NAME
       GetAPen -- Get the A Pen value for a rastport (v39).


   SYNOPSIS
       pen = GetAPen  ( rp )
         d0              a0

        ULONG GetAPen(struct rastport *)

   FUNCTION
        Return the current value of the A pen for the rastport. This function
        should be used instead of peeking the structure directly, because future
        graphics devices may store it differently, for instance, using more bits.

   INPUTS
       rp  =  a pointer to a valid rastport structure.

   BUGS

   NOTES

   SEE ALSO
        setapen() graphics/gfx.h