Definition compressionBlockSizeY (c : compressionMethod) : nat :=
  match c with
  | CompressionUncompressed       => 0
  | CompressionBC1                => 4
  | CompressionBC2                => 4
  | CompressionBC3                => 4
  | CompressionBC4                => 4
  | CompressionBC5                => 4
  | CompressionBC6                => 4
  | CompressionBC7                => 4
  | CompressionETC1               => 4
  | CompressionETC2               => 4
  | CompressionEAC                => 4
  | CompressionASTC _ y           => y
  | CompressionCustom _ _ y _ _ _ => y
  end.
