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Author SHA1 Message Date
Claude
9719dc4111
ir/codegen: signed comparison lowering for i8/i16
Closes the §A follow-up gap: ordering compares (`<`, `<=`, `>`, `>=`)
on signed integer types now use the canonical 6502 `CMP / SBC / BVC /
EOR #$80` overflow-correction idiom so the N flag reflects the true
sign of the difference, instead of the previous BCC/BCS-based path
that always treated `$FFxx` as greater than `$00yy`.

The same change also fixes narrow-to-wide widening: assigning a
runtime `i8` expression to an `i16` variable now sign-extends the
high byte via a new `IrOp::SignExtend` op instead of zero-extending
it, so `var w: i16 = some_i8_neg` round-trips negative values.

The lowerer tracks signedness on each IR temp (analogous to the
existing `wide_hi` map) and threads it onto the new `Signedness`
field of `CmpLt`/`CmpGt`/`CmpLtEq`/`CmpGtEq` and their 16-bit
variants. The optimizer's constant-folder uses the same flag to
fold compares correctly under either signedness. Casts to `u8`/`u16`
strip the signed flag so an explicit `as` opt-out stays unsigned.

`examples/signed_compare.ne` exercises both bit widths through the
emulator harness — the four pip sprites at the top of the screen
show three lit (signed-correct) and one dark (would only light if
the compare regressed to unsigned semantics).
2026-04-19 00:17:34 +00:00
Claude
854b61ea1e
docs + example: HUD demo and language-guide VRAM buffer section
Follow-up to 807c9c7 (the VRAM update buffer core). Adds the
realistic-HUD example the core was missing, plus a language-guide
section that explains when and how to use the three buffer
intrinsics.

**examples/hud_demo.ne**

A bouncing-ball playfield with a classic status bar across the
top:
- 5-cell lives indicator that ticks down once per second and
  resets at zero, drawn via `nt_fill_h` (plus a second
  `nt_fill_h` to erase the stale tail).
- Score counter at the right edge that bumps on every wall
  bounce, drawn via `nt_set`.
- One-shot `nt_attr` call on the first frame flipping the
  top-left metatile group to sub-palette 1 (the red HUD
  palette) so the UI chrome reads as distinct from the
  playfield.

The demo's point is the `last_score != score` / `last_lives !=
lives` shadow-compare pattern: on the ~58-of-60 frames where
nothing changed, the buffer stays empty and drain work is zero.
That's the whole reason the VRAM buffer exists — per-frame cost
scales with what moved, not with HUD complexity. Committed
`.nes` + pixel/audio goldens.

**docs/language-guide.md**

New "VRAM Update Buffer" section between "Hardware Intrinsics"
and "Inline Assembly". Covers:
- Why user code can't just poke `$2006` / `$2007` directly.
- The three intrinsics + their coordinate systems (cell, not
  pixel).
- The HUD pattern with a ready-to-paste code snippet and a
  pointer at `examples/hud_demo.ne`.
- A per-entry budget table + worked 1000-cycle drain example
  against the ~2273-cycle vblank budget.
- Known limits: horizontal-only, no overflow check,
  no coalescing — all already tracked under `future-work.md` §G.

**examples/README.md**

`vram_buffer_demo.ne` reframed as the minimal test-case exercise
it actually is, with a pointer at `hud_demo.ne` for the realistic
pattern. New table row for `hud_demo.ne`.

All 758 tests pass. Clippy clean. 48/48 emulator goldens match.
2026-04-18 21:34:44 +00:00
Claude
807c9c7318
compiler: VRAM update buffer (nt_set / nt_attr / nt_fill_h)
Closes the highest-priority remaining catalogue item (§G). User
code queues PPU writes during `on frame` via three new intrinsics;
the NMI drains the 256-byte ring at `$0400-$04FF` to `$2007`
during vblank. Programs that never touch the buffer pay zero
bytes and zero cycles for the feature — verified by the existing
46 ROMs all matching their goldens with no drift.

Also fixes the failing CI Format check from 7b4570e by running
cargo fmt across the working tree.

**Runtime:**
- New `runtime::gen_vram_buf_drain` emits the drain routine
  (`__vram_buf_drain`). Walks entries `[len][addr_hi][addr_lo]
  [byte_0]...[byte_(len-1)]` and stops at `len == 0`. Uses
  `LDA $0400,X` indexed-absolute so no ZP scratch is needed.
  Drain costs ~12 setup cycles + 8 cycles per data byte; the
  256-byte buffer can hold ~50 single-tile writes that drain
  in roughly 1000 cycles, well inside the ~2273-cycle vblank.
- `NmiOptions` gains `has_vram_buf`. The NMI JSRs the drain
  after the existing palette/background handshake (compiler-
  queued PPU writes win priority for vblank cycles).

**IR + codegen:**
- Three new ops `IrOp::NtSet`, `IrOp::NtAttr`, `IrOp::NtFillH`.
- The codegen helpers compute the PPU address inline:
  `$2000 + y*32 + x` for nametable, `$23C0 + (y/4)*8 + (x/4)`
  for attribute. Each append lays down a fresh `0` sentinel so
  the NMI sees a well-formed buffer regardless of whether more
  entries get appended later in the frame.
- `__vram_buf_used` marker drops on first use; gates the
  runtime splice + NMI JSR.

**Analyzer:**
- AST-walking helper `program_uses_vram_buf` detects intrinsic
  use at analyze-init time so the user-RAM bump pointer can
  start at `$0500` (past the buffer) rather than the legacy
  `$0300`. Programs that don't use the buffer keep the legacy
  start.
- Three intrinsic names registered in `is_intrinsic` /
  `is_void_intrinsic` with arity checks.

**Tests + example:**
- `examples/vram_buffer_demo.ne` exercises all three intrinsics
  on a backgrounded program — three single-tile score writes,
  a 16-tile horizontal fill, and an attribute write that flips
  the top-left metatile group's palette to red. Committed
  golden + audio hash.
- Four new integration tests: byte-level JSR-to-drain
  assertion, drain-omitted-when-unused, RAM-bump assertion for
  programs that DO use the buffer, and arity enforcement for
  `nt_set`.

**CI fix:**
- `cargo fmt` ran across the tree. Picks up a one-line fmt
  diff in `tests/integration_test.rs` that the prior commit
  shipped without running fmt, causing the Format CI job to
  fail on `7b4570e`.

All 758 tests pass. Clippy clean. 47/47 emulator goldens match.
2026-04-18 21:14:31 +00:00
Claude
7b4570eee5
compiler: i16 / SRAM saves / inline-asm dot labels / docs
Another batch from the cc65/nesdoug catalogue. All gated on
parser-level opt-in or default-false attributes so existing
programs produce byte-identical ROMs (no committed .nes file
changed).

**§A — `i16` signed 16-bit type:**
- New `KwI16` lexer token, `NesType::I16` AST variant, parser
  case in `parse_type`. Type-size and integer-type tables
  treat `i16` like `u16` (2 bytes, integer).
- IR lowering accepts `i16` everywhere it accepts `u16` for
  wide-load / wide-store / widen-narrow paths.
- New constant fold for `UnaryOp::Negate(IntLiteral(v))` that
  emits the wide two's-complement form. Without it, `var vy:
  i16 = -10` would zero-extend to `$00F6` (= 246) instead of
  sign-extending to `$FFF6` (= -10). Negative literals now
  store the right bytes.
- Comparisons reuse the existing unsigned 16-bit compare ops
  (matching the existing `i8` behaviour). Documented in the
  `NesType::I16` doc comment and in `future-work.md` §A.
- Example `examples/i16_demo.ne` with committed golden.
- Tests cover the literal-fold sign-extension and end-to-end
  compile of the example.

