaindecomposition.f90 sourcefile~self_vector_2d.f90 SELF_Vector_2D.f90 sourcefile~self_mappedvector_2d_t.f90->sourcefile~self_vector_2d.f90 sourcefile~self_lagrange.f90 SELF_Lagrange.f90 sourcefile~self_mappedvector_2d_t.f90->sourcefile~self_lagrange.f90 sourcefile~self_constants.f90 SELF_Constants.f90 sourcefile~self_mappedvector_2d_t.f90->sourcefile~self_constants.f90 sourcefile~self_tensor_2d.f90 SELF_Tensor_2D.f90 sourcefile~self_mappedvector_2d_t.f90->sourcefile~self_tensor_2d.f90 sourcefile~self_geometry_2d.f90 SELF_Geometry_2D.f90 sourcefile~self_mappedvector_2d_t.f90->sourcefile~self_geometry_2d.f90 sourcefile~self_gpuinterfaces.f90->sourcefile~self_gpu.f90 sourcefile~self_gpu_enums.f90 SELF_GPU_enums.f90 sourcefile~self_gpu.f90->sourcefile~self_gpu_enums.f90 sourcefile~self_mesh_2d_t.f90 SELF_Mesh_2D_t.f90 sourcefile~self_mesh_2d.f90->sourcefile~self_mesh_2d_t.f90 sourcefile~self_domaindecomposition_t.f90 SELF_DomainDecomposition_t.f90 sourcefile~self_domaindecomposition.f90->sourcefile~self_domaindecomposition_t.f90 sourcefile~self_vector_2d_t.f90 SELF_Vector_2D_t.f90 sourcefile~self_vector_2d.f90->sourcefile~self_vector_2d_t.f90 sourcefile~self_lagrange.f90->sourcefile~self_constants.f90 sourcefile~self_lagrange_t.f90 SELF_Lagrange_t.f90 sourcefile~self_lagrange.f90->sourcefile~self_lagrange_t.f90 sourcefile~self_tensor_2d_t.f90 SELF_Tensor_2D_t.f90 sourcefile~self_tensor_2d.f90->sourcefile~self_tensor_2d_t.f90 sourcefile~self_geometry_2d.f90->sourcefile~self_mesh_2d.f90 sourcefile~self_geometry_2d.f90->sourcefile~self_vector_2d.f90 sourcefile~self_geometry_2d.f90->sourcefile~self_lagrange.f90 sourcefile~self_geometry_2d.f90->sourcefile~self_constants.f90 sourcefile~self_geometry_2d.f90->sourcefile~self_tensor_2d.f90 sourcefile~self_scalar_2d.f90 SELF_Scalar_2D.f90 sourcefile~self_geometry_2d.f90->sourcefile~self_scalar_2d.f90 sourcefile~self_supportroutines.f90 SELF_SupportRoutines.f90 sourcefile~self_geometry_2d.f90->sourcefile~self_supportroutines.f90 sourcefile~self_data.f90 SELF_Data.f90 sourcefile~self_geometry_2d.f90->sourcefile~self_data.f90 sourcefile~self_mesh_2d_t.f90->sourcefile~self_domaindecomposition.f90 sourcefile~self_mesh_2d_t.f90->sourcefile~self_lagrange.f90 sourcefile~self_mesh_2d_t.f90->sourcefile~self_constants.f90 sourcefile~self_mesh_2d_t.f90->sourcefile~self_supportroutines.f90 sourcefile~self_quadrature.f90 SELF_Quadrature.f90 