Replace audio event fetching with hook (#603)

Takes the previous audio event code, which relied on reading out a register using masm, and replaces it with a new hook.
Adapted from NorthstarPrime https://github.com/F1F7Y/NorthstarPrime

Co-authored-by: F1F7Y <filip.bartos07@proton.me>

3 files changed, 11 insertions, 31 deletions

diff --git a/NorthstarDLL/CMakeLists.txt b/NorthstarDLL/CMakeLists.txt
index 5c275887..d238f61f 100644
--- a/NorthstarDLL/CMakeLists.txt
+++ b/NorthstarDLL/CMakeLists.txt
@@ -148,7 +148,6 @@ add_library(NorthstarDLL SHARED
             "util/version.h"
             "util/wininfo.cpp"
             "util/wininfo.h"
-            "audio_asm.asm"
             "dllmain.cpp"
             "dllmain.h"
             "ns_version.h"
diff --git a/NorthstarDLL/audio_asm.asm b/NorthstarDLL/audio_asm.asm
deleted file mode 100644
index 1b2d3f8d..00000000
--- a/NorthstarDLL/audio_asm.asm
+++ /dev/null
@@ -1,8 +0,0 @@
-public Audio_GetParentEvent
-
-.code
-Audio_GetParentEvent proc
-	mov rax, r12
-	ret
-Audio_GetParentEvent endp
-end
diff --git a/NorthstarDLL/client/audio.cpp b/NorthstarDLL/client/audio.cpp
index 66d34404..aa32e390 100644
--- a/NorthstarDLL/client/audio.cpp
+++ b/NorthstarDLL/client/audio.cpp
@@ -10,11 +10,7 @@
 
 AUTOHOOK_INIT()
 
-extern "C"
-{
-	// should be called only in LoadSampleMetadata_Hook
-	extern void* __fastcall Audio_GetParentEvent();
-}
+static const char* pszAudioEventName;
 
 ConVar* Cvar_mileslog_enable;
 ConVar* Cvar_ns_print_played_sounds;
@@ -366,32 +362,16 @@ bool ShouldPlayAudioEvent(const char* eventName, const std::shared_ptr<EventOver
 	return true; // good to go
 }
 
-// forward declare
-bool __declspec(noinline) __fastcall LoadSampleMetadata_Internal(
-	uintptr_t parentEvent, void* sample, void* audioBuffer, unsigned int audioBufferLength, int audioType);
-
-// DO NOT TOUCH THIS FUNCTION
-// The actual logic of it in a separate function (forcefully not inlined) to preserve the r12 register, which holds the event pointer.
 // clang-format off
 AUTOHOOK(LoadSampleMetadata, mileswin64.dll + 0xF110, 
 bool, __fastcall, (void* sample, void* audioBuffer, unsigned int audioBufferLength, int audioType))
 // clang-format on
 {
-	uintptr_t parentEvent = (uintptr_t)Audio_GetParentEvent();
-
 	// Raw source, used for voice data only
 	if (audioType == 0)
 		return LoadSampleMetadata(sample, audioBuffer, audioBufferLength, audioType);
 
-	return LoadSampleMetadata_Internal(parentEvent, sample, audioBuffer, audioBufferLength, audioType);
-}
-
-// DO NOT INLINE THIS FUNCTION
-// See comment below.
-bool __declspec(noinline) __fastcall LoadSampleMetadata_Internal(
-	uintptr_t parentEvent, void* sample, void* audioBuffer, unsigned int audioBufferLength, int audioType)
-{
-	char* eventName = (char*)parentEvent + 0x110;
+	const char* eventName = pszAudioEventName;
 
 	if (Cvar_ns_print_played_sounds->GetInt() > 0)
 		spdlog::info("[AUDIO] Playing event {}", eventName);
@@ -491,6 +471,15 @@ bool __declspec(noinline) __fastcall LoadSampleMetadata_Internal(
 }
 
 // clang-format off
+AUTOHOOK(sub_1800294C0, mileswin64.dll + 0x294C0,
+void*, __fastcall, (void* a1, void* a2))
+// clang-format on
+{
+	pszAudioEventName = reinterpret_cast<const char*>((*((__int64*)a2 + 6)));
+	return sub_1800294C0(a1, a2);
+}
+
+// clang-format off
 AUTOHOOK(MilesLog, client.dll + 0x57DAD0, 
 void, __fastcall, (int level, const char* string))
 // clang-format on