0xrsydn/gameboy-rust
1
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

fix(memory): ignore CPU and DMA writes to unused I/O addresses

Browse source 
Stores to I/O addresses with no register returned Unmapped and stopped the
machine. Hardware ignores them. Emulated writes there now pay their bus cost and
change nothing; host writes stay strict. The unmodeled internal memory control
register at 0x04xx0800 and all unused I/O reads remain diagnostics.

Rollback tests that used unused I/O as their failing word now run the block on
to a register that rejects the stored value: SIOMULTI2 outside multiplayer
mode, an RCNT GPIO serial IRQ, or 64-sample wave playback. Where no reachable
register can fail (JOYSTAT, POSTFLG/HALTCNT, IME, DMA3CNT), the test now checks
that the block commits and the unused word is ignored.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HhfHfHEuzv2AUTd6erW1gU
This commit is contained in:
0xrsydn 2026-10-14 11:38:51 +07:00
commit 20176716d9
16 changed files with 166 additions and 92 deletions
Download patch file Download diff file Expand all files Collapse all files

2
crates/gba-core/tests/dma/latch.rs
View file

@ -146,7 +146,7 @@ fn failed_units_preserve_the_old_latch_without_new_data_or_irq() {
for (source, destination, control) in [
(0x0e00_0000, DEST, 0x4400), // Unmapped reads do not use a known latch.
(SOURCE, 0x0d00_0000, 0x4400),
(SOURCE, 0x0400_0058, 0x4400),
(SOURCE, 0x0400_0800, 0x4400),
(SOURCE, DMA_BASE, 0x4400),
(SOURCE, 0x0400_0300, 0x4400),
(SOURCE, DEST, 0x4580), // Unsupported source mode.