1. A method for determining a state of a memristor in a crossbar array, the method comprising: applying, to a target row line in the crossbar array, a bias voltage that causes a bias current to pass through a target memristor in the target row line; increasing the bias voltage by a predetermined amount to a state voltage; determining a state current flowing through the target memristor, in which the state current is based on the state voltage; and determining the state of the target memristor based on the state current.