chore: re-organise source files for color LCD UI (#5358)

radio/src/lib_file.h

@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) EdgeTX
+ *
+ * Based on code named
+ *   libopenui - https://github.com/opentx/libopenui
+ *
+ * License GPLv2: http://www.gnu.org/licenses/gpl-2.0.html
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#pragma once
+
+#include <string>
+#include <cstring>
+#include "ff.h"
+
+constexpr uint8_t LEN_FILE_EXTENSION_MAX = 5;  // longest used, including the dot, excluding null term.
+
+const char * getFileExtension(const char * filename, uint8_t size = 0, uint8_t extMaxLen = 0, uint8_t * fnlen = nullptr, uint8_t * extlen = nullptr);
+bool isExtensionMatching(const char * extension, const char * pattern, char * match = nullptr);
+FRESULT sdReadDir(DIR * dir, FILINFO * fno, bool & firstTime);
+
+// comparison, not case sensitive.
+inline bool compare_nocase(const std::string & first, const std::string & second)
+{
+  return strcasecmp(first.c_str(), second.c_str()) < 0;
+}