Since cocotb/cocotb#2793, writes happen before the clock instead of
after the clock. This breaks the collision test, since we test for
differing behavior over a difference of 1 ns. Fix the failure by
applying an adjustment for newer versions.
Signed-off-by: Sean Anderson <seanga2@gmail.com>
This adds support for half-duplex. This is mostly done by predicating
col and crs on half_duplex. In one place we need to go to IPG_LATE
directly (although we could go to IPG_LATE like FCS with no loss of
standard compliance).
Signed-off-by: Sean Anderson <seanga2@gmail.com>
get_sim_time can return floating point values. This will cause tests to
fail since there is an epsilon of error. Fix this by timing things in
steps (which is always an int).
Fixes: 0495ae3 ("Add TX MAC (most of it)")
Signed-off-by: Sean Anderson <seanga2@gmail.com>
We might not release rst synchronously if clk was already high. Fix this
by forcing clk to z.
Fixes: 19f2f65 ("axis_mii_tx: Add reset")
Signed-off-by: Sean Anderson <seanga2@gmail.com>
If we ever see an error, we shouldn't retry if we get a collision at the
same time, as we will just have to jam next time. Test for this case
instead.
Signed-off-by: Sean Anderson <seanga2@gmail.com>
This adds the transmit half of a MAC, supporting 100M and half-duplex.
It's roughly analogous to the axis_(x)gmii_tx modules in Alex
Forencich's ethernet repo. I've taken the approach of moving all state
into the state variable. All decisions are made once and have a
different state for each path. For example, instead of checking against
a "bytes_sent" variable to determine what to do on collision, we have a
different state for each set of actions.
This whole module is heinously complex, especially because of the many
corner cases caused by the spec. I have probably not tested it nearly
enough, but the basics of sending packets have mostly had the bugs wrung
out.
Signed-off-by: Sean Anderson <seanga2@gmail.com>
Sean Anderson