readHeader

        pub fn readHeader(reader: *Reader, options: Options) !Params {
            var props = try reader.takeByte();
            if (props >= 225) return error.CorruptInput;

            const lc: u4 = @intCast(props % 9);
            props /= 9;
            const lp: u3 = @intCast(props % 5);
            props /= 5;
            const pb: u3 = @intCast(props);

            const dict_size_provided = try reader.takeInt(u32, .little);
            const dict_size = @max(0x1000, dict_size_provided);

            const unpacked_size = switch (options.unpacked_size) {
                .read_from_header => blk: {
                    const unpacked_size_provided = try reader.takeInt(u64, .little);
                    const marker_mandatory = unpacked_size_provided == 0xFFFF_FFFF_FFFF_FFFF;
                    break :blk if (marker_mandatory) null else unpacked_size_provided;
                },
                .read_header_but_use_provided => |x| blk: {
                    _ = try reader.takeInt(u64, .little);
                    break :blk x;
                },
                .use_provided => |x| x,
            };

            return .{
                .properties = .{ .lc = lc, .lp = lp, .pb = pb },
                .dict_size = dict_size,
                .unpacked_size = unpacked_size,
            };
        }