From e461ebb90a7b30480fa64e5544e9772602a8ef7b Mon Sep 17 00:00:00 2001
From: CasualPokePlayer <50538166+CasualPokePlayer@users.noreply.github.com>
Date: Fri, 15 May 2026 22:48:36 -0700
Subject: [PATCH] Fix GBA serial timings to pass serial timing tests

Yes, this is weird. There is apparently just an extra 6 cycles for serial transfers, at least as far as testing indicates.

See https://github.com/mgba-emu/suite and https://github.com/alyosha-tas/gba-tests for serial timing tests.
---
 Core/GBA/GbaSerial.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Core/GBA/GbaSerial.h b/Core/GBA/GbaSerial.h
index 6ff3b8a51..15935355e 100644
--- a/Core/GBA/GbaSerial.h
+++ b/Core/GBA/GbaSerial.h
@@ -133,6 +133,7 @@ class GbaSerial final : public ISerializable
 				if(active && !_state.Active) {
 					_state.StartMasterClock = _memoryManager->GetMasterClock();
 					_state.EndMasterClock = _state.StartMasterClock + (_state.InternalShiftClockSpeed2MHz ? 8 : 64) * (_state.TransferWord ? 32 : 8);
+					_state.EndMasterClock += 6;
 					if(_state.IrqEnabled) {
 						_state.IrqMasterClock = _state.EndMasterClock;
 						_memoryManager->SetPendingUpdateFlag();
@@ -156,6 +157,7 @@ class GbaSerial final : public ISerializable
 					if(_state.StartMasterClock == _memoryManager->GetMasterClock()) {
 						//Update end based on params
 						_state.EndMasterClock = _state.StartMasterClock + (_state.InternalShiftClockSpeed2MHz ? 8 : 64) * (_state.TransferWord ? 32 : 8);
+						_state.EndMasterClock += 6;
 					}
 					if(_state.IrqEnabled) {
 						_state.IrqMasterClock = _state.EndMasterClock;