NAME
       SetMaxPen -- set maximum pen value for a rastport (V39).


   SYNOPSIS
       SetMaxPen ( rp, maxpen)
                    a0   d0

        void SetMaxPen(struct rastport *,ulong)

   FUNCTION
        This will instruct the graphics library that the owner of the rastport
        will not be rendering in any colors whose index is >maxpen. If there
        are any speed optimizations which the graphics device can make based
        on this fact (for instance, setting the pixel write mask), they will
        be done.

        Basically this call sets the rastport mask, if this would improve
        speed. On devices where masking would slow things down (like with
        chunky pixels), it will be a no-op.

   INPUTS
       rp  =  a pointer to a valid rastport structure.
        maxpen =  a longword pen value.

   BUGS

   NOTES
        The maximum pen value passed must take into account not only which
        colors you intend to render in the future, but what colors you will
        be rendering on top of.
        SetMaxPen(rp,0) doesn't make much sense.

   SEE ALSO
        setwritemask()