NAME
       GetRGB4 -- Inquire value of entry in ColorMap.

   SYNOPSIS
       value = GetRGB4( colormap, entry )
          d0              a0       d0

	ULONG GetRGB4(struct ColorMap *, LONG);

   FUNCTION
	Read and format a value from the ColorMap.

   INPUTS
	colormap - pointer to ColorMap structure
	entry - index into colormap

   RESULT
	returns -1 if no valid entry
	return UWORD RGB value 4 bits per gun right justified

   NOTE
	Intuition's DisplayBeep() changes color 0. Reading Color 0 during a
	DisplayBeep() will lead to incorrect results.

   BUGS

   SEE ALSO
       SetRGB4() LoadRGB4() GetColorMap() FreeColorMap() graphics/view.h