/*
  Code for manipulating distributed regular arrays in parallel.
*/

#include <petsc/private/dmdaimpl.h> /*I   "petscdmda.h"   I*/
extern PetscErrorCode DMLocalToLocalCreate_DA(DM);

/*@C
   DMDAGetScatter - Gets the global-to-local, and
   local-to-local vector scatter contexts for a distributed array.

   Collective on da

   Input Parameter:
.  da - the distributed array

   Output Parameters:
+  gtol - global-to-local scatter context (may be NULL)
-  ltol - local-to-local scatter context (may be NULL)

   Level: developer

   Notes:
   The output contexts are valid only as long as the input da is valid.
   If you delete the da, the scatter contexts will become invalid.

.seealso: `DMGlobalToLocalBegin()`, `DMGlobalToLocalEnd()`, `DMLocalToGlobalBegin()`
@*/
PetscErrorCode DMDAGetScatter(DM da, VecScatter *gtol, VecScatter *ltol) {
  DM_DA *dd = (DM_DA *)da->data;

  PetscFunctionBegin;
  PetscValidHeaderSpecificType(da, DM_CLASSID, 1, DMDA);
  if (gtol) *gtol = dd->gtol;
  if (ltol) {
    if (!dd->ltol) { PetscCall(DMLocalToLocalCreate_DA(da)); }
    *ltol = dd->ltol;
  }
  PetscFunctionReturn(0);
}