mirror of
https://github.com/imjasonh/nescript
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9878b7d87d
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 `$4002` (pulse-1 period low), advance the pointer. The block bails on a zero high-byte pointer so a single program can mix scalar-pitch and varying-pitch sfx without one clobbering the other. 2. `emit_play_pulse` seeds `AUDIO_SFX_PITCH_PTR_LO/HI` with the pitch-blob label for varying-pitch sfx and zeros it for scalar-pitch sfx. The per-call branch is skipped entirely when the program has no varying-pitch sfx anywhere. The new `examples/sfx_pitch_envelope.ne` exercises the path with a 16-frame siren sweep. Triangle and noise per-frame pitch are deferred — they share the same data shape but the runtime ticks for those channels still write only their volume registers, see docs/future-work.md for the gap. https://claude.ai/code/session_01KEczoNUX3WmcFLfq6iAQxB
80 lines
4.8 KiB
Markdown
80 lines
4.8 KiB
Markdown
# NEScript Examples
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## Quick Start
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```bash
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# Build the compiler
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cargo build --release
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# Compile all examples
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for f in examples/*.ne; do cargo run -- build "$f"; done
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# Or compile one
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cargo run -- build examples/hello_sprite.ne
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```
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Open any `.nes` file in an NES emulator ([Mesen](https://www.mesen.ca/), [FCEUX](https://fceux.com/), etc.)
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## Examples
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| File | Features | Description |
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|------|----------|-------------|
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| `hello_sprite.ne` | input, draw | Move a sprite with the d-pad |
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| `bouncing_ball.ne` | if/else, variables | Auto-bouncing sprite with edge detection |
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| `coin_cavern.ne` | states, functions, constants | 3-state game with gravity and coin collection |
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| `arrays_and_functions.ne` | arrays, functions, while | Enemy array with collision detection |
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| `state_machine.ne` | on enter/exit, transitions | Multi-state flow with timers |
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| `sprites_and_palettes.ne` | sprites, scroll, cast | Inline CHR data, PPU scroll writes, type casting |
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| `mmc1_banked.ne` | MMC1, banks, multiply | Banked mapper with software multiply |
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| `uxrom_user_banked.ne` | UxROM, `bank Foo { fun ... }`, cross-bank trampoline | First example to put real user code inside a switchable bank. The animation step lives in `bank Extras` and is invoked from the fixed-bank state handler via a generated `__tramp_step_animation` stub that selects bank 0, JSRs the body, then restores the fixed bank before returning. |
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| `uxrom_banked_to_banked.ne` | UxROM, banked → banked cross-bank call | Two `bank Foo { fun ... }` blocks: `step` lives in bank Logic and calls `clamp` in bank Helpers. The trampoline uses `ZP_BANK_CURRENT + PHA/PLA` to save and restore the caller's bank, so the same per-callee stub works whether the caller is in the fixed bank or another switchable bank. |
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| `palette_and_background.ne` | palette, background, set_palette, load_background | Reset-time initial load plus vblank-safe runtime swaps |
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| `friendly_assets.ne` | named colours, grouped palette, pixel art, tilemap+legend, palette_map, scalar sfx pitch, note-name music | Exercises every "friendlier" asset syntax at once — the `palette` uses `bg0..sp3` + a shared `universal:`, the sprite is authored as ASCII pixel art, the background uses a `legend { ... } + map:` tilemap with a `palette_map:` for attributes, the sfx uses a scalar `pitch:` + `envelope:` alias, and the music uses note names (`C4, E4 40, rest 10`) with a `tempo:` default. |
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| `noise_triangle_sfx.ne` | `channel: noise`, `channel: triangle` on `sfx` blocks | Demonstrates the noise and triangle sfx channels. Declares one noise burst and one triangle bass note, plays each on a timer so the emulator harness captures both the pixel output and the APU state. |
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| `sfx_pitch_envelope.ne` | varying-pitch pulse SFX | A 16-frame frequency sweep written as a per-frame `pitch:` array on a Pulse-1 sfx. The compiler emits a separate `__sfx_pitch_<name>` blob and gates the audio tick's pitch update path on the `__sfx_pitch_used` marker, so programs that stick to the scalar `pitch:` form still get byte-identical ROM output. |
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| `nested_structs.ne` | nested struct fields, array struct fields, chained literals | Two `Hero` instances each carry a `Vec2` position and a `u8[4]` inventory. Exercises `hero.pos.x` chained access, `hero.inv[i]` array-field access, and chained struct-literal initializers (`Hero { pos: Vec2 { x: ..., y: ... }, inv: [...] }`). |
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| `platformer.ne` | **every subsystem** | End-to-end side-scrolling demo: custom CHR tileset, full 32×30 nametable with per-region attribute palettes, 2×2 metasprite hero with gravity/jump physics, wrap-around horizontal scrolling, stomp-or-die enemy collisions with a live stomp-count HUD, coin pickups, user-declared SFX + music, and a Title → Playing → GameOver state machine with a proximity-based autopilot so the headless harness cycles through stomp, stomp, die, and retry inside six seconds. Regenerate the tile art with `cargo run --bin gen_platformer_tiles`. |
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## Emulator Controls
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| NES Button | Typical Key |
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|------------|-------------|
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| D-pad | Arrow keys |
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| A | Z |
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| B | X |
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| Start | Enter |
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| Select | Right Shift |
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## About Sprites
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Sprite names in `draw Player at: (x, y)` are parsed and recorded in the AST.
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You can define sprites with inline CHR tile data:
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```
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sprite Player {
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chr: [0x3C, 0x42, 0x81, 0x81, 0x81, 0x81, 0x42, 0x3C,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]
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}
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```
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If no matching sprite declaration exists, the draw uses the built-in default
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tile (a smiley face). See `sprites_and_palettes.ne` for a full example.
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## Compiler Commands
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```bash
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# Compile to ROM
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cargo run -- build game.ne
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# Custom output path
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cargo run -- build game.ne --output my_game.nes
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# Type-check only
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cargo run -- check game.ne
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# View generated 6502 assembly
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cargo run -- build game.ne --asm-dump
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# Debug mode
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cargo run -- build game.ne --debug
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```
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