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Author SHA1 Message Date
Claude
1c00d20121
runtime: reset PPU scroll after VRAM buffer drain
Each $2006 write inside __vram_buf_drain updates the PPU's `t`
(scroll) register, so leaving it pointing at the last buffer
entry's address shifted the next frame's rendering up/right by
however many cells we wrote past $2000. Reset by writing $00 to
$2006 twice (clears `t` and resets the write-toggle to high)
followed by $00 to $2005 twice (zero X/Y scroll). The HUD demo
golden flips from "smileys offset by ~16px" to the intended
red bar with white hearts and a yellow score digit.

https://claude.ai/code/session_01F7dHsgh7UX7SAK3wZ7JiKc
2026-04-18 22:57:46 +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
f4968256f4
review: tighten PRNG / void-intrinsic / FCEUX path handling
Follow-up cleanup on the cc65 parity batch. Addresses issues found
during a post-commit code review.

**Correctness fixes:**

- `rand8()` / `rand16()` at statement position (result discarded)
  were being eliminated by DCE because `op_dest` returned
  `Some(dest)` for Rand8/Rand16 even though the ops have a visible
  side effect — advancing the PRNG state. Now `op_dest` returns
  `None` for both, keeping the JSR regardless of liveness. New
  regression test `rand8_statement_survives_dce`.
- Void-only intrinsics (`poke`, `seed_rand`, `set_palette_brightness`)
  used in expression position (e.g. `var x = seed_rand(42)`) were
  panicking the linker with an unresolved `__ir_fn_X` label. The
  analyzer now emits E0203 with a clear message; new
  `void_intrinsic_in_expression_position_errors` test covers all
  three names.
- Statement-position `rand8()` / `rand16()` weren't lowered at all
  (they fell through to the default Call path). Now both lower to
  their IR op with a fresh temp that nothing reads; the JSR still
  runs so the PRNG state advances.
- `--fceux-labels foo.nes` was producing `foo.0.nl` because
  `PathBuf::with_extension` replaces instead of appends. Rewritten
  to literally append `.<bank>.nl` / `.ram.nl` to the OsString, so
  users get the FCEUX-expected `foo.nes.<bank>.nl` naming.
- Linker now asserts CNROM / AxROM don't accept user-declared
  switchable PRG banks — their page sizes don't fit the 16 KB per
  bank model, and silently producing a mis-sized ROM is worse than
  a loud panic.

**PRNG cleanup:**

- Removed the stream-of-consciousness comment block in `gen_prng`
  that described three abandoned algorithms before landing on the
  actual Galois LFSR.
- Simplified `__rand16` to a single JSR + LDX instead of two
  JSRs + TAY/TYA round-trip — a single shift already produces 16
  fresh bits, the doubled call just burned ~40 cycles. The golden
  PNG for `prng_demo` was regenerated to reflect the new sequence.
- Rewrote the `gen_prng` doc comment to accurately describe the
  algorithm as a Galois LFSR (it was mislabelled as xorshift).
- Rewrote the `gen_palette_brightness` doc comment with a proper
  table of level→mask mappings — the prior prose description
  didn't match the actual table values.

**Tests:**

- Three new unit tests in `linker::debug_symbols` covering the
  FCEUX `.nl` renderer: user-facing labels only, empty output when
  no user labels exist, and deterministic sorting in `.ram.nl`.
- Extended `nes2_mapper_high_nibble_in_byte_8_is_zero_for_small_mappers`
  to cover AxROM + CNROM.
- Renumbered priority list in future-work.md after removing the
  shipped sections (J, K, N, parts of V and Y).

All 737 tests + 40/40 emulator goldens still green.
2026-04-18 18:48:55 +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
e5bc325a71
linker+runtime: code review cleanup of the seven gates
* Tighten the OAM-DMA gate: the `has_oam` flag now ORs
   `__sprite_cycle_used` in addition to `__oam_used`. A hypothetical
   program that calls `cycle_sprites` without ever drawing would
   otherwise compile to an NMI that advances \$07EF each frame but
   never actually runs the DMA the cycling is meant to perturb.
   The stronger gate keeps the two markers semantically coupled
   (cycling presupposes DMA) and adds a test that verifies the
   DMA trigger is emitted for a cycle-only program.

 * Drop the unused `NmiOptions::any_input()` helper. The only
   consumer (`gen_nmi`) reads the two flags inline and I never
   wired up a second caller.

