mirror of
https://github.com/paboyle/Grid.git
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259 lines
8.0 KiB
C++
259 lines
8.0 KiB
C++
#include "Grid.h"
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namespace Grid {
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CartesianStencil::CartesianStencil(GridBase *grid,
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int npoints,
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int checkerboard,
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const std::vector<int> &directions,
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const std::vector<int> &distances)
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: _offsets(npoints),
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_is_local(npoints),
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_comm_buf_size(npoints),
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_permute_type(npoints),
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_permute(npoints)
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{
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_npoints = npoints;
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_grid = grid;
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_directions = directions;
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_distances = distances;
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_unified_buffer_size=0;
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_request_count =0;
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CommsRequests.resize(0);
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int osites = _grid->oSites();
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for(int i=0;i<npoints;i++){
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int point = i;
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_offsets[i].resize( osites);
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_is_local[i].resize(osites);
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_permute[i].resize( osites);
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int dimension = directions[i];
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int displacement = distances[i];
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int shift = displacement;
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int fd = _grid->_fdimensions[dimension];
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int rd = _grid->_rdimensions[dimension];
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_permute_type[point]=_grid->PermuteType(dimension);
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_checkerboard = checkerboard;
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// the permute type
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int simd_layout = _grid->_simd_layout[dimension];
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int comm_dim = _grid->_processors[dimension] >1 ;
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int splice_dim = _grid->_simd_layout[dimension]>1 && (comm_dim);
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int sshift[2];
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// Underlying approach. For each local site build
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// up a table containing the npoint "neighbours" and whether they
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// live in lattice or a comms buffer.
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if ( !comm_dim ) {
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sshift[0] = _grid->CheckerBoardShift(_checkerboard,dimension,shift,0);
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sshift[1] = _grid->CheckerBoardShift(_checkerboard,dimension,shift,1);
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if ( sshift[0] == sshift[1] ) {
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Local(point,dimension,shift,0x3);
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} else {
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Local(point,dimension,shift,0x1);// if checkerboard is unfavourable take two passes
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Local(point,dimension,shift,0x2);// both with block stride loop iteration
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}
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} else { // All permute extract done in comms phase prior to Stencil application
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// So tables are the same whether comm_dim or splice_dim
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sshift[0] = _grid->CheckerBoardShift(_checkerboard,dimension,shift,0);
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sshift[1] = _grid->CheckerBoardShift(_checkerboard,dimension,shift,1);
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if ( sshift[0] == sshift[1] ) {
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Comms(point,dimension,shift,0x3);
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} else {
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Comms(point,dimension,shift,0x1);// if checkerboard is unfavourable take two passes
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Comms(point,dimension,shift,0x2);// both with block stride loop iteration
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}
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}
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}
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}
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void CartesianStencil::Local (int point, int dimension,int shift,int cbmask)
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{
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int fd = _grid->_fdimensions[dimension];
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int rd = _grid->_rdimensions[dimension];
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int ld = _grid->_ldimensions[dimension];
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int gd = _grid->_gdimensions[dimension];
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// Map to always positive shift modulo global full dimension.
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shift = (shift+fd)%fd;
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// the permute type
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int permute_dim =_grid->PermuteDim(dimension);
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for(int x=0;x<rd;x++){
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int o = 0;
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int bo = x * _grid->_ostride[dimension];
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int cb= (cbmask==0x2)? 1 : 0;
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int sshift = _grid->CheckerBoardShift(_checkerboard,dimension,shift,cb);
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int sx = (x+sshift)%rd;
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int permute_slice=0;
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if(permute_dim){
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int wrap = sshift/rd;
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int num = sshift%rd;
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if ( x< rd-num ) permute_slice=wrap;
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else permute_slice = 1-wrap;
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}
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CopyPlane(point,dimension,x,sx,cbmask,permute_slice);
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}
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}
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void CartesianStencil::Comms (int point,int dimension,int shift,int cbmask)
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{
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GridBase *grid=_grid;
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int fd = _grid->_fdimensions[dimension];
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int rd = _grid->_rdimensions[dimension];
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int simd_layout = _grid->_simd_layout[dimension];
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int comm_dim = _grid->_processors[dimension] >1 ;
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assert(simd_layout==1);
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assert(comm_dim==1);
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assert(shift>=0);
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assert(shift<fd);
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int buffer_size = _grid->_slice_nblock[dimension]*_grid->_slice_block[dimension];
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_comm_buf_size[point] = buffer_size; // Size of _one_ plane. Multiple planes may be gathered and
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// send to one or more remote nodes.
