pub const HEADER_LEN: usize = 13;
pub const FOOTER_LEN: usize = 18;

// Descriptor bits:
// bit 5-4 = origin
// bit 3-0 = alpha depth
pub const ORIGIN_BOTTOM_LEFT: u8 = 0b0000_0000;
pub const ORIGIN_BOTTOM_RIGHT: u8 = 0b0001_0000;
pub const ORIGIN_TOP_LEFT: u8 = 0b0010_0000;
pub const ORIGIN_TOP_RIGHT: u8 = 0b0011_0000;