    -- #hide
    --------------------------------------------------------------------------------
    -- |
    -- Module      :  Graphics.Rendering.OpenGL.GL.DataType
    -- Copyright   :  (c) Sven Panne 2002-2009
    -- License     :  BSD-style (see the file libraries/OpenGL/LICENSE)
    --
    -- Maintainer  :  sven.panne@aedion.de
    -- Stability   :  stable
    -- Portability :  portable
    --
    -- This is a purely internal module for (un-)marshaling DataType.
    --
    --------------------------------------------------------------------------------

    module Graphics.Rendering.OpenGL.GL.DataType (
       DataType(..), marshalDataType, unmarshalDataType
    ) where

    import Graphics.Rendering.OpenGL.Raw.ARB.Compatibility (
       gl_2_BYTES, gl_3_BYTES, gl_4_BYTES, gl_BITMAP )
    import Graphics.Rendering.OpenGL.Raw.Core31

    --------------------------------------------------------------------------------

    -- basically table 3.2 (pixel data type parameter) plus a few additions
    data DataType =
         UnsignedByte
       | Byte
       | UnsignedShort
       | Short
       | UnsignedInt
       | Int
       | HalfFloat
       | Float
       | UnsignedByte332
       | UnsignedByte233Rev
       | UnsignedShort565
       | UnsignedShort565Rev
       | UnsignedShort4444
       | UnsignedShort4444Rev
       | UnsignedShort5551
       | UnsignedShort1555Rev
       | UnsignedInt8888
       | UnsignedInt8888Rev
       | UnsignedInt1010102
       | UnsignedInt2101010Rev
       | UnsignedInt248
       | UnsignedInt10f11f11fRev
       | UnsignedInt5999Rev
       | Float32UnsignedInt248Rev
       | Bitmap                    -- pixel data, deprecated in 3.1
       | UnsignedShort88           -- MESA_ycbcr_texture/APPLE_ycbcr_422
       | UnsignedShort88Rev        -- MESA_ycbcr_texture/APPLE_ycbcr_422
       | Double                    -- vertex arrays (EXT_vertex_array, now core)
       | TwoBytes                  -- CallLists
       | ThreeBytes                -- CallLists
       | FourBytes                 -- CallLists
       deriving ( Eq, Ord, Show )

    marshalDataType :: DataType -> GLenum
    marshalDataType x = case x of
       UnsignedByte -> gl_UNSIGNED_BYTE
       Byte -> gl_BYTE
       UnsignedShort -> gl_UNSIGNED_SHORT
       Short -> gl_SHORT
       UnsignedInt -> gl_UNSIGNED_INT
       Int -> gl_INT
       HalfFloat -> gl_HALF_FLOAT
       Float -> gl_FLOAT
       UnsignedByte332 -> gl_UNSIGNED_BYTE_3_3_2
       UnsignedByte233Rev -> gl_UNSIGNED_BYTE_2_3_3_REV
       UnsignedShort565 -> gl_UNSIGNED_SHORT_5_6_5
       UnsignedShort565Rev -> gl_UNSIGNED_SHORT_5_6_5_REV
       UnsignedShort4444 -> gl_UNSIGNED_SHORT_4_4_4_4
       UnsignedShort4444Rev -> gl_UNSIGNED_SHORT_4_4_4_4_REV
       UnsignedShort5551 -> gl_UNSIGNED_SHORT_5_5_5_1
       UnsignedShort1555Rev -> gl_UNSIGNED_SHORT_1_5_5_5_REV
       UnsignedInt8888 -> gl_UNSIGNED_INT_8_8_8_8
       UnsignedInt8888Rev -> gl_UNSIGNED_INT_8_8_8_8_REV
       UnsignedInt1010102 -> gl_UNSIGNED_INT_10_10_10_2
       UnsignedInt2101010Rev -> gl_UNSIGNED_INT_2_10_10_10_REV
       UnsignedInt248 -> gl_UNSIGNED_INT_24_8
       UnsignedInt10f11f11fRev -> gl_UNSIGNED_INT_10F_11F_11F_REV
       UnsignedInt5999Rev -> gl_UNSIGNED_INT_5_9_9_9_REV
       Float32UnsignedInt248Rev -> gl_FLOAT_32_UNSIGNED_INT_24_8_REV
       Bitmap -> gl_BITMAP
       -- TODO: Use UNSIGNED_SHORT_8_8_APPLE from APPLE_ycbcr_422 extension
       UnsignedShort88 -> 0x85ba
       -- TODO: Use UNSIGNED_SHORT_8_8_REV_APPLE from APPLE_ycbcr_422 extension
       UnsignedShort88Rev -> 0x85bb
       Double -> gl_DOUBLE
       TwoBytes -> gl_2_BYTES
       ThreeBytes -> gl_3_BYTES
       FourBytes -> gl_4_BYTES

    unmarshalDataType :: GLenum -> DataType
    unmarshalDataType x
       | x == gl_UNSIGNED_BYTE = UnsignedByte
       | x == gl_BYTE = Byte
       | x == gl_UNSIGNED_SHORT = UnsignedShort
       | x == gl_SHORT = Short
       | x == gl_UNSIGNED_INT = UnsignedInt
       | x == gl_INT = Int
       | x == gl_HALF_FLOAT = HalfFloat
       | x == gl_FLOAT = Float
       | x == gl_UNSIGNED_BYTE_3_3_2 = UnsignedByte332
       | x == gl_UNSIGNED_BYTE_2_3_3_REV = UnsignedByte233Rev
       | x == gl_UNSIGNED_SHORT_5_6_5 = UnsignedShort565
       | x == gl_UNSIGNED_SHORT_5_6_5_REV = UnsignedShort565Rev
       | x == gl_UNSIGNED_SHORT_4_4_4_4 = UnsignedShort4444
       | x == gl_UNSIGNED_SHORT_4_4_4_4_REV = UnsignedShort4444Rev
       | x == gl_UNSIGNED_SHORT_5_5_5_1 = UnsignedShort5551
       | x == gl_UNSIGNED_SHORT_1_5_5_5_REV = UnsignedShort1555Rev
       | x == gl_UNSIGNED_INT_8_8_8_8 = UnsignedInt8888
       | x == gl_UNSIGNED_INT_8_8_8_8_REV = UnsignedInt8888Rev
       | x == gl_UNSIGNED_INT_10_10_10_2 = UnsignedInt1010102
       | x == gl_UNSIGNED_INT_2_10_10_10_REV = UnsignedInt2101010Rev
       | x == gl_UNSIGNED_INT_24_8 = UnsignedInt248
       | x == gl_UNSIGNED_INT_10F_11F_11F_REV = UnsignedInt10f11f11fRev
       | x == gl_UNSIGNED_INT_5_9_9_9_REV = UnsignedInt5999Rev
       | x == gl_FLOAT_32_UNSIGNED_INT_24_8_REV = Float32UnsignedInt248Rev
       | x == gl_BITMAP = Bitmap
       -- TODO: Use UNSIGNED_SHORT_8_8_APPLE from APPLE_ycbcr_422 extension
       | x == 0x85ba = UnsignedShort88
       -- TODO: Use UNSIGNED_SHORT_8_8_REV_APPLE from APPLE_ycbcr_422 extension
       | x == 0x85bb = UnsignedShort88Rev
       | x == gl_DOUBLE = Double
       | x == gl_2_BYTES = TwoBytes
       | x == gl_3_BYTES = ThreeBytes
       | x == gl_4_BYTES = FourBytes
       | otherwise = error ("unmarshalDataType: illegal value " ++ show x)