0xrsydn/gameboy-rust
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feat(bios): implement byte and halfword differential filters

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Add SWI 0x16, 0x17, and 0x18 as original ARM routines. Reconstruct samples with modular addition and byte or halfword output. Validate headers, alignment, lengths, and address ranges; preserve earlier completed writes on failure.

Add 17 regression tests for sample round trips, wraparound, large byte lengths, caller state, partial failures, bus behavior, and DMA/IRQ progress. Validate 635 default and 624 core-only tests in debug and release, plus all 10 native Darwin ARM64 window smoke tests.
This commit is contained in:
0xrsydn 2026-10-05 13:10:46 +07:00
commit 3ebc1f03d0
6 changed files with 534 additions and 12 deletions
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9
src/bios.rs
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@ -1,6 +1,6 @@
//! Original, optional ARM BIOS replacement. No Nintendo firmware is included.
//! Supports interrupt waits, integer arithmetic, memory copy/fill, bit unpacking,
//! and LZ77/run-length decoding.
//! LZ77/run-length decoding, and differential filters.
//! This is a functional subset, not a complete boot ROM or a timing-compatible BIOS.
use std::collections::BTreeMap;
@ -8,6 +8,7 @@ use std::collections::BTreeMap;
mod arithmetic;
mod bit_unpack;
mod decompression;
mod differential;
mod lz77;
mod run_length;
@ -25,7 +26,7 @@ pub const IRQ_FLAGS: u32 = 0x0300_7ff8;
pub const IRQ_HANDLER: u32 = 0x0300_7ffc;
/// An intentional undefined instruction used for unsupported SWIs/vectors and invalid IRQ pointers.
pub const UNSUPPORTED_TRAP: u32 = 0xe7f0_00f0;
/// A separate diagnostic trap for division by zero or invalid unpacking/decompression arguments.
/// A diagnostic trap for division by zero or invalid unpacking, decompression, or filter arguments.
pub const INVALID_ARGUMENT_TRAP: u32 = 0xe7f0_00f1;
/// Start at reset with our optional firmware. Call Machine::step to execute boot.
@ -126,6 +127,9 @@ pub fn image() -> Vec<u8> {
(0x12, "lz_vram"),
(0x14, "rl_wram"),
(0x15, "rl_vram"),
(0x16, "diff8_wram"),
(0x17, "diff8_vram"),
(0x18, "diff16"),
] {
a.emit(0xe35c_0000 | number); // CMP r12,#service
a.branch(0, target);
@ -221,6 +225,7 @@ pub fn image() -> Vec<u8> {
bit_unpack::emit(&mut a);
lz77::emit(&mut a);
run_length::emit(&mut a);
differential::emit(&mut a);
decompression::emit_writer(&mut a);
a.label("return");