661f00d682
Add --suite memory with verified source hashes, ARM eval checkpoint 0x08000350, and the r12 result assertion. Keep default ARM and explicit Thumb preparation unchanged. Extend offline adapter and CLI tests; retain public binaries outside tracked files. The unmodified memory ROM passes in debug and release after 174 steps and 1478 nominal cycles, without changing core behavior. Document weak byte-write assertions and mode-selection caveats. Add original CPU-driven tests with exact sentinels, mode/mirror boundaries, byte lanes, forced blank, readback, and nominal device timing. Validated on Darwin arm64: 851 workspace tests in debug and release; 782 core/demo tests separately; 30 Python tests; all three pinned public suites in both profiles; native ROM windows; all ten demo smoke tests; fmt, clippy, rustdoc, and local documentation links.
94 lines
6.2 KiB
Markdown
94 lines
6.2 KiB
Markdown
# Pinned public memory test
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The headless runner executes the unmodified memory ROM from [jsmolka/gba-tests](https://github.com/jsmolka/gba-tests).
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It passes its result checkpoint on Darwin arm64 in debug and release builds without a core behavior change.
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This suite samples memory mirrors and video-byte writes. It does not establish complete memory-bus compatibility.
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## Prepare and run
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```sh
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direnv exec . python3 tools/prepare_gba_tests.py /tmp/gba-public-memory --suite memory
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direnv exec . cargo run --locked --release -- --test-suite /tmp/gba-public-memory/suite.json > /tmp/gba-public-memory-report.json
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```
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Use a new directory outside the repository or inside ignored `roms/`. Its parent directory must exist.
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Every selected source and binary file has a pinned byte count and SHA-256 digest.
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The adapter checks all files before creating output, retains the upstream license, and writes `suite.json` and `source-lock.json`.
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No ROM patch, source rewrite, header replacement, test skip, or result adjustment occurs.
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Downloaded ROMs and header sources must not enter tracked files.
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Offline preparation applies the same checks:
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```sh
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direnv exec . python3 tools/prepare_gba_tests.py /tmp/gba-public-memory-offline --suite memory --source-dir /path/to/gba-tests
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```
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The default remains the [ARM suite](public-arm-tests.md). `--suite thumb` selects the [Thumb suite](public-thumb-tests.md).
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Each invocation prepares one suite. Normal Rust and Python tests do not download public files.
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Python comes from Nix and requires no extra packages. Preparation alone is not a compatibility verdict.
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## Provenance and result protocol
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- Repository: `jsmolka/gba-tests`.
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- Revision: `a7113b67e63f83a9b321696ddd7042ccfad6c881`.
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- Upstream project license: MIT, copyright Julian Smolka; retained with downloaded files.
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- ROM: `memory/memory.gba`, 2,172 bytes.
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- SHA-256: `21024fb6aae6343f5f0466dd54e3149de1fbeb23f78e7d85a015c983684d2f87`.
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- Selected file hashes and sizes: [`tools/gba-tests-memory.lock.json`](../tools/gba-tests-memory.lock.json).
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The adapter uses the committed upstream binary. No FASMARM rebuild or source-to-binary reproduction was performed on Darwin.
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Startup initializes Mode 4 display state and sets r12 to zero.
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Failure paths set r12 to their test number and branch to `eval`.
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Successful execution reaches `eval` with r12 still zero.
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The source exits and their binary ARM branch targets were checked against this address.
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`eval` is `0x08000350`, in ARM state. Its first word is `0xe92d0003`, the shared `m_vsync` register save.
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Preparation checks this word in addition to whole-file hashes.
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The manifest stops before executing `eval` and requires `r12 == 0`.
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This runs startup and all memory tests without depending on result rendering, VBlank polling, or BIOS number formatting.
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The budget is 1,000,000 successful machine steps, including original BIOS boot.
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Diagnostics, timeouts, STOP, and failed assertions remain failures under the [runner's normal rules](rom-tests.md).
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## Observed result on Darwin arm64
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- The ROM reaches `0x08000350` after 174 successful steps and 1,478 nominal cycles.
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- The CPU is in System/ARM state, with CPSR `0x6000001f` and r12 = 0.
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- Debug and release builds exit zero with `reason: checkpoint`, no error, and the result assertion passing.
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- The existing ARM and Thumb suites also retain their passing results.
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- No emulator behavior change was needed for this result.
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## Coverage and limits
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The mirror tests sample external RAM, internal RAM, palette RAM, video RAM, object attribute memory, and both alternate cartridge windows.
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The byte-write tests sample palette duplication, background video RAM duplication, and ignored object-memory writes.
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They do not cover open bus, BIOS protection, save hardware, unused I/O, memory timing, or display-bus contention.
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The pinned source also has limits that weaken its video-byte checks:
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- Tests 50–52 reject one exact byte-sized value, rather than requiring the complete prior word to remain unchanged.
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An incorrect duplicated-halfword write can therefore escape these checks.
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- Startup selects Mode 4. Test 51 applies `ORR #3` to that mode, selecting reserved Mode 7 rather than a supported bitmap mode.
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- Test 52 clears only mode bits 0–1. This leaves Mode 4 selected rather than selecting a tile mode.
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- Test 5 explicitly selects Mode 0 for its upper video RAM mirror check. It does not validate every mirror in every mode.
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These source behaviors are retained, not patched to make the suite stronger or easier to pass.
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Passing this ROM must not be described as exhaustive video-memory validation.
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Original CPU-driven regressions in `crates/gba-core/tests/video_bus_cpu.rs` provide separate, stronger byte-write checks.
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They select each supported mode explicitly and require the exact duplicated halfword or unchanged nonzero sentinel.
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They cover both byte lanes, physical and mirrored addresses, tile/bitmap boundaries, forced blank, and CPU readback.
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Adjacent halfwords must remain unchanged. Ignored stores still pay their nominal data-access cost and advance devices.
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Halfword and word stores still modify object video RAM and object attribute memory.
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These are implementation regressions based on documented rules, not new hardware measurements.
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No public BIOS, timing, graphics, save, or unsafe suite is claimed as passing.
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Pokémon Emerald compatibility remains unverified.
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## References
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- [Pinned memory entry and result flow](https://github.com/jsmolka/gba-tests/blob/a7113b67e63f83a9b321696ddd7042ccfad6c881/memory/memory.asm).
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- [Memory mirror checks](https://github.com/jsmolka/gba-tests/blob/a7113b67e63f83a9b321696ddd7042ccfad6c881/memory/mirrors.asm).
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- [Video-byte checks and mode selection](https://github.com/jsmolka/gba-tests/blob/a7113b67e63f83a9b321696ddd7042ccfad6c881/memory/video_strb.asm).
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- [Display initialization](https://github.com/jsmolka/gba-tests/blob/a7113b67e63f83a9b321696ddd7042ccfad6c881/lib/text.asm) and [shared result macros](https://github.com/jsmolka/gba-tests/blob/a7113b67e63f83a9b321696ddd7042ccfad6c881/lib/macros.inc).
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- [GBATEK memory mirrors and video-byte writes](https://problemkaputt.de/gbatek-gba-unpredictable-things.htm).
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- [Pinned license](https://github.com/jsmolka/gba-tests/blob/a7113b67e63f83a9b321696ddd7042ccfad6c881/LICENSE).
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