sourcefile~self_mesh_2d_t.f90->sourcefile~self_quadrature.f90 sourcefile~self_mesh.f90 SELF_Mesh.f90 sourcefile~self_mesh_2d_t.f90->sourcefile~self_mesh.f90 sourcefile~self_hdf5.f90 SELF_HDF5.f90 sourcefile~self_mesh_2d_t.f90->sourcefile~self_hdf5.f90 sourcefile~self_domaindecomposition_t.f90->sourcefile~self_lagrange.f90 sourcefile~self_domaindecomposition_t.f90->sourcefile~self_constants.f90 sourcefile~self_domaindecomposition_t.f90->sourcefile~self_supportroutines.f90 sourcefile~self_vector_2d_t.f90->sourcefile~self_lagrange.f90 sourcefile~self_vector_2d_t.f90->sourcefile~self_constants.f90 sourcefile~self_vector_2d_t.f90->sourcefile~self_data.f90 sourcefile~self_metadata.f90 SELF_Metadata.f90 sourcefile~self_vector_2d_t.f90->sourcefile~self_metadata.f90 sourcefile~self_vector_2d_t.f90->sourcefile~self_hdf5.f90 sourcefile~self_tensor_2d_t.f90->sourcefile~self_lagrange.f90 sourcefile~self_tensor_2d_t.f90->sourcefile~self_constants.f90 sourcefile~self_tensor_2d_t.f90->sourcefile~self_data.f90 sourcefile~self_tensor_2d_t.f90->sourcefile~self_metadata.f90 sourcefile~self_tensor_2d_t.f90->sourcefile~self_hdf5.f90 sourcefile~self_scalar_2d.f90->sourcefile~self_constants.f90 sourcefile~self_scalar_2d_t.f90 SELF_Scalar_2D_t.f90 sourcefile~self_scalar_2d.f90->sourcefile~self_scalar_2d_t.f90 sourcefile~self_supportroutines.f90->sourcefile~self_constants.f90 sourcefile~self_lagrange_t.f90->sourcefile~self_constants.f90 sourcefile~self_lagrange_t.f90->sourcefile~self_supportroutines.f90 sourcefile~self_lagrange_t.f90->sourcefile~self_quadrature.f90 sourcefile~self_lagrange_t.f90->sourcefile~self_hdf5.f90 sourcefile~self_data.f90->sourcefile~self_lagrange.f90 sourcefile~self_data.f90->sourcefile~self_constants.f90 sourcefile~self_data.f90->sourcefile~self_metadata.f90 sourcefile~self_data.f90->sourcefile~self_hdf5.f90 sourcefile~self_quadrature.f90->sourcefile~self_constants.f90 sourcefile~self_mesh.f90->sourcefile~self_domaindecomposition.f90 sourcefile~self_mesh.f90->sourcefile~self_constants.f90 sourcefile~self_metadata.f90->sourcefile~self_hdf5.f90 sourcefile~self_hdf5.f90->sourcefile~self_constants.f90 sourcefile~self_scalar_2d_t.f90->sourcefile~self_lagrange.f90 sourcefile~self_scalar_2d_t.f90->sourcefile~self_constants.f90 sourcefile~self_scalar_2d_t.f90->sourcefile~self_data.f90 sourcefile~self_scalar_2d_t.f90->sourcefile~self_metadata.f90 sourcefile~self_scalar_2d_t.f90->sourcefile~self_hdf5.f90

