NAME
    SetRast - Set an entire drawing area to a specified color.
SYNOPSIS
    SetRast( rp, pen )
             a1  d0
    void SetRast( struct rastport *, ubyte );
FUNCTION
    Set the entire contents of the specified rastport to the
    specified pen.
INPUTS
    rp - pointer to rastport structure
    pen - the pen number (0-255) to jam into bitmap
RESULT
    All pixels within the drawing area are set to the
    selected pen number.
BUGS
SEE ALSO
    rectfill() graphics/rastport.h