From 2b06bb5a5980acaf69090fde58c7e4bb563b5a50 Mon Sep 17 00:00:00 2001
From: Luke Usher <luke.usher@outlook.com>
Date: Wed, 4 Oct 2017 10:19:55 +0100
Subject: [PATCH] Derive Gamepad Structure from XAPI functions

---
 src/CxbxKrnl/EmuXapi.cpp    | 43 +++++++++++++++++++++++++++++++++++++
 src/CxbxKrnl/EmuXapi.h      | 11 ++++++++++
 src/CxbxKrnl/HLEIntercept.h |  4 ++++
 3 files changed, 58 insertions(+)

diff --git a/src/CxbxKrnl/EmuXapi.cpp b/src/CxbxKrnl/EmuXapi.cpp
index f44b71c6e..41202eacf 100644
--- a/src/CxbxKrnl/EmuXapi.cpp
+++ b/src/CxbxKrnl/EmuXapi.cpp
@@ -61,6 +61,8 @@ extern HANDLE g_hInputHandle[XINPUT_HANDLE_SLOTS] = {0};
 
 bool g_bXInputOpenCalled = false;
 
+XTL::PXPP_DEVICE_TYPE gDeviceType_Gamepad = nullptr;
+
 bool CxbxMountUtilityDrive(bool formatClean);
 
 // ******************************************************************
@@ -136,6 +138,47 @@ VOID WINAPI XTL::EMUPATCH(XInitDevices)
 		LOG_FUNC_ARG(PreallocTypes)
 		LOG_FUNC_END;
 
+
+	// If we don't yet have the offset to gDeviceType_Gamepad, work it out!
+	if (gDeviceType_Gamepad == nullptr) {
+		// First, attempt to find GetTypeInformation
+		auto typeInformation = g_SymbolAddresses.find("GetTypeInformation");
+		if (typeInformation != g_SymbolAddresses.end() && typeInformation->second != (xbaddr)nullptr) {
+			DbgPrintf("Deriving XDEVICE_TYPE_GAMEPAD from GetTypeInformation");
+			// Read the offset values of the device table structure from GetTypeInformation
+			uint32_t deviceTableStartOffset = *(uint32_t*)((uint32_t)typeInformation->second + 0x01);
+			uint32_t deviceTableEndOffset = *(uint32_t*)((uint32_t)typeInformation->second + 0x09);
+
+			// Calculate the number of device entires in the table
+			size_t deviceTableEntryCount = (deviceTableEndOffset - deviceTableStartOffset) / sizeof(uint32_t);
+			
+			// Iterate through the table until we find gamepad
+			PXID_TYPE_INFORMATION* deviceTable = (PXID_TYPE_INFORMATION*)(deviceTableStartOffset);
+			for (int i = 0; i < deviceTableEntryCount; i++) {
+				// If we found the gamepad structure (type 1), use it and exit the loop
+				if (deviceTable[i]->ucType == 1) {
+					gDeviceType_Gamepad = deviceTable[i]->XppType;
+					break;
+				}
+			}
+		} else {
+			// XDKs without GetTypeInformation have the GamePad address hardcoded in XInputOpen
+			// Only the earliest XDKs use this code path, and the offset never changed between them
+			// so this works well for us.
+			DbgPrintf("XAPI: Deriving XDEVICE_TYPE_GAMEPAD from XInputOpen");
+			void* XInputOpenAddr = (VOID*)g_SymbolAddresses["XInputOpen"];
+			gDeviceType_Gamepad = *(PXPP_DEVICE_TYPE*)((uint32_t)XInputOpenAddr + 0x0B);
+		}
+
+		if (gDeviceType_Gamepad == nullptr) {
+			CxbxKrnlCleanup("XAPI: XDEVICE_TYPE_GAMEPAD was not found");
+		}
+
+		DbgPrintf("XAPI: XDEVICE_TYPE_GAMEPAD Found at 0x%08X", gDeviceType_Gamepad);
+		// Set the device as connected
+		gDeviceType_Gamepad->CurrentConnected = 1;
+	}
+
     for(int v=0;v<XINPUT_SETSTATE_SLOTS;v++)
     {
         g_pXInputSetStateStatus[v].hDevice = 0;
diff --git a/src/CxbxKrnl/EmuXapi.h b/src/CxbxKrnl/EmuXapi.h
index 10bdec0ac..6349f0fb6 100644
--- a/src/CxbxKrnl/EmuXapi.h
+++ b/src/CxbxKrnl/EmuXapi.h
@@ -148,6 +148,17 @@ typedef struct _XPP_DEVICE_TYPE
 }
 XPP_DEVICE_TYPE, *PXPP_DEVICE_TYPE;
 
+// ******************************************************************
+// * XID_TYPE_INFORMATION
+// ******************************************************************
+typedef struct _XID_TYPE_INFORMATION
+{
+	UCHAR				ucType;
+	UCHAR				ucUnknown[3];
+	PXPP_DEVICE_TYPE    XppType;
+	DWORD				dwUnknown[5];
+} XID_TYPE_INFORMATION, *PXID_TYPE_INFORMATION;
+
 // ******************************************************************
 // * XDEVICE_PREALLOC_TYPE
 // ******************************************************************
diff --git a/src/CxbxKrnl/HLEIntercept.h b/src/CxbxKrnl/HLEIntercept.h
index ef169019a..e702248b1 100644
--- a/src/CxbxKrnl/HLEIntercept.h
+++ b/src/CxbxKrnl/HLEIntercept.h
@@ -34,10 +34,14 @@
 #ifndef HLEINTERCEPT_H
 #define HLEINTERCEPT_H
 
+#include <map>
+
 extern bool bLLE_APU; // Set this to true for experimental APU (sound) LLE
 extern bool bLLE_GPU; // Set this to true for experimental GPU (graphics) LLE
 extern bool bLLE_JIT; // Set this to true for experimental JIT
 
+extern std::map<std::string, xbaddr> g_SymbolAddresses;
+
 void EmuHLEIntercept(Xbe::Header *XbeHeader);
 
 std::string GetDetectedSymbolName(xbaddr address, int *symbolOffset);