Contents


Source Code

! //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// !
!
! Maintainers : support@fluidnumerics.com
! Official Repository : https://github.com/FluidNumerics/self/
!
! Copyright © 2024 Fluid Numerics LLC
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!    this software without specific prior written permission.
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! //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// !

module SELF_MappedVector_2D

  use SELF_MappedVector_2D_t
  use SELF_GPU
  use SELF_GPUInterfaces
  use iso_c_binding

  implicit none

  type,extends(MappedVector2D_t),public :: MappedVector2D

    type(c_ptr) :: mortarBuff_gpu = c_null_ptr ! mortar trace staging (lazy allocation)

    ! Packed device buffers for the aggregated MPI halo exchange. The side
    ! tables are shared across fields and live on mesh%decomp; the buffers
    ! are per-field (sized for 2*nvar variables, since both vector components
    ! are exchanged) and allocated lazily on the first exchange.
    type(c_ptr) :: halo_sendbuf_gpu = c_null_ptr ! packed device send buffer
    type(c_ptr) :: halo_recvbuf_gpu = c_null_ptr ! packed device receive buffer

  contains
    procedure,public :: Free => Free_MappedVector2D
    procedure,public :: SetInteriorFromEquation => SetInteriorFromEquation_MappedVector2D

    procedure,public :: SideExchange => SideExchange_MappedVector2D
    procedure,private :: MPIExchangeAsync => MPIExchangeAsync_MappedVector2D

    procedure,public :: MortarExchange => MortarExchange_MappedVector2D
    procedure,public :: MortarFluxCollect => MortarFluxCollect_MappedVector2D
    procedure,private :: MPIMortarExchangeAsync => MPIMortarExchangeAsync_MappedVector2D
    procedure,private :: MPIMortarFluxAsync => MPIMortarFluxAsync_MappedVector2D

    generic,public :: MappedDivergence => MappedDivergence_MappedVector2D
    procedure,private :: MappedDivergence_MappedVector2D

    generic,public :: MappedDGDivergence => MappedDGDivergence_MappedVector2D
    procedure,private :: MappedDGDivergence_MappedVector2D

  endtype MappedVector2D

  interface
    subroutine ContravariantProjection_2D_gpu(f,dsdx,N,nvar,nel) &
      bind(c,name="ContravariantProjection_2D_gpu")
      use iso_c_binding
      implicit none
      type(c_ptr),value :: f,dsdx
      integer(c_int),value :: N,nvar,nel
    endsubroutine ContravariantProjection_2D_gpu
  endinterface

contains

  subroutine Free_MappedVector2D(this)
    implicit none
    class(MappedVector2D),intent(inout) :: this

    if(c_associated(this%mortarBuff_gpu)) then
      call gpuCheck(hipFree(this%mortarBuff_gpu))
      this%mortarBuff_gpu = c_null_ptr
    endif

    call Free_Vector2D(this)

    if(c_associated(this%halo_sendbuf_gpu)) call gpuCheck(hipFree(this%halo_sendbuf_gpu))
    if(c_associated(this%halo_recvbuf_gpu)) call gpuCheck(hipFree(this%halo_recvbuf_gpu))
    this%halo_sendbuf_gpu = c_null_ptr
    this%halo_recvbuf_gpu = c_null_ptr

  endsubroutine Free_MappedVector2D

  subroutine SetInteriorFromEquation_MappedVector2D(this,geometry,time)
  !!  Sets the this % interior attribute using the eqn attribute,
  !!  geometry (for physical positions), and provided simulation time.
    implicit none
    class(MappedVector2D),intent(inout) :: this
    type(SEMQuad),intent(in) :: geometry
    real(prec),intent(in) :: time
    ! Local
    integer :: i,j,iEl,iVar
    real(prec) :: x
    real(prec) :: y

    do iVar = 1,this%nVar
      do iEl = 1,this%nElem
        do j = 1,this%interp%N+1
          do i = 1,this%interp%N+1

            ! Get the mesh positions
            x = geometry%x%interior(i,j,iEl,1,1)
            y = geometry%x%interior(i,j,iEl,1,2)

            this%interior(i,j,iEl,iVar,1) = &
              this%eqn(1+2*(iVar-1))%Evaluate((/x,y,0.0_prec,time/))

            this%interior(i,j,iEl,iVar,2) = &
              this%eqn(2+2*(iVar-1))%Evaluate((/x,y,0.0_prec,time/))

          enddo
        enddo
      enddo
    enddo

    call gpuCheck(hipMemcpy(this%interior_gpu,c_loc(this%interior),sizeof(this%interior),hipMemcpyHostToDevice))

  endsubroutine SetInteriorFromEquation_MappedVector2D

  subroutine MPIExchangeAsync_MappedVector2D(this,mesh)
  !! Post the aggregated halo exchange: one MPI_Irecv/MPI_Isend pair per
  !! neighboring rank, carrying every (side,variable,component) boundary
  !! trace shared with that rank in a single packed device buffer. The
  !! boundary array is laid out with the component index outermost, so the
  !! pack/unpack kernels treat the vector as 2*nvar scalar variables. Packed
  !! buffers are allocated on first use; the shared side tables are built by
  !! SideExchange before this is called.
    implicit none
    class(MappedVector2D),intent(inout) :: this
    type(Mesh2D),intent(inout) :: mesh
    ! Local
    integer :: n,npts,cnt,disp
    integer :: iError
    integer :: msgCount
    integer(c_size_t) :: worksize
    real(prec),pointer :: sendbuf(:)
    real(prec),pointer :: recvbuf(:)

