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feat(dma): retain per-channel transfer data

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Retain independent known data across DMA blocks. Duplicate mapped halfword sources and select the destination lane for blocked sources below work RAM. Keep cold history diagnostic, commit only successful units, and preserve separate CPU/BIOS history rules.

Add 13 original regressions and pinned source research. CPU resume ownership, general DMA open bus, and IWRAM DMA lane effects remain explicit limits.

Validated on Darwin arm64: 930 workspace and 861 core/demo tests in debug and release, 39 Python tests, native ROM windows, ten window smoke modes, fmt, clippy, and rustdoc. Public ARM/Thumb/memory/BIOS reports match the previous results exactly.
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0xrsydn 2026-10-06 02:14:19 +07:00
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12 changed files with 465 additions and 24 deletions
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docs/references.md
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@ -121,6 +121,15 @@ IWRAM refill research:
These sources support bounded refill sampling, not a claim of cycle-accurate pipeline or DMA behavior.
DMA data-latch research:
- [NanoBoyAdvance hardware latch test at cc3f4a28](https://codeberg.org/nba-emu/hw-test/src/commit/cc3f4a286cdef823980d9b353bd70befc9927d28/dma/latch/source/main.c), for per-channel ownership, halfword duplication, blocked-source retention, and destination lane selection.
Its [BSD-3-Clause license](https://codeberg.org/nba-emu/hw-test/src/commit/cc3f4a286cdef823980d9b353bd70befc9927d28/LICENSE) was reviewed. No source or ROM was imported.
- [NanoBoyAdvance DMA at 55b5cf0a](https://github.com/nba-emu/NanoBoyAdvance/blob/55b5cf0ae3d929582ac5bfd486558173502b8354/src/nba/src/hw/dma/dma.cc) and [its data structures](https://github.com/nba-emu/NanoBoyAdvance/blob/55b5cf0ae3d929582ac5bfd486558173502b8354/src/nba/src/hw/dma/dma.hh), compared with its bus read ordering.
- [ares DMA at 6f6786e0](https://github.com/ares-emulator/ares/blob/6f6786e04f0822a3475463df284f313ab8518d51/ares/gba/cpu/dma.cpp), compared with its IWRAM and general-bus dispatch above.
See [DMA data-latch findings](research/dma-data-latches.md). Source review is not a local hardware-test pass.
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.