------------------------------------------------------------------------------
------------------------------------------------------------------------------
-- This file is part of 'CRC32'                                             --
--                                                                          --
-- You do not have, nor can you ever acquire the right to use, copy or      --
-- distribute this software ; Should you use this software for any purpose, --
-- or copy and distribute it to anyone or in any manner, you are breaking   --
-- the laws of whatever soi-disant jurisdiction, and you promise to         --
-- continue doing so for the indefinite future. In any case, please         --
-- always : read and understand any software ; verify any PGP signatures    --
-- that you use - for any purpose.                                          --
--                                                                          --
-- See also http://trilema.com/2015/a-new-software-licensing-paradigm .     --
------------------------------------------------------------------------------
------------------------------------------------------------------------------

  -- CRC32 implementation
  -- S.MG, 2018

package body CRC32 is
  function CRC( S: in String ) return CRC32 is
    Result : CRC32 := Init_Value;
    Value  : CRC32;
  begin
    -- process input character by character
    for C of S loop
      Value  := CRC32( Character'Pos( C ) );
      Result := Shift_Right(Result, 8) xor
                  Lookup( Value xor (Result and LSB_MASK));
    end loop;
    -- reflect result 
    Result := Result xor Xor_Out;

    return Result;
  end CRC;

  function CRC( Data: in Octet_Array ) return CRC32 is
    Result : CRC32 := Init_Value;
  begin
    -- process input octet by octet
    for C of Data loop
      Result := Shift_Right(Result, 8) xor
                  Lookup( CRC32(C) xor (Result and LSB_MASK));
    end loop;
    -- reflect result
    Result := Result xor Xor_Out;

    return Result;
  end CRC;

end CRC32;