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

fix(memory): ignore CPU and DMA writes to the Game Pak ROM windows

Browse source 
Stores to 0x08-0x0c returned ReadOnly and stopped the machine. Hardware ignores
them, and a second game's boot code stores to a ROM mirror. Emulated writes now
pay their bus cost and change nothing. The 0x0d window stays a diagnostic until
EEPROM is modeled there, and host writes stay strict.

Tests that used a ROM store as their failing write now cross an ignored ROM
word into the 0x0d window.

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 08:26:03 +07:00
commit 258fbff2fa
25 changed files with 86 additions and 74 deletions
Download patch file Download diff file Expand all files Collapse all files

5
crates/gba-core/tests/bios/affine.rs
View file

@ -498,12 +498,11 @@ fn destination_failure_keeps_preceding_halfword_stores() {
angle: 0,
}])
};
let (mut m, _) = prepare(service, false, [DATA, 0x07ff_fffc, 1, 2], 0x1f, &data);
let (mut m, _) = prepare(service, false, [DATA, 0x0cff_fffc, 1, 2], 0x1f, &data);
assert_eq!(
fail(&mut m),
MachineError::Cpu(MemoryError::ReadOnly(ROM_START).into())
MachineError::Cpu(MemoryError::ReadOnly(0x0d00_0000).into())
);
assert_eq!(m.memory().read32(0x07ff_fffc).unwrap(), 256);
}
}