**§S — SRAM / battery-backed saves:**
- New `save { var ... }` top-level block. Lexer + parser opt
  into a dedicated `KwSave` token. Analyzer allocates save
  vars from a separate `next_sram_addr` bump pointer starting
  at `$6000`, capped at `$8000` (8 KB cartridge SRAM window).
- Linker reads `analysis.has_battery_saves` and flips iNES
  byte-6 bit-1 via the new `RomBuilder::set_battery` /
  `Linker::with_battery` chain.
- New `W0111` warning for save-var initializers — SRAM is
  preserved across power cycles, so an init expression would
  either silently never run or clobber persisted data on
  every boot. The warning teaches the user about the
  magic-byte sentinel pattern.
- Struct fields in save blocks are explicitly rejected for now
  (the field-flattening path uses the main-RAM allocator).
- Example `examples/sram_demo.ne` with committed golden, plus
  4 integration tests.

**§D (partial) — inline-asm `.label:` syntax:**
- Codegen-side mangler rewrites `.IDENT` → `__ilab_<N>_IDENT`
  per inline-asm block, where `<N>` is the call site's
  monotonic suffix. Two `asm { .loop: ... }` blocks in the
  same function now coexist without colliding in the linker's
  label table.
- Bounds checks on `.` placement: `$2002` and `name.field`
  are unaffected; only `.IDENT` in label / branch context
  triggers the rewrite. Two integration tests pin the
  uniqueness and dollar-vs-dot disambiguation.

**§X follow-up — Mesen trace-log docs:**
- New "Debugger-assisted workflows" section in
  `docs/nes-reference.md` walking through the Mesen / FCEUX
  log workflows alongside the new `debug_port:` attribute.

**Misc:**
- `future-work.md` updated to mark the shipped items out of
  the catalogue and reshuffle the priority ranking. Remaining
  niche follow-ups (signedness on Cmp16, struct save fields,
  inline-asm format specifiers) documented inline so future
  passes know the design.

All 757 tests pass. Clippy clean. 46/46 emulator goldens match.
2026-04-18 20:49:06 +00:00
Claude
e0b268eea9
compiler: GNROM / debug port / sprite flicker / fade / sprite-0 split + docs
Another batch from the cc65/nesdoug gap catalogue. All six items
gated on marker labels (or default-false attributes) so existing
programs produce byte-identical ROMs — every pre-existing .nes
file round-trips unchanged.

**Language / runtime additions:**

- `mapper: GNROM` (iNES 66). Combines AxROM's 32 KB PRG pages with
  CNROM's 8 KB CHR banks in a single `$8000` register. Linker
  pads single-page ROMs to 32 KB to match mapper-66 expectations.
- `game { debug_port: fceux | mesen | 0xXXXX }`. `debug.log`,
  `debug.assert`, and the `__debug_halt` sentinel now target a
  user-selected address. `fceux` (default, $4800) and `mesen`
  ($4018) are named aliases; custom hex addresses are accepted
  for unusual debuggers.
- `game { sprite_flicker: true }`. IR lowerer injects an
  `IrOp::CycleSprites` at the top of every `on frame` handler,
  which flips on the rotating-OAM NMI variant with no per-site
  boilerplate. Default false so existing ROMs keep their layout.
- `fade_out(step_frames)` / `fade_in(step_frames)` builtins.
  Blocking helpers that walk brightness 4 → 0 or 0 → 4 with
  `step_frames` frames between each step. Runtime splices
  `__fade_out`, `__fade_in`, and a callable `__wait_frame_rt`
  helper when the builtin is used. Zero-guard on step_frames
  prevents a pathological 256-frame spin when the caller
  accidentally passes 0.
- `sprite_0_split(scroll_x, scroll_y)` intrinsic. Emits a
  two-phase busy-wait on `$2002` bit 6 (wait-for-clear,
  wait-for-set) then writes the new scroll values to `$2005`.
  Works on any mapper — unlike `on_scanline(N)` which requires
  MMC3. Enables HUD-over-playfield scrolling on NROM/UxROM/MMC1.

**Docs:**

- New paragraph in the language guide explaining the no-recursion
  design choice and the explicit-stack workaround pattern.
- `future-work.md` updated to mark the shipped items out of the
  catalogue; remaining items reshuffled in the priority ranking.
- README + examples/README updated with the new mapper and
  builtins.

**Tests:**

- 12 new integration tests covering: GNROM header emission,
  debug-port targeting (fceux/mesen/custom), unknown-alias
  rejection, sprite_flicker on/off/bad-value, fade_out JSR + marker
  coupling, fade omitted-when-unused, fade-in-expression rejected,
  sprite_0_split byte-level busy-wait verification, sprite_0_split
  arity enforcement, sprite_0_split omitted-when-unused, and an
  extended void-intrinsic-in-expression-position test covering the
  three new void builtins.
- `nes2_mapper_high_nibble_in_byte_8_is_zero_for_small_mappers`
  extended to include GNROM.
- Four new examples with committed .nes ROMs + pixel/audio
  goldens: `gnrom_simple`, `auto_sprite_flicker`, `fade_demo`,
  `sprite_0_split_demo`.

All 752 tests pass. Clippy clean. 44/44 emulator goldens match.
2026-04-18 19:31:55 +00:00
Claude
7507459787
compiler: PRNG / edge input / palette fade / AxROM / CNROM / FCEUX labels
Closes seven of the cc65/nesdoug parity gaps catalogued in
docs/future-work.md in a single pass. All of the new features are
gated on marker labels so programs that don't use them produce
byte-identical ROM output (every pre-existing committed .nes file
round-trips unchanged).

Language / runtime additions:
- `rand8()` / `rand16()` / `seed_rand(u16)` intrinsics backed by a
  16-bit Galois LFSR (~30 bytes of runtime, ~40 cycles per draw).
  Reset path seeds state to 0xACE1 so the first draw is useful even
  without explicit seeding.
- `p1.button.a.pressed` / `.released` edge-triggered input via a
  new ReadInputEdge IR op plus an NMI-side prev-frame snapshot into
  $07E6/$07E7, gated on the `__edge_input_used` marker.
- `set_palette_brightness(level)` builtin mapping levels 0..8 to
  PPU mask emphasis bytes (`$2001`) for neslib-style screen fades.
- `mapper: AxROM` (iNES 7) with automatic 32 KB PRG padding so
  emulators that enforce mapper-7's 32 KB page size boot cleanly.
- `mapper: CNROM` (iNES 3) with a reset-time CHR bank 0 select.
- `--fceux-labels <prefix>` CLI flag emitting per-bank `.nl` label
  files and a `.ram.nl` file for FCEUX's debugger.

Tests + examples:
- Five new example programs with committed .nes ROMs and
  pixel+audio goldens: prng_demo, edge_input_demo,
  palette_brightness_demo, axrom_simple, cnrom_simple.
- Seven integration tests covering JSR emission, the
  omitted-when-unused invariant, the NMI prev-input snapshot, the
  correct mapper numbers for AxROM/CNROM, and negative tests for
  unknown button names and bad rand8 arity.
- `is_intrinsic()` now runs in expression-position Call paths too,
  so `var x = rand8(1, 2)` errors at compile time instead of
  silently dropping the extra arguments.
2026-04-18 18:13:18 +00:00
Claude
ee3dddb19e
examples: add feature_canary that turns red on any memory silent-drop regression
Phase 5 of the post-PR-#31 audit, and the structural piece that
closes the failure mode the earlier phases couldn't fix alone.

The audit's recurring diagnosis: pixel/audio goldens capture
*whatever* the program does, not what it *should* do. A silent
drop in codegen is still deterministic — the golden locks in
the broken behaviour and every future run agrees with it. That's
how state-locals, uninitialized struct-field writes, `on exit`
handlers, and `slow` placement each sat broken for months-to-a-
year in a green CI.

