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https://github.com/imjasonh/nescript
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7b4570eee5
Another batch from the cc65/nesdoug catalogue. All gated on
parser-level opt-in or default-false attributes so existing
programs produce byte-identical ROMs (no committed .nes file
changed).
**§A — `i16` signed 16-bit type:**
- New `KwI16` lexer token, `NesType::I16` AST variant, parser
case in `parse_type`. Type-size and integer-type tables
treat `i16` like `u16` (2 bytes, integer).
- IR lowering accepts `i16` everywhere it accepts `u16` for
wide-load / wide-store / widen-narrow paths.
- New constant fold for `UnaryOp::Negate(IntLiteral(v))` that
emits the wide two's-complement form. Without it, `var vy:
i16 = -10` would zero-extend to `$00F6` (= 246) instead of
sign-extending to `$FFF6` (= -10). Negative literals now
store the right bytes.
- Comparisons reuse the existing unsigned 16-bit compare ops
(matching the existing `i8` behaviour). Documented in the
`NesType::I16` doc comment and in `future-work.md` §A.
- Example `examples/i16_demo.ne` with committed golden.
- Tests cover the literal-fold sign-extension and end-to-end
compile of the example.
**§S — SRAM / battery-backed saves:**
- New `save { var ... }` top-level block. Lexer + parser opt
into a dedicated `KwSave` token. Analyzer allocates save
vars from a separate `next_sram_addr` bump pointer starting
at `$6000`, capped at `$8000` (8 KB cartridge SRAM window).
- Linker reads `analysis.has_battery_saves` and flips iNES
byte-6 bit-1 via the new `RomBuilder::set_battery` /
`Linker::with_battery` chain.
- New `W0111` warning for save-var initializers — SRAM is
preserved across power cycles, so an init expression would
either silently never run or clobber persisted data on
every boot. The warning teaches the user about the
magic-byte sentinel pattern.
- Struct fields in save blocks are explicitly rejected for now
(the field-flattening path uses the main-RAM allocator).
- Example `examples/sram_demo.ne` with committed golden, plus
4 integration tests.
**§D (partial) — inline-asm `.label:` syntax:**
- Codegen-side mangler rewrites `.IDENT` → `__ilab_<N>_IDENT`
per inline-asm block, where `<N>` is the call site's
monotonic suffix. Two `asm { .loop: ... }` blocks in the
same function now coexist without colliding in the linker's
label table.
- Bounds checks on `.` placement: `$2002` and `name.field`
are unaffected; only `.IDENT` in label / branch context
triggers the rewrite. Two integration tests pin the
uniqueness and dollar-vs-dot disambiguation.
**§X follow-up — Mesen trace-log docs:**
- New "Debugger-assisted workflows" section in
`docs/nes-reference.md` walking through the Mesen / FCEUX
log workflows alongside the new `debug_port:` attribute.
**Misc:**
- `future-work.md` updated to mark the shipped items out of
the catalogue and reshuffle the priority ranking. Remaining
niche follow-ups (signedness on Cmp16, struct save fields,
inline-asm format specifiers) documented inline so future
passes know the design.
All 757 tests pass. Clippy clean. 46/46 emulator goldens match.
48 lines
1.4 KiB
Text
48 lines
1.4 KiB
Text
// i16 demo — exercises the signed 16-bit type with negative
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// literals, signed velocity, and round-tripping through wide
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// arithmetic.
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//
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// Position is stored as `i16` so negative deltas (the ball moving
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// left or up) can be represented directly instead of having to
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// shadow them with a sign byte. The lowering folds `-N` literals
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// into wide two's-complement constants, so `vy = -10` lands as
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// `$FFF6` (=-10) rather than the zero-extended `$00F6` (=246).
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game "i16 Demo" {
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mapper: NROM
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}
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var px: i16 = 64
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var py: i16 = 80
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var vx: i16 = 1
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var vy: i16 = -1
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var frame: u8 = 0
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on frame {
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frame += 1
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// Bounce off the visible-area edges. Comparisons against the
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// small positive bounds use the unsigned 16-bit compare path
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// (matching the existing i8 behaviour) — for purely positive
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// ranges this matches signed semantics.
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px += vx
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py += vy
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// Reverse vx every 100 frames so we exercise both the
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// positive-velocity and negative-velocity arithmetic paths.
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if frame == 100 {
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frame = 0
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vx = vx + vx // double-then-negate would be cleaner once
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vx = vx - vx // we add unary `-` on a runtime expression
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vx = 1
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vy = -1
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}
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// Clamp position into u8 range for `draw`. The cast truncates
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// the high byte; for our 0..255 motion that's the right thing.
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var dx: u8 = px as u8
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var dy: u8 = py as u8
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draw Ball at: (dx, dy)
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}
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start Main
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