Record a 6-second gif of examples/pong.nes running in jsnes and
embed it alongside docs/platformer.gif and docs/war.gif as the
third project demo. The gif opens on Pong's title menu (CPU VS
CPU / 1 PLAYER / 2 PLAYERS) — warmup = 4 frames keeps the menu
as the thumbnail the way war's recording does, and then the
headless autopilot advances to gameplay partway through the
clip.
- docs/pong.gif committed (128 KB)
- README.md links it under the war demo
- scripts/pre-commit rebuilds it when examples/pong* or the
recorder/harness change
- .github/workflows/ci.yml fails if the committed copy is stale
- CLAUDE.md and tests/emulator/record_gif.mjs reference the new
gif in the "how to regenerate" sections
https://claude.ai/code/session_0134F5uwDEVTes2Ee9S7JeXy
Captures the first ~6 s of examples/war.ne via the same
puppeteer + jsnes + gifenc pipeline that powers
docs/platformer.gif: title menu thumbnail, 52-card deal
animation, and a few rounds of CPU vs CPU play. Embedded
in the top-level README right under the platformer demo.
record_gif.mjs gains a 6th positional arg for the warmup
override (defaulting to the existing WARMUP env / 30) so
the war command can keep its title menu as the first frame
while platformer keeps skipping past its own title. The
CI emulator job and the pre-commit hook both rebuild the
gif into a tmp path and fail-with-fix-command if the
committed copy is stale; the war trigger covers war.ne,
war.nes, any examples/war/*.ne include, plus the recorder
and harness.
The optimizer fix in the previous commit changes the observable
gameplay of `examples/platformer.ne` — pre-fix the player got
spurious enemy-1 stomp bounces every time coin 2 drifted into its
pickup window, so the README demo gif showed the player bouncing
mid-air around emu frames 85-125 instead of walking through the
coin at ground level. Regenerate `docs/platformer.gif` from the
fixed compiler so the README matches reality.
To stop this from drifting again, treat the gif the same way the
repo already treats `examples/*.nes`:
- `gifenc` + `jsnes` + the harness are deterministic, so a fresh
recording byte-matches a valid commit. Verified across two
back-to-back runs (identical md5).
- `.github/workflows/ci.yml`'s `emulator` job now renders the gif
into `/tmp/platformer.gif` and `cmp`s it against `docs/platformer.gif`,
emitting a `::error` annotation pointing at the exact rerun
command if the committed copy is stale. This piggybacks on the
existing puppeteer + node setup, adding ~20s to the job.
- `scripts/pre-commit` runs the same check locally, but only when
`examples/platformer.{ne,nes}`, `tests/emulator/record_gif.mjs`,
or `tests/emulator/harness.html` is staged, and only if
`tests/emulator/node_modules` is already installed. Cold-start
puppeteer is ~20s — too slow to pay on every commit, but cheap
enough to pay when something gif-relevant changed.
- The header of `tests/emulator/record_gif.mjs` and the project
conventions section of `CLAUDE.md` both spell out the rerun
command and the invariant, so the next agent doesn't have to
re-derive any of this.
https://claude.ai/code/session_013Bi4H4YQ5or5HtMB4doUFi
Adds `examples/platformer.ne`, a full side-scrolling game that
exercises nearly every subsystem of the compiler in one program:
custom CHR tileset, 32×30 background nametable with per-region
attribute palettes, 2×2 metasprite hero with gravity/jump physics,
wrap-around horizontal scrolling, moving enemies, coin pickups,
user-declared SFX + music, and a Title → Playing state machine
with autopilot so the headless jsnes harness captures real
gameplay at frame 180. Tile art + nametable are generated by
`scripts/gen_platformer_tiles.rs` (`cargo run --bin gen_platformer_tiles`).
Building this out uncovered three independent runtime bugs that
together made the example render as black-on-black smileys. All
three are fixed in this commit:
1. **`gen_init` enabled sprite rendering before the linker's
initial palette/background load runs.** The PPU's v-register
auto-increments on every `$2007` write *during active
rendering*, so the palette load (32 B) and nametable load
(1024 B) were scrambled past the first ~72 bytes — every
existing program with a `background Level { ... }` block was
silently rendering zero-filled VRAM. Fix: leave `PPU_MASK = 0`
at the end of `gen_init` and emit a new `gen_enable_rendering`
call *after* all initial VRAM writes complete.
2. **Audio tick corrupted `ZP_CURRENT_STATE`.** The audio
driver's period-table lookup reused `$02/$03` as a temporary
indirect pointer with a comment claiming the slots were free
because the tick doesn't call mul/div. But `$03` is also
`ZP_CURRENT_STATE` used by the state dispatch loop, so every
music note silently overwrote the state index with the high
byte of `__period_table` (`0xC5` in the platformer ROM),
wedging the state machine forever. Fix: `gen_nmi` now PHAs
`$02/$03` on entry and PLA-restores them on exit, and the
audio tick JSR moves inside that save/restore window (it used
to be spliced by the linker *before* the register saves, so
even A/X/Y were technically being trashed pre-save). Only
`audio_demo`'s audio hash shifts (its note timings move a few
cycles); every other golden is unchanged.
3. **Sub-palette mirroring footgun.** Writing a 32-byte palette
blob sequentially causes the sprite sub-palettes' "index 0"
slots at `$3F10/$3F14/$3F18/$3F1C` to clobber the background
universal colour at `$3F00/$3F04/$3F08/$3F0C` via NES hardware
mirroring. The example's palette sets all eight first bytes
to `$22` (sky blue) for this reason; `docs/future-work.md`
picks up a TODO to warn on inconsistent first-byte values in
the analyzer.
Also:
- `docs/platformer.gif` — 6-second recording of the example
running in jsnes, generated by the new
`tests/emulator/record_gif.mjs` puppeteer helper (encodes via
`gifenc`, committed as a dev-dependency under
`tests/emulator/package.json`).
- README / examples/README tables and the 497-test count are
updated to cover the new example.
https://claude.ai/code/session_01BcCcHi6FUmTh8jC7UgkA3A