The canary inverts the relationship: the committed golden is a
solid-green universal backdrop that only appears when every
round-trip check passes. Each check writes a distinctive constant
through one language construct, reads it back, and clears
`all_ok` on mismatch. A final `if all_ok == 0 { set_palette Fail }`
flips the entire screen red for the rest of the run.

Checks cover the silent-drop shapes caught by this audit:
  - state-local variable write-read (PR #31)
  - uninitialized struct-field write-read (caught by phase 1)
  - u8 / u16 globals (u16 exercises both StoreVar + StoreVarHi)
  - array-element write at nonzero index
  - `slow`-placed global still round-trips
  - function call return value

The canary doesn't use `debug.assert` on purpose — debug-only
ops get stripped in release and the emulator harness runs
release builds. The palette swap works in release and is what
the harness pixel-diff sees.

### Why this matters as a long-lived test

The harness already had 34 pixel goldens covering full-program
behaviour, but none of them exist specifically to fail if a
*specific language feature* silently drops. The canary does.
Every silent-drop bug the audit found would have flipped it
red the moment the check was added, which is the "behaviour
assertion that can't be satisfied by silence" the plan called
for.

### Harness footprint

`tests/emulator/goldens/feature_canary.{png,audio.hash}` +
`examples/feature_canary.{ne,nes}`. 35/35 ROMs match their
goldens with the canary added. Listed in both README tables.

https://claude.ai/code/session_01AoQ678uVeqpyayvWHpfDhC
2026-04-18 00:14:40 +00:00
Claude
ba23f8578a
examples/sha256: interactive SHA-256 hasher with on-screen keyboard
An end-to-end FIPS 180-4 SHA-256 hasher running entirely on the NES.
The player types up to 16 ASCII characters on a 5x8 on-screen
keyboard, presses Enter, and the program computes and displays the
64-character hex digest.

Layout (`examples/sha256/*.ne`):
  constants.ne         layout + K[64] / H_INIT[8] tables
                       (declared as `var` with init_array because the
                       v0.1 compiler treats `const u8[N] = [...]` as
                       a no-op — noted in the file)
  assets.ne            44-tile Tileset (A..Z, 0..9, punctuation,
                       special keys, cursor) shared between BG and
                       sprite layers
  background.ne        static nametable (title, labels, keyboard
                       grid) painted at reset
  state.ne             globals
  sha_core.ne          32-bit byte primitives (copy, xor, and, add,
                       not, rotr, shr) in inline asm + sigma/Sigma
                       mixers + schedule/round steps + fold
  render.ne            OAM helpers for cursor, input buffer, and
                       64-nibble digest
  keyboard.ne          key dispatch table
  entering_state.ne    cursor navigation + typing + auto-demo
  computing_state.ne   phased driver (48 schedule steps + 64 rounds
                       + fold across ~30 frames at 4 iterations each)
  showing_state.ne     renders the 256-bit digest as 8 rows of 8
                       sprite glyphs

Implementation notes:
  - All 32-bit words live as 4 little-endian bytes in `wk[64]`,
    `w[256]`, `h_state[32]` so every primitive walks four bytes with
    `LDA {arr},X`/`STA {arr},X` chains and, for adds, a carry chain.
  - Every primitive reads its parameters straight out of the
    transport slots `$04`/`$05` rather than `{dst}`/`{src}`
    substitutions: the inline-asm resolver looks parameters up in
    the analyzer's allocation table but the codegen spills them to a
    different per-function RAM slot, so `{dst}` would resolve to a
    ZP slot nothing ever writes to. Bypassing the substitution
    entirely sidesteps the issue without a compiler change.
  - Rotate-right by any amount is a byte-rotate loop plus a bit-
    rotate loop so the 10 SHA amounts (2, 6, 7, 11, 13, 17, 18, 19,
    22, 25) all compile to a handful of chained `ROR`s.
  - The headless jsnes golden auto-types "NES" after 1 s of idle and
    captures its SHA-256 digest
    AE9145DB5CABC41FE34B54E34AF8881F462362EA20FD8F861B26532FFBB84E0D
    — byte-identical to `shasum` / `hashlib.sha256(b"NES")`.

Build: `cargo run --release -- build examples/sha256.ne`

https://claude.ai/code/session_01FRmSBruVWCufm3LsUVMs8v
2026-04-16 14:02:58 +00:00
Claude
21b91f6398
examples/pong: production-quality Pong game with powerups and multi-ball
A complete, playable Pong game split across examples/pong/*.ne files
and pulled in from a top-level examples/pong.ne. Features:

- **Title screen** with a 3-option menu (CPU VS CPU / 1 PLAYER /
  2 PLAYERS), a cursor sprite, blinking "PRESS A" prompt, brisk
  title march on pulse 2, and autopilot that auto-confirms CPU VS
  CPU after 45 frames of no input so the headless jsnes golden
  harness reaches gameplay by frame 180.

- **Ball physics** with signed-magnitude velocity (u8 magnitude +
  sign bit per axis), wall bounce at top/bottom, paddle AABB
  collision with push-out, and score-out detection at left/right
  exits.

- **Multi-ball** via parallel ball_* arrays (MAX_BALLS = 3). Each
  ball scores a point independently; the round continues until the
  last ball exits the playfield.

- **CPU AI** that tracks the nearest active ball heading toward its
  side with a per-frame step, 4 px dead zone, and CPU_SPEED = 1 so
  rallies can end naturally.

- **Three powerup types** that spawn every ~4 seconds, bounce off
  all four walls, and are caught by paddle AABB overlap:
  1. LONG — extends the catching paddle from 24 → 40 px for 5 hits
  2. FAST — doubles ball x-velocity on the catcher's next hit
  3. MULTI — spawns two extra balls on the catcher's next hit

- **Victory** at first-to-7 with a "PLAYER N WINS" banner and the
  builtin fanfare, auto-returning to Title.

- **Audio**: 5 user-declared sfx (WallBounce, PaddleHit, Score,
  PowerSpawn, PowerCatch) plus a title march and the builtin
  fanfare for victory.

Source layout mirrors examples/war:

    examples/pong.ne               top-level game shell
    examples/pong/PLAN.md          living design doc
    examples/pong/constants.ne     layout + gameplay constants
    examples/pong/assets.ne        45-tile Tileset (paddles, ball, alphabet,
                                   digits, cursor, center-line, powerup icons)
    examples/pong/audio.ne         sfx + music declarations
    examples/pong/state.ne         all mutable globals
    examples/pong/rng.ne           8-bit Galois LFSR
    examples/pong/render.ne        draw helpers
    examples/pong/input.ne         paddle step (human + CPU AI)
    examples/pong/ball.ne          multi-ball physics + paddle collision
    examples/pong/powerup.ne       powerup entity (spawn, bounce, catch, apply)
    examples/pong/title_state.ne   state Title + menu
    examples/pong/play_state.ne    state Playing (P_SERVE/P_PLAY/P_POINT)
    examples/pong/victory_state.ne state Victory

Verification:
- 616 compiler unit tests pass (cargo test --all-targets)
- cargo fmt / cargo clippy --all-targets -- -D warnings clean
- 33/33 emulator harness goldens match
- examples/pong.nes builds byte-identically from source

https://claude.ai/code/session_0134F5uwDEVTes2Ee9S7JeXy
2026-04-16 01:25:29 +00:00
Claude
548787ac8a
W0110 inline fallback warning + docs refresh
W0110: when a function marked `inline` has a body shape the IR
lowerer can't splice (conditional early return, loops, nested
control flow, empty void body), the analyzer now emits a
warning at the declaration site so the declined hint is
visible instead of silently falling back to a regular JSR.

