1. A nanowire-crossbar array comprising: a first nanowire; a number of substantially parallel control nanowires positioned so that each control nanowire overlaps the first nanowire; a number of spintronic devices, each spintronic device being non-volatile and including a permanent magnetic material and a free magnetic material, each spintronic device connecting one of the control nanowires to the first nanowire and operating as a latch for controlling signal transmissions between the control nanowire and the first nanowire a pull-down resistor coupled to the first nanowire; a ground coupled to the pull-down resistor; and a number of voltage sources, each voltage source coupled to one of the control nanowires.