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

4
crates/desktop/tests/rom_cli.rs
View file

@ -403,9 +403,11 @@ fn rtc_selection_is_explicit_and_does_not_modify_the_rom_file() {
let fixture = Fixture::new();
let path = fixture.rom(&rtc_setup());
let original = fs::read(&path).unwrap();
// Without the device, the GPIO store is an ordinary ignored ROM write. The read-back
// then reaches past this short image, which remains a diagnostic.
let absent = run(&path, "100");
assert_eq!(absent.status.code(), Some(1));
assert!(stderr(&absent).contains("read-only memory at 0x080000c8"));
assert!(stderr(&absent).contains("unmapped memory at 0x080000c8"));
let selected = command()
.arg("--rtc")
.arg("--rom")