fn genSteps(square: Chess.Square, piece: Chess.Figures, color: Chess.Colors) Chess.BoardType {

pub fn genSteps(square: Chess.Square, piece: Chess.Figures, color: Chess.Colors) Chess.BoardType {

const Attacks = @import("attacks.zig");

fn setOccupancy(index: usize, attack_mask: BoardType) BoardType {
    var occupancy: BitBoard = .{};
    var attack: BitBoard = .{ .board = attack_mask };
    var count: u6 = 0;
    while (count < @popCount(attack_mask)) : (count += 1) {
        const square = @ctz(attack.board);
        attack.pop(@intToEnum(Square, square));
        if (index & @as(BoardType, 1) << count != 0) {
            occupancy.set(@intToEnum(Square, square));
        }
    }
    return occupancy.board;
}
test "occupancy bits" {
    const attack_mask = Attacks.genSteps(.a1, .rook, .white);
    var occupancy: BitBoard = .{};
    occupancy.board = setOccupancy(4095, attack_mask);
    var expected: BitBoard = .{};
    expected.setSlice(&[_]Square{ .a2, .a3, .a4, .a5, .a6, .a7, .b1, .c1, .d1, .e1, .f1, .g1 });
    try std.testing.expectEqual(expected, occupancy);
}