Manipulate a pointer to a stream.

PointStream.cs

public struct StreamPoint
{
    private Stream stream;
    private long offset;
    public StreamPoint(Stream s) : this(s, s.Position) { }
    public StreamPoint(Stream s, long pos)
    {
        if (s == null)
            throw new ArgumentNullException("stream");
        stream = s;
        offset = pos;
    }

    public static StreamPoint operator +(StreamPoint sp, long plus) { return new StreamPoint(sp.stream, sp.offset + plus); }
    public static StreamPoint operator -(StreamPoint sp, long plus) { return new StreamPoint(sp.stream, sp.offset - plus); }

    public static long operator -(StreamPoint sp, StreamPoint sp2)
    {
        if (sp.stream != sp2.stream)
            throw new ArgumentException();
        return sp.offset - sp2.offset;
    }

    public static explicit operator Stream(StreamPtr ptr)
    {
        ptr.stream.Position = ptr.offset;
        return ptr.stream;
    }
}