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https://github.com/imjasonh/nescript
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807c9c7318
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.
57 lines
1.9 KiB
Text
57 lines
1.9 KiB
Text
// VRAM update buffer demo — `nt_set`, `nt_attr`, and `nt_fill_h`
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// append entries to a 256-byte ring at `$0400-$04FF` during
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// `on frame`; the NMI handler drains them to PPU `$2007` during
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// vblank. This is the idiom every nesdoug HUD / dialog box / score
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// counter is built on — the user code never touches `$2006` or
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// `$2007` directly, just appends record after record.
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//
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// This demo paints a "scoreboard" of three tiles in the top row
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// each frame, then fills a 16-tile horizontal stripe a few rows
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// down with a single tile pattern. Frame 180 captures the scene
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// after the buffer has drained the same set of writes for ~3
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// seconds — the visible output is stable.
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game "VRAM Buffer Demo" {
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mapper: NROM
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mirroring: horizontal
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}
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palette Default {
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universal: black
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bg0: [dk_blue, blue, sky_blue]
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bg1: [dk_red, red, lt_red]
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bg2: [dk_green, green, lt_green]
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bg3: [black, lt_gray, white]
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sp0: [dk_blue, blue, sky_blue]
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sp1: [red, orange, white]
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sp2: [dk_teal, teal, lt_teal]
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sp3: [dk_olive, olive, yellow]
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}
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background Empty {
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legend { ".": 0 }
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map: [
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"................................"
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]
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}
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on frame {
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// Three single-tile writes for a tiny "score" digit row.
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// Each call appends a 4-byte buffer entry: [len=1][hi][lo][tile].
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nt_set(2, 1, 1)
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nt_set(3, 1, 2)
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nt_set(4, 1, 3)
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// A horizontal fill: 16 copies of the smiley starting at (8, 4).
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// Buffer entry is [len=16][hi][lo][tile × 16] = 19 bytes.
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nt_fill_h(8, 4, 16, 0)
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// Update the attribute byte for the metatile that contains the
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// score row so it picks up sub-palette 1 (red gradient) for
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// visual contrast against the rest of the screen. (x, y) here
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// are nametable cell coordinates; the codegen translates to
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// the attribute table address $23C0+.
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nt_attr(0, 0, 0b01010101)
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}
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start Main
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