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

feat(cpu): retain ARM instruction pipeline words

Browse source 
Buffer ARM sequential fetch results and refill target pairs after branches, PC writes, and machine exception entry. Stage advances transactionally, defer speculative fetch diagnostics, and preserve buffered words across CPU/DMA stores and host edits. Add explicit CPU pipeline invalidation for debugger repair and memory rebinding.

Add 15 original instruction-buffer regressions. Keep full-state rollback equality while distinguishing architectural comparisons in semantic tests. Update the display error test for an already buffered branch. Document evidence and separate remaining Thumb, bus-history, and timing work.

Validated on Darwin arm64: 967 workspace and 898 core/demo tests in each debug/release profile, 39 Python tests, native ROM windows, ten window smoke modes, fmt, clippy, and rustdoc. Public ARM/Thumb/memory/BIOS reports and nominal cycles remain unchanged.
This commit is contained in:
0xrsydn 2026-10-06 03:57:57 +07:00
commit 47df9d05a7
24 changed files with 629 additions and 37 deletions
Download patch file Download diff file Expand all files Collapse all files

14
crates/gba-core/src/memory.rs
View file

@ -69,7 +69,7 @@ struct CpuAccess {
/// Successful refills into Thumb IWRAM sample the target pair to establish history.
/// DMA accesses drive existing Thumb IWRAM continuation lanes before the next fetch.
/// Channel data remains separate; general and sub-instruction CPU bus handoff is unmodeled.
/// A full fetch pipeline and ARM-target refill history are not modeled.
/// CPU-owned ARM instruction buffering does not yet drive complete bus history or timing.
pub struct Memory {
external_ram: Vec<u8>,
internal_ram: Vec<u8>,
@ -408,6 +408,18 @@ impl Memory {
]))
}
/// Strict ARM fetch without CPU data context, timing trace, or bus-history changes.
pub(crate) fn fetch_arm_word(&self, address: u32) -> Result<u32, MemoryError> {
if address & 3 != 0 {
return Err(MemoryError::Unaligned(address));
}
let mut bytes = [0; 4];
for (offset, byte) in bytes.iter_mut().enumerate() {
*byte = self.read_mapped_byte(address.wrapping_add(offset as u32))?;
}
Ok(u32::from_le_bytes(bytes))
}
fn snapshot_mapped_word(&self, address: u32) -> Option<u32> {
let mut bytes = [0; 4];
for (offset, byte) in bytes.iter_mut().enumerate() {