1 Commits

Author SHA1 Message Date
sylph-decoder
dcaa322146 re: the decoder's timers are a double-tap latch on LB/LT, not key repeat
Answers H1's first half with a negative, and decodes what the timing
constants are for.

C_PAD_DECODER's +0xB4/+0xB8 and +0xBC/+0xC0 (10 and 90, twice) are not a
key-repeat delay/interval pair. They are two identical channels of a
DOUBLE-TAP detector, on cfg +0x74 (LT) and +0x70 (LB), firing output bits
0x20 and 0x40.

The mechanism, from the image: both timers tick down once per update; a
press arms the short timer to 10; a RELEASE adds 1000 to it as a flag
stored inside the counter, which is why the tick watches for exactly 1000
and clears both there; a second press while the flag is set arms the long
timer to 90; and while the long timer runs the output bit is asserted on
EVERY update, with the short timer re-armed to 1010 each time.

So it is a latch, not a repeat: a double-tap opens a 90-update window and
the bit is held for its whole duration. That is a dash or barrel-roll
shape, which fits the buttons it is wired to.

H1: the directions have NO timer. The D-pad and left stick reach the output
word through bare mask tests -- the four left-stick literals at 0x8220C458,
C474, C490, C4AC, and DPAD DOWN through cfg +0xA4 -- with no counter
loaded, decremented or tested on any of those paths. On the evidence of
this layer a held direction does not repeat.

Reach: one layer. A menu could implement repeat on top of a held bit, and
this says nothing about that -- but it does establish the repeat is not in
the shared decoder, so it would have to be per-screen. "One step per
deflection" stays authored for the port; this narrows rather than settles.

Refutation of my own earlier note that a decoder "is where a game normally
puts its repeat timing, its edge detection and its button remap": remap
survives, edge detection survives, repeat timing is REFUTED. That clause
was a prior about how games are written, not a reading of this one.

Also commits tools/ppc-dis, the minimal PowerPC disassembler this corpus
has been rebuilding in scratch and losing to container restarts three times
in one session.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Jc4pciRArGHfxGGhEbwp5t
2026-09-02 16:20:50 +00:00