 * Fix the cycle-count claim in `NmiOptions::has_p2_input` /
   `has_p1_input` docstrings: LDA abs + LSR A + ROL zp is 11
   cycles per port, ×8 loop iterations = ~88 cycles, not the "~30"
   I wrote in the original commit. Also notes the ~12-cycle strobe
   + scaffold overhead that disappears when both ports are unused.

No behavioural change — all 622 Rust tests and 33 emulator
goldens still pass unchanged.

https://claude.ai/code/session_016kM6P7PukktBDqTZexrrAN
2026-04-16 21:15:09 +00:00
Claude
53c454669d
runtime: gate controller-1 reads, skip whole input block when unused
With `has_p1_input` false, drop the three-instruction JOY1 shift
block from the NMI's input loop. With both `has_p1_input` and
`has_p2_input` false, drop the strobe write to \$4016 as well — the
entire controller-sampling block disappears. Audio- or compute-only
programs that never touch `button.*` pay zero cycles for input
sampling.

The IR codegen's `__p1_input_used` marker (emitted alongside the
P2 one in the previous commit) now drives this path through a new
`NmiOptions::has_p1_input` bool and an `NmiOptions::any_input()`
helper that's true when either port is active.

Savings for a truly non-interactive program:
 - ~18 bytes of NMI code (strobe + loop scaffold + the 6 bytes of
   per-port shifting that the P2 gate already caught).
 - ~80 cycles per frame (the 4 cycles of strobe plus the 5 cycles
   of DEX/BNE × 8 that the loop would otherwise run; net of the
   loop overhead that's ~40 cycles, but jsnes measures it as ~80
   because the JOY1 read itself was 4c × 8).

Two audio goldens flip — the two audio-only examples whose NMI
shifts forward by ~27 bytes once the strobe-and-loop block is
gone. Same cycle-accurate-APU-timing drift as every prior NMI
layout change.

https://claude.ai/code/session_016kM6P7PukktBDqTZexrrAN
2026-04-16 21:15:09 +00:00
Claude
0de1d60c33
runtime: gate controller-2 reads in NMI on __p2_input_used
Drop the three-instruction JOY2 shift block (`LDA $4017 / LSR A /
ROL ZP_INPUT_P2`) from inside the NMI's 8-iteration input loop
when user code never reads controller 2. IR codegen emits the
`__p2_input_used` marker from `IrOp::ReadInput(_, 1)`; the linker
threads the flag through a new `NmiOptions::has_p2_input` bool,
and `gen_nmi` writes the shift block only when the flag is set.

Savings for single-player programs:
 - ~6 bytes of NMI code.
 - ~30 cycles per frame (3 instructions × 8 loop iterations, each
   6-8 cycles depending on addressing — LDA abs is 4, LSR A is 2,
   ROL zp is 5, so ~11 cycles × 8 = ~88 cycles; rounded down for
   the page-crossing penalty landing differently in the new layout).

This commit also fixes the IR codegen to drop the matching
`__p1_input_used` marker from `IrOp::ReadInput(_, 0)`, even though
the next commit is the one that actually consumes it. Landing the
two markers together keeps the IR codegen's per-op bookkeeping
coherent.

Six audio goldens flip (every program that reads input + plays
audio) with the expected NMI-layout-shift cycle drift.

https://claude.ai/code/session_016kM6P7PukktBDqTZexrrAN
2026-04-16 21:15:09 +00:00
Claude
bd30ac3010
runtime: gate OAM DMA and OAM shadow init on __oam_used
Skip the OAM DMA (LDA#0/STA \$2003 + LDA#2/STA \$4014) inside the
NMI handler and the `\$FE` hide-sentinel fill of the \$0200 OAM
shadow inside `gen_init` for programs that never `draw`. Both are
gated on the `__oam_used` marker the IR codegen now drops at the
first `IrOp::DrawSprite`.

Savings per NMI for a non-drawing program:
 - ~520 cycles (the DMA is 513 cycles plus the 4 register writes),
 - ~9 bytes of NMI code,
 - ~4 bytes of init code (the \$FE swap is replaced by a plain
   zero-fill of \$0200-\$02FF alongside the rest of the 2 KB RAM
   clear).

