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fix(bios): preserve documented protected-read words at firmware exits

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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.
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0xrsydn 2026-10-06 00:37:20 +07:00
commit efdc288db6
15 changed files with 387 additions and 34 deletions
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7
docs/rom-tests.md
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@ -4,7 +4,7 @@ Use `--test-suite PATH.json` to run repeatable ROM checks without opening a wind
Each case has a machine-step budget, a completion address, and explicit assertions.
A timeout never counts as a pass. Existing `--rom ... --steps ...` remains a diagnostic mode, not a test verdict.
Original programs cover the runner itself. Pinned public [ARM](public-arm-tests.md), [Thumb](public-thumb-tests.md), and [memory](public-memory-tests.md) ROMs provide independent compatibility results.
Original programs cover the runner itself. Pinned public [ARM](public-arm-tests.md), [Thumb](public-thumb-tests.md), [memory](public-memory-tests.md), and [BIOS](public-bios-tests.md) ROMs provide independent compatibility results.
These pinned ROMs pass their checkpoints on Darwin arm64 in debug and release builds.
The memory ROM has documented assertion and mode-selection limits; a pass is not exhaustive memory validation.
Passing the runner's unit tests does not mean an external suite passes.
@ -137,8 +137,9 @@ The first public integration is [jsmolka/gba-tests ARM](public-arm-tests.md), wi
The pinned ARM ROM now passes this checkpoint on Darwin arm64. Historical failures remain documented.
The [pinned Thumb ROM](public-thumb-tests.md) also passes its verified r7 checkpoint after the empty-list store correction.
The [pinned memory ROM](public-memory-tests.md) also passes, without a core change and with explicit coverage limits.
The [pinned BIOS read-protection ROM](public-bios-tests.md) reaches its checkpoint but fails test 1 with the original replacement BIOS.
Its expected values depend on Nintendo firmware. Record that failure rather than changing the assertion or returning guessed constants.
The [pinned BIOS read-protection ROM](public-bios-tests.md) also passes with the original replacement BIOS.
Its documented boundary values come from compatibility data in our firmware's exit layout, not a bus override.
The ROM, assertions, checkpoint, and budget remain unchanged. This is not a complete BIOS service test.
For further public ARM7TDMI/GBA tests, inspect their source, license, entry assumptions, and result protocol.
Pin source revisions and build instructions before comparing emulator changes.
Adapt suites to verified completion addresses and result locations; do not guess them or treat timeouts as passes.