    npts = (this%interp%N+1)*2*this%nvar

    if(.not. c_associated(this%halo_sendbuf_gpu)) then
      worksize = int(mesh%decomp%halo_nsides,c_size_t)* &
                 int(npts,c_size_t)*prec
      call gpuCheck(hipMalloc(this%halo_sendbuf_gpu,worksize))
      call gpuCheck(hipMalloc(this%halo_recvbuf_gpu,worksize))
    endif

    call HaloPack_2D_gpu(this%boundary_gpu,this%halo_sendbuf_gpu, &
                         mesh%decomp%halo_sides_gpu,this%interp%N,2*this%nvar, &
                         this%nelem,mesh%decomp%halo_nsides)

    call c_f_pointer(this%halo_sendbuf_gpu,sendbuf,[mesh%decomp%halo_nsides*npts])
    call c_f_pointer(this%halo_recvbuf_gpu,recvbuf,[mesh%decomp%halo_nsides*npts])

    msgCount = 0
    do n = 1,mesh%decomp%halo_nnbr

      cnt = (mesh%decomp%halo_offset(n+1)-mesh%decomp%halo_offset(n))*npts
      disp = mesh%decomp%halo_offset(n)*npts

      msgCount = msgCount+1
      call MPI_IRECV(recvbuf(disp+1),cnt, &
                     mesh%decomp%mpiPrec, &
                     mesh%decomp%halo_rank(n),0, &
                     mesh%decomp%mpiComm, &
                     mesh%decomp%requests(msgCount),iError)

      msgCount = msgCount+1
      call MPI_ISEND(sendbuf(disp+1),cnt, &
                     mesh%decomp%mpiPrec, &
                     mesh%decomp%halo_rank(n),0, &
                     mesh%decomp%mpiComm, &
                     mesh%decomp%requests(msgCount),iError)

    enddo

    mesh%decomp%msgCount = msgCount

  endsubroutine MPIExchangeAsync_MappedVector2D

  subroutine SideExchange_MappedVector2D(this,mesh)
    implicit none
    class(MappedVector2D),intent(inout) :: this
    type(Mesh2D),intent(inout) :: mesh
    ! Local
    integer :: offset

    offset = mesh%decomp%offsetElem(mesh%decomp%rankid+1)

    if(mesh%decomp%mpiEnabled) then
      if(.not. mesh%decomp%halo_built) then
        call mesh%decomp%BuildHaloExchange(mesh%sideInfo,mesh%nElem,4)
      endif
      if(mesh%decomp%halo_nsides > 0) then
        call this%MPIExchangeAsync(mesh)
      endif
    endif

    ! The local (same-rank) side exchange runs on the device while the
    ! aggregated MPI messages are in flight.
    call SideExchange_2D_gpu(this%extboundary_gpu, &
                             this%boundary_gpu,mesh%sideinfo_gpu,mesh%decomp%elemToRank_gpu, &
                             mesh%decomp%rankid,offset,this%interp%N,2*this%nvar,this%nelem)

    if(mesh%decomp%mpiEnabled) then
      if(mesh%decomp%halo_nsides > 0) then
        call mesh%decomp%FinalizeMPIExchangeAsync()
        ! Unpack the received traces into extBoundary, applying side flips
        call HaloUnpack_2D_gpu(this%halo_recvbuf_gpu,this%extboundary_gpu, &
                               mesh%decomp%halo_sides_gpu,this%interp%N,2*this%nvar, &
                               this%nelem,mesh%decomp%halo_nsides)
      endif
    endif

