from artiq import *


def print_skew(p):
    print("Input/output skew: {} ns".format(p))


def print_failed():
    print("Pulse was not received back")


class RTIOSkew(AutoContext):
    pmt0 = Device("ttl_in")
    ttl0 = Device("ttl_out")

    @kernel
    def run(self):
        with parallel:
            self.pmt0.gate_rising(10*us)
            with sequential:
                delay(5*us)
                out_t = now()
                self.ttl0.pulse(5*us)
        in_t = self.pmt0.timestamp()
        if in_t < 0*s:
            print_failed()
        else:
            print_skew(int((out_t - in_t)/(1*ns)))