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feat(memory): support ARM unused-memory open-bus reads

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Snapshot mapped PC+8 bytes for ARM data reads in the documented unused ranges. Preserve strict host/fetch/Thumb/DMA diagnostics, missing-ROM errors, existing write rules, and nominal timing. Add original regressions and document the bounded model.

The unmodified pinned jsmolka ARM ROM now reaches its verified checkpoint with r12=0 in debug and release: 1344 steps and 11257 nominal cycles. No ROM, manifest, or assertion changes.

Validated on Darwin arm64: 842 workspace tests in debug and release; 773 core/demo tests separately; Python adapter tests; native ROM windows; all ten demo window smoke tests; fmt, clippy, and rustdoc.
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0xrsydn 2026-10-05 20:25:18 +07:00
commit a9493d4cc6
11 changed files with 418 additions and 26 deletions
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7
docs/testing.md
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@ -49,7 +49,7 @@ Do not set a Linux cross-compilation target for this validation.
The [headless ROM suite runner](rom-tests.md) provides explicit checkpoint and assertion results through `--test-suite PATH.json`.
Its tests verify manifest limits, whole-suite validation, exact step boundaries, ARM/Thumb checkpoints, and register/CPSR/memory checks.
Additional tests cover DMA/IRQ accounting, HALT/STOP, diagnostic state, case isolation, repeatable JSON output, and failure exit status.
These original tests validate the runner. The [public ARM adapter](public-arm-tests.md) is a separate, currently failing compatibility baseline.
These original tests validate the runner. The [public ARM adapter](public-arm-tests.md) provides a separate passing checkpoint result for its pinned ROM.
Its preparation tests use only synthetic original bytes and no network:
```sh
@ -60,7 +60,10 @@ They verify pinned URLs, hashes, sizes, checkpoint validation, offline copies, d
Compare/status CPU regressions verify saved flags/masks, bank switching, sequential PC/timing, User/System fallback, and atomic diagnostics.
Load-alias regressions cover widths, signed/unaligned values, immediate/register offsets, pre/post-indexing, every non-PC register bank, and address wrapping.
They verify loaded-value precedence, preserved flags, unchanged stores, nominal timing, I/O reads before device progress, deferred IRQ delivery, and atomic errors.
The public ARM ROM progresses past tests 360–361 but still fails on the high-address read in test 362.
ARM open-bus regressions cover unused-range boundaries, PC+8 source regions, byte lanes, signed/unaligned loads, writeback, and block loads.
They check branch-target resampling, missing lookahead, skipped conditions, nominal timing, device progress, and retained host/fetch/Thumb/DMA diagnostics.
The pinned public ARM ROM now reaches its completion checkpoint with r12 = 0 in debug and release builds.
This does not establish public Thumb, timing, graphics, BIOS, or commercial-game compatibility.
ROM-runner tests use temporary files containing original instructions, without Nintendo assets or a desktop session.
They check file-size boundaries, bounded reads, short reads, I/O errors, paths, symlinks, and read-only loading.