Implementation:
  - New `W0110` error code in `src/errors/diagnostic.rs` (warning level).
  - New `pub fn can_inline_fun(return_type, body) -> bool` in
    `src/ir/lowering.rs`, extracted from the existing capture
    logic so the analyzer and the IR lowerer share the same
    eligibility rules and can never drift.
  - New `check_inline_declinability` analyzer pass called from
    the tail of `analyze_program`, mirroring the existing
    `check_sprite_scanline_budget` / `check_unreachable_states`
    passes. Emits W0110 with help + note text pointing at the
    two accepted body shapes.
  - `capture_inline_bodies` now defers to `can_inline_fun`
    instead of duplicating the match pattern, so the two sides
    stay in lockstep by construction.

Four regression tests in `src/analyzer/tests.rs` cover the
conditional-return and while-loop declines plus the two
accepted shapes (single-return expression, void sequence).

Example source cleanups: `wrap52` in `examples/war/deck.ne`
and `abs_diff` in both `examples/arrays_and_functions.ne` and
`examples/loop_break_continue.ne` drop the `inline` keyword.
All three were dead hints — the `inline` was being silently
declined before this change, so removing it is source-only;
the three ROMs are byte-identical, all 32 emulator goldens
still match.

Docs refresh
  - `docs/language-guide.md`: rewrote the Inline Functions section
    (real behaviour + W0110), added W0105/W0106/W0107/W0108/W0109/
    W0110 to the warnings table, added the `debug.sprite_overflow*`
    builtins + sprite-per-scanline mitigations section to the
    Debug Mode docs, added a `cycle_sprites` statement entry and
    cross-referenced it from `draw`.
  - `docs/nes-reference.md`: fleshed out the "NEScript Memory
    Usage" block with the full ZP + high-RAM layout, including
    the new `$07EF` / `$07FC` / `$07FD` slots for sprite cycling
    and the debug sprite-overflow telemetry.
  - `docs/future-work.md`: documented all four debug query
    builtins in the "What ships today" block; updated the open
    "OAM allocation strategy" question to reference the shipped
    `cycle_sprites` path and ask about an automatic-flicker
    game attribute as a follow-up.
  - `docs/architecture.md`: updated the `ir/` and `optimizer/`
    module summaries to describe real inline splicing (now
    in lowering, not the optimizer).
  - `README.md`: reframed the `inline` bullet from "hint" to
    "real splicing for single-return / void-body shapes";
    expanded the debug-support bullet to mention the four
    query builtins and their stripping in release builds; added
    a new bullet for the three-layer sprite-per-scanline
    mitigations; bumped the test count from 497 → 694; updated
    the war.ne entry to mention the seven compiler bugs are all
    fixed and point readers at `git log` (instead of the
    deleted COMPILER_BUGS.md).
  - `examples/README.md`: same `git log`-pointing rewrite for
    the war.ne entry.

Deletions
  - `examples/war/COMPILER_BUGS.md` is removed. All seven
    catalogued bugs are fixed; the file's historical value
    lives in `git log` now. Every source-code comment and doc
    reference to the file has been updated to either point at
    `git log` or just describe the bug in place.

Test count: 616 unit + 75 integration + 3 doctests = 694 total.
Clippy / fmt clean. 32/32 emulator goldens match.

https://claude.ai/code/session_0143dTgh3UeRrtfHgQwzcv5z
2026-04-15 23:19:07 +00:00
Claude
5e5bed39a5
sprite-per-scanline: add cycle_sprites runtime flicker + debug telemetry
W0109 (shipped last commit) catches the 8-sprites-per-scanline
hardware limit at compile time for static layouts, but the
dynamic case — enemy formations, projectile clusters, animated
NPCs where coordinates come from variables — was still silent.
This change adds two layers of defense on top of W0109:

Layer 2: `cycle_sprites` runtime flicker intrinsic
  New keyword statement that rotates the OAM DMA start offset
  one slot per call. When called once per `on frame`, the PPU's
  sprite evaluation picks up a different subset of the 12+
  overlapping sprites each frame, so the permanent-dropout
  failure mode becomes visible flicker — the classic NES
  technique used by Gradius, Battletoads, and every shmup.

  Implementation:
    - Lexer keyword `KwCycleSprites` and parser production.
    - AST `Statement::CycleSprites(Span)`.
    - `IrOp::CycleSprites` lowered by the IR pass.
    - Codegen emits `LDA $07EF / CLC / ADC #4 / STA $07EF` with
      natural u8 wrap, plus a one-shot `__sprite_cycle_used`
      marker label the first time it fires.
    - Linker detects the marker and switches `gen_nmi` to the
      cycling variant, which reads the rotating offset from
      `$07EF` into OAM_ADDR before the DMA instead of writing
      a literal 0. Programs that don't call `cycle_sprites`
      skip the marker and get byte-identical ROM output.

Layer 3: debug-mode sprite overflow telemetry
  Mirrors the frame-overrun pair (`debug.frame_overrun_count` /
  `debug.frame_overran`). In debug builds the NMI handler reads
  `$2002` at the top of vblank, masks bit 5 (the PPU's sprite
  overflow flag), and if set bumps a cumulative counter at
  `$07FD` plus a sticky bit at `$07FC`. The sticky bit clears
  on every `wait_frame`.

  New debug builtins:
    - `debug.sprite_overflow_count()` → u8 peek of $07FD
    - `debug.sprite_overflow()` → u8 peek of $07FC (sticky bit)

  The hardware flag has well-known quirks but is correct for
  the overwhelming majority of cases and costs ~15 cycles per
  frame to sample. Release builds emit no overflow-check code
  at all, so the four bytes at `$07EF` / `$07FC`-`$07FD` stay
  free for user allocation.

Related changes:
  - `gen_nmi` now takes an `NmiOptions` struct. Four bool
    parameters tripped clippy's `fn_params_excessive_bools`.
  - CLI `build` now renders analyzer warnings on a successful
    build. Previously warnings were silently dropped unless
    the user also ran `nescript check`, which made W0109
    effectively invisible to CI and local dev alike. Existing
    pre-existing W0103 / W0106 warnings on `coin_cavern`,
    `mmc3_per_state_split`, `sprites_and_palettes` surface
    too — not regressions, just now visible.

New example: `examples/sprite_flicker_demo.ne`
  Draws 12 sprites into a 4-pixel band, W0109 fires at compile
  time with nine labels pointing at the offenders, and a
  `cycle_sprites` call at the end of `on frame` turns the
  hardware dropout into flicker. The committed emulator golden
  captures one frame of the cycling pattern (deterministic).

Tests:
  - `runtime::tests::nmi_debug_mode_samples_sprite_overflow`
  - `runtime::tests::nmi_sprite_cycle_variant_reads_rotating_offset`
  - `ir_codegen::*::debug_sprite_overflow_count_loads_07fd`
  - `ir_codegen::*::debug_sprite_overflow_flag_loads_07fc`
  - `ir_codegen::*::wait_frame_clears_sprite_overflow_sticky_in_debug_mode`
  - `ir_codegen::*::wait_frame_release_does_not_touch_sprite_overflow_sticky`
  - `ir_codegen::*::cycle_sprites_emits_marker_and_add4`
  - `ir_codegen::*::cycle_sprites_marker_dedup_across_multiple_calls`
  - `ir_codegen::*::program_without_cycle_sprites_emits_no_marker`
  - `analyzer::*::accepts_debug_sprite_overflow_builtins`
  - `analyzer::*::rejects_unknown_debug_method_lists_all_four_known_names`
  - `analyzer::*::accepts_cycle_sprites_statement`

Docs: `examples/war/COMPILER_BUGS.md` §4 now describes all three
layers (W0109, `cycle_sprites`, debug telemetry) with reasoning
for when each applies. `README.md` and `examples/README.md` add
the new example to their tables.

