"""Puts 2 channel sine and cosine wafeform through pseudo terminal

    continuously."""

    i = 0

    period = 200

    while True:

        sin = math.sin(2 * math.pi * i / period)

        # cos = math.sin(2 * math.pi * (i / period + 1 / 4))

        data = struct.pack('ff', sin, -sin)

        os.write(port, data)

        i = (i + 1) % period

        time.sleep(0.1)

def run():

    # create the pseudo terminal

    master, slave = pty.openpty()

    master_name = os.ttyname(master)

    slave_name = os.ttyname(slave)

    print("Master terminal: {}\nSlave terminal: {}".format(master_name, slave_name))

    try:

        float_sine(master)

    finally:

        # close the pseudo terminal files