add mp3 player code

Code/MP3Player/sd_reader_task.h

@@ -0,0 +1,50 @@
+#ifndef SD_READER_TASK_H
+#define SD_READER_TASK_H
+
+#include <cstdint>
+#include "task.h"
+#include "lock_base_rp2040.h"
+#include "mutex.h"
+#include "condition_variable.h"
+#include "ff.h"
+
+class sd_reader_task : public task
+{
+public:
+    sd_reader_task();
+
+    void run() override;
+
+    // Start the SD reading with a new file
+    void start(FatFs * fs, FatFs::FILE * file);
+    // Read some data from the file
+    FatFs::FRESULT read_data(uint8_t* buff, uint16_t btr, uint16_t* br);
+    // EOF handling
+    inline bool eof() const {
+        return _eof || _force_eof;
+    }
+    inline void force_eof() {
+        _force_eof = true;
+    }
+
+private:
+
+    FatFs *         _fs;       // FatFs object
+    FatFs::FILE *   _file;     // MP3 file on SD
+
+    uint8_t *       _req_buff;
+    uint16_t        _req_btr;
+    uint16_t *      _req_br;
+    FatFs::FRESULT  _req_result;
+    bool            _eof;
+    bool            _force_eof;
+
+    volatile bool                         _execute;
+    mutex<lock_base_rp2040>               _execute_mutex;
+    condition_variable<lock_base_rp2040>  _execute_cv;
+
+    mutex<lock_base_rp2040>               _caller_mutex;
+    condition_variable<lock_base_rp2040>  _caller_cv;
+};
+
+#endif // SD_READER_TASK_H