NAME
        InitRastPort -- Initialize raster port structure

   SYNOPSIS
     InitRastPort( rp )
                      a1

        void InitRastPort(struct rastport *rp);

   FUNCTION
       Initialize a rastport structure to standard values.

   INPUTS
        rp      = pointer to a rastport structure.

   RESULT
        all entries in rastport get zeroed out, with the following exceptions:

            Mask, FgPen, AOLPen, and LinePtrn are set to -1.
            The DrawMode is set to JAM2
            The font is set to the standard system font

   NOTES
        The struct Rastport describes a control structure
       for a write-able raster. The rastport structure
       describes how a complete single playfield display
       will be written into. A rastport structure is
       referenced whenever any drawing or filling
       operations are to be performed on a section of
       memory.

       The section of memory which is being used in this
       way may or may not be presently a part of the
       current actual onscreen display memory. The name
       of the actual memory section which is linked to
       the rastport is referred to here as a "raster" or
       as a bitmap.

       NOTE: Calling the routine InitRastPort only
       establishes various defaults. It does NOT
       establish where, in memory, the rasters are
       located. To do graphics with this rastport the user
        must set up the bitmap pointer in the rastport.

   BUGS

   SEE ALSO
     graphics/rastport.h