From 864a4b38aaa0a7268a278fb5821e230182337a84 Mon Sep 17 00:00:00 2001
From: LunaMoo <LunaMoo@users.noreply.github.com>
Date: Wed, 18 Sep 2024 11:51:07 +0200
Subject: [PATCH] Work around Brothers in Arms speed issue via compat hack
 (#18513)
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Co-authored-by: Henrik Rydgård <hrydgard@gmail.com>
---
 Core/Compatibility.cpp     | 1 +
 Core/Compatibility.h       | 1 +
 Core/HLE/sceKernelTime.cpp | 2 ++
 assets/compat.ini          | 6 ++++++
 4 files changed, 10 insertions(+)

diff --git a/Core/Compatibility.cpp b/Core/Compatibility.cpp
index f0d00747a6..e9a6f1a201 100644
--- a/Core/Compatibility.cpp
+++ b/Core/Compatibility.cpp
@@ -136,6 +136,7 @@ void Compatibility::CheckSettings(IniFile &iniFile, const std::string &gameID) {
 	CheckSetting(iniFile, gameID, "LoadCLUTFromCurrentFrameOnly", &flags_.LoadCLUTFromCurrentFrameOnly);
 	CheckSetting(iniFile, gameID, "ForceUMDReadSpeed", &flags_.ForceUMDReadSpeed);
 	CheckSetting(iniFile, gameID, "AllowDelayedReadbacks", &flags_.AllowDelayedReadbacks);
+	CheckSetting(iniFile, gameID, "KernelGetSystemTimeLowEatMoreCycles", &flags_.KernelGetSystemTimeLowEatMoreCycles);
 	CheckSetting(iniFile, gameID, "TacticsOgreEliminateDebugReadback", &flags_.TacticsOgreEliminateDebugReadback);
 	CheckSetting(iniFile, gameID, "FramebufferAllowLargeVerticalOffset", &flags_.FramebufferAllowLargeVerticalOffset);
 	CheckSetting(iniFile, gameID, "DisableMemcpySlicing", &flags_.DisableMemcpySlicing);
diff --git a/Core/Compatibility.h b/Core/Compatibility.h
index 75939a5340..bf6bca0295 100644
--- a/Core/Compatibility.h
+++ b/Core/Compatibility.h
@@ -106,6 +106,7 @@ struct CompatFlags {
 	bool LoadCLUTFromCurrentFrameOnly;
 	bool ForceUMDReadSpeed;
 	bool AllowDelayedReadbacks;
+	bool KernelGetSystemTimeLowEatMoreCycles;
 	bool TacticsOgreEliminateDebugReadback;
 	bool FramebufferAllowLargeVerticalOffset;
 	bool DisableMemcpySlicing;
diff --git a/Core/HLE/sceKernelTime.cpp b/Core/HLE/sceKernelTime.cpp
index 5c300283ac..60f16286d8 100644
--- a/Core/HLE/sceKernelTime.cpp
+++ b/Core/HLE/sceKernelTime.cpp
@@ -83,6 +83,8 @@ u32 sceKernelGetSystemTimeLow()
 	u64 t = CoreTiming::GetGlobalTimeUs();
 	VERBOSE_LOG(Log::sceKernel,"%08x=sceKernelGetSystemTimeLow()",(u32)t);
 	hleEatCycles(165);
+	if (PSP_CoreParameter().compat.flags().KernelGetSystemTimeLowEatMoreCycles)
+		hleEatCycles(70000);
 	hleReSchedule("system time");
 	return (u32)t;
 }
diff --git a/assets/compat.ini b/assets/compat.ini
index bf5aa82d1e..beabb9aa6b 100644
--- a/assets/compat.ini
+++ b/assets/compat.ini
@@ -264,6 +264,12 @@ ULJM06365 = true
 # ULJM05036 = true
 # ULUS10044 = true
 
+[KernelGetSystemTimeLowEatMoreCycles]
+# Brothers in Arms: D-Day works around weird FPS(falling under 100% even on powerful hardware) as well as it's animation speed #18509
+# recommend to OC PSP CPU to at least twice as much as real PSP to get constant 60 fps
+ULES00608 = true
+ULUS10193 = true
+
 [DrawSyncInstant]
 # Bizarre timing issue in Sakura-sou no Pet na Kanojo, see issue #15224. Note that an instant DrawSync is not logical.
 NPJH50745 = true