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https://github.com/imjasonh/nescript
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An end-to-end FIPS 180-4 SHA-256 hasher running entirely on the NES.
The player types up to 16 ASCII characters on a 5x8 on-screen
keyboard, presses Enter, and the program computes and displays the
64-character hex digest.
Layout (`examples/sha256/*.ne`):
constants.ne layout + K[64] / H_INIT[8] tables
(declared as `var` with init_array because the
v0.1 compiler treats `const u8[N] = [...]` as
a no-op — noted in the file)
assets.ne 44-tile Tileset (A..Z, 0..9, punctuation,
special keys, cursor) shared between BG and
sprite layers
background.ne static nametable (title, labels, keyboard
grid) painted at reset
state.ne globals
sha_core.ne 32-bit byte primitives (copy, xor, and, add,
not, rotr, shr) in inline asm + sigma/Sigma
mixers + schedule/round steps + fold
render.ne OAM helpers for cursor, input buffer, and
64-nibble digest
keyboard.ne key dispatch table
entering_state.ne cursor navigation + typing + auto-demo
computing_state.ne phased driver (48 schedule steps + 64 rounds
+ fold across ~30 frames at 4 iterations each)
showing_state.ne renders the 256-bit digest as 8 rows of 8
sprite glyphs
Implementation notes:
- All 32-bit words live as 4 little-endian bytes in `wk[64]`,
`w[256]`, `h_state[32]` so every primitive walks four bytes with
`LDA {arr},X`/`STA {arr},X` chains and, for adds, a carry chain.
- Every primitive reads its parameters straight out of the
transport slots `$04`/`$05` rather than `{dst}`/`{src}`
substitutions: the inline-asm resolver looks parameters up in
the analyzer's allocation table but the codegen spills them to a
different per-function RAM slot, so `{dst}` would resolve to a
ZP slot nothing ever writes to. Bypassing the substitution
entirely sidesteps the issue without a compiler change.
- Rotate-right by any amount is a byte-rotate loop plus a bit-
rotate loop so the 10 SHA amounts (2, 6, 7, 11, 13, 17, 18, 19,
22, 25) all compile to a handful of chained `ROR`s.
- The headless jsnes golden auto-types "NES" after 1 s of idle and
captures its SHA-256 digest
AE9145DB5CABC41FE34B54E34AF8881F462362EA20FD8F861B26532FFBB84E0D
— byte-identical to `shasum` / `hashlib.sha256(b"NES")`.
Build: `cargo run --release -- build examples/sha256.ne`
https://claude.ai/code/session_01FRmSBruVWCufm3LsUVMs8v
153 lines
11 KiB
Markdown
153 lines
11 KiB
Markdown
# NEScript
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A statically-typed, compiled programming language for NES game development.
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NEScript compiles `.ne` source files directly into playable iNES ROM files, with no external assembler or linker dependencies. The compiler handles everything from source text to a ROM you can run in any NES emulator.
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_Source: [`examples/platformer.ne`](examples/platformer.ne)_
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_Source: [`examples/war.ne`](examples/war.ne)_
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_Source: [`examples/pong.ne`](examples/pong.ne)_
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## Quick Start
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```bash
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# Build the compiler
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cargo build --release
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# Compile an example
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cargo run -- build examples/hello_sprite.ne
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# Run the output ROM in an emulator
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# (produces examples/hello_sprite.nes)
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```
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## Hello World
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```
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game "Hello" {
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mapper: NROM
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}
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var px: u8 = 128
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var py: u8 = 120
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on frame {
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if button.right { px += 2 }
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if button.left { px -= 2 }
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if button.down { py += 2 }
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if button.up { py -= 2 }
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draw Smiley at: (px, py)
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}
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start Main
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```
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## Features
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- **Game-aware syntax** -- states, sprites, palettes, backgrounds, and input are first-class constructs
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- **Full type system** -- `u8`, `i8`, `u16`, `bool`, fixed-size arrays (`u8[N]`), `enum`, `struct`
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- **Rich control flow** -- `if`/`else`, `while`, `for i in 0..N`, `loop`, `match`
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- **Functions** -- with parameters, return types, real `inline fun` splicing for single-return and void-body shapes, recursion detection
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- **State machines** -- `state` with `on enter`, `on exit`, `on frame`, `on scanline(N)` handlers
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- **Compile-time safety** -- call depth limits, recursion detection, type checking, unused-var warnings
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- **IR-based optimizer** -- constant folding, dead code elimination, strength reduction (incl. div/mod by power-of-two), copy propagation, peephole passes including INC/DEC fold and live-range slot recycling
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- **Full 16-bit arithmetic** -- u16 add/sub/compare lower to carry-propagating paired operations
