/*
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
+ Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
//// Includes
////
-#include "direction.h"
#include "square.h"
+int8_t DirectionTable[64][64];
-////
-//// Variables
-////
-uint8_t DirectionTable[64][64];
-uint8_t SignedDirectionTable[64][64];
+static SquareDelta direction(Square orig, Square dest) {
+ const SquareDelta directions[] = {
+ DELTA_E, DELTA_N, DELTA_NE, DELTA_NW, DELTA_W, DELTA_S, DELTA_SW, DELTA_SE
+ };
-////
-//// Functions
-////
+ Square from, to;
-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 (int idx = 0; idx < 8; idx++)
+ {
+ from = orig;
+ to = from + directions[idx];
+
+ while (to != dest && square_distance(to, from) == 1 && square_is_ok(to))
+ {
+ from = to;
+ to += directions[idx];
}
- }
+
+ if (to == dest && square_distance(from, to) == 1)
+ return directions[idx];
+ }
+ return DELTA_NONE;
+}
+
+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(direction(s1, s2));
}