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https://github.com/imjasonh/nescript
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compiler: VRAM update buffer (nt_set / nt_attr / nt_fill_h)
Closes the highest-priority remaining catalogue item (§G). User code queues PPU writes during `on frame` via three new intrinsics; the NMI drains the 256-byte ring at `$0400-$04FF` to `$2007` during vblank. Programs that never touch the buffer pay zero bytes and zero cycles for the feature — verified by the existing 46 ROMs all matching their goldens with no drift. Also fixes the failing CI Format check from7b4570eby running cargo fmt across the working tree. **Runtime:** - New `runtime::gen_vram_buf_drain` emits the drain routine (`__vram_buf_drain`). Walks entries `[len][addr_hi][addr_lo] [byte_0]...[byte_(len-1)]` and stops at `len == 0`. Uses `LDA $0400,X` indexed-absolute so no ZP scratch is needed. Drain costs ~12 setup cycles + 8 cycles per data byte; the 256-byte buffer can hold ~50 single-tile writes that drain in roughly 1000 cycles, well inside the ~2273-cycle vblank. - `NmiOptions` gains `has_vram_buf`. The NMI JSRs the drain after the existing palette/background handshake (compiler- queued PPU writes win priority for vblank cycles). **IR + codegen:** - Three new ops `IrOp::NtSet`, `IrOp::NtAttr`, `IrOp::NtFillH`. - The codegen helpers compute the PPU address inline: `$2000 + y*32 + x` for nametable, `$23C0 + (y/4)*8 + (x/4)` for attribute. Each append lays down a fresh `0` sentinel so the NMI sees a well-formed buffer regardless of whether more entries get appended later in the frame. - `__vram_buf_used` marker drops on first use; gates the runtime splice + NMI JSR. **Analyzer:** - AST-walking helper `program_uses_vram_buf` detects intrinsic use at analyze-init time so the user-RAM bump pointer can start at `$0500` (past the buffer) rather than the legacy `$0300`. Programs that don't use the buffer keep the legacy start. - Three intrinsic names registered in `is_intrinsic` / `is_void_intrinsic` with arity checks. **Tests + example:** - `examples/vram_buffer_demo.ne` exercises all three intrinsics on a backgrounded program — three single-tile score writes, a 16-tile horizontal fill, and an attribute write that flips the top-left metatile group's palette to red. Committed golden + audio hash. - Four new integration tests: byte-level JSR-to-drain assertion, drain-omitted-when-unused, RAM-bump assertion for programs that DO use the buffer, and arity enforcement for `nt_set`. **CI fix:** - `cargo fmt` ran across the tree. Picks up a one-line fmt diff in `tests/integration_test.rs` that the prior commit shipped without running fmt, causing the Format CI job to fail on `7b4570e`. All 758 tests pass. Clippy clean. 47/47 emulator goldens match.
This commit is contained in:
Claude
parent
7b4570eee5
commit
807c9c7318
15 changed files with 699 additions and 27 deletions
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@ -3505,6 +3505,168 @@ start Main
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let _rom = compile(source);
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}
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#[test]
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fn nt_set_emits_buffer_append_and_drain_marker() {
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// `nt_set(x, y, tile)` should:
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// 1. Mark `__vram_buf_used` so the linker splices the
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// drain routine and gates the NMI JSR.
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// 2. Emit a 4-byte append: write `[1][addr_hi][addr_lo][tile]`
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// starting at VRAM_BUF_BASE+head, bump the head, write a
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// fresh `0` sentinel after.
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let source = r#"
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game "VramSet" { mapper: NROM }
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on frame {
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nt_set(2, 1, 7)
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}
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start Main
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"#;
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let (program, _) = nescript::parser::parse(source);
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let program = program.unwrap();
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let analysis = analyzer::analyze(&program);
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let mut ir_program = ir::lower(&program, &analysis);
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optimizer::optimize(&mut ir_program);
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let sprites = assets::resolve_sprites(&program, Path::new(".")).unwrap();
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let sfx = assets::resolve_sfx(&program).unwrap();
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let music = assets::resolve_music(&program).unwrap();
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let mut codegen = IrCodeGen::new(&analysis.var_allocations, &ir_program)
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.with_sprites(&sprites)
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.with_audio(&sfx, &music);
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let mut instructions = codegen.generate(&ir_program);
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nescript::codegen::peephole::optimize(&mut instructions);
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let linked = Linker::new(program.game.mirroring).link_banked_with_ppu_detailed(
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&instructions,
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&sprites,
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&sfx,
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&music,
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&[],
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&[],
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&[],
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);
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// The drain routine must be linked in.
