D-Flipflop VCD generator

dflipflop.py

import asyncio
import sys
import time

from aiostream import stream
from vcd import VCDWriter

start = time.monotonic()

async def oscillator(writer, variable, freq):
    loop = asyncio.get_event_loop()
    while True:
        await asyncio.sleep(4/freq)
        writer.change(variable, (loop.time()-start)*1000, 1)
        yield (variable, 1)
        await asyncio.sleep(4/freq)
        writer.change(variable, (loop.time()-start)*1000, 0)
        yield (variable, 0)

async def main():
    loop = asyncio.get_event_loop()

    with VCDWriter(sys.stdout, timescale='1 ms') as writer:
        d_var = writer.register_var('DFF', 'd', 'integer', size=1, init=0)
        clk_var = writer.register_var('DFF', 'clk', 'integer', size=1, init=0)
        q_var = writer.register_var('DFF', 'q', 'integer', size=1, init=0)

        transitions = stream.merge(oscillator(writer, d_var, 100), oscillator(writer, clk_var, 90.01))

        async with transitions.stream() as streamer:
            async for signal, transition in streamer:
                if signal is clk_var and transition == 1:
                    if q_var.value != d_var.value:
                        writer.change(q_var, (loop.time()-start)*1000, d_var.value)


asyncio.run(main())