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

  6: #include <petsc/private/dmdaimpl.h>    /*I   "petscdmda.h"   I*/

 10: /*
 11:    DMLocalToLocalCreate_DA - Creates the local to local scatter

 13:    Collective on DMDA

 15:    Input Parameter:
 16: .  da - the distributed array

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


 28:   if (dd->ltol) return(0);
 29:   /*
 30:      We simply remap the values in the from part of
 31:      global to local to read from an array with the ghost values
 32:      rather then from the plain array.
 33:   */
 34:   VecScatterCopy(dd->gtol,&dd->ltol);
 35:   PetscLogObjectParent((PetscObject)da,(PetscObject)dd->ltol);
 36:   if (dim == 1) {
 37:     left = dd->xs - dd->Xs;
 38:     PetscMalloc1(dd->xe-dd->xs,&idx);
 39:     for (j=0; j<dd->xe-dd->xs; j++) idx[j] = left + j;
 40:   } else if (dim == 2) {
 41:     left  = dd->xs - dd->Xs; down  = dd->ys - dd->Ys; up    = down + dd->ye-dd->ys;
 42:     PetscMalloc1((dd->xe-dd->xs)*(up - down),&idx);
 43:     count = 0;
 44:     for (i=down; i<up; i++) {
 45:       for (j=0; j<dd->xe-dd->xs; j++) {
 46:         idx[count++] = left + i*(dd->Xe-dd->Xs) + j;
 47:       }
 48:     }
 49:   } else if (dim == 3) {
 50:     left   = dd->xs - dd->Xs;
 51:     bottom = dd->ys - dd->Ys; top = bottom + dd->ye-dd->ys;
 52:     down   = dd->zs - dd->Zs; up  = down + dd->ze-dd->zs;
 53:     count  = (dd->xe-dd->xs)*(top-bottom)*(up-down);
 54:     PetscMalloc1(count,&idx);
 55:     count  = 0;
 56:     for (i=down; i<up; i++) {
 57:       for (j=bottom; j<top; j++) {
 58:         for (k=0; k<dd->xe-dd->xs; k++) {
 59:           idx[count++] = (left+j*(dd->Xe-dd->Xs))+i*(dd->Xe-dd->Xs)*(dd->Ye-dd->Ys) + k;
 60:         }
 61:       }
 62:     }
 63:   } else SETERRQ1(PetscObjectComm((PetscObject)da),PETSC_ERR_ARG_CORRUPT,"DMDA has invalid dimension %D",dim);

 65:   VecScatterRemap(dd->ltol,idx,NULL);
 66:   PetscFree(idx);
 67:   return(0);
 68: }

 72: /*
 73:    DMLocalToLocalBegin_DA - Maps from a local vector (including ghost points
 74:    that contain irrelevant values) to another local vector where the ghost
 75:    points in the second are set correctly. Must be followed by DMLocalToLocalEnd_DA().

 77:    Neighbor-wise Collective on DMDA and Vec

 79:    Input Parameters:
 80: +  da - the distributed array context
 81: .  g - the original local vector
 82: -  mode - one of INSERT_VALUES or ADD_VALUES

 84:    Output Parameter:
 85: .  l  - the local vector with correct ghost values

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

 93: */
 94: PetscErrorCode  DMLocalToLocalBegin_DA(DM da,Vec g,InsertMode mode,Vec l)
 95: {
 97:   DM_DA          *dd = (DM_DA*)da->data;

101:   if (!dd->ltol) {
102:     DMLocalToLocalCreate_DA(da);
103:   }
104:   VecScatterBegin(dd->ltol,g,l,mode,SCATTER_FORWARD);
105:   return(0);
106: }

110: /*
111:    DMLocalToLocalEnd_DA - Maps from a local vector (including ghost points
112:    that contain irrelevant values) to another local vector where the ghost
113:    points in the second are set correctly.  Must be preceeded by
114:    DMLocalToLocalBegin_DA().

116:    Neighbor-wise Collective on DMDA and Vec

118:    Input Parameters:
119: +  da - the distributed array context
120: .  g - the original local vector
121: -  mode - one of INSERT_VALUES or ADD_VALUES

123:    Output Parameter:
124: .  l  - the local vector with correct ghost values

126:    Note:
127:    The local vectors used here need not be the same as those
128:    obtained from DMCreateLocalVector(), BUT they
129:    must have the same parallel data layout; they could, for example, be
130:    obtained with VecDuplicate() from the DMDA originating vectors.

132: */
133: PetscErrorCode  DMLocalToLocalEnd_DA(DM da,Vec g,InsertMode mode,Vec l)
134: {
136:   DM_DA          *dd = (DM_DA*)da->data;

142:   VecScatterEnd(dd->ltol,g,l,mode,SCATTER_FORWARD);
143:   return(0);
144: }