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- **Multiple mappers** -- NROM, MMC1, UxROM, MMC3 (including multi-scanline IRQ dispatch per state)
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- **Audio subsystem** -- frame-walking pulse driver with user-declared `sfx`/`music` blocks, builtin effects and tracks, period table, and zero-cost elision when unused
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- **Palette & background pipeline** -- `palette` and `background` blocks, initial values loaded at reset, vblank-safe `set_palette` / `load_background` runtime swaps
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- **Asset pipeline** -- PNG-to-CHR conversion, inline tile data, sfx envelopes, music note streams
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- **Inline assembly** -- `asm { ... }` with `{var}` substitution, plus `raw asm { ... }` for verbatim blocks
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- **Hardware intrinsics** -- `poke(addr, value)` / `peek(addr)` for direct register access
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- **Debug support** -- `--debug` flag enables `debug.log` / `debug.assert`, runtime array bounds checks, frame-overrun and sprite-overflow counters, and the `debug.frame_overrun_count()` / `debug.frame_overran()` / `debug.sprite_overflow_count()` / `debug.sprite_overflow()` query builtins — all stripped entirely in release builds
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- **Sprite-per-scanline mitigations** -- three layers of defense for the NES's 8-sprites-per-scanline hardware limit: compile-time `W0109` static check for literal layouts, runtime `cycle_sprites` flicker intrinsic for dynamic scenes, and debug-mode telemetry via `debug.sprite_overflow()` for playtest assertions
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- **Compile-time diagnostics** -- `--dump-ir`, `--memory-map`, `--call-graph` flags
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- **Single binary** -- no dependencies on ca65, Python, or any external tools
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## Documentation
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- **[Language Guide](docs/language-guide.md)** -- complete reference for every language feature
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- **[Architecture](docs/architecture.md)** -- compiler internals and module overview
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- **[NES Reference](docs/nes-reference.md)** -- hardware quick reference for contributors
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- **[Examples README](examples/README.md)** -- how to build and run examples
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## Examples
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| Example | Features demonstrated |
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|---------|---------------------|
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| [`hello_sprite.ne`](examples/hello_sprite.ne) | D-pad input, sprite drawing |
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| [`bouncing_ball.ne`](examples/bouncing_ball.ne) | Automatic movement, edge detection |
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| [`coin_cavern.ne`](examples/coin_cavern.ne) | Multi-state game, functions, constants, gravity |
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| [`arrays_and_functions.ne`](examples/arrays_and_functions.ne) | Arrays, functions, while loops, inline functions |
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| [`state_machine.ne`](examples/state_machine.ne) | State transitions, on enter/exit, timers |
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| [`sprites_and_palettes.ne`](examples/sprites_and_palettes.ne) | Inline CHR data, scroll, type casting |
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| [`mmc1_banked.ne`](examples/mmc1_banked.ne) | MMC1 mapper, bank declarations, multiply |
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| [`uxrom_user_banked.ne`](examples/uxrom_user_banked.ne) | UxROM mapper with a `bank Foo { fun ... }` block — first example to put real user code in a switchable bank, called via a generated cross-bank trampoline |
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| [`uxrom_banked_to_banked.ne`](examples/uxrom_banked_to_banked.ne) | UxROM with two `bank Foo { fun ... }` blocks — exercises a banked→banked call (`step` in `Logic` calls `clamp` in `Helpers`) routed through the same trampoline that handles fixed→banked |
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| [`palette_and_background.ne`](examples/palette_and_background.ne) | Palette and background declarations, reset-time load, vblank-safe `set_palette` / `load_background` swaps |
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| [`auto_chr_background.ne`](examples/auto_chr_background.ne) | `background Stage @nametable("file.png")` with **automatic CHR generation** — the resolver dedupes the PNG's 8×8 cells, encodes them as 2-bitplane CHR, and slots them into CHR ROM after the sprite tile range |
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| [`friendly_assets.ne`](examples/friendly_assets.ne) | **Pleasant asset syntax** — named NES colours, grouped `bg0..sp3` palettes with `universal:`, ASCII pixel-art sprites, `legend { } + map:` tilemaps, `palette_map:` attribute grids, scalar sfx `pitch:`, note-name music with `tempo:` |
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| [`structs_enums_for.ne`](examples/structs_enums_for.ne) | Structs, enums, `for` loops, struct literals |
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| [`nested_structs.ne`](examples/nested_structs.ne) | Nested-struct fields (`hero.pos.x`) and array struct fields (`hero.inv[0]`) with chained literal initializers |
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| [`inline_asm_demo.ne`](examples/inline_asm_demo.ne) | Inline asm with `{var}` substitution, `poke`/`peek` |
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| [`audio_demo.ne`](examples/audio_demo.ne) | Audio subsystem: user `sfx`/`music` blocks, builtin effects, `play`/`start_music`/`stop_music` |
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| [`noise_triangle_sfx.ne`](examples/noise_triangle_sfx.ne) | Noise and triangle channel sfx via `channel: noise` / `channel: triangle` on `sfx` blocks |