All 32 emulator goldens still match — the cycling is opt-in
and programs that don't call `cycle_sprites` or enable debug
mode are byte-identical to the pre-change output.

https://claude.ai/code/session_0143dTgh3UeRrtfHgQwzcv5z
2026-04-15 22:07:19 +00:00
Claude
9137b1f713
examples/war: polish pass + README entry + plan close-out
End-of-implementation polish for the War example after the
compiler bugs were fixed:

- Title state now calls draw_big_war_banner instead of inlining
  12 draws — same pixel output, fewer lines.
- P_WAR_BURY redraws the previous round's face-up cards while
  the noise thumps fire so the table doesn't look empty for
  24 frames between the WAR banner and the new face-ups.
- Drop draw_word_war from render.ne (orphaned by the BIG WAR
  metasprite).
- Refresh comments in background.ne (now references the real
  felt tile) and deal_state.ne (drop the stale FRAMES_DEAL_STEP
  reference now that the deal pace is hard-coded at 2 frames).
- README.md and examples/README.md gain a war row.
- PLAN.md marks every implementation step complete and records
  the design revisions made along the way.
- Refresh the war audio hash to match the new ROM (the title
  screen helper change shifts one frame of pulse-2 timing
  enough to flip the FNV-1a). The frame-180 PNG is unchanged.

https://claude.ai/code/session_0143dTgh3UeRrtfHgQwzcv5z
2026-04-15 16:08:03 +00:00
Claude
cc3f7eec7e
assets: auto-generate CHR data from @nametable() PNG sources
`background Foo @nametable("file.png")` previously decoded the PNG
into a tile-index table and an attribute table but left CHR
generation to the user — they had to supply matching tiles via a
separate `sprite Tileset @chr(...)` declaration in the same
deduplication order, which was both error-prone and the main thing
keeping the shortcut form from being a one-liner.

The CHR pipeline now closes the gap. `png_to_nametable_with_chr`
returns a `PngNametable` carrying the tile-index table, the
attribute table, *and* a per-tile CHR blob encoded with the same
brightness-bucketing `png_to_chr` already uses for sprites. The
resolver passes `next_sprite_tile` (computed from the resolved
sprite list) so each background's CHR allocation slots in
immediately after the sprite range, and rewrites the nametable
indices to point at the actual physical tile numbers. The linker
copies each background's `chr_bytes` into CHR ROM at
`chr_base_tile * 16`, so the final image renders without any
user-supplied CHR.

`BackgroundData` carries `chr_bytes` and `chr_base_tile` so the
linker has everything it needs at a glance. Inline `tiles:` /
`attributes:` declarations leave them empty and behave exactly
like before — that path doesn't auto-generate CHR because the
user is implicitly opting into "I'll provide tiles myself" by
typing the indices out by hand.

The new `examples/auto_chr_background.ne` is a 256×240 grayscale
gradient committed alongside its `auto_chr_bg.png` source; the
emulator harness verifies the rendered output against a
committed golden so a regression in the dedupe/encode/linker
plumbing fails CI loudly. Existing example ROMs are byte-
identical because their backgrounds either have no PNG source or
already provided their own CHR.

https://claude.ai/code/session_01KEczoNUX3WmcFLfq6iAQxB
2026-04-15 03:29:58 +00:00
Claude
6b080316a4
parser/lowering: declarative metasprites for multi-tile sprite groups
Multi-tile sprites used to require one hand-written `draw` per tile,
e.g. the four-call sequence in `examples/platformer.ne`'s
`draw_player()`. The new `metasprite Name { ... }` declaration
collects parallel `dx`/`dy`/`frame` arrays plus a reference to the
underlying sprite, and `draw Name at: (x, y)` expands to one OAM
slot per tile in the IR lowering — the codegen sees N regular
DrawSprite ops, so the runtime OAM cursor allocator picks them up
without any metasprite-specific awareness.

The metasprite's `frame:` array is interpreted *relative to the
underlying sprite's base tile*: index 0 means "the first tile this
sprite owns", which is the natural reading for a 16×16 hero whose
pixel art the asset resolver split into four consecutive tiles.
The lowering walks `program.sprites` to compute base tile indices
the same way `assets::resolve_sprites` would, then folds the base
into each frame entry before storing the metasprite info. Sprites
sourced from external `@chr(...)` / `@binary(...)` files whose
bytes aren't available at parse time fall back to a one-tile
assumption — those programs are rare and can declare metasprites
against pixel-art sprites instead.

The new `examples/metasprite_demo.ne` declares a 16×16 hero sprite
and arranges its four tiles into a metasprite, then sweeps the
hero across the screen so the harness captures it mid-motion.
The new keyword is added to the lexer/token list, and the parser
accepts `sprite:` (the otherwise-keyword) as a property name in
metasprite bodies so the natural spelling parses.

https://claude.ai/code/session_01KEczoNUX3WmcFLfq6iAQxB
2026-04-15 03:13:30 +00:00
Claude
9878b7d87d
audio: per-frame pitch envelopes for pulse SFX
Pulse-channel sfx with a multi-byte `pitch:` array used to silently
ignore everything past the first byte — the runtime audio tick
latched the period at trigger time and never updated it. Programs
that wanted a frequency sweep had no way to express it.

The compiler now compiles a per-frame pitch envelope blob alongside
the existing volume envelope when `decl.pitch` has more than one
distinct value. The blob is padded (or truncated) to the volume
envelope's length and ends in a zero sentinel so the runtime
walker stops both pointers on the same NMI. Sfx with a single
scalar pitch (or an array where every byte is the same) keep their
historical "no pitch blob, latch once" path and emit byte-identical
ROM bytes.

The runtime gains two new pieces, both gated on a new
`__sfx_pitch_used` codegen marker so programs without varying-pitch
sfx pay zero bytes:

1. `gen_audio_tick` emits a per-frame pitch update block inside
   the SFX tick: read a byte through `(AUDIO_SFX_PITCH_PTR),Y`,
   write it to `$4002` (pulse-1 period low), advance the pointer.
   The block bails on a zero high-byte pointer so a single
   program can mix scalar-pitch and varying-pitch sfx without
   one clobbering the other.

2. `emit_play_pulse` seeds `AUDIO_SFX_PITCH_PTR_LO/HI` with the
   pitch-blob label for varying-pitch sfx and zeros it for
   scalar-pitch sfx. The per-call branch is skipped entirely
   when the program has no varying-pitch sfx anywhere.

The new `examples/sfx_pitch_envelope.ne` exercises the path with
a 16-frame siren sweep. Triangle and noise per-frame pitch are
deferred — they share the same data shape but the runtime ticks
for those channels still write only their volume registers, see
docs/future-work.md for the gap.

https://claude.ai/code/session_01KEczoNUX3WmcFLfq6iAQxB
2026-04-15 02:54:56 +00:00
Claude
db3a4adc57
codegen: support banked → banked cross-bank function calls
Programs that put functions in switchable banks can now call across
bank boundaries — `bank A { fun step() { helper() } }` where
`helper` lives in `bank B` used to panic in the IR codegen. Three
small pieces unblock it:

1. **Generic trampoline.** `runtime/gen_bank_trampoline` no longer
   takes a `fixed_bank_index` argument. Instead it reads the
   caller's current bank from `ZP_BANK_CURRENT`, pushes it on the
   hardware stack, switches to the target, JSRs the entry, then
   pulls and restores the saved bank. The same per-callee stub
   works for fixed→banked and banked→banked direction; nested
   trampolines compose because each PHA/PLA pair sits inside its
   own JSR/RTS frame. `gen_mapper_init` seeds `ZP_BANK_CURRENT`
   with the fixed bank index for any banked mapper so the very
   first cross-bank call from the fixed bank still restores to
   the fixed bank (matching pre-banked-banked semantics).

