#include "square.h"
+uint8_t DirectionTable[64][64];
-////
-//// Local definitions
-////
-namespace {
+static bool reachable(Square orig, Square dest, Direction d) {
const SquareDelta directionToDelta[] = {
- DELTA_E, DELTA_W, DELTA_N, DELTA_S, DELTA_NE, DELTA_SW, DELTA_NW, DELTA_SE
+ DELTA_E, DELTA_N, DELTA_NE, DELTA_NW, DELTA_W, DELTA_S, DELTA_SW, 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);
- }
+ SquareDelta delta = directionToDelta[dest > orig ? d : d + 4];
+ 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++)
+ for (Direction d = DIR_E; d != DIR_NONE; d++)
{
if (reachable(s1, s2, d))
{
- SignedDirectionTable[s1][s2] = uint8_t(d);
- DirectionTable[s1][s2] = uint8_t(d / 2);
+ DirectionTable[s1][s2] = uint8_t(d);
break;
}
}