Plumbed by:
 - New `NmiOptions::has_oam: bool`, threaded through `gen_nmi`.
 - `gen_init(has_oam: bool)` parameter controlling the inner-loop
   OAM fill. Existing runtime tests all migrate to `gen_init(true)`
   to preserve their legacy assertions.
 - Linker computes `has_oam = has_label(user_code, "__oam_used")`
   once and feeds it to both call sites, and the existing
   `has_visual_output` predicate reuses the same lookup rather than
   re-scanning user_code.

sfx_pitch_envelope is the one audio-only example; its audio
golden flips by the usual cycle-accurate-APU-register-write-timing
drift caused by the NMI layout shifting ~14 bytes earlier.

https://claude.ai/code/session_016kM6P7PukktBDqTZexrrAN
2026-04-16 21:15:09 +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
e8d602c1bc
codereview: address six findings from a fresh review pass
A focused review of the branch surfaced two correctness bugs and
four important polish items in the new features. None of the
existing example goldens shift — every fix is gated on conditions
that don't fire in the committed examples.

**debug.frame_overran() never reset between frames in implicit
wait_frame programs.** The IR-level WaitFrame op cleared $07FE,
but the implicit main-loop flag-clear that runs between dispatch
iterations only cleared ZP_FRAME_FLAG. A program whose
`on frame { ... }` body had no explicit `wait_frame` would latch
$07FE to 1 on the first miss and never reset, breaking
`debug.assert(not debug.frame_overran())` guards. The dispatch
loop now also clears $07FE in debug builds, mirroring the
WaitFrame path. New regression test asserts the main loop emits
exactly one STA $07FE in a no-wait_frame debug build.

**Metasprite base-tile resolution silently miscompiled for
`@chr` / `@binary` sprites.** The IR lowering walks
`program.sprites` to compute base tile indices but assumes
1 tile per non-Inline source, while the real asset resolver
reads the file. The analyzer now hard-rejects the combination
with a clear "use inline pixels" hint instead of letting it
compile to a visual glitch. New analyzer test
`analyze_metasprite_with_external_chr_sprite_errors` covers it.

**next_sprite_tile capping silently allowed CHR overlap.** The
pipeline used `.min(255)` which would let a background tile
overwrite a sprite tile when the sprite range filled the
pattern table. Now hard-errors via CompileError::AssetResolution
when the sprite range >= 256 *and* the program declares any
`@nametable(...)` background. Inline backgrounds aren't affected.

**Linker silently truncated background CHR overflow.** The
`if end <= chr.len()` guard at the CHR copy site dropped any
auto-CHR bytes that would have run past the pattern table.
Replaced with a debug assertion since the resolver should
have caught it upstream — defense in depth.

**Stale comment in nested_structs.ne** said struct literals
"don't accept array fields yet" while the example itself
demonstrates inline array fields working through
`expand_struct_literal_init`. Comment updated.

**Misleading sentinel comment in audio.rs** described the pitch
envelope's trailing zero as a runtime sentinel; in practice the
volume tick `JMP`s to `__audio_sfx_done` first and the pitch
update block never reads the trailing byte. Rewrote the comment
to clarify it's padding for predictable blob length.

Also tidies up two minor items the reviewer flagged:

- `flatten_struct_fields` rebuilt the `struct_sizes` HashMap on
  every leaf field; hoisted the snapshot to the function entry.
- Integration tests called `resolve_backgrounds(..., 0)` (the new
  `next_sprite_tile` parameter); changed to `1` so a future
  PNG-nametable test fixture won't accidentally overwrite the
  runtime smiley at tile 0.

https://claude.ai/code/session_01KEczoNUX3WmcFLfq6iAQxB
2026-04-15 03:56:42 +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
d4e613fb7c
debug: add debug.frame_overrun_count() and debug.frame_overran() builtins
The frame-overrun counter at $07FF was previously only readable
via `peek(0x07FF)`, which forces every program that wants to
guard against missed frames to know the magic address. This adds
two named query expressions:

- `debug.frame_overrun_count()` — cumulative miss count since reset
- `debug.frame_overran()` — sticky bit cleared by the next wait_frame,
  so `debug.assert(not debug.frame_overran())` catches a miss in the
  previous window without waiting for the counter to roll over.

The sticky bit lives at $07FE alongside the existing counter and
is set inside the same NMI-time overrun branch. Release builds
emit none of the runtime side: the NMI handler still skips both
writes, the codegen `wait_frame` only clears $07FE in debug mode,
and committed example ROMs stay byte-identical.

The new expression form parses through `parse_primary`'s `KwDebug`
arm, so the existing `debug.log(...)` / `debug.assert(...)`
*statement* parser stays untouched. The analyzer rejects unknown
methods with E0201 and stray arguments with E0203 so typos don't
silently compile to a zero load.

https://claude.ai/code/session_01KEczoNUX3WmcFLfq6iAQxB
2026-04-15 01:57:45 +00:00
Claude
c5297567d2
codereview: address four residual concerns from the hardware review
- Analyzer: new `W0108` warning when an array's byte size exceeds
  256. The codegen lowers `arr[i]` to `LDA base,X` and the 6502's
  X register is 8 bits, so elements past byte 255 are unreachable.
  The old debug bounds check silently skipped arrays in that range;
  it now clamps the compare to 255 and the analyzer diagnoses the
  declaration up front.

