- PIECE_NONE_DARK_SQ = 0, WP = 1, WN = 2, WB = 3, WR = 4, WQ = 5, WK = 6,
- BP = 9, BN = 10, BB = 11, BR = 12, BQ = 13, BK = 14, PIECE_NONE = 16
+ NO_PIECE = 16, // color_of(NO_PIECE) == NO_COLOR
+ W_PAWN = 1, W_KNIGHT = 2, W_BISHOP = 3, W_ROOK = 4, W_QUEEN = 5, W_KING = 6,
+ B_PAWN = 9, B_KNIGHT = 10, B_BISHOP = 11, B_ROOK = 12, B_QUEEN = 13, B_KING = 14