2. **Codegen drops the panic.** The `Some(from), Some(to)` arm in
   the call-resolution switch now emits `JSR __tramp_<name>` like
   the fixed→banked case instead of panicking. Banked→fixed calls
   still go direct (the fixed bank is always mapped at $C000).

3. **Bank-namespaced local labels.** Two banks emitting the same
   `__ir_cmp_e_8` would trip the linker's discovery-pass duplicate-
   label check the moment any banked code generated a comparison.
   The new `local_label_suffix` helper prefixes the suffix with the
   current bank name when banked code is being emitted, leaving
   fixed-bank label generation untouched (so existing examples are
   byte-identical apart from the trampoline / init bytes
   themselves).

The new `examples/uxrom_banked_to_banked.ne` demonstrates the path
end-to-end: `bank Logic { fun step() { ... clamp() } }` calls
`bank Helpers { fun clamp() { ... } }` once per frame. The harness
golden is committed alongside it. The five existing banked example
ROMs change byte-for-byte because of the new trampoline shape and
the seed-ZP_BANK_CURRENT init, but their emulator goldens still
match exactly — observable behaviour is unchanged.

https://claude.ai/code/session_01KEczoNUX3WmcFLfq6iAQxB
2026-04-15 02:37:19 +00:00
Claude
7294ae3efa
analyzer/lowering: support nested struct fields and array struct fields
Struct field types beyond the v1 scalar set (`u8`, `i8`, `u16`,
`bool`) used to error out with `E0201: struct fields must be
u8/i8/u16/bool`. The size accumulator already handled them
correctly — what was missing was: (1) the analyzer side that
synthesizes per-leaf symbols and allocations for nested structs
plus a single array-typed symbol for array fields, (2) the
parser's chained-field-access path, and (3) the IR-lowering
recursion through nested struct literal initializers and array
literal field values.

The synthetic-variable model carries through unchanged: a
`var p: Player` where `Player { pos: Vec2, hp: u8, inv: u8[4] }`
and `Vec2 { x: u8, y: u8 }` produces flat allocations for
`p.pos.x`, `p.pos.y`, `p.hp`, and `p.inv`, plus an intermediate
`p.pos` Struct symbol so dotted-name lookups still resolve. Array
fields get a single allocation with the array type so the
existing `Expr::ArrayIndex` lowering path handles `p.inv[i]`
without changes. Array-of-structs is still rejected with E0201
because the synthetic model can't index per-element layouts
without further codegen work.

The parser change is the only structural move: `parse_primary`
and `parse_assign_or_call` now loop the dot chain into a single
joined identifier so `p.pos.x` becomes `FieldAccess("p.pos", "x")`
and `p.inv[0]` becomes `ArrayIndex("p.inv", 0)`. The downstream
analyzer and IR lowering use the same `format!("{name}.{field}")`
join they already used for one-level access — no plumbing
changes required.

Includes a new `examples/nested_structs.ne` that exercises both
features end-to-end with two `Hero` instances carrying nested
positions and inventory arrays. The reproducibility tripwire
ROM is committed alongside it and the emulator harness has a
matching pair of golden files.

https://claude.ai/code/session_01KEczoNUX3WmcFLfq6iAQxB
2026-04-15 02:19:49 +00:00
Claude
2fe943b056
codegen: user code in switchable banks via cross-bank trampolines
Adds a `bank Foo { fun bar() { ... } }` parser form so user functions
can opt into living in a switchable PRG bank instead of the fixed
bank, plus the IR codegen, runtime, and linker work to make calls
across the bank boundary actually run. Programs that don't use the
new syntax produce byte-identical ROMs to before — verified by
rebuilding every existing example and diffing.

Pipeline shape:

* Parser accepts both `bank Foo: prg` (legacy reserved slot) and
  `bank Foo { fun ... }` (functions land in the named bank). Nested
  functions get tagged `bank: Some("Foo")` on the FunDecl + IrFunction.
* Analyzer bumps the user zero-page start past `$10` whenever the
  program declares any banked function, so `__bank_select`'s STA into
  ZP_BANK_CURRENT can't clobber a user variable. Programs without
  banked functions keep the legacy `$10` start.
* IrCodeGen emits each banked function into its own per-bank
  instruction stream (`banked_streams: HashMap<String, Vec<Instruction>>`)
  while the fixed-bank stream gets the dispatcher loop + state
  handlers + top-level functions, exactly like before. Cross-bank
  calls from the fixed bank rewrite `JSR __ir_fn_<name>` to
  `JSR __tramp_<name>`; in-bank calls stay direct. Banked → fixed
  calls are direct (the fixed bank is always mapped at $C000-$FFFF).
  Banked → other-banked calls aren't supported in this pass and
  panic loudly during codegen.
* Runtime's `gen_bank_trampoline` takes the trampoline label and
  entry label as parameters now (one trampoline per banked function,
  not one per bank) so the linker can request any number of stubs.
* Linker assembles banked banks twice: a discovery pass to learn
  each bank's labels, then a final pass that seeds the merged label
  table so banked code can JSR into the fixed bank's runtime helpers
  (math, audio, etc.). The fixed-bank assembler is also seeded with
  the cross-bank labels so the trampolines' `JSR __ir_fn_<name>`
  resolves into the bank's $8000 window. New `asm::assemble_with_labels`
  / `asm::assemble_discover_labels` helpers wire this up.
* PrgBank carries `Vec<Instruction>` + a list of `BankTrampoline`
  requests now, replacing the old `data: Vec<u8>` + single
  `entry_label: Option<String>` shape. The compiler populates both
  from the codegen output; the linker's two-pass assembly handles
  the rest.

New example: `examples/uxrom_user_banked.ne` puts a sprite-stepping
helper inside `bank Extras { fun step_animation() { ... } }`. The
fixed-bank state handler calls it via the generated trampoline, and
the harness golden locks in pixel + audio output at frame 180.

UxROM is the only mapper exercised by the new example. MMC1 and
MMC3 also work through the same path (the linker emits the right
mapper-specific bank-select code), but no example uses them yet —
the existing `mmc1_banked.ne` / `mmc3_per_state_split.ne` keep
their fixed-bank-only layout.

Limitations carried forward:
* No banked → banked cross-bank calls (panics in codegen).
* No greedy size-packing; placement is explicit-only.
* MMC3 state handlers don't get banked (the per-state split path
  is untouched).
2026-04-14 11:41:20 +00:00
Claude
201664ea04
audio: triangle and noise sfx channels
Adds `channel: triangle` / `channel: noise` to the `sfx` declaration
form. The existing pulse-1 / pulse-2 driver is unchanged (and is
still byte-identical for programs that don't use the new channels)
— when a program declares a triangle or noise sfx the runtime
splices in an additional per-channel slot that writes to $4008-
$400B (triangle) or $400C-$400F (noise) on play. Includes a new
`examples/noise_triangle_sfx.ne` demo with committed golden PNG +
audio hash.

https://claude.ai/code/session_01MaNVcDmK9gsspRkdxowQAM
2026-04-14 10:42:53 +00:00
Claude
169a481099
feat(platformer): add stomp-or-die enemy collisions, live HUD, GameOver state
The previous platformer example drew enemies but had almost no
interaction with them: only enemy 1 had a stomp check, the stomp
window was unreachable under the default +1-px-per-frame-plus-a-
jump-every-40-frames autopilot, contact from any other angle was
a silent no-op, and the header comment promised a "title → playing
→ game-over state machine" that didn't actually exist. The README
demo gif and the committed golden both froze that state — a level
the player could walk through indefinitely with no consequence.

