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/>.
29 //// Local definitions
34 const SquareDelta directionToDelta[] = {
35 DELTA_E, DELTA_W, DELTA_N, DELTA_S, DELTA_NE, DELTA_SW, DELTA_NW, DELTA_SE
38 bool reachable(Square orig, Square dest, SignedDirection dir) {
40 SquareDelta delta = directionToDelta[dir];
42 Square to = from + delta;
43 while (to != dest && square_distance(to, from) == 1 && square_is_ok(to))
48 return (to == dest && square_distance(from, to) == 1);
58 uint8_t DirectionTable[64][64];
59 uint8_t SignedDirectionTable[64][64];
66 void init_direction_table() {
68 for (Square s1 = SQ_A1; s1 <= SQ_H8; s1++)
69 for (Square s2 = SQ_A1; s2 <= SQ_H8; s2++)
71 DirectionTable[s1][s2] = uint8_t(DIR_NONE);
72 SignedDirectionTable[s1][s2] = uint8_t(SIGNED_DIR_NONE);
76 for (SignedDirection d = SIGNED_DIR_E; d != SIGNED_DIR_NONE; d++)
78 if (reachable(s1, s2, d))
80 SignedDirectionTable[s1][s2] = uint8_t(d);
81 DirectionTable[s1][s2] = uint8_t(d / 2);