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fix(bios): return cleanly for empty LZ77 streams

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0xrsydn 2026-10-07 09:05:45 +07:00
commit 7772a9d8eb
8 changed files with 156 additions and 11 deletions
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31
crates/gba-core/tests/bios/lz77.rs
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@ -305,16 +305,39 @@ fn decompression_restores_user_mode_masks_and_all_caller_registers() {
}
#[test]
fn zero_output_length_does_not_read_flags_or_touch_destination() {
fn empty_headers_ignore_type_without_reading_payload_or_accessing_destination() {
// Original synthetic headers, including the all-zero empty-stream case.
// The unmapped, odd destination also proves no output alignment/access is needed.
for service in [0x11, 0x12] {
let (mut machine, return_pc) = prepare(service, false, 0x0e00_0000, &[0x10, 0, 0, 0]);
complete(&mut machine, return_pc); // Destination and next source byte are unmapped.
for thumb in [false, true] {
for low_byte in 0..=255 {
let (mut machine, return_pc) =
prepare(service, thumb, 0x0e00_0001, &[low_byte, 0, 0, 0]);
let before = machine.cpu().clone();
complete(&mut machine, return_pc); // Header ends at the last supplied ROM byte.
assert_eq!(&machine.cpu().registers()[..15], &before.registers()[..15]);
assert_eq!(machine.cpu().cpsr(), before.cpsr());
}
}
}
}
#[test]
fn empty_headers_preserve_ram_video_and_stack_sentinels() {
for service in [0x11, 0x12] {
for thumb in [false, true] {
for destination in [DEST, VRAM_START + 4] {
for low_byte in [0, 0x10, 0xff] {
verify(service, thumb, destination, &[low_byte, 0, 0, 0], &[]);
}
}
}
}
}
#[test]
fn bad_headers_alignment_and_wrapping_destinations_are_rejected() {
for header in [0_u32, 0x0200, 0x0211, 0x0220, 0x02ff] {
for header in [0x0100_u32, 0x0200, 0x0211, 0x0220, 0x02ff] {
let (mut machine, _) = prepare(0x11, false, DEST, &header.to_le_bytes());
assert_invalid(fail(&mut machine));
assert_eq!(machine.memory().read32(DEST).unwrap(), 0);