--
-- Copyright (C) 2016 secunet Security Networks AG
--
-- This program is free software; you can redistribute it and/or modify
-- it under the terms of the GNU General Public License as published by
-- the Free Software Foundation; version 2 of the License.
--
-- This program is distributed in the hope that it will be useful,
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-- GNU General Public License for more details.
--

package HW.GFX.EDID
is

   use type Word8;
   use type Word16;

   subtype Raw_EDID_Index is Natural range 0 .. 127;
   subtype Raw_EDID_Data is Buffer (Raw_EDID_Index);

   function Valid (Raw_EDID : Raw_EDID_Data) return Boolean;

   DESCRIPTOR_1 : constant := 54;

   function Read_LE16
     (Raw_EDID : Raw_EDID_Data;
      Offset   : Raw_EDID_Index)
      return Word16
   with
      Pre => Offset < Raw_EDID_Index'Last;

   function Has_Preferred_Mode (Raw_EDID : Raw_EDID_Data) return Boolean
   with
      Pre => Valid (Raw_EDID),
      Post =>
        (Has_Preferred_Mode'Result =
           (Int64 (Read_LE16 (Raw_EDID, DESCRIPTOR_1)) * 10_000
               in Frequency_Type and
            ( Raw_EDID (DESCRIPTOR_1 +  2) /= 0 or
             (Raw_EDID (DESCRIPTOR_1 +  4) and 16#f0#) /= 0) and
            ( Raw_EDID (DESCRIPTOR_1 +  8) /= 0 or
             (Raw_EDID (DESCRIPTOR_1 + 11) and 16#c0#) /= 0) and
            ( Raw_EDID (DESCRIPTOR_1 +  9) /= 0 or
             (Raw_EDID (DESCRIPTOR_1 + 11) and 16#30#) /= 0) and
            ( Raw_EDID (DESCRIPTOR_1 +  3) /= 0 or
             (Raw_EDID (DESCRIPTOR_1 +  4) and 16#0f#) /= 0) and
            ( Raw_EDID (DESCRIPTOR_1 +  5) /= 0 or
             (Raw_EDID (DESCRIPTOR_1 +  7) and 16#f0#) /= 0) and
            ((Raw_EDID (DESCRIPTOR_1 + 10) and 16#f0#) /= 0 or
             (Raw_EDID (DESCRIPTOR_1 + 11) and 16#0c#) /= 0) and
            ((Raw_EDID (DESCRIPTOR_1 + 10) and 16#0f#) /= 0 or
             (Raw_EDID (DESCRIPTOR_1 + 11) and 16#03#) /= 0) and
            ( Raw_EDID (DESCRIPTOR_1 +  6) /= 0 or
             (Raw_EDID (DESCRIPTOR_1 +  7) and 16#0f#) /= 0)));
   function Preferred_Mode (Raw_EDID : Raw_EDID_Data) return Mode_Type
   with
      Pre =>
         Int64 (Read_LE16 (Raw_EDID, DESCRIPTOR_1)) * 10_000
            in Frequency_Type and
         ( Raw_EDID (DESCRIPTOR_1 +  2) /= 0 or
          (Raw_EDID (DESCRIPTOR_1 +  4) and 16#f0#) /= 0) and
         ( Raw_EDID (DESCRIPTOR_1 +  8) /= 0 or
          (Raw_EDID (DESCRIPTOR_1 + 11) and 16#c0#) /= 0) and
         ( Raw_EDID (DESCRIPTOR_1 +  9) /= 0 or
          (Raw_EDID (DESCRIPTOR_1 + 11) and 16#30#) /= 0) and
         ( Raw_EDID (DESCRIPTOR_1 +  3) /= 0 or
          (Raw_EDID (DESCRIPTOR_1 +  4) and 16#0f#) /= 0) and
         ( Raw_EDID (DESCRIPTOR_1 +  5) /= 0 or
          (Raw_EDID (DESCRIPTOR_1 +  7) and 16#f0#) /= 0) and
         ((Raw_EDID (DESCRIPTOR_1 + 10) and 16#f0#) /= 0 or
          (Raw_EDID (DESCRIPTOR_1 + 11) and 16#0c#) /= 0) and
         ((Raw_EDID (DESCRIPTOR_1 + 10) and 16#0f#) /= 0 or
          (Raw_EDID (DESCRIPTOR_1 + 11) and 16#03#) /= 0) and
         ( Raw_EDID (DESCRIPTOR_1 +  6) /= 0 or
          (Raw_EDID (DESCRIPTOR_1 +  7) and 16#0f#) /= 0);

end HW.GFX.EDID;