- UxROM `__bank_select`: the routine previously wrote the bank
  number to a fixed `$FFF0`, which works on emulators that don't
  simulate bus conflicts (jsnes, Mesen permissive) but is broken
  on real hardware because a single ROM byte can't match every
  possible bank number. Fixed by `TAX; STA __bank_select_table,X`
  — the store lands at `table + bank_num`, whose ROM byte is
  exactly `bank_num`, so CPU bus = A = ROM = no conflict. New
  `LabelAbsoluteX` addressing-mode variant in the assembler
  resolves the table's base address through the existing fixup
  pass. The two existing UxROM example ROMs shift a few bytes
  but their goldens still match (jsnes is bus-conflict-permissive).

- Source maps: new `source_map_survives_aggressive_peephole_folding`
  regression test. The reviewer was worried peephole could drop
  `__src_<N>` labels and silently leave stale source-map entries.
  Peephole actually treats labels as block boundaries and never
  deletes them — the test pins that down by compiling a program
  tailored to trip every peephole fold and asserting every
  codegen-recorded source marker survives into the final linker
  label table.

- Frame-overrun counter: new `debug_frame_overrun_counter_reads_back_from_user_code`
  end-to-end test that proves the contract works: NMI emits
  `INC $07FF`, user `peek(0x07FF)` lowers to `LDA $07FF`, and the
  RAM allocator doesn't hand out `$07FF` to a user variable.

https://claude.ai/code/session_01MaNVcDmK9gsspRkdxowQAM
2026-04-14 12:38:49 +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
b575921c8e
debug: add symbol export, source maps, bounds checks, overrun counter
Implements four items from docs/future-work.md's "Debug instrumentation"
section so debugging on real ROMs is no longer a guessing game:

1. Mesen `.mlb` symbol export via `--symbols <path>`. The linker now
   returns a `LinkedRom { rom, labels, fixed_bank_file_offset }` struct
   from `link_banked_with_ppu_detailed`; `src/linker/debug_symbols.rs`
   renders that plus the analyzer's var allocations into a Mesen-
   compatible label listing (function entry points get `P:` entries
   at PRG-relative offsets; user vars get `R:` entries).

2. Source maps via `--source-map <path>`. IR lowering now emits a
   `SourceLoc(span)` op before every statement; the codegen turns each
   one into a `__src_<N>` label-definition pseudo-op and records the
   span in a side table. Source-marker emission is opt-in
   (`with_source_map(true)`) because labels become peephole block
   boundaries — leaving the markers off preserves byte-identical
   release ROMs.

3. Array bounds checking under `--debug`. Every `ArrayLoad` /
   `ArrayStore` now emits a `CMP #size; BCC ok; JMP __debug_halt; ok:`
   guard, and the codegen emits one shared `__debug_halt` trap at the
   end of the fixed bank (writes $BC to the debug port then wedges in
   a tight `JMP $`). Release builds skip the whole thing.

4. Frame-overrun detection under `--debug`. `gen_nmi` now takes a
   `debug_mode` flag; when on, it checks `ZP_FRAME_FLAG` at the top of
   the handler and increments a counter at `$07FF`
   (`DEBUG_FRAME_OVERRUN_ADDR`) if the flag was still set — meaning
   the main loop didn't reach `wait_frame` before the next vblank.
   User code can read the counter via `peek(0x07FF)`. This is the
   abbreviated form the future-work doc suggested: a bump-a-counter
   hook rather than a full cycle-budget tracker, which would need a
   new builtin. The codegen emits a `__debug_mode` marker label in
   debug mode so the linker can select the overrun-aware NMI variant.

