mirror of
https://github.com/imjasonh/nescript
synced 2026-07-08 08:55:38 +00:00
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
|
||
|---|---|---|
| .. | ||
| arrays_and_functions.ne | ||
| audio_demo.ne | ||
| bitwise_ops.ne | ||
| bouncing_ball.ne | ||
| coin_cavern.ne | ||
| comparisons.ne | ||
| function_chain.ne | ||
| hello_sprite.ne | ||
| inline_asm_demo.ne | ||
| logic_ops.ne | ||
| loop_break_continue.ne | ||
| match_demo.ne | ||
| mmc1_banked.ne | ||
| mmc3_per_state_split.ne | ||
| README.md | ||
| scanline_split.ne | ||
| sprites_and_palettes.ne | ||
| state_machine.ne | ||
| structs_enums_for.ne | ||
| two_player.ne | ||
| uxrom_banked.ne | ||
NEScript Examples
Quick Start
# Build the compiler
cargo build --release
# Compile all examples
for f in examples/*.ne; do cargo run -- build "$f"; done
# Or compile one
cargo run -- build examples/hello_sprite.ne
Open any .nes file in an NES emulator (Mesen, FCEUX, etc.)
Examples
| File | Features | Description |
|---|---|---|
hello_sprite.ne |
input, draw | Move a sprite with the d-pad |
bouncing_ball.ne |
if/else, variables | Auto-bouncing sprite with edge detection |
coin_cavern.ne |
states, functions, constants | 3-state game with gravity and coin collection |
arrays_and_functions.ne |
arrays, functions, while | Enemy array with collision detection |
state_machine.ne |
on enter/exit, transitions | Multi-state flow with timers |
sprites_and_palettes.ne |
sprites, scroll, cast | Inline CHR data, PPU scroll writes, type casting |
mmc1_banked.ne |
MMC1, banks, multiply | Banked mapper with software multiply |
Emulator Controls
| NES Button | Typical Key |
|---|---|
| D-pad | Arrow keys |
| A | Z |
| B | X |
| Start | Enter |
| Select | Right Shift |
About Sprites
Sprite names in draw Player at: (x, y) are parsed and recorded in the AST.
You can define sprites with inline CHR tile data:
sprite Player {
chr: [0x3C, 0x42, 0x81, 0x81, 0x81, 0x81, 0x42, 0x3C,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]
}
If no matching sprite declaration exists, the draw uses the built-in default
tile (a smiley face). See sprites_and_palettes.ne for a full example.
Compiler Commands
# Compile to ROM
cargo run -- build game.ne
# Custom output path
cargo run -- build game.ne --output my_game.nes
# Type-check only
cargo run -- check game.ne
# View generated 6502 assembly
cargo run -- build game.ne --asm-dump
# Debug mode
cargo run -- build game.ne --debug