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assert!(
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linked.labels.contains_key("__vram_buf_drain"),
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"nt_set should pull __vram_buf_drain into the ROM"
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);
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// The NMI must JSR the drain. JSR opcode is 0x20; target
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// address is the drain label resolved by the linker.
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let drain_addr = *linked.labels.get("__vram_buf_drain").unwrap();
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let lo = (drain_addr & 0xFF) as u8;
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let hi = (drain_addr >> 8) as u8;
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assert!(
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linked
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.rom
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.windows(3)
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.any(|w| w[0] == 0x20 && w[1] == lo && w[2] == hi),
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"NMI should JSR __vram_buf_drain"
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);
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}
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#[test]
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fn vram_buf_omitted_without_use() {
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// Programs that never call any of the buffer intrinsics should
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// not link in the drain routine and should keep main RAM
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// starting at $0300.
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let source = r#"
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game "NoVram" { mapper: NROM }
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var x: u8 = 0
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on frame { x = x + 1 }
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start Main
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"#;
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let (program, _) = nescript::parser::parse(source);
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let program = program.unwrap();
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let analysis = analyzer::analyze(&program);
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let x_alloc = analysis
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.var_allocations
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.iter()
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.find(|a| a.name == "x")
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.expect("x should be allocated");
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// Without the buffer, `x` lives in zero page (the default
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// for u8 globals); pre-buffer programs never had main-RAM
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// allocations bumped to $0500.
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assert!(
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x_alloc.address < 0x100,
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"u8 global should still land in zero page when buffer unused"
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);
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let mut ir_program = ir::lower(&program, &analysis);
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optimizer::optimize(&mut ir_program);
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let sprites = assets::resolve_sprites(&program, Path::new(".")).unwrap();
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let sfx = assets::resolve_sfx(&program).unwrap();
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let music = assets::resolve_music(&program).unwrap();
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let mut codegen = IrCodeGen::new(&analysis.var_allocations, &ir_program)
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.with_sprites(&sprites)
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.with_audio(&sfx, &music);
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let mut instructions = codegen.generate(&ir_program);
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nescript::codegen::peephole::optimize(&mut instructions);
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let linked = Linker::new(program.game.mirroring).link_banked_with_ppu_detailed(
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&instructions,
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&sprites,
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&sfx,
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&music,
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&[],
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&[],
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&[],
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);
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assert!(
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!linked.labels.contains_key("__vram_buf_drain"),
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"drain routine must not be linked when no buffer intrinsic was used"
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);
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}
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#[test]
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fn vram_buf_bumps_user_ram_past_buffer_when_used() {
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// When user code touches the buffer, the analyzer should bump
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// the main-RAM allocator to $0500 so user globals don't alias
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// the buffer at $0400-$04FF. Force a main-RAM allocation by
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// declaring a large array (too big for ZP).
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let source = r#"
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game "VramBigVar" { mapper: NROM }
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var big: u8[200]
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on frame {
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nt_set(0, 0, 1)
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}
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start Main
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"#;
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let (program, _) = nescript::parser::parse(source);
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let program = program.expect("parse should succeed");
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let analysis = analyzer::analyze(&program);
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let big_alloc = analysis
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.var_allocations
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.iter()
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.find(|a| a.name == "big")
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.expect("big should be allocated");
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assert!(
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big_alloc.address >= 0x0500,
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"user array should land at $0500+ when VRAM buffer is in use, got ${:04X}",
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big_alloc.address
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);
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assert!(
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big_alloc.address + big_alloc.size <= 0x0800,
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"and should fit in main RAM"
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);
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}
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#[test]
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fn nt_set_arity_enforced() {
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let source = r#"
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game "BadVram" { mapper: NROM }
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on frame {
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nt_set(1, 2)
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}
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start Main
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"#;
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let (program, _) = nescript::parser::parse(source);
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let program = program.expect("parse should succeed");
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let analysis = analyzer::analyze(&program);
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assert!(
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analysis
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.diagnostics
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.iter()
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.any(|d| d.is_error() && d.message.contains("nt_set")),
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"wrong-arity nt_set should error; got {:?}",
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analysis.diagnostics
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);
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}
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#[test]
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fn save_block_allocates_at_sram_window_and_sets_battery_bit() {
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// `save { var x: u16 = 0 }` should land at $6000+ (iNES SRAM
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@ -3586,8 +3748,7 @@ start Main
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analysis
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.diagnostics
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.iter()
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.any(|d| !d.is_error()
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&& matches!(d.code, nescript::errors::ErrorCode::W0111)),
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.any(|d| !d.is_error() && matches!(d.code, nescript::errors::ErrorCode::W0111)),
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"save-block initializer should emit W0111; got {:?}",
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analysis.diagnostics
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);
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