roughly:
```python
        trigger_d0 = Signal()
        with m.If(counter == 0):
            m.d.sync += trigger_d0.eq(~trigger_d0)

        def buf(i, o):
            return Instance("SB_LUT4", a_keep=1, p_LUT_INIT=C(0b10, 16),
                i_I0=i, i_I1=C(0), i_I2=C(0), i_I3=C(0), o_O=o)
        def xor(a, b, o):
            return Instance("SB_LUT4", a_keep=1, p_LUT_INIT=C(0b0110, 16),
                i_I0=a, i_I1=b, i_I2=C(0), i_I3=C(0), o_O=o)

        trigger_d1 = Signal()
        m.submodules.buf_d1 = buf(trigger_d0, trigger_d1)

        trigger_d2 = Signal()
        m.submodules.buf_d2 = buf(trigger_d1, trigger_d2)

        trigger_d3 = Signal()
        m.submodules.buf_d3 = buf(trigger_d2, trigger_d3)

        trigger_d4 = Signal()
        m.submodules.buf_d4 = buf(trigger_d3, trigger_d4)

        output = Signal()
        m.submodules.xor = xor(trigger_d1, trigger_d4, output)

        m.d.comb += [
            oe_buf.o.eq(1),
            io_buf.o.eq(output)
        ]
```