better support for multiple devices

src/flash_filer.cpp

@@ -137,6 +137,21 @@ const char *flash_filer::rewind() {
 	return advance();
 }
 
+const char *flash_filer::filename() const {
+#if defined(USE_SPIFFS) || defined(USE_LITTLEFS)
+	File &f = files[_current];
+	if (f)
+		return f.name();
+#endif
+	return 0;
+}
+
+void flash_filer::next_device() {
+	_current++;
+	if (_current == MAX_FILES)
+		_current = 0;
+}
+
 #if !defined(NO_CHECKPOINT)
 #if defined(USE_SPIFFS)
 static char buf[32];

src/flash_filer.h

@@ -24,14 +24,18 @@ public:
 
 	const char *advance();
 	const char *rewind();
+	const char *filename() const;
+	void next_file() { advance(); }
 
 	const char *checkpoint();
 	void restore(const char *);
 
 	bool start();
 	void stop();
+	void reset() { stop(); start(); }
 
-	void select(uint8_t f) { _current = f; }
+	void next_device();
+	uint8_t device() const { return _current; }
 
 private:
 	const char *_programs;