  endsubroutine SideExchange_MappedVector2D

  subroutine MPIMortarExchangeAsync_MappedVector2D(this,mesh)
    !! GPU-resident mortar message posting for vector data; messages are posted on
    !! device memory (GPU-aware MPI), one per variable and physical direction.
    implicit none
    class(MappedVector2D),intent(inout) :: this
    type(Mesh2D),intent(inout) :: mesh
    ! Local
    integer :: m,k,ivar,idir
    integer :: eB,sB,rB,eS,sS,rS
    integer :: globalSideId,tag
    integer :: offset
    integer :: iError
    integer :: msgCount
    real(prec),pointer :: boundary(:,:,:,:,:)
    real(prec),pointer :: mortarBuff(:,:,:,:,:)

    msgCount = 0
    offset = mesh%decomp%offsetElem(mesh%decomp%rankId+1)
    call c_f_pointer(this%boundary_gpu,boundary,[this%interp%N+1,4,this%nelem,this%nvar,2])
    call c_f_pointer(this%mortarBuff_gpu,mortarBuff, &
                     [this%interp%N+1,4,mesh%nMortars,this%nvar,2])

    do idir = 1,2
      do ivar = 1,this%nvar
        do m = 1,mesh%nMortars

          eB = mesh%mortarInfo(1,m)
          sB = mesh%mortarInfo(2,m)
          rB = mesh%decomp%elemToRank(eB)

          do k = 1,2

            eS = mesh%mortarInfo(2*k+1,m)
            sS = mesh%mortarInfo(2*k+2,m)/10
            rS = mesh%decomp%elemToRank(eS)
            globalSideId = mesh%mortarInfo(6+k,m)
            tag = globalSideId+mesh%nUniqueSides*(ivar-1+this%nvar*(idir-1))

            if(rB == mesh%decomp%rankId .and. rS /= mesh%decomp%rankId) then

              msgCount = msgCount+1
              call MPI_IRECV(mortarBuff(:,2+k,m,ivar,idir), &
                             (this%interp%N+1), &
                             mesh%decomp%mpiPrec, &
                             rS,tag, &
                             mesh%decomp%mpiComm, &
                             mesh%decomp%requests(msgCount),iError)

              msgCount = msgCount+1
              call MPI_ISEND(boundary(:,sB,eB-offset,ivar,idir), &
                             (this%interp%N+1), &
                             mesh%decomp%mpiPrec, &
                             rS,tag, &
                             mesh%decomp%mpiComm, &
                             mesh%decomp%requests(msgCount),iError)

            elseif(rS == mesh%decomp%rankId .and. rB /= mesh%decomp%rankId) then

              msgCount = msgCount+1
              call MPI_IRECV(mortarBuff(:,k,m,ivar,idir), &
                             (this%interp%N+1), &
                             mesh%decomp%mpiPrec, &
                             rB,tag, &
                             mesh%decomp%mpiComm, &
                             mesh%decomp%requests(msgCount),iError)

              msgCount = msgCount+1
              call MPI_ISEND(boundary(:,sS,eS-offset,ivar,idir), &
                             (this%interp%N+1), &
                             mesh%decomp%mpiPrec, &
                             rB,tag, &
                             mesh%decomp%mpiComm, &
                             mesh%decomp%requests(msgCount),iError)

            endif

          enddo
        enddo
      enddo
    enddo

    mesh%decomp%msgCount = msgCount

  endsubroutine MPIMortarExchangeAsync_MappedVector2D

  subroutine MortarExchange_MappedVector2D(this,mesh)
    !! GPU implementation of the vector mortar exchange; the kernels treat the
    !! (variable, direction) pairs as 2*nvar independent trace lines.
    implicit none
    class(MappedVector2D),intent(inout) :: this
    type(Mesh2D),intent(inout) :: mesh
    ! Local
    integer :: offset
    integer(c_size_t) :: buffSize

    offset = mesh%decomp%offsetElem(mesh%decomp%rankId+1)

    if(.not. c_associated(this%mortarBuff_gpu)) then
      buffSize = int(this%interp%N+1,c_size_t)*4*mesh%nMortars*this%nvar*2*prec
      call gpuCheck(hipMalloc(this%mortarBuff_gpu,buffSize))
    endif

