/*
- Glaurung, a UCI chess playing engine.
- Copyright (C) 2004-2008 Tord Romstad
+ Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+ Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+ Copyright (C) 2008-2009 Marco Costalba
- Glaurung is free software: you can redistribute it and/or modify
+ Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
-
- Glaurung is distributed in the hope that it will be useful,
+
+ Stockfish is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
-
+
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "square.h"
+////
+//// Local definitions
+////
+
+namespace {
+
+ const SquareDelta directionToDelta[] = {
+ DELTA_E, DELTA_W, DELTA_N, DELTA_S, DELTA_NE, DELTA_SW, DELTA_NW, DELTA_SE
+ };
+
+ bool reachable(Square orig, Square dest, SignedDirection dir) {
+
+ SquareDelta delta = directionToDelta[dir];
+ Square from = orig;
+ Square to = from + delta;
+ while (to != dest && square_distance(to, from) == 1 && square_is_ok(to))
+ {
+ from = to;
+ to += delta;
+ }
+ return (to == dest && square_distance(from, to) == 1);
+ }
+
+}
+
+
////
//// Variables
////
////
void init_direction_table() {
- SquareDelta deltas[8] = {
- DELTA_E, DELTA_W, DELTA_N, DELTA_S, DELTA_NE, DELTA_SW, DELTA_NW, DELTA_SE
- };
- for(Square s1 = SQ_A1; s1 <= SQ_H8; s1++)
- for(Square s2 = SQ_A1; s2 <= SQ_H8; s2++) {
- DirectionTable[s1][s2] = uint8_t(DIR_NONE);
- SignedDirectionTable[s1][s2] = uint8_t(SIGNED_DIR_NONE);
- if(s1 == s2) continue;
- for(SignedDirection d = SIGNED_DIR_E; d <= SIGNED_DIR_SE; d++) {
- SquareDelta delta = deltas[d];
- Square s3, s4;
- for(s4 = s1 + delta, s3 = s1;
- square_distance(s4, s3) == 1 && s4 != s2 && square_is_ok(s4);
- s3 = s4, s4 += delta);
- if(s4 == s2 && square_distance(s4, s3) == 1) {
- SignedDirectionTable[s1][s2] = uint8_t(d);
- DirectionTable[s1][s2] = uint8_t(d/2);
- break;
- }
+
+ for (Square s1 = SQ_A1; s1 <= SQ_H8; s1++)
+ for (Square s2 = SQ_A1; s2 <= SQ_H8; s2++)
+ {
+ DirectionTable[s1][s2] = uint8_t(DIR_NONE);
+ SignedDirectionTable[s1][s2] = uint8_t(SIGNED_DIR_NONE);
+ if (s1 == s2)
+ continue;
+
+ for (SignedDirection d = SIGNED_DIR_E; d != SIGNED_DIR_NONE; d++)
+ {
+ if (reachable(s1, s2, d))
+ {
+ SignedDirectionTable[s1][s2] = uint8_t(d);
+ DirectionTable[s1][s2] = uint8_t(d / 2);
+ break;
+ }
+ }
}
- }
}