Implements two items from docs/future-work.md's language-feature gaps:
NES 2.0 header support: `RomBuilder` gains a `header_format` field
and a matching `enable_nes2()` method. When enabled, byte 7 bits 2-3
are set to `10` and bytes 8-15 are populated per the NES 2.0 spec
(submapper, PRG/CHR MSBs, PRG/CHR RAM, timing). The header stays
16 bytes. Programs opt in via `game Foo { header: nes2 }`; the
default remains iNES 1.0 so every committed example ROM is byte
identical. `validate_ines` now detects and reports which format it
parsed.
u16 struct fields: the analyzer's `register_struct` accepts `u16`
fields with a two-byte size and the struct-variable allocator tracks
per-field sizes so the synthesized `pos.x`/`pos.y` globals get the
right address span. IR lowering's `LValue::Field` and
`Expr::FieldAccess` follow the same wide path as u16 globals, and
struct-literal initialization writes both bytes for u16 fields.
Array and nested-struct fields stay rejected with a clearer
message. Existing u8/i8/bool struct programs are unaffected.
https://claude.ai/code/session_01MaNVcDmK9gsspRkdxowQAM
Extends the analyzer with the warnings listed under "Error message
polish" in docs/future-work.md:
- W0102 (existing): now also fires for `while true { ... }` and
`loop { if cond { continue } }`. `continue` is explicitly not
counted as an exit — the loop still spins forever.
- W0105 (new): palette declarations whose sub-palette first-bytes
disagree. The NES mirrors $3F10/$3F14/$3F18/$3F1C onto $3F00/
$3F04/$3F08/$3F0C, so a 32-byte sequential write silently
overwrites the background universal colour; the grouped
`universal:` form auto-fixes this so only flat `colors: [...]`
declarations can trip it.
- W0106 (new): a call at statement position whose callee has a
declared return type — the value is silently dropped.
- W0107 (new): `fast` variables with fewer than three observed
reads+writes, which don't justify holding a scarce zero-page
slot. Leading-underscore names are exempt.
All four are warnings only — no IR, codegen, or runtime changes,
so every committed example ROM rebuilds byte-identical and no
emulator goldens flip. Tests added in src/analyzer/tests.rs.
One legitimate W0106 surfaces on examples/platformer.ne (the
`resolve_enemy_hit` helper uses early-return for control flow
but its return value is discarded by the caller); fixing it
would shift the ROM and flip goldens, so it is left in place
as an informational hint rather than a hard fix.
https://claude.ai/code/session_01MaNVcDmK9gsspRkdxowQAM
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
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
A \`return\` with no value inside a function that has a declared
return type is an error — the caller expects a value. Previously
it compiled silently and the callee returned whatever was in A
from the last computation.
https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
Previously an assignment to an undeclared name was silently accepted
because the IR lowering would synthesize a fresh VarId for it. Now
the analyzer emits E0502 with the same "did you mean" suggestion
path as read-side undefined variable errors.
https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
Adds composite \`struct\` types with field access:
struct Vec2 { x: u8, y: u8 }
var pos: Vec2
pos.x = 100
pos.y = pos.x + 5
- Lexer: \`struct\` keyword
- AST: \`StructDecl\` with \`StructField\` list; \`NesType::Struct(name)\`
for struct-typed variable declarations; \`Expr::FieldAccess\` and
\`LValue::Field\` for reads/writes
- Parser: top-level \`struct Name { field: type, ... }\` (optional
trailing comma) and \`ident.field\` syntax in both expression and
lvalue position
- Analyzer: \`register_struct\` computes contiguous field offsets
(no padding) and stores them in \`struct_layouts\`. Struct variables
synthesize a \`VarAllocation\` per field under the name
\`"struct_var.field"\`, and \`Expr::FieldAccess\` / \`LValue::Field\`
resolve against those. Unknown struct types and unknown fields
emit E0201.
- IR lowering + AST codegen: treat struct field access as ordinary
variable access against the synthetic per-field symbols. No new IR
ops are needed.
v1 structs only support primitive fields (u8/i8/bool). Nested structs,
u16 fields, and array fields are not yet allowed.
https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
Adds \`enum Name { V1, V2, ... }\` as a top-level declaration. Each
variant is registered as a \`u8\` constant equal to its index in the
declaration. Variant names are global and must be unique across all
enums and other symbols (E0501 on collision).
