Initial HID PAD work, with GLFW only.

src/common/key_map.h

@@ -0,0 +1,35 @@
+// Copyright 2013 Dolphin Emulator Project
+// Licensed under GPLv2
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include "core/hle/service/hid.h"
+
+namespace KeyMap {
+
+class CitraKey {
+public:
+    CitraKey() : keyCode(0) {}
+    CitraKey(int code) : keyCode(code) {}
+
+    int keyCode;
+
+    bool operator < (const CitraKey &other) const {
+        return keyCode < other.keyCode;
+    }
+
+    bool operator == (const CitraKey &other) const {
+        return keyCode == other.keyCode;
+    }
+};
+
+struct DefaultKeyMapping {
+    KeyMap::CitraKey key;
+    HID_User::PADState state;
+};
+
+void SetKeyMapping(CitraKey key, HID_User::PADState padState);
+HID_User::PADState Get3DSKey(CitraKey key);
+
+}