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| [`sfx_pitch_envelope.ne`](examples/sfx_pitch_envelope.ne) | Per-frame pulse `pitch:` arrays — the audio tick walks the pitch envelope in lockstep with the volume envelope and writes `$4002` on every NMI for a frequency-sweeping siren tone |
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| [`metasprite_demo.ne`](examples/metasprite_demo.ne) | `metasprite Hero { sprite: ..., dx: [...], dy: [...], frame: [...] }` declarative multi-tile groups — `draw Hero at: (x, y)` expands to one OAM slot per tile so 16×16 sprites stop needing four hand-written `draw` statements |
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| [`sprite_flicker_demo.ne`](examples/sprite_flicker_demo.ne) | `cycle_sprites` — rotates the OAM DMA start offset one slot per frame so scenes with more than 8 sprites on a scanline drop a *different* one each frame. Turns the NES's permanent sprite-dropout hardware symptom into visible flicker, which the eye reconstructs from adjacent frames. Pairs with the compile-time `W0109` warning and the debug-mode `debug.sprite_overflow()` / `debug.sprite_overflow_count()` telemetry for a three-layer defense against the 8-sprites-per-scanline limit. |
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| [`platformer.ne`](examples/platformer.ne) | **End-to-end side-scroller** — custom CHR tileset, full background nametable, metasprite player with gravity/jump physics, wrap-around scrolling, stomp-or-die enemy collisions, live stomp-count HUD, pickup coins, user-declared SFX + music, and a Title → Playing → GameOver state machine with a proximity-based autopilot so the headless harness demonstrates the full gameplay loop (stomp, stomp, die, retry) inside six seconds |
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| [`war.ne`](examples/war.ne) | **Production-quality card game** — a complete port of War split across `examples/war/*.ne`: title screen with a 0/1/2-player menu, animated deal, sliding face-up cards, deck-count HUD, "WAR!" tie-break with buried cards, victory screen with a fanfare, and a brisk 4/4 march on pulse 2. Pulls in nearly every NEScript subsystem (custom 88-tile sheet, felt nametable, 8-bit LFSR PRNG, queue-based decks, phase machine inside `Playing`, multiple sfx + music tracks). Building it surfaced seven compiler bugs, all fixed on the same branch — see `git log` for the details. |
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| [`sha256.ne`](examples/sha256.ne) | **Interactive SHA-256 hasher** — an on-screen keyboard lets the player type up to 16 ASCII characters, and pressing ↵ runs a full FIPS 180-4 SHA-256 compression on the NES (64 rounds + 48-entry message-schedule expansion, all written in NEScript with inline-asm 32-bit primitives). The 64-character hex digest renders as sprites across eight 8-character rows at the bottom of the screen. Splits across `examples/sha256/*.ne` with a phased driver that runs four iterations per frame so the full hash finishes in well under a second; the jsnes golden captures `SHA-256("NES")` = `AE9145DB5CABC41FE34B54E34AF8881F462362EA20FD8F861B26532FFBB84E0D`. |
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## Compiler Commands
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```bash
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# Compile to ROM
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nescript build game.ne
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# Compile with custom output path
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nescript build game.ne --output my_game.nes
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# Type-check only (no ROM output)
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nescript check game.ne
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# View generated 6502 assembly
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nescript build game.ne --asm-dump
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# Enable debug mode
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nescript build game.ne --debug
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```
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## Emulator Compatibility
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Output ROMs are standard iNES format and work with any NES emulator:
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- **[Mesen](https://www.mesen.ca/)** -- recommended, best debugging support
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- **[FCEUX](https://fceux.com/)**
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- **[Nestopia](http://nestopia.sourceforge.net/)**
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## Project Status
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NEScript implements all five planned milestones:
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| Milestone | Status | Key Features |
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|-----------|--------|-------------|
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| M1: Hello Sprite | Done | Full compiler pipeline, assembler, ROM builder |
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| M2: Game Loop | Done | Functions, arrays, IR, optimizer, call graph analysis |
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| M3: Asset Pipeline | Done | PNG-to-CHR, sprites, `debug.log` / `debug.assert` |
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| M4: Optimization | Done | Strength reduction, ZP promotion, type casting, asm-dump |
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| M5: Bank Switching | Done | MMC1/UxROM/MMC3, bank declarations, software mul/div |
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694 tests across the lexer, parser, analyzer, IR, optimizer, codegen, assembler, linker, runtime, ROM, and asset modules, plus a pixel- and audio-exact emulator harness that captures a golden framebuffer + audio hash for every example. CI runs fmt, clippy, test, example compilation, and the emulator harness on every push.
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## License
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[MIT](LICENSE)
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