- Lexer: \`enum\` keyword
- AST: \`EnumDecl { name, variants, span }\` field on \`Program\`
- Parser: top-level \`enum\` syntax with optional trailing commas
- Analyzer: \`register_enum\` flattens variants into the symbol table
- IR lowering and AST codegen: variants resolve through the existing
\`const_values\` path
- Tests cover parsing, duplicate detection, and usage
https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
Previously the unused-variable warning only ran on globals. Now it
walks \`state.locals\` too, so state-scoped variables that are
declared and never read also emit W0103. Factored out to
\`check_unused_var\` to share the \`_\`-prefix exemption and help text.
https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
When a block contains a statement after \`return\`, \`break\`,
\`continue\`, or \`transition\`, the trailing statement is unreachable
and the analyzer now emits W0104 pointing at it. The warning includes
a secondary label on the terminator showing where execution stops.
Adds \`Statement::span\` helper to the AST so diagnostics can point at
arbitrary statements cleanly.
https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
The linear RAM allocator now checks for overflow. The zero-page region
is capped at \$80 (leaving \$80-\$FF for IR codegen temp slots), and the
main RAM allocator stops at \$0800 (end of NES internal RAM). Overflow
emits E0301 with a helpful note pointing at the declaration.
https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
Emits W0101 on \`a * b\`, \`a / b\`, \`a % b\` expressions where both
operands are non-constant (neither is an integer literal). These lower
to calls into the software multiply/divide routines and can blow the
6502 cycle budget. Multiplying by a constant is still silent because
the optimizer can strength-reduce power-of-2 cases to shifts and small
factors to add chains.
https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
Adds parser support for \`on scanline(N) { ... }\` event handlers
inside state bodies. The analyzer enforces that scanline handlers
are only allowed with the MMC3 mapper (the only mapper we target
with scanline IRQ support), and validates the body like any other
state handler.
Codegen for the scanline IRQ vector is still TODO — the handler
is parsed and validated but not yet hooked up to the MMC3 IRQ
counter. When we get to it, the linker needs to install an IRQ
handler that writes to \$C000/\$C001/\$E000/\$E001.
https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
Emits W0102 when a \`loop\` body contains no \`break\`, \`return\`,
\`transition\`, or \`wait_frame\`, since such loops spin forever and
prevent vblank from being handled. The check recurses into nested
if/while bodies so that \`break\` behind a condition still counts.
https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
Tracks the current function's declared return type and checks that
`return value` statements match it. Returning from a void function
with a value produces E0203; returning a value with the wrong type
produces E0201. State handler `return value` is still silently
accepted (the value is discarded).
https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
Tracks parameter types per function in a signature map, and validates
that each Statement::Call and Expr::Call has the right number of
arguments (E0203). Also type-checks each argument against its declared
parameter type. Previously, calls with the wrong argument count silently
passed semantic analysis and only broke later at codegen or runtime.
https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
Sprite/asset pipeline:
- Linker::link_with_assets() places sprite CHR data in ROM at correct tile
- assets::resolve_sprites() walks Program for inline sprite bytes
- CodeGen::with_sprites() maps sprite names to tile indices
- gen_draw() uses correct tile index from sprite declarations
- main.rs wires the full resolution pipeline
Shift-assign operators (<<= and >>=):
- AssignOp::ShiftLeftAssign and ShiftRightAssign variants
- Parser handles in both statement and array index contexts
- Codegen emits ASL A / LSR A
- IR lowering maps to ShiftLeft/ShiftRight ops
Unreachable state warning (W0104):
- BFS from start state finds reachable states via transitions
- States not reached produce W0104 warning
Error polish helpers:
- suggest_var_name() for "did you mean" suggestions
- emit_undefined_var() for E0502 with typo hints
- Used by analyzer for better diagnostics
242 tests pass, clippy clean.
https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
Analyzer extensions:
- Call graph construction from function bodies and state handlers
- DFS-based recursion detection (direct and mutual) with E0402 errors
- Max call depth computation per entry point with E0401 enforcement
- Function declarations registered as symbols (E0503 for undefined calls)
- Collects calls from all statement/expression types recursively
Optimizer (new module):
- Constant folding: evaluate known-constant arithmetic at compile time
- Dead code elimination: remove ops with unused destination temps
- Both operate per-basic-block in a single pass
171 tests total (22 new: 6 analyzer + 11 IR lowering + 5 optimizer)
https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
