0xrsydn/gameboy-rust
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feat(memory): retain IWRAM lane effects across DMA

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Update existing Thumb IWRAM continuation lanes from successful DMA reads and writes before the resumed PC+4 snapshot. Keep channel halfword duplication separate from actual lane accesses. Preserve atomic errors, cold-entry diagnostics, IRQ invalidation, and nominal timing.

Add original DMA matrices and resume regressions; update prior invalidation expectations. Record pinned ares and jgenesis evidence and explicit limits for cross-state history, general open bus, and sub-instruction arbitration.

Validated on Darwin arm64: 939 workspace and 870 core/demo tests per debug/release profile, 39 Python tests, native ROM windows, ten window smoke modes, fmt, clippy, and rustdoc. Public ARM/Thumb/memory/BIOS reports remain identical to the previous results.
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0xrsydn 2026-10-06 02:34:58 +07:00
commit 663b25e5d1
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docs/references.md
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@ -130,6 +130,15 @@ DMA data-latch research:
See [DMA data-latch findings](research/dma-data-latches.md). Source review is not a local hardware-test pass.
DMA IWRAM continuation research:
- [jgenesis bus at fab6e2cc](https://github.com/jsgroth/jgenesis/blob/fab6e2ccc60e492dd68b7f1e927b0829a6d80195/backend/gba-core/src/bus.rs), for DMA read/write dispatch through the same lane-retaining IWRAM helpers as CPU accesses.
Its [DMA controller](https://github.com/jsgroth/jgenesis/blob/fab6e2ccc60e492dd68b7f1e927b0829a6d80195/backend/gba-core/src/dma.rs) and [memory storage](https://github.com/jsgroth/jgenesis/blob/fab6e2ccc60e492dd68b7f1e927b0829a6d80195/backend/gba-core/src/memory.rs) distinguish channel data from local bus lanes.
- The pinned ares DMA, bus dispatch, and IWRAM helpers above independently use the same local lane ownership.
See [the bounded DMA continuation extension](research/iwram-bus-history.md#dma-continuation-extension).
These source reviews do not establish sub-instruction arbitration, exact CPU resume timing, or hardware conformance.
Use [GBATEK](https://problemkaputt.de/gbatek.htm) and ARM7TDMI documentation for further hardware work.
Only use game ROMs that you may lawfully use. Do not commit game ROMs, BIOS files, or game assets.
The ignore file excludes `roms/`, common game ROM extensions, and save files.