Flesh the enemy interaction model out into something real:

- `resolve_enemy_hit(e_sx)`: one helper, called symmetrically for
  both enemies. Computes the player/enemy hitbox overlap (horizontal
  in `e_sx ∈ (72, 96)`, vertical in `player_y ∈ (152, 176)`) and
  branches three ways — falling onto the head is a stomp bounce
  (`rise_count = 6`, `fall_vy = 0`, `stomp_count += 1`, `play Boing`);
  overlap while `rise_count > 0` is a grace pass-through so the
  stomp bounce itself can't retrigger contact on the same enemy;
  anything else (walking into the side, standing on the ground
  against the enemy) is fatal — `alive = 0` and `play hit`.

- New `GameOver` state: draws four enemy tiles across the middle
  of the screen plus a coin row sized to `stomp_count`, stops the
  music, lingers 60 frames then auto-retries, and also honours
  Start for an instant retry.

- Proximity-based autopilot: pre-jump when an enemy is exactly 19 px
  ahead (`e1_sx == 99` or `e2_sx == 99`), capped at two jumps per
  life by `auto_jumps < AUTOPILOT_JUMPS`. Tuning: a JUMP_RISE=12,
  GRAVITY_CAP=4 jump lands the player's feet at enemy-head height
  exactly 21 frames after lift-off, by which point the autopilot
  camera has scrolled the enemy under the player. The first jump
  fires on Playing frame 1 and stomps enemy 1 on frame 22; the
  second fires on Playing frame 101 and stomps enemy 2 on frame
  122. After that the autopilot is exhausted and the third enemy
  encounter (camera wraps back past enemy 1) is fatal — the
  golden harness now sees the full stomp, stomp, die, retry, stomp
  loop instead of a frozen walk.

- Live HUD: up to four coin sprites in the top-left, one per
  stomp, rendered both during `Playing` and on the `GameOver`
  screen so the score is visible in the death frame. `Playing`'s
  player draw is now guarded by `if alive == 1` so the hero
  disappears on the fatal-contact frame and the enemy that killed
  them is visible underneath.

Verified with a per-frame ZP trace through the patched puppeteer
+ jsnes harness: first stomp at emu frame 44 (camera_x=22), second
at emu frame 144 (camera_x=122), death at emu frame 283 (camera_x=5
after a 256-px wrap), `Playing` restart at emu frame 343, third
stomp at emu frame 365. All 22 emulator goldens still match after
the update, and `docs/platformer.gif` regenerated from the new ROM
now shows two clean stomps, a clean side-collision death, the
GameOver screen, and the retry cycle all inside the 6-second demo
window.

Golden updates:
- `tests/emulator/goldens/platformer.png` — the frame-180 capture
  now shows the hero walking forward with a two-coin HUD after
  both autopilot stomps (previously: a frozen bouncing hero).
- `tests/emulator/goldens/platformer.audio.hash` — the track now
  includes two `Boing` stomp bounces, which shifts the hash.
- `examples/platformer.nes` — rebuilt from the rewritten source.

Also updates the platformer rows in `README.md` and
`examples/README.md` to match the new gameplay.

https://claude.ai/code/session_013Bi4H4YQ5or5HtMB4doUFi
2026-04-13 20:23:07 +00:00
Claude
48832ccb13
language: pleasant asset syntax for palettes, CHR, bg, sfx, music
Adds six NES-friendly authoring shortcuts so programs don't have to
hand-pack hex bytes for every kind of art asset. Every new syntax is
strictly additive — existing examples keep their byte-identical ROMs
and goldens.

  * palette: ~50 named NES colours (`black`, `sky_blue`, `dk_red`, …)
    usable anywhere a colour byte is expected, plus a grouped-form
    `bg0..sp3` + `universal:` shape that auto-fills every sub-
    palette's first byte (fixing the `$3F10` mirror trap).
  * sprite: `pixels:` ASCII-art alternative to 16-byte CHR, supporting
    multi-tile sprites split in row-major reading order.
  * sfx: scalar `pitch:` matching the v1 driver's latch-once behaviour,
    plus `envelope:` as a friendlier alias for `volume:`.
  * music: `tempo:` default duration + note-name notes (`C4, Eb4,
    rest 10`) alongside the existing `pitch, duration` pair form.
  * background: `legend { '.': 0, '#': 1 }` + `map:` string rows,
    plus `palette_map:` grids that auto-pack the 64-byte attribute
    table from 16×15 sub-palette digits.

A new `examples/friendly_assets.ne` exercises every shortcut at once
with a matching pixel + audio golden; the other 22 golden tests still
match byte-for-byte.

https://claude.ai/code/session_01PzaSFj3VahDzxEYTKCESkz
2026-04-13 16:09:53 +00:00
Claude
688d9afcec
platformer: end-to-end side-scroller demo + three runtime bug fixes
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
2026-04-13 13:04:26 +00:00
Claude
d98c7f3d82
palette/background: first-class declarations with reset-time load and runtime swaps
Re-adds `palette Name { colors: [...] }` and
`background Name { tiles: [...], attributes: [...] }` as first-class
declarations, plus `set_palette Name` and `load_background Name`
statements for runtime swaps. Unlike the previous iteration that
quietly no-op'd, this one is fully wired through the pipeline and
its behavior is pinned by both unit tests and an emulator golden.

Pipeline:

- Lexer: re-adds `palette`, `background`, `set_palette`,
  `load_background` keywords and tokenizes them.
- AST: `PaletteDecl` (name + 1..=32 colour bytes) and `BackgroundDecl`
  (name + 0..=960 tile bytes + 0..=64 attribute bytes) live in
  `Program`. `Statement::SetPalette` and `Statement::LoadBackground`
  name-reference these declarations.
- Parser: `palette Name { colors: [...] }` / `background Name
  { tiles: [...], attributes: [...] }` blocks and their statement
  forms parse via the existing byte-array helper.
- Analyzer: validates colour indices ($00-$3F), palette length
  (<=32), nametable length (<=960), attribute length (<=64), and
  duplicate decl names. `set_palette` / `load_background` targets
  must reference a declared name (E0502 otherwise). When a program
  declares palette or background, the analyzer bumps the user
  zero-page allocator's starting address from `$10` to `$18` to
  reserve `$11-$17` for the runtime update handshake — programs
  that don't use the feature keep the old layout so their emulator
  goldens stay byte-exact.
- Assets: `PaletteData` and `BackgroundData` resolve declarations
  into zero-padded fixed-size blobs (32 / 960 / 64 bytes) and
  expose `label()` / `tiles_label()` / `attrs_label()` for codegen
  to reference.
- IR: new `IrOp::SetPalette(String)` and
  `IrOp::LoadBackground(String)`; lowering forwards the names
  verbatim.
- Codegen: `gen_set_palette` writes the palette label pointer into
  ZP `$12/$13` and ORs bit 0 into the update flags at `$11`;
  `gen_load_background` does the same for tile/attribute pointers
  at `$14/$15/$16/$17` with bit 1. Both emit a `__ppu_update_used`
  marker so the linker splices in the NMI apply helper only when
  the feature is actually used.
- Runtime: `gen_initial_palette_load` and
  `gen_initial_background_load` write the first declared
  palette/background at reset time (before rendering is enabled,
  where PPU writes are safe). `gen_nmi(has_ppu_updates)` takes a
  new flag; when true it splices `gen_ppu_update_apply` at the top
  of the NMI body, which checks the `$11` flags byte and copies
  pending palette / nametable data to `$3F00` / `$2000` inside
  vblank. All helpers use only ZP $02/$03 as scratch at reset time
  and never clobber ZP slots live across NMI.
- Linker: new `link_banked_with_ppu` takes slice of `PaletteData` /
  `BackgroundData`; splices each blob as a labelled data block in
  PRG ROM, picks the first-declared as the reset-time load target,
  enables background rendering automatically when a background is
  declared, and threads `has_ppu_updates` into `gen_nmi`. Old
  `link_banked` remains as a thin wrapper for callers without
  palette/background data so existing tests don't shift.

