from migen import *


class PriorityEncoderMSB(Module):
    def __init__(self, width):
        self.i = Signal(width)  # one-hot, msb has priority
        self.o = Signal(max=max(2, width))  # binary
        self.n = Signal()  # none
        for j in range(width):  # first has priority
            self.comb += If(self.i[j], self.o.eq(j))
        self.comb += self.n.eq(self.i == 0)