efdc288db6
Place skipped compatibility data at boot, SoftReset, SWI, and IRQ exit PC+8 locations. Preserve the real IRQ callback return instruction as its readback word. Keep CPU and memory behavior image-derived, including caller-supplied images. Add original boundary, load-lane, caller-state, wait, supplied-image, and builder-fixup regressions. Document the historical failures, research decision, passing public BIOS checkpoint, and remaining fetch-history limits. Validated on Darwin arm64: 868 workspace tests in debug and release; 799 core/demo tests separately in both profiles; 39 preparation tests; native ROM window tests in both profiles; ten graphics/window smoke modes; fmt, clippy, and rustdoc. Hash-verified public ARM, Thumb, memory, and BIOS suites pass unchanged with identical debug/release reports. BIOS: r12=0, 17606 steps, 197456 nominal cycles, one IRQ entry.
95 lines
6 KiB
Markdown
95 lines
6 KiB
Markdown
# Pinned public Thumb test
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The headless runner executes the unmodified Thumb ROM from [jsmolka/gba-tests](https://github.com/jsmolka/gba-tests).
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It now passes its result checkpoint on Darwin arm64 in debug and release builds. The initial test 229 failure is retained below.
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This is an independent compatibility baseline, not complete ARM7TDMI conformance or a hardware measurement.
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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-thumb --suite thumb
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direnv exec . cargo run --locked --release -- --test-suite /tmp/gba-public-thumb/suite.json > /tmp/gba-public-thumb-report.json
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```
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Use a new directory outside the repository or inside ignored `roms/`. The parent directory must exist.
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The adapter checks every selected file's byte count and SHA-256 digest before creating output.
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It retains the upstream sources, license, README, ROM, generated `suite.json`, and `source-lock.json`.
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No source, binary, header, expected result, or instruction is patched or skipped.
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Downloaded binaries and header sources must not enter tracked files.
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Offline preparation uses the same checks:
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```sh
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direnv exec . python3 tools/prepare_gba_tests.py /tmp/gba-public-thumb-offline --suite thumb --source-dir /path/to/gba-tests
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```
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The existing [ARM command](public-arm-tests.md) remains the default. Explicit `--suite arm` selects the same ARM lock.
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Each preparation creates one suite. The suite name does not select the checkpoint's instruction state.
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Python comes from Nix and requires no extra packages. Ordinary unit tests use original synthetic data, without downloads.
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Preparation is not a compatibility verdict. Inspect the runner's JSON result and exit status.
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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: `thumb/thumb.gba`, 3,680 bytes.
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- SHA-256: `b5cb2291df4ab314b31c598acd9bff2ccfa0b38efff29daadfe97422ce369b67`.
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- Selected file hashes and sizes: [`tools/gba-tests-thumb.lock.json`](../tools/gba-tests-thumb.lock.json).
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The adapter uses the upstream committed binary. No FASMARM rebuild or source-to-binary reproduction was performed on Darwin.
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The entry code initializes the display, switches to Thumb, and initializes r7 to zero.
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Each `m_exit` failure writes its test number to r7 and calls `tmain_end`.
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Branch tests also use r7 as a progress marker, then reset it to zero on their successful path.
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Successful completion of the memory tests reaches the same `tmain_end` with r7 still zero.
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At this revision:
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- `tmain_end` is Thumb code at `0x08000930`.
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- `ADR r0, eval` (`0xa000`) and `BX r0` (`0x4700`) switch execution back to ARM.
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- `eval` is ARM code at `0x08000934`, starting with `0xe92d0003`, the `m_vsync` register save.
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- The later result macro reads r7, not the ARM suite's r12.
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The source exit paths and binary Thumb `BL` targets were checked against `tmain_end`.
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The adapter verifies the bridge and initial evaluation word, in addition to whole-file hashes.
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The manifest stops before `eval`, requires ARM state and `r7 == 0`, and allows 1,000,000 successful machine steps.
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The budget includes the original BIOS boot. Startup and CPU tests execute normally; result rendering does not execute.
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Diagnostics, timeouts, STOP, and nonzero r7 remain failures under the [runner's normal rules](rom-tests.md).
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## Observed result on Darwin arm64
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Initial integration, before fixing empty-list Thumb stores:
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- The runner reaches `0x08000934` after 771 successful steps and 3,858 nominal cycles.
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- The CPU is in System/ARM state with CPSR `0x0000001f` and r7 = 229.
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- Both builds exit nonzero with `reason: assertion_failed`; there is no emulator diagnostic.
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- Test 229 executes `STMIA r0!, {}` (`0xc000`) at `0x080008ba`.
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- The stored PC value is `0x080008be`, but the following PC read expects `0x080008c0`.
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- The public ARM ROM still passes its unchanged checkpoint.
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After correcting the empty-list store PC offset:
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- Thumb empty-list stores use executing PC+6 instead of PC+4. ARM stores retain PC+12.
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- Test 229 and the later memory tests complete without taking their failure paths.
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- The runner reaches `0x08000934` after 807 successful steps and 4,170 nominal cycles.
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- The CPU is in System/ARM state with CPSR `0x0000001f` and r7 = 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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- Both public ROMs pass with their original bytes, checkpoint addresses, budgets, and assertions unchanged.
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Original regressions reproduce the stored-PC mismatch without public ROM bytes.
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They cover all low base registers, banked stack pointers, code/data alignment, ROM windows, timing, and atomic diagnostics.
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Existing empty-list expectations that incorrectly required PC+4 were corrected; empty loads and ARM stores retain their behavior.
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See [CPU transfer semantics](hardware/cpu.md#instruction-demo-and-execution-rules).
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This proves only the pinned suites' checkpoints and assertions, not complete CPU, bus, or timing compatibility.
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The [pinned public memory ROM](public-memory-tests.md) also passes, with documented video-byte coverage limits.
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The [public BIOS read-protection ROM](public-bios-tests.md) has a separate bounded passing result.
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No public timing, graphics, save, or unsafe suite is claimed as passing.
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These results do not establish Pokémon Emerald compatibility.
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## References
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- [Pinned Thumb entry and result flow](https://github.com/jsmolka/gba-tests/blob/a7113b67e63f83a9b321696ddd7042ccfad6c881/thumb/thumb.asm).
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- [Branch progress markers and successful reset](https://github.com/jsmolka/gba-tests/blob/a7113b67e63f83a9b321696ddd7042ccfad6c881/thumb/branches.asm).
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- [Memory tests, including test 229](https://github.com/jsmolka/gba-tests/blob/a7113b67e63f83a9b321696ddd7042ccfad6c881/thumb/memory.asm).
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- [Shared startup and result macros](https://github.com/jsmolka/gba-tests/blob/a7113b67e63f83a9b321696ddd7042ccfad6c881/lib/macros.inc).
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- [Pinned license](https://github.com/jsmolka/gba-tests/blob/a7113b67e63f83a9b321696ddd7042ccfad6c881/LICENSE).
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