Tests:

- Lexer: tokenization of the 4 new keywords (single added test case).
- Parser: 5 new tests for `palette` / `background` decls with and
  without attributes, plus `set_palette` / `load_background`
  statements.
- Analyzer: 9 new tests covering acceptance of declared
  palettes/backgrounds, E0502 for unknown names, E0201 for
  out-of-range NES colors and oversized blobs, E0501 for duplicate
  names, and the zero-page-layout guard (palette/bg decls bump ZP
  start; no decls keeps it at $10).
- Resolver: 3 new tests for zero-padding, truncation of oversized
  decls, and label derivation.
- IR: 2 new lowering tests for `set_palette` and `load_background`.
- Integration: 5 new tests — blob contents spliced verbatim into
  PRG, `STA $12` / `STA $14` emitted by set_palette /
  load_background codegen, and a regression guard that programs
  without palette/background still land user vars at $10.
- Emulator: new `examples/palette_and_background.ne` driven by a
  frame counter that toggles between `CoolBlues` / `WarmReds` and
  `TitleScreen` / `StageOne` every 90 frames. Golden PNG and audio
  hash checked in under `tests/emulator/goldens/` and verified via
  `node run_examples.mjs` — rendered image shows the blue
  `CoolBlues` palette with the nametable populated from
  `TitleScreen`.

Docs:

- `README.md` adds the feature to the headline list and the example
  table.
- `docs/language-guide.md` restores the palette/background sections
  with the full 32-byte layout table and `set_palette` /
  `load_background` statement references.
- `docs/future-work.md` replaces the "removed as dead code" entry
  with the remaining gaps (PNG-sourced palette and nametable
  assets, cross-vblank large background updates, memory-map
  reporting).
- `spec.md` restores the grammar productions and usage examples.
- `examples/README.md` lists the new demo.

All 497 unit + integration tests pass. Clippy clean. All 21
emulator goldens match after the update pass.

https://claude.ai/code/session_012fKB251HvEUQwG3tizFyqt
2026-04-13 11:11:33 +00:00
Claude
fdb1ec7c91
cleanup: fix silent miscompiles and delete dead code exposed by code review
Two correctness bugs were silently producing wrong ROMs:

  - `x << n` / `x >> n` always shifted by 1, regardless of `n`, because
    the IR lowering for `BinOp::ShiftLeft`/`ShiftRight` hardcoded the
    count. Now eval_const the RHS into a compile-time count; fall back
    to a new `IrOp::ShiftLeftVar` / `ShiftRightVar` (runtime loop) when
    the amount isn't constant. Strength reduction folds the variable
    form back to a fixed count once the optimizer knows the value.

  - `x / n` / `x % n` always returned 0, because the lowering emitted
    `LoadImm(t, 0)` for `BinOp::Div`/`Mod` with a comment saying the
    runtime call was "TODO for now". Added real `IrOp::Div` and
    `IrOp::Mod`, wired them through use-counting and DCE, gave codegen
    `__divide`-based implementations, and taught strength reduction to
    rewrite power-of-two divisors into shifts and modulo-by-2ⁿ into
    AND masks. Constant folding now handles `Mul`/`Div`/`Mod`/shifts
    too, which were previously left for the codegen to emit inefficient
    software calls.

Dead code removed (no backward-compat shims kept):

  - `src/debug/` entirely. `DebugSymbols`, `SourceMap`, and the
    Mesen/.sym emitters had no callers outside their own tests;
    `main.rs` never wrote a symbol file. Documented the intent in
    `docs/future-work.md` so it comes back intentionally if needed.
  - `ErrorCode::E0202` (invalid cast) and `E0403` (unreachable state):
    defined, formatted, and marked `#[allow(dead_code)]` but never
    emitted. W0104 now carries the unreachable-state semantics too.
  - `Level::Info`: never constructed.
  - `load_background` / `set_palette` statements and their
    `BackgroundDecl` / `PaletteDecl` parser support: parsed and
    silently dropped by IR lowering (`// TODO: implement in asset
    pipeline`). Removed keywords, AST variants, parser paths, analyzer
    arms, and tests. `docs/future-work.md` documents the runtime
    palette/nametable design for when it comes back.

Doc cleanup:

  - `docs/architecture.md` was describing files that don't exist
    (`analyzer/types.rs`, `optimizer/const_fold.rs`, `codegen/regalloc.rs`,
    `rom/header.rs`, `debug/symbols.rs`, …). Rewrote it to match the
    real flat `mod.rs` + `tests.rs` layout and the real pipeline order.
  - `docs/future-work.md` was a hybrid of open work and "recently
    completed" entries that duplicated the active stubs at the top of
    the file. Collapsed to just the gaps that are actually still open.
  - `README.md` claimed Mesen symbol export and 210 tests; updated both.
  - `docs/language-guide.md` and `spec.md` described `palette` decls,
    `set_palette` / `load_background`, `debug.overlay`, and error codes
    that were never emitted. Trimmed.
  - Stale comments on `Statement::Play`/`StartMusic`/`StopMusic`
    claimed the audio subsystem was "a no-op at codegen time".

Tests:

  - Regression tests for every fix above (`lower_shift_left_with_literal
    _count_uses_that_count`, `lower_shift_right_with_variable_count
    _uses_runtime_variant`, `lower_divide_emits_div_op_not_load_imm
    _zero`, `lower_modulo_emits_mod_op_not_load_imm_zero`,
    `strength_reduce_div_by_power_of_two`, `strength_reduce_mod_by
    _power_of_two`, `strength_reduce_shift_var_with_constant_amount`).
  - Renamed the `program_with_sprites_and_palette` integration test
    (which was exercising the now-removed `load_background`/`set_palette`)
    to `program_with_inline_sprite_chr`.

`examples/sprites_and_palettes.ne` lost its `palette`/`set_palette`
usage. Nothing in the emulator test presses A, so the headless
jsnes render shouldn't move, but the golden may need regeneration
via `UPDATE_GOLDENS=1` if it does.

https://claude.ai/code/session_012fKB251HvEUQwG3tizFyqt
2026-04-13 02:47:37 +00:00
Claude
b8c9e41276
Add README, LICENSE, examples, fix draw parser lookahead
README: project overview, quick start, feature list, example table
LICENSE: MIT
4 new examples covering all language features:
  - arrays_and_functions: arrays, while loops, inline/regular functions
  - state_machine: multi-state flow with on enter/exit handlers
  - sprites_and_palettes: inline CHR data, palette switching, scroll, cast
  - mmc1_banked: MMC1 mapper, bank declarations, software multiply

Parser fix: draw statement keyword-arg parsing now checks for ':'
lookahead before consuming an identifier, preventing it from eating
the next statement as a keyword argument (e.g., `i += 1` after a draw).

https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
2026-04-12 00:38:19 +00:00
Claude
fd5a940c89
Add example builds to CI, document sprite name behavior
- CI: new "Build Examples" job compiles all .ne files and validates
  the output ROMs have correct iNES headers
- Examples: add notes explaining that sprite names (Smiley, Ball) are
  parsed but not yet resolved — all draws use the built-in CHR tile 0.
  Custom sprite declarations come in M3.
- Codegen: explicit `let _ = &draw.sprite_name` to document the
  intentional skip, with comment about M2/M3 scope

https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
2026-04-11 22:55:43 +00:00
Claude
a20ddcbbab
Add example games and quick-start guide
Two example .ne programs with compiled .nes ROMs:
- hello_sprite: d-pad controlled sprite movement
- bouncing_ball: auto-bouncing sprite with edge detection

Includes README with build instructions and emulator setup.

https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
2026-04-11 22:17:18 +00:00