NAME
    BltPattern --  Using standard drawing rules for areafill,
                                     blit through a mask.
SYNOPSIS
    BltPattern(rp, mask, xl, yl, maxx, maxy, bytecnt)
              a1,  a0   d0  d1   d2   d3     d4
    void BltPattern
       (struct RastPort *, void *, SHORT, SHORT, SHORT, SHORT, SHORT);
FUNCTION
    Blit using drawmode,areafill pattern, and mask
    at position rectangle (xl,yl) (maxx,maxy).
INPUTS
    rp    -  points to the destination RastPort for the blit.
    mask  -  points to 2 dimensional mask if needed
             if mask == NULL then use a rectangle.
    xl,yl -  coordinates of upper left of rectangular region in RastPort
    maxx,maxy - points to lower right of rectangular region in RastPort
    bytecnt - BytesPerRow for mask
RESULT
SEE ALSO
    AreaEnd