removed restriction that the world dimensions must be even divisible by the grid dimensions

cellular_automaton/wireworld_c++/FileIO.cpp

@@ -59,27 +59,37 @@ void FileIO::WriteHeader(const HeaderInfo& header, const std::string& path,
 	MPI_File_close(&fh);
 }
 
-Size FileIO::GetTileSize(Size globalSize, Size gridSize) {
-	const auto tileSizeCols = globalSize.Cols / gridSize.Cols;
-	const auto tileSizeRows = globalSize.Rows / gridSize.Rows;
-	return {tileSizeCols, tileSizeRows};
+SizeCoord FileIO::GetTileSizeCoord(Size globalSize, Size gridSize,
+                                   std::size_t rank) {
+	const auto tileX = rank % gridSize.Cols;
+	const auto tileY = rank / gridSize.Cols;
+
+	const auto xBeg = (tileX + 0) * globalSize.Cols / gridSize.Cols;
+	const auto xEnd = (tileX + 1) * globalSize.Cols / gridSize.Cols;
+
+	const auto yBeg = (tileY + 0) * globalSize.Rows / gridSize.Rows;
+	const auto yEnd = (tileY + 1) * globalSize.Rows / gridSize.Rows;
+
+	const auto tileSizeCols = xEnd - xBeg;
+	const auto tileSizeRows = yEnd - yBeg;
+	return {{tileSizeCols, tileSizeRows}, {xBeg, yBeg}};
 }
 
 FileIO::Tile::Tile(const std::string& path, HeaderInfo header, Size gridSize,
                    std::size_t rank, State* buf)
     : _path(path), _headerLength(header.HeaderLength),
       _srcSize(header.GlobalSize), _gridSize(gridSize), _rank(rank), _buf(buf),
-      _tileSize(FileIO::GetTileSize(header.GlobalSize, gridSize)), //
-      _tileX(rank % gridSize.Cols),                                //
-      _tileY(rank / gridSize.Cols),                                //
+      _tileSizeCoord(
+          FileIO::GetTileSizeCoord(header.GlobalSize, gridSize, rank)),
+      _tileSize(_tileSizeCoord.Size), _tileCoord(_tileSizeCoord.Coord),
       _tileType(
           MpiSubarray({{header.GlobalSize.Rows, _tileSize.Rows, 0},
                        {header.GlobalSize.Cols + LF, _tileSize.Cols, 0}})),
       _bufType(MpiSubarray({{_tileSize.Rows + 2, _tileSize.Rows, 1},
                             {_tileSize.Cols + 2, _tileSize.Cols, 1}})),
       _displ(header.HeaderLength +
-             (header.GlobalSize.Cols + LF) * _tileSize.Rows * _tileY +
-             _tileSize.Cols * _tileX) {}
+
+             (header.GlobalSize.Cols + LF) * _tileCoord.Y + _tileCoord.X) {}
 
 void FileIO::Tile::Read() {
 	MPI_File file;
@@ -106,21 +116,15 @@ void FileIO::Tile::Write() const {
 	// ranks actually write line feeds
 
 	// are we a rightMost tile?
-	const auto rightMost = _tileX == _gridSize.Cols - 1;
-	const auto bottomMost = _tileY == _gridSize.Rows - 1;
-	const auto noLfNeeded = rightMost ?                       //
-	                            (bottomMost ?                 //
-	                                 _tileSize.Rows - 1       //
-	                                        : _tileSize.Rows) //
-	                                  : 0;                    //
+	const auto rightMost = _tileCoord.X == _gridSize.Cols - 1;
+	const auto noLfNeeded = rightMost ? _tileSize.Rows : 0;
 	const auto lfType = MpiSubarray( // subsize must be > 0
 	    {{_srcSize.Rows, std::max<std::size_t>(noLfNeeded, 1), 0},
 	     {_srcSize.Cols + LF, 1, 0}});
 	const std::vector<char> lfs(noLfNeeded, '\n');
 
-	const auto lfDisp = _headerLength +
-	                    (_srcSize.Cols + LF) * _tileSize.Rows * _tileY +
-	                    _srcSize.Cols;
+	const auto lfDisp = _headerLength + (_srcSize.Cols + LF) * _tileCoord.Y +
+	                    _tileCoord.X + _tileSize.Cols;
 
 	MPI_File_set_view(file, lfDisp, MPI_CHAR, lfType.type(), "native",
 	                  MPI_INFO_NULL);

cellular_automaton/wireworld_c++/FileIO.hpp

@@ -2,6 +2,7 @@
 
 #include <cstddef>
 #include <string>
+#include <tuple>
 
 #include "MpiEnvironment.hpp"
 #include "MpiSubarray.hpp"
@@ -19,7 +20,7 @@ struct FileIO {
 	static void WriteHeader(const HeaderInfo& header, const std::string& path,
 	                        const MpiEnvironment& env);
 
-	static Size GetTileSize(Size globalSize, Size gridSize);
+	static SizeCoord GetTileSizeCoord(Size globalSize, Size gridSize, std::size_t rank);
 
 	// helper class to share commonly used data for reading and writing
 	class Tile {
@@ -31,9 +32,9 @@ struct FileIO {
 		const std::size_t _rank;
 		State* _buf;
 
+		const SizeCoord _tileSizeCoord;
 		const Size _tileSize;
-		const std::size_t _tileX;
-		const std::size_t _tileY;
+		const Coord _tileCoord;
 		const MpiSubarray _tileType;
 		const MpiSubarray _bufType;
 		const std::size_t _displ;

cellular_automaton/wireworld_c++/Tile.cpp

@@ -11,13 +11,8 @@
 
 Tile::Tile(const Configuration& cfg, const MpiEnvironment& env)
     : _env(env), _cfg(cfg), _header(FileIO::ReadHeader(cfg.InputFilePath)), //
-      _tileSize(FileIO::GetTileSize(_header.GlobalSize, cfg.Grid)),
+      _tileSize(FileIO::GetTileSizeCoord(_header.GlobalSize, cfg.Grid, env.worldRank()).Size),
       _modelWidth(_tileSize.Cols + 2) {
-	if ((_header.GlobalSize.Cols % _tileSize.Cols) != 0 ||
-	    (_header.GlobalSize.Rows % _tileSize.Rows) != 0) {
-		MpiReportErrorAbort(
-		    "Wireworld size is not even divisible by the grid size.");
-	}
 	const auto bufsize = (_tileSize.Cols + 2) * (_tileSize.Rows + 2);
 	_memoryA.resize(bufsize);
 	_memoryB.resize(bufsize);

cellular_automaton/wireworld_c++/Util.hpp

@@ -2,6 +2,7 @@
 
 #include <cstddef>
 #include <string>
+
 struct Size {
 	std::size_t Cols{};
 	std::size_t Rows{};
@@ -10,6 +11,12 @@ struct Size {
 struct Coord {
 	std::size_t X{};
 	std::size_t Y{};
+	Coord(std::size_t x, std::size_t y) : X(x), Y(y) {}
+};
+
+struct SizeCoord {
+	::Size Size;
+	::Coord Coord;
 };
 
 [[noreturn]] void MpiReportErrorAbort(const std::string& err);
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