1: /*
  2:   Code for manipulating distributed regular arrays in parallel.
  3: */

  5: #include <petsc/private/dmdaimpl.h>

  7: /*
  8:    DMLocalToLocalCreate_DA - Creates the local to local scatter

 10:    Collective

 12:    Input Parameter:
 13: .  da - the `DMDA`

 15: */
 16: PetscErrorCode DMLocalToLocalCreate_DA(DM da)
 17: {
 18:   PetscInt *idx, left, j, count, up, down, i, bottom, top, k, dim = da->dim;
 19:   DM_DA    *dd = (DM_DA *)da->data;

 21:   PetscFunctionBegin;

 24:   if (dd->ltol) PetscFunctionReturn(PETSC_SUCCESS);
 25:   /*
 26:      We simply remap the values in the from part of
 27:      global to local to read from an array with the ghost values
 28:      rather than from the plain array.
 29:   */
 30:   PetscCall(VecScatterCopy(dd->gtol, &dd->ltol));
 31:   if (dim == 1) {
 32:     left = dd->xs - dd->Xs;
 33:     PetscCall(PetscMalloc1(dd->xe - dd->xs, &idx));
 34:     for (j = 0; j < dd->xe - dd->xs; j++) idx[j] = left + j;
 35:   } else if (dim == 2) {
 36:     left = dd->xs - dd->Xs;
 37:     down = dd->ys - dd->Ys;
 38:     up   = down + dd->ye - dd->ys;
 39:     PetscCall(PetscMalloc1((dd->xe - dd->xs) * (up - down), &idx));
 40:     count = 0;
 41:     for (i = down; i < up; i++) {
 42:       for (j = 0; j < dd->xe - dd->xs; j++) idx[count++] = left + i * (dd->Xe - dd->Xs) + j;
 43:     }
 44:   } else if (dim == 3) {
 45:     left   = dd->xs - dd->Xs;
 46:     bottom = dd->ys - dd->Ys;
 47:     top    = bottom + dd->ye - dd->ys;
 48:     down   = dd->zs - dd->Zs;
 49:     up     = down + dd->ze - dd->zs;
 50:     count  = (dd->xe - dd->xs) * (top - bottom) * (up - down);
 51:     PetscCall(PetscMalloc1(count, &idx));
 52:     count = 0;
 53:     for (i = down; i < up; i++) {
 54:       for (j = bottom; j < top; j++) {
 55:         for (k = 0; k < dd->xe - dd->xs; k++) idx[count++] = (left + j * (dd->Xe - dd->Xs)) + i * (dd->Xe - dd->Xs) * (dd->Ye - dd->Ys) + k;
 56:       }
 57:     }
 58:   } else SETERRQ(PetscObjectComm((PetscObject)da), PETSC_ERR_ARG_CORRUPT, "DMDA has invalid dimension %" PetscInt_FMT, dim);

 60:   PetscCall(VecScatterRemap(dd->ltol, idx, NULL));
 61:   PetscCall(PetscFree(idx));
 62:   PetscFunctionReturn(PETSC_SUCCESS);
 63: }

 65: PetscErrorCode DMLocalToLocalBegin_DA(DM da, Vec g, InsertMode mode, Vec l)
 66: {
 67:   DM_DA *dd = (DM_DA *)da->data;

 69:   PetscFunctionBegin;
 71:   if (!dd->ltol) PetscCall(DMLocalToLocalCreate_DA(da));
 72:   PetscCall(VecScatterBegin(dd->ltol, g, l, mode, SCATTER_FORWARD));
 73:   PetscFunctionReturn(PETSC_SUCCESS);
 74: }

 76: PetscErrorCode DMLocalToLocalEnd_DA(DM da, Vec g, InsertMode mode, Vec l)
 77: {
 78:   DM_DA *dd = (DM_DA *)da->data;

 80:   PetscFunctionBegin;
 83:   PetscCall(VecScatterEnd(dd->ltol, g, l, mode, SCATTER_FORWARD));
 84:   PetscFunctionReturn(PETSC_SUCCESS);
 85: }