add mp3 player code

Code/MP3Player/sd_reader_task.cpp

@@ -0,0 +1,52 @@
+#include "config.h"
+#include "sd_reader_task.h"
+
+sd_reader_task::sd_reader_task() : task("SD reader", SD_READER_STACKSIZE),
+    _fs(nullptr),
+    _