func (w *window) writeByte(c byte) {
	w.buf[w.w] = c
	w.w = (w.w + 1) & w.mask
}
func (w *window) writeByte(c byte) {
	w.buf[w.w] = c
	w.w = (w.w + 1) & w.mask
}
func ( w * window ) writeByte ( c byte ) { w . buf [ w . w ] = c w . w = ( w . w + 1 ) & w . mask }
// writeByte writes c to the end of the window
writeByte writes c to the end of the window