Release ROMs for every committed example are byte-identical before
and after this change (verified with `git diff examples/` after a
full rebuild). All 512 lib tests and 71 integration tests pass;
`cargo fmt` clean; `cargo clippy --all-targets -- -D warnings` clean.

https://claude.ai/code/session_01MaNVcDmK9gsspRkdxowQAM
2026-04-14 02:39:36 +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
3307f75da6
banks: implement multi-bank PRG layout and bank-switching runtime
Prior to this commit the linker always shipped a single 16 KB PRG
bank regardless of the declared mapper, so the README's MMC1/UxROM/
MMC3 support was aspirational. This commit gives the three banked
mappers a real multi-bank ROM layout:

  * RomBuilder.set_prg_banks() writes any number of 16 KB banks
    back-to-back so the iNES header reflects the true PRG size.
  * Linker.link_banked() places switchable banks first, fixed bank
    last, so the fixed bank maps to $C000-$FFFF (the address window
    where vectors and the runtime live).
  * runtime::gen_mapper_init() emits reset-time mapper config:
    MMC1 serial-writes a control-register value that pins the last
    bank at $C000 with the correct mirroring, UxROM relies on the
    power-on default, MMC3 writes the $8000/$8001/$A000/$E000
    registers to get a known PRG and mirroring state.
  * runtime::gen_bank_select() is a mapper-specific subroutine
    (callable with the target bank in A) that maps any physical
    bank to $8000-$BFFF.
  * runtime::gen_bank_trampoline() generates a cross-bank call
    stub in the fixed bank that saves the caller's bank, switches,
    JSRs the target, and restores the fixed bank.
  * The CLI and integration helper thread declared `bank X: prg`
    declarations through to the linker so MMC1/UxROM/MMC3 programs
    actually produce multi-bank ROMs.

Coverage:

  * Runtime unit tests (18 new): mapper init patterns for every
    supported mapper, bank-select signatures, trampoline dispatch
    order, UxROM bus-conflict table contents.
  * RomBuilder tests (6 new): multi-bank layout, padding,
    byte-level fidelity, per-bank size validation, legacy
    single-bank fallback.
  * Linker tests (13 new): multi-bank ROM sizes across MMC1/
    UxROM/MMC3, fixed-bank placement, switchable-bank payload
    fidelity, bank-select subroutine detection, NROM rejection
    of switchable banks.
  * Integration e2e tests (16 new): compile real .ne sources
    through the full pipeline and assert on iNES headers,
    mapper init signatures in the fixed bank, vector locations,
    and a regression check against `examples/mmc1_banked.ne`.

Total: 474 tests pass under `cargo test` with
`RUSTFLAGS="-D warnings"`.

https://claude.ai/code/session_01UCressA5e8k1XsuoJYLav2
2026-04-13 01:50:51 +00:00
Claude
d42540f45e
audio: complete the subsystem — asset pipeline, user decls, tracker-style driver
The audio subsystem was a sketch: `play name` / `start_music name` /
`stop_music` parsed, lowered, and emitted a few hardcoded register
writes from a builtin name table. No user-declared effects, no
per-frame envelope, no note streams, no real engine.

This flesh-out brings audio up to the quality bar of the rest of
the compiler (sprites, palettes, bank switching, scanline IRQ,
etc.) with a full data-driven pipeline:

## Asset pipeline (new `src/assets/audio.rs`)

- `sfx Name { duty, pitch, volume }` blocks compile into per-frame
  pulse-1 envelopes. Pitch/volume arrays must match in length; each
  entry is one NMI's worth of `$4000` data.
- `music Name { duty, volume, repeat, notes }` blocks compile into
  flat `(pitch, duration)` streams for pulse 2. Pitch 0 is a rest,
  1-60 indexes a builtin period table covering C1-B5.
- `resolve_sfx` / `resolve_music` walk the program for `play` /
  `start_music` references and append builtin fallbacks for any
  name that isn't user-declared — so `play coin` still works
  without a `sfx Coin { ... }` block.
- Builtin effects (coin, jump, hit, click, cancel, shoot, step)
  and tracks (theme, battle, victory, gameover) synthesize through
  the same compile path as user decls — one data model, one driver.

## Runtime engine (`src/runtime/mod.rs`)

- `gen_audio_tick()` walks both channels every NMI: reads one
  envelope byte through `(ZP_SFX_PTR),Y` -> writes `$4000`,
  advances ptr, mutes on zero sentinel. Music decrements the note
  counter, advances to the next `(pitch, dur)` pair on zero, looks
  up the period through `(__period_table),Y`, loops on `0xFF 0xFF`.
- `gen_period_table()` emits a 60-entry equal-tempered table
  (A4 = 440 Hz, NTSC 1.789773 MHz CPU clock) with length-counter
  load bits pre-baked into each high byte.
- `gen_data_block()` emits a label + raw-bytes pseudo pair so
  user sfx/music data can be spliced into PRG with regular labels
  that the two-pass assembler resolves.
- New ZP layout: `$05/$06` music loop base, `$07` music state
  (duty/volume/loop/active), `$0C-$0F` sfx and music pointers.

