Add support for custom calling convention passing arguments in registers

If the compiler decided to pass an argument in a register on an internal function instead of pushing it on the stack to save time, allow us to specify the register the parameter is going to be in.

DHookAddParam received another parameter to set the register.

util.h

@@ -4,6 +4,45 @@
 #include "vhook.h"
 #include "convention.h"
 
+enum PluginRegister
+{
+	// Don't change the register and use the default for the calling convention.
+	DHookRegister_Default,
+
+	// 8-bit general purpose registers
+	DHookRegister_AL,
+	DHookRegister_CL,
+	DHookRegister_DL,
+	DHookRegister_BL,
+	DHookRegister_AH,
+	DHookRegister_CH,
+	DHookRegister_DH,
+	DHookRegister_BH,
+
+	// 32-bit general purpose registers
+	DHookRegister_EAX,
+	DHookRegister_ECX,
+	DHookRegister_EDX,
+	DHookRegister_EBX,
+	DHookRegister_ESP,
+	DHookRegister_EBP,
+	DHookRegister_ESI,
+	DHookRegister_EDI,
+
+	// 128-bit XMM registers
+	DHookRegister_XMM0,
+	DHookRegister_XMM1,
+	DHookRegister_XMM2,
+	DHookRegister_XMM3,
+	DHookRegister_XMM4,
+	DHookRegister_XMM5,
+	DHookRegister_XMM6,
+	DHookRegister_XMM7,
+
+	// 80-bit FPU registers
+	DHookRegister_ST0
+};
+
 size_t GetParamOffset(HookParamsStruct *params, unsigned int index);
 void * GetObjectAddr(HookParamType type, unsigned int flags, void **params, size_t offset);
 size_t GetParamTypeSize(HookParamType type);
@@ -11,4 +50,5 @@ size_t GetParamsSize(DHooksCallback *dg);
 
 DataType_t DynamicHooks_ConvertParamTypeFrom(HookParamType type);
 DataType_t DynamicHooks_ConvertReturnTypeFrom(ReturnType type);
+Register_t DynamicHooks_ConvertRegisterFrom(PluginRegister reg);
 #endif