//fmt.Printf("Operand: %v\n", p.input)
	if len(p.input) == 0 {
		p.errorf("empty operand: cannot happen")
		return
	}
	// General address (with a few exceptions) looks like
	//	$sym±offset(SB)(reg)(index*scale)
	// Exceptions are:
	//
	//	R1
	//	offset
	//	$offset
	// Every piece is optional, so we scan left to right and what
	// we discover tells us where we are.

	// Prefix: $.