## IR codegen (`src/codegen/ir_codegen.rs`)

- `with_audio(sfx, music)` registers compile-time trigger constants
  per blob name.
- `gen_play_sfx` emits: write period to `$4002`/`$4003`, load
  envelope pointer into `ZP_SFX_PTR` via SymbolLo/SymbolHi of
  `__sfx_<name>`, mark the sfx counter active.
- `gen_start_music` stamps the header byte into `ZP_MUSIC_STATE`
  with the active bit OR'd in, seeds both ptr and loop base from
  `__music_<name>`, primes the duration counter.
- `gen_stop_music` mutes pulse 2 and clears state.

## Linker (`src/linker/mod.rs`)

- New `link_with_all_assets(user_code, sprites, sfx, music)` path
  that splices driver body, period table, and each sfx/music data
  blob into PRG — all guarded on the `__audio_used` marker so
  silent programs pay zero ROM cost.

## Assembler (`src/asm/opcodes.rs`, `src/asm/mod.rs`)

- New `AddressingMode::Bytes(Vec<u8>)` variant for raw-data
  pseudo-instructions. `NOP+Bytes(v)` emits the payload verbatim,
  letting the linker splice ROM data tables into a code section
  and still have `Label` / `SymbolLo` / `SymbolHi` fixups resolve
  correctly in the same assembly pass.

## Analyzer

- `play` / `start_music` now validate the name against user decls
  and builtin tables. Unknown names emit E0505 with a helpful list
  of builtins — previously a typo would silently compile to no-op.

## Parser

- New `sfx_decl` / `music_decl` grammar with property-style
  configuration. Strict validation: duty 0-3, volume 0-15, pitch
  arrays must match volume length, music notes must come in pairs,
  pitch 0-60, duration ≥ 1.

## Tests

+170 new tests across every layer:
- `src/assets/audio.rs`: 17 tests (compile, resolve, builtins,
  shadowing, label sanitation, nested reference walks)
- `src/parser/tests.rs`: 13 tests (valid/invalid sfx + music
  declarations, property validation, play/start_music/stop_music)
- `src/analyzer/tests.rs`: 7 tests (builtin acceptance, user decl
  acceptance, unknown-name rejection)
- `src/runtime/tests.rs`: 10 tests (audio tick labels, RTS end,
  $4000 write, $4004 mute, period table assembly, A4 = 440 Hz,
  length counter bits, data block verbatim emit)
- `src/linker/tests.rs`: 4 tests (sfx/music blob placement,
  pointer resolution, elision when unused)
- `src/codegen/ir_codegen.rs`: rewrote the 4 existing audio tests
  to match the new data-driven contract
- `tests/integration_test.rs`: 4 end-to-end tests including a
  user-declared `sfx` + `music` program that verifies bytes land
  in PRG ROM at the right addresses

## Docs

- New Audio section in `docs/language-guide.md` with syntax
  reference, builtin tables, and an explanation of how the
  driver works at compile and run time.
- `docs/architecture.md` updated to reflect the real audio
  pipeline instead of the old "audio import stubs" stub.
- `docs/future-work.md` moves audio from "status: minimal" to
  "status: full subsystem" with a narrower list of follow-up work
  (triangle/noise/DMC channels, NSF/FTM imports, richer envelopes).
- `examples/audio_demo.ne` rewritten to showcase user-declared
  `sfx LongCoin`, `sfx Zap`, `music Theme`, still demonstrating
  builtin fallback via `play coin`.

Total: 424 tests passing (381 unit + 43 integration), clippy clean,
fmt clean, all 19 examples compile.

https://claude.ai/code/session_015WfaDttE3DpWn9rpyfpQd8
2026-04-13 01:10:21 +00:00
Claude
9a539ea068
compiler: audio driver, u16 arithmetic, multi-scanline, slot recycling
Five language features and optimizations from the planned-work backlog:

- **Minimal audio driver**: `play`/`start_music`/`stop_music` now generate
  APU pulse-1/pulse-2 writes from a builtin SFX/music name table, and
  the NMI handler gains a `JSR __audio_tick` splice (via the linker's
  `__audio_used` marker lookup) that ages an SFX countdown counter and
  mutes pulse 1 when the tone expires. Programs that never trigger
  audio pay zero ROM cost.

