mirror of
https://github.com/imjasonh/nescript
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Fills the biggest feature-coverage gaps in the existing example set:
- match_demo.ne — match statement over a Screen enum,
driving a title / playing / paused /
game-over flow with a debounced controller.
- loop_break_continue.ne — `loop { ... }` with `break` and `continue`,
scanning an enemy array for the first hit.
- logic_ops.ne — keyword-based `and` / `or` / `not` gating
movement and scoring on alive/paused flags.
- bitwise_ops.ne — packed status-byte flags with `&` / `|` /
`^` / `>>` plus a health-bar render loop.
- scanline_split.ne — MMC3 `on scanline(120)` handler rewriting
the scroll register mid-frame for a
classic status-bar split.
All 14 examples (9 existing + 5 new) pass the jsnes smoke test
(`14/14 ROMs rendered successfully`) and still pass `cargo fmt`,
`cargo clippy -D warnings`, and `cargo test`.
Known limitations surfaced while authoring these examples, to be
fixed in follow-up commits:
1. Array-literal global initializers (`var xs: u8[4] = [1,2,3,4]`)
are silently dropped by `lower_program` — `eval_const` returns
None for `Expr::ArrayLiteral` and no synthetic per-element
init code is emitted. Affects `arrays_and_functions`,
`structs_enums_for`, `loop_break_continue`, and any future
array-using example. Arrays effectively boot at all-zero.
2. `draw` inside a loop body reuses one static OAM slot —
`next_oam_slot` increments at IR-codegen time rather than at
runtime, so N iterations all write to the same 4-byte OAM
entry. Affects `arrays_and_functions`, `structs_enums_for`,
`bitwise_ops` (health pips), and any loop that wants to
render per-iteration sprites.
Both bugs are latent and didn't surface until I tried to write
examples that exercise the relevant features — the existing
integration tests only check iNES header structure, and the
jsnes smoke test's "at least one sprite rendered" bar is
satisfied by one sprite even when several were intended.
https://claude.ai/code/session_014Z5y3Q9krLcAxYpZQJhZ5V
|
||
|---|---|---|
| .. | ||
| arrays_and_functions.ne | ||
| bitwise_ops.ne | ||
| bouncing_ball.ne | ||
| coin_cavern.ne | ||
| hello_sprite.ne | ||
| inline_asm_demo.ne | ||
| logic_ops.ne | ||
| loop_break_continue.ne | ||
| match_demo.ne | ||
| mmc1_banked.ne | ||
| README.md | ||
| scanline_split.ne | ||
| sprites_and_palettes.ne | ||
| state_machine.ne | ||
| structs_enums_for.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, palettes, scroll, cast | Inline CHR data, palette switching, 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