1: !
  2: !
  3: !    Fortran kernel for sparse matrix-vector product in the AIJ matrix format
  4: !
  5: #include <petsc/finclude/petscsys.h>
  6: !
  7: pure subroutine FortranMultTransposeAddAIJ(n,x,ii,jj,a,y)
  8:   use, intrinsic :: ISO_C_binding
  9:   implicit none (type, external)
 10:   PetscScalar, intent(in) :: x(0:*),a(0:*)
 11:   PetscScalar, intent(inout) :: y(0:*)
 12:   PetscInt, intent(in) :: n,ii(*),jj(0:*)

 14:   PetscInt :: i,jstart,jend

 16:   jend = ii(1)
 17:   do i=1,n
 18:     jstart = jend
 19:     jend   = ii(i+1)
 20:     y(jj(jstart:jend-1)) = y(jj(jstart:jend-1)) + x(i-1)*a(jstart:jend-1)
 21:   end do
 22: end subroutine FortranMultTransposeAddAIJ

 24: pure subroutine FortranMultAIJ(n,x,ii,jj,a,y)
 25:   use, intrinsic :: ISO_C_binding
 26:   implicit none (type, external)
 27:   PetscScalar, intent(in) :: x(0:*),a(0:*)
 28:   PetscScalar, intent(inout) :: y(*)
 29:   PetscInt, intent(in) :: n,ii(*),jj(0:*)

 31:   PetscInt :: i,jstart,jend

 33: #ifdef PETSC_USE_OPENMP_KERNELS
 34:   !omp parallel do private(jstart,jend)
 35: #endif
 36:   do i=1,n
 37:     jstart = ii(i)
 38:     jend   = ii(i+1)
 39:     y(i) = sum(a(jstart:jend-1)*x(jj(jstart:jend-1)))
 40:   end do
 41: end subroutine FortranMultAIJ