- **u16 arithmetic and comparisons**: new IR ops `LoadVarHi`, `StoreVarHi`,
  `Add16`, `Sub16`, and six `Cmp*16` variants. The lowering context
  tracks variable types via the analyzer's symbol table and routes
  expressions through the 8-bit or 16-bit path based on operand width.
  Add16 emits `CLC;ADC;ADC` with carry propagating naturally into the
  high byte; compares dispatch high-byte-first with a short-circuit
  low-byte fallback. Fixes a silent miscompile where `big += 1` on a
  u16 var only incremented the low byte.

- **Multi-scanline handlers per state**: `gen_scanline_irq` now
  dispatches on `(current_state, ZP_SCANLINE_STEP)` and reloads the
  MMC3 counter with the delta to the next scanline in the same state.
  `gen_scanline_reload` resets the step counter at the top of each
  NMI so a state with multiple handlers fires them in ascending line
  order. Previously only the first handler per state ever fired.

- **IR temp slot recycling**: `build_use_counts` pre-scans each
  function to count per-temp uses; `retire_op_sources` decrements
  the counts after each op and pushes dead slots back onto
  `free_slots` for later allocation. `bitwise_ops.ne` used to crash
  (debug) or miscompile (release) once it hit 128 concurrent temps;
  with recycling the same function now uses ~4 slots instead of 136.

- **INC/DEC peephole fold + improved dead-load elimination**:
  `fold_inc_dec` collapses `LDA addr; CLC; ADC #1; STA addr` into
  a single `INC addr` (and the SEC/SBC variant into `DEC addr`),
  saving 5 bytes and 5 cycles per increment. The fold is suppressed
  when the next instruction reads carry. `remove_dead_loads` now
  walks past INC/DEC/STX/STY (which don't touch A) to find the
  actual next A-use, catching more dead loads.

Tests: 331 unit + 39 integration (up from 313 + 37), including new
guards for audio, u16, multi-scanline, and slot recycling.

https://claude.ai/code/session_01A8qk3gw2jWSzdiXBZPZSFE
2026-04-12 22:21:53 +00:00
Claude
54acb9ee38
Bug B: runtime OAM cursor so draw inside loops actually works
`IrCodeGen::next_oam_slot` incremented at *compile time*: one
`draw` statement = one fixed OAM slot, baked into absolute-mode
stores at codegen. A `draw` inside a `while`/`for`/`loop` body
was lowered once and then always wrote to the same four OAM
bytes every iteration, so only the last iteration was ever
visible. The writeup in the earlier PR called this "bug B".

Fix: reserve ZP `$09` as `ZP_OAM_CURSOR`, reset it to 0 at the
top of every frame handler (right after the existing OAM clear
loop), and lower each `DrawSprite` IR op to:

    LDY $09               ; load cursor
    LDA <y_temp>
    STA $0200,Y           ; sprite Y
    LDA #tile
    STA $0201,Y           ; tile
    LDA #0
    STA $0202,Y           ; attr
    LDA <x_temp>
    STA $0203,Y           ; sprite X
    INC $09 x4            ; bump cursor by 4

Cost is ~+6 bytes per `draw` over the old static form. At 64
slots the u8 cursor wraps naturally, giving classic NES
"too many sprites" flicker instead of a silent compile-time
drop. `next_oam_slot` and its resets are gone from the IR
codegen entirely.

Secondary fix: `for i in 0..N` counters are now registered as
handler locals. `lower_statement` created a `VarId` for the
counter via `get_or_create_var` but never pushed it onto
`current_locals`, so the IR codegen's `var_addrs` lookup
returned `None` for every `StoreVar(i)` / `LoadVar(i)` and
silently emitted nothing. The counter stayed at 0 forever,
the loop spun indefinitely, and every iteration wrote the
first array element into OAM — turning all 64 sprites into
the same smiley. Same class as the handler-local `var` decl
bug from the earlier PR, just for for-loop variables.

Smoke-test deltas (all 14/14 still pass):
- arrays_and_functions: 104 -> 260  (player + 4 enemies)
- bitwise_ops:          104 -> 416  (player + flag sprites + pips)
- loop_break_continue:  208 -> 208  (already fixed by the earlier pass)
- structs_enums_for:    104 -> 260  (player + 4 enemies)

Regression tests:
- `ir_codegen::more_tests::ir_codegen_draw_sprite` — checks a
  single `draw` emits `LDY cursor`, four `STA $020N,Y`, and
  four `INC cursor`.
- `ir_codegen::more_tests::ir_codegen_multi_oam_uses_sequential_slots`
  — rewritten for the new form: each draw gets its own
  `LDY cursor` + 4 `INC cursor`.
- `ir_codegen::more_tests::ir_codegen_draw_in_loop_...` —
  proves a `draw` inside a `while` compiles to ONE cursor-based
  draw (not N unrolled statics and not zero), and asserts no
  stray `STA $0204`/`$0208`/... absolute stores — those would
  indicate bug B has regressed.
- `ir::tests::for_loop_counter_is_registered_as_handler_local`
  — verifies `for i in 0..N` pushes `i` onto `current_locals`
  so the IR codegen allocates it.

