mirror of
https://github.com/imjasonh/nescript
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db3a4adc57
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 $C000).
3. **Bank-namespaced local labels.** Two banks emitting the same
`__ir_cmp_e_8` would trip the linker's discovery-pass duplicate-
label check the moment any banked code generated a comparison.
The new `local_label_suffix` helper prefixes the suffix with the
current bank name when banked code is being emitted, leaving
fixed-bank label generation untouched (so existing examples are
byte-identical apart from the trampoline / init bytes
themselves).
The new `examples/uxrom_banked_to_banked.ne` demonstrates the path
end-to-end: `bank Logic { fun step() { ... clamp() } }` calls
`bank Helpers { fun clamp() { ... } }` once per frame. The harness
golden is committed alongside it. The five existing banked example
ROMs change byte-for-byte because of the new trampoline shape and
the seed-ZP_BANK_CURRENT init, but their emulator goldens still
match exactly — observable behaviour is unchanged.
https://claude.ai/code/session_01KEczoNUX3WmcFLfq6iAQxB
79 lines
4.5 KiB
Markdown
79 lines
4.5 KiB
Markdown
# NEScript Examples
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## Quick Start
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```bash
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# Build the compiler
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cargo build --release
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# Compile all examples
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for f in examples/*.ne; do cargo run -- build "$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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| `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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