diff --git a/Source/Project64-core/N64System/Arm/ArmOpCode.h b/Source/Project64-core/N64System/Arm/ArmOpCode.h
new file mode 100644
index 000000000..ec5c50aba
--- /dev/null
+++ b/Source/Project64-core/N64System/Arm/ArmOpCode.h
@@ -0,0 +1,63 @@
+/****************************************************************************
+*                                                                           *
+* Project64 - A Nintendo 64 emulator.                                      *
+* http://www.pj64-emu.com/                                                  *
+* Copyright (C) 2012 Project64. All rights reserved.                        *
+*                                                                           *
+* License:                                                                  *
+* GNU/GPLv2 http://www.gnu.org/licenses/gpl-2.0.html                        *
+*                                                                           *
+****************************************************************************/
+#pragma once
+
+#pragma warning(push)
+#pragma warning(disable : 4201) // warning C4201: nonstandard extension used : nameless struct/union
+
+union ArmThumbOpcode
+{
+    uint16_t Hex;
+    uint8_t Ascii[2];
+
+    struct
+    {
+        unsigned rt : 3;
+        unsigned rn : 3;
+        unsigned rm : 3;
+        unsigned opcode : 7;
+    };
+};
+
+union Arm32Opcode
+{
+    uint32_t Hex;
+    uint8_t Ascii[4];
+
+    // uint16 + uint16 type instuction
+    struct
+    {
+        unsigned rn : 4;
+        unsigned opcode : 12;
+        unsigned rm : 4;
+        unsigned imm2 : 2;
+        unsigned reserved : 6;
+        unsigned rt : 4;
+    } uint16;
+
+    struct
+    {
+        unsigned rm : 4;
+        unsigned opcode2 : 8;
+        unsigned rt : 4;
+        unsigned rn : 4;
+        unsigned opcode : 12;
+    } uint32;
+};
+#pragma warning(pop)
+
+enum ArmThumbOpCodes
+{
+    ArmSTR_Reg = 40,
+    ArmLDR_Reg = 44, 
+    ArmLDRH_Reg = 0xE19,
+    ArmLDRH_W = 0xF83,
+};