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int cb= (cbmask==0x2)? 1 : 0;
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int sshift= _grid->CheckerBoardShift(_checkerboard,dimension,shift,cb);
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for(int x=0;x<rd;x++){
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int offnode = ( x+sshift >= rd );
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int sx = (x+sshift)%rd;
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int comm_proc = (x+sshift)/rd;
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if (!offnode) {
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int permute_slice=0;
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CopyPlane(point,dimension,x,sx,cbmask,permute_slice);
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} else {
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int words = buffer_size;
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if (cbmask != 0x3) words=words>>1;
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// GatherPlaneSimple (point,dimension,sx,cbmask);
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int rank = grid->_processor;
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int recv_from_rank;
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int xmit_to_rank;
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CommsRequest cr;
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cr.tag = _request_count++;
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cr.words = words;
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cr.unified_buffer_offset = _unified_buffer_size;
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_unified_buffer_size += words;
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grid->ShiftedRanks(dimension,comm_proc,cr.to_rank,cr.from_rank);
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CommsRequests.push_back(cr);
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ScatterPlane(point,dimension,x,cbmask,cr.unified_buffer_offset); // permute/extract/merge is done in comms phase
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}
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}
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}
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// Routine builds up integer table for each site in _offsets, _is_local, _permute
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void CartesianStencil::CopyPlane(int point, int dimension,int lplane,int rplane,int cbmask,int permute)
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{
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int rd = _grid->_rdimensions[dimension];
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if ( !_grid->CheckerBoarded(dimension) ) {
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int o = 0; // relative offset to base within plane
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int ro = rplane*_grid->_ostride[dimension]; // base offset for start of plane
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int lo = lplane*_grid->_ostride[dimension]; // offset in buffer
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// Simple block stride gather of SIMD objects
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for(int n=0;n<_grid->_slice_nblock[dimension];n++){
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for(int b=0;b<_grid->_slice_block[dimension];b++){
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_offsets [point][lo+o+b]=ro+o+b;
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_is_local[point][lo+o+b]=1;
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_permute [point][lo+o+b]=permute;
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}
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o +=_grid->_slice_stride[dimension];
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}
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} else {
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int ro = rplane*_grid->_ostride[dimension]; // base offset for start of plane
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int lo = lplane*_grid->_ostride[dimension]; // base offset for start of plane
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int o = 0; // relative offset to base within plane
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for(int n=0;n<_grid->_slice_nblock[dimension];n++){
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for(int b=0;b<_grid->_slice_block[dimension];b++){
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int ocb=1<<_grid->CheckerBoardFromOindex(o+b);
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if ( ocb&cbmask ) {
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_offsets [point][lo+o+b]=ro+o+b;
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_is_local[point][lo+o+b]=1;
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_permute [point][lo+o+b]=permute;
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}
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}
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o +=_grid->_slice_stride[dimension];
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}
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}
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}
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// Routine builds up integer table for each site in _offsets, _is_local, _permute
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void CartesianStencil::ScatterPlane (int point,int dimension,int plane,int cbmask,int offset)
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{
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int rd = _grid->_rdimensions[dimension];
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if ( !_grid->CheckerBoarded(dimension) ) {
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int so = plane*_grid->_ostride[dimension]; // base offset for start of plane
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int o = 0; // relative offset to base within plane
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int bo = 0; // offset in buffer
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// Simple block stride gather of SIMD objects
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for(int n=0;n<_grid->_slice_nblock[dimension];n++){
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for(int b=0;b<_grid->_slice_block[dimension];b++){
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_offsets [point][so+o+b]=offset+(bo++);
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_is_local[point][so+o+b]=0;
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_permute [point][so+o+b]=0;
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}
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o +=_grid->_slice_stride[dimension];
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}
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} else {
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int so = plane*_grid->_ostride[dimension]; // base offset for start of plane
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int o = 0; // relative offset to base within plane
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int bo = 0; // offset in buffer
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for(int n=0;n<_grid->_slice_nblock[dimension];n++){
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for(int b=0;b<_grid->_slice_block[dimension];b++){
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int ocb=1<<_grid->CheckerBoardFromOindex(o+b);// Could easily be a table lookup
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if ( ocb & cbmask ) {
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_offsets [point][so+o+b]=offset+(bo++);
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_is_local[point][so+o+b]=0;
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_permute [point][so+o+b]=0;
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}
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}
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o +=_grid->_slice_stride[dimension];
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}
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}
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}
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}
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