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

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

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

 13:    Collective on DMDA

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

 18: */
 19: PetscErrorCode  DMDALocalToLocalCreate(DM da)
 20: {
 22:   PetscInt       *idx,left,j,count,up,down,i,bottom,top,k;
 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(da,dd->ltol);
 36:   if (dd->dim == 1) {
 37:     left = dd->xs - dd->Xs;
 38:     PetscMalloc((dd->xe-dd->xs)*sizeof(PetscInt),&idx);
 39:     for (j=0; j<dd->xe-dd->xs; j++) idx[j] = left + j;
 40:   } else if (dd->dim == 2) {
 41:     left  = dd->xs - dd->Xs; down  = dd->ys - dd->Ys; up    = down + dd->ye-dd->ys;
 42:     PetscMalloc((dd->xe-dd->xs)*(up - down)*sizeof(PetscInt),&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 (dd->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:     PetscMalloc(count*sizeof(PetscInt),&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",dd->dim);

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

 72: /*@
 73:    DMDALocalToLocalBegin - 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 DMDALocalToLocalEnd().

 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:    Level: intermediate

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

 95: .keywords: distributed array, local-to-local, begin

 97: .seealso: DMDALocalToLocalEnd(), DMLocalToGlobalBegin()
 98: @*/
 99: PetscErrorCode  DMDALocalToLocalBegin(DM da,Vec g,InsertMode mode,Vec l)
100: {
102:   DM_DA          *dd = (DM_DA*)da->data;

106:   if (!dd->ltol) {
107:     DMDALocalToLocalCreate(da);
108:   }
109:   VecScatterBegin(dd->ltol,g,l,mode,SCATTER_FORWARD);
110:   return(0);
111: }

115: /*@
116:    DMDALocalToLocalEnd - Maps from a local vector (including ghost points
117:    that contain irrelevant values) to another local vector where the ghost
118:    points in the second are set correctly.  Must be preceeded by
119:    DMDALocalToLocalBegin().

121:    Neighbor-wise Collective on DMDA and Vec

123:    Input Parameters:
124: +  da - the distributed array context
125: .  g - the original local vector
126: -  mode - one of INSERT_VALUES or ADD_VALUES

128:    Output Parameter:
129: .  l  - the local vector with correct ghost values

131:    Level: intermediate

133:    Note:
134:    The local vectors used here need not be the same as those
135:    obtained from DMCreateLocalVector(), BUT they
136:    must have the same parallel data layout; they could, for example, be
137:    obtained with VecDuplicate() from the DMDA originating vectors.

139: .keywords: distributed array, local-to-local, end

141: .seealso: DMDALocalToLocalBegin(), DMLocalToGlobalBegin()
142: @*/
143: PetscErrorCode  DMDALocalToLocalEnd(DM da,Vec g,InsertMode mode,Vec l)
144: {
146:   DM_DA          *dd = (DM_DA*)da->data;

152:   VecScatterEnd(dd->ltol,g,l,mode,SCATTER_FORWARD);
153:   return(0);
154: }