    if(mesh%decomp%mpiEnabled) then
      call this%MPIMortarExchangeAsync(mesh)
    endif

    call MortarGather_2D_gpu(this%mortarBuff_gpu,this%boundary_gpu, &
                             mesh%mortarInfo_gpu,mesh%decomp%elemToRank_gpu, &
                             mesh%decomp%rankId,offset,this%interp%N,2*this%nvar, &
                             mesh%nMortars,this%nelem)

    if(mesh%decomp%mpiEnabled) then
      call mesh%decomp%FinalizeMPIExchangeAsync()
      call MortarFlip_2D_gpu(this%mortarBuff_gpu,mesh%mortarInfo_gpu, &
                             mesh%decomp%elemToRank_gpu,mesh%decomp%rankId, &
                             this%interp%N,2*this%nvar,mesh%nMortars)
    endif

    call MortarScatter_2D_gpu(this%extBoundary_gpu,this%mortarBuff_gpu, &
                              this%interp%mortarR_gpu,this%interp%mortarP_gpu, &
                              mesh%mortarInfo_gpu,mesh%decomp%elemToRank_gpu, &
                              mesh%decomp%rankId,offset,this%interp%N,2*this%nvar, &
                              mesh%nMortars,this%nelem)

  endsubroutine MortarExchange_MappedVector2D

  subroutine MPIMortarFluxAsync_MappedVector2D(this,mesh)
    !! One-directional messages for MortarFluxCollect on device memory : each remote
    !! small side sends its boundaryNormal trace to the big side's rank.
    implicit none
    class(MappedVector2D),intent(inout) :: this
    type(Mesh2D),intent(inout) :: mesh
    ! Local
    integer :: m,k,ivar
    integer :: eB,rB,eS,sS,rS
    integer :: globalSideId,tag
    integer :: offset
    integer :: iError
    integer :: msgCount
    real(prec),pointer :: boundaryNormal(:,:,:,:)
    real(prec),pointer :: mortarBuff(:,:,:,:)

    msgCount = 0
    offset = mesh%decomp%offsetElem(mesh%decomp%rankId+1)
    call c_f_pointer(this%boundarynormal_gpu,boundaryNormal, &
                     [this%interp%N+1,4,this%nelem,this%nvar])
    call c_f_pointer(this%mortarBuff_gpu,mortarBuff, &
                     [this%interp%N+1,4,mesh%nMortars,this%nvar])

    do ivar = 1,this%nvar
      do m = 1,mesh%nMortars

        eB = mesh%mortarInfo(1,m)
        rB = mesh%decomp%elemToRank(eB)

        do k = 1,2

          eS = mesh%mortarInfo(2*k+1,m)
          sS = mesh%mortarInfo(2*k+2,m)/10
          rS = mesh%decomp%elemToRank(eS)
          globalSideId = mesh%mortarInfo(6+k,m)
          tag = globalSideId+mesh%nUniqueSides*(ivar-1)

          if(rB == mesh%decomp%rankId .and. rS /= mesh%decomp%rankId) then

            msgCount = msgCount+1
            call MPI_IRECV(mortarBuff(:,2+k,m,ivar), &
                           (this%interp%N+1), &
                           mesh%decomp%mpiPrec, &
                           rS,tag, &
                           mesh%decomp%mpiComm, &
                           mesh%decomp%requests(msgCount),iError)

          elseif(rS == mesh%decomp%rankId .and. rB /= mesh%decomp%rankId) then

            msgCount = msgCount+1
            call MPI_ISEND(boundaryNormal(:,sS,eS-offset,ivar), &
                           (this%interp%N+1), &
                           mesh%decomp%mpiPrec, &
                           rB,tag, &
                           mesh%decomp%mpiComm, &
                           mesh%decomp%requests(msgCount),iError)

