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direction.cpp
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direction.cpp
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/*
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
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.
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/>.
*/
////
//// Includes
////
#include "direction.h"
#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
////
uint8_t DirectionTable[64][64];
uint8_t SignedDirectionTable[64][64];
////
//// Functions
////
void init_direction_table() {
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;
}
}
}
}