2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
6 Stockfish is free software: you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation, either version 3 of the License, or
9 (at your option) any later version.
11 Stockfish is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <http://www.gnu.org/licenses/>.
27 uint8_t DirectionTable[64][64];
30 static bool reachable(Square orig, Square dest, Direction d) {
32 const SquareDelta directionToDelta[] = {
33 DELTA_E, DELTA_N, DELTA_NE, DELTA_NW, DELTA_W, DELTA_S, DELTA_SW, DELTA_SE
36 SquareDelta delta = directionToDelta[dest > orig ? d : d + 4];
38 Square to = from + delta;
40 while (to != dest && square_distance(to, from) == 1 && square_is_ok(to))
45 return to == dest && square_distance(from, to) == 1;
48 void init_direction_table() {
50 for (Square s1 = SQ_A1; s1 <= SQ_H8; s1++)
51 for (Square s2 = SQ_A1; s2 <= SQ_H8; s2++)
53 DirectionTable[s1][s2] = uint8_t(DIR_NONE);
58 for (Direction d = DIR_E; d != DIR_NONE; d++)
60 if (reachable(s1, s2, d))
62 DirectionTable[s1][s2] = uint8_t(d);