          endif

        enddo
      enddo
    enddo

    mesh%decomp%msgCount = msgCount

  endsubroutine MPIMortarFluxAsync_MappedVector2D

  subroutine MortarFluxCollect_MappedVector2D(this,mesh)
    !! GPU implementation of MortarFluxCollect (see the base class for the algorithm
    !! and conservation statement). Stages the small sides' boundaryNormal traces in
    !! the mortar buffer, then overwrites the big side's integrand on device.
    implicit none
    class(MappedVector2D),intent(inout) :: this
    type(Mesh2D),intent(inout) :: mesh
    ! Local
    integer :: offset
    integer(c_size_t) :: buffSize

    offset = mesh%decomp%offsetElem(mesh%decomp%rankId+1)

    if(.not. c_associated(this%mortarBuff_gpu)) then
      buffSize = int(this%interp%N+1,c_size_t)*4*mesh%nMortars*this%nvar*2*prec
      call gpuCheck(hipMalloc(this%mortarBuff_gpu,buffSize))
    endif

    if(mesh%decomp%mpiEnabled) then
      call this%MPIMortarFluxAsync(mesh)
    endif

    ! Stage rank-local small-side integrands (the big-side slots are gathered too
    ! but unused by the flux scatter)
    call MortarGather_2D_gpu(this%mortarBuff_gpu,this%boundarynormal_gpu, &
                             mesh%mortarInfo_gpu,mesh%decomp%elemToRank_gpu, &
                             mesh%decomp%rankId,offset,this%interp%N,this%nvar, &
                             mesh%nMortars,this%nelem)

    if(mesh%decomp%mpiEnabled) then
      call mesh%decomp%FinalizeMPIExchangeAsync()
      call MortarFlip_2D_gpu(this%mortarBuff_gpu,mesh%mortarInfo_gpu, &
                             mesh%decomp%elemToRank_gpu,mesh%decomp%rankId, &
                             this%interp%N,this%nvar,mesh%nMortars)
    endif

    call MortarFluxScatter_2D_gpu(this%boundarynormal_gpu,this%mortarBuff_gpu, &
                                  this%interp%mortarP_gpu, &
                                  mesh%mortarInfo_gpu,mesh%decomp%elemToRank_gpu, &
                                  mesh%decomp%rankId,offset,this%interp%N,this%nvar, &
                                  mesh%nMortars,this%nelem)

  endsubroutine MortarFluxCollect_MappedVector2D

  subroutine MappedDivergence_MappedVector2D(this,df)
    implicit none
    class(MappedVector2D),intent(inout) :: this
    type(c_ptr),intent(out) :: df
    ! Contravariant projection
    call ContravariantProjection_2D_gpu(this%interior_gpu, &
                                        this%geometry%dsdx%interior_gpu,this%interp%N,this%nvar,this%nelem)

    call Divergence_2D_gpu(this%interior_gpu,df,this%interp%dMatrix_gpu, &
                           this%interp%N,this%nvar,this%nelem)

    call JacobianWeight_2D_gpu(df,this%geometry%J%interior_gpu,this%interp%N,this%nVar,this%nelem)

  endsubroutine MappedDivergence_MappedVector2D

  subroutine MappedDGDivergence_MappedVector2D(this,df)
    implicit none
    class(MappedVector2D),intent(inout) :: this
    type(c_ptr),intent(out) :: df

    ! Contravariant projection
    call ContravariantProjection_2D_gpu(this%interior_gpu, &
                                        this%geometry%dsdx%interior_gpu,this%interp%N,this%nvar,this%nelem)

    call Divergence_2D_gpu(this%interior_gpu,df,this%interp%dgMatrix_gpu, &
                           this%interp%N,this%nvar,this%nelem)

    ! Boundary terms
    call DG_BoundaryContribution_2D_gpu(this%interp%bmatrix_gpu,this%interp%qweights_gpu, &
                                        this%boundarynormal_gpu,df,this%interp%N,this%nvar,this%nelem)

    call JacobianWeight_2D_gpu(df,this%geometry%J%interior_gpu,this%interp%N,this%nVar,this%nelem)

  endsubroutine MappedDGDivergence_MappedVector2D

endmodule SELF_MappedVector_2D