Compat TODO items 3 and 4. Every register libogc2 writes now stores writes and
reads back, with the documented hardware reset defaults: NCRB (0x01), BP
(0x0A/0B), TLBP (0x0C/0D), RXINTT (0x14/15), RHBP (0x1A/1B), NWAYC (0x30,
default 0x84), GCA (0x32), MISC (0x3D, default 0x3C), MISC2 (0x50). BP and
RHBP reset to OUR layout (page 1, page 15) so a driver reading them back
without writing sees something consistent with where the ring actually is.
Previously all of these read 0x00 and dropped writes, so a driver doing
read-modify-write or sanity-checking a default saw zero -- and libogc2 does
read NWAYC before writing it.
Deliberately still reading 0x00: LTPS, LRPS, TWP, TRP, TXFIFOCNT. Those are
STATUS registers, not configuration, so storing what was written to them would
be a lie rather than a default. Drivers read LRPS/LTPS only on error bits and
0x00 reads as "no error", which is truthful for a device that does not detect
them.
NCRB, BP and RHBP are also exported as BBARegisterFile.ncrb/.bp/.rhbp for the
RX-filtering work (item 1) and the ring-geometry check (item 2). Nothing
consumes them yet -- the decode lands first so the behaviour that uses it is a
separate, testable change.
T15 checks the defaults, replays libogc2's twelve init writes in its order and
reads every one back, and asserts the NCRB export is 0x52 with PR=0, PM=0,
AB=1 -- i.e. that the real BBA delivers own-MAC + broadcast only, which is the
fact item 1 has to act on. Mutation-tested: dropping NWAYC's 0x84 default
fails it, as does dropping NCRB writes.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Records the differences between this implementation and what real GC software
expects, with the evidence and the driver source for each, so they are worked
through rather than rediscovered. Open items: no hardware RX filtering,
hardcoded ring geometry, NCRB undecoded, and registers that read 0x00 where
real hardware has non-zero defaults. Also records what is deliberately NOT to
be implemented (the device-initiated challenge/response) and that two of our
registers (TWD, HIPR) do not exist on real hardware.
Notes explicitly that games use the official Nintendo SDK driver, which none of
the three readable drivers is, so "no open driver does this" is weaker evidence
than "the hardware has no such register".
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Roflin