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