func (b counterStateBits) decReader() counterStateBits    { return b - 1 }
func (b counterStateBits) setLocked() counterStateBits    { return b | stateLocked }
func (b counterStateBits) clearLocked() counterStateBits  { return b &^ stateLocked }
func (b counterStateBits) setHavePtr() counterStateBits   { return b | stateHavePtr }
func (b counterStateBits) clearHavePtr() counterStateBits { return b &^ stateHavePtr }