2: /*
  3:   Code for manipulating distributed regular arrays in parallel.
  4: */

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

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

 11:    Collective on DMDA

 13:    Input Parameter:
 14: .  da - the distributed array

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


 26:   if (dd->ltol) return(0);
 27:   /*
 28:      We simply remap the values in the from part of
 29:      global to local to read from an array with the ghost values
 30:      rather then from the plain array.
 31:   */
 32:   VecScatterCopy(dd->gtol,&dd->ltol);
 33:   PetscLogObjectParent((PetscObject)da,(PetscObject)dd->ltol);
 34:   if (dim == 1) {
 35:     left = dd->xs - dd->Xs;
 36:     PetscMalloc1(dd->xe-dd->xs,&idx);
 37:     for (j=0; j<dd->xe-dd->xs; j++) idx[j] = left + j;
 38:   } else if (dim == 2) {
 39:     left  = dd->xs - dd->Xs; down  = dd->ys - dd->Ys; up    = down + dd->ye-dd->ys;
 40:     PetscMalloc1((dd->xe-dd->xs)*(up - down),&idx);
 41:     count = 0;
 42:     for (i=down; i<up; i++) {
 43:       for (j=0; j<dd->xe-dd->xs; j++) {
 44:         idx[count++] = left + i*(dd->Xe-dd->Xs) + j;
 45:       }
 46:     }
 47:   } else if (dim == 3) {
 48:     left   = dd->xs - dd->Xs;
 49:     bottom = dd->ys - dd->Ys; top = bottom + dd->ye-dd->ys;
 50:     down   = dd->zs - dd->Zs; up  = down + dd->ze-dd->zs;
 51:     count  = (dd->xe-dd->xs)*(top-bottom)*(up-down);
 52:     PetscMalloc1(count,&idx);
 53:     count  = 0;
 54:     for (i=down; i<up; i++) {
 55:       for (j=bottom; j<top; j++) {
 56:         for (k=0; k<dd->xe-dd->xs; k++) {
 57:           idx[count++] = (left+j*(dd->Xe-dd->Xs))+i*(dd->Xe-dd->Xs)*(dd->Ye-dd->Ys) + k;
 58:         }
 59:       }
 60:     }
 61:   } else SETERRQ1(PetscObjectComm((PetscObject)da),PETSC_ERR_ARG_CORRUPT,"DMDA has invalid dimension %D",dim);

 63:   VecScatterRemap(dd->ltol,idx,NULL);
 64:   PetscFree(idx);
 65:   return(0);
 66: }

 68: /*
 69:    DMLocalToLocalBegin_DA - Maps from a local vector (including ghost points
 70:    that contain irrelevant values) to another local vector where the ghost
 71:    points in the second are set correctly. Must be followed by DMLocalToLocalEnd_DA().

 73:    Neighbor-wise Collective on DMDA and Vec

 75:    Input Parameters:
 76: +  da - the distributed array context
 77: .  g - the original local vector
 78: -  mode - one of INSERT_VALUES or ADD_VALUES

 80:    Output Parameter:
 81: .  l  - the local vector with correct ghost values

 83:    Notes:
 84:    The local vectors used here need not be the same as those
 85:    obtained from DMCreateLocalVector(), BUT they
 86:    must have the same parallel data layout; they could, for example, be
 87:    obtained with VecDuplicate() from the DMDA originating vectors.

 89: */
 90: PetscErrorCode  DMLocalToLocalBegin_DA(DM da,Vec g,InsertMode mode,Vec l)
 91: {
 93:   DM_DA          *dd = (DM_DA*)da->data;

 97:   if (!dd->ltol) {
 98:     DMLocalToLocalCreate_DA(da);
 99:   }
100:   VecScatterBegin(dd->ltol,g,l,mode,SCATTER_FORWARD);
101:   return(0);
102: }

104: /*
105:    DMLocalToLocalEnd_DA - Maps from a local vector (including ghost points
106:    that contain irrelevant values) to another local vector where the ghost
107:    points in the second are set correctly.  Must be preceeded by
108:    DMLocalToLocalBegin_DA().

110:    Neighbor-wise Collective on DMDA and Vec

112:    Input Parameters:
113: +  da - the distributed array context
114: .  g - the original local vector
115: -  mode - one of INSERT_VALUES or ADD_VALUES

117:    Output Parameter:
118: .  l  - the local vector with correct ghost values

120:    Note:
121:    The local vectors used here need not be the same as those
122:    obtained from DMCreateLocalVector(), BUT they
123:    must have the same parallel data layout; they could, for example, be
124:    obtained with VecDuplicate() from the DMDA originating vectors.

126: */
127: PetscErrorCode  DMLocalToLocalEnd_DA(DM da,Vec g,InsertMode mode,Vec l)
128: {
130:   DM_DA          *dd = (DM_DA*)da->data;

136:   VecScatterEnd(dd->ltol,g,l,mode,SCATTER_FORWARD);
137:   return(0);
138: }