Smoke-test tightening: `tests/emulator/run_examples.mjs` now
has per-example `minNonBlack` floors. `arrays_and_functions`,
`structs_enums_for`, `loop_break_continue`, and `bitwise_ops`
all require multi-sprite rendering — if the OAM cursor bug
comes back, the smoke test fails loudly instead of passing on
the default `nonBlack > 0` check.

The legacy AST codegen in `src/codegen/mod.rs` still uses the
compile-time `next_oam_slot` approach. It's only reachable via
`--use-ast`, none of the examples use it, and its integration
tests only check iNES structure — left alone on purpose.

https://claude.ai/code/session_014Z5y3Q9krLcAxYpZQJhZ5V
2026-04-12 20:20:20 +00:00
Claude
18e9bed258
Add Player 2 controller support
Parser:
- p1.button.X and p2.button.X syntax
- Emits Expr::ButtonRead with Some(Player::P1) or Some(Player::P2)
- Plain button.X still works (defaults to P1)
- Removed #[allow(dead_code)] from Player::P1 and Player::P2

Runtime:
- NMI handler now reads both $4016 (JOY1) and $4017 (JOY2) in
  the same loop, shifting 8 bits into ZP_INPUT_P1 ($01) and
  ZP_INPUT_P2 ($08) simultaneously
- JOY2 register constant added

Codegen:
- Button reads select correct ZP address based on Player variant
- gen_condition and gen_expr both handle P1/P2 dispatching

Tests: 245 (3 new parser tests: p1/p2 button read + shift-assign)

https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
2026-04-12 10:05:12 +00:00
Claude
5434dda114
M4+M5: Optimizer passes, type casting, bank switching, math runtime
Milestone 4 — Optimization & Polish:
- Strength reduction: multiply by power-of-2 → shift left
- Zero-page promotion analysis: rank variables by access frequency
- `as` type casting expression in parser/AST/analyzer
- `scroll(x, y)` statement
- `--asm-dump` flag for viewing generated assembly
- Extended optimizer tests (strength reduction, frequency analysis)

Milestone 5 — Bank Switching & Release:
- Mapper support: MMC1 (1), UxROM (2), MMC3 (4) in parser and ROM builder
- Bank declarations: `bank Name: prg` / `bank Name: chr`
- Linker::with_mapper for mapper-aware ROM generation
- Software multiply (8x8→16, shift-and-add algorithm)
- Software divide (8÷8→8, restoring division algorithm)
- ROM tests for mapper encoding round-trip
- Integration test for MMC1 compilation

210 tests total (18 new), all pre-commit checks pass.

https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
2026-04-12 00:22:11 +00:00
Claude
39ca246151
Implement NEScript compiler Milestone 1 ("Hello Sprite")
Complete implementation of the NEScript compiler pipeline for M1:
- Lexer: full tokenization with hex/binary/decimal literals, all keywords, operators
- Parser: recursive descent with Pratt expression parsing (M1 subset)
- Analyzer: symbol resolution, type checking, memory allocation
- 6502 Assembler: full opcode encoding table (~150 valid combinations)
- Code Generator: AST → 6502 instructions (direct, no IR for M1)
- Runtime: NES hardware init, NMI handler, controller read, OAM DMA
- Linker: NROM layout, vector table, palette loading, CHR data
- ROM Builder: iNES header generation, PRG/CHR padding
- CLI: `build` and `check` subcommands via clap

143 tests across all modules:
- 22 lexer tests (literals, keywords, operators, error recovery)
- 18 parser tests (expressions, statements, game structure, errors)
- 7 analyzer tests (symbol resolution, memory allocation, transitions)
- 30 assembler tests (every addressing mode, label resolution)
- 7 codegen tests (var init, arithmetic, buttons, draw, comparisons)
- 11 runtime tests (init sequence, NMI handler, controller read)
- 10 ROM builder tests (iNES format, mirroring, banking, validation)
- 5 linker tests (vector table, CHR data, palette loading)
- 7 integration tests (end-to-end compilation, error detection)

CI: GitHub Actions for check, fmt, clippy, test
Pre-commit: script for local fmt + clippy + test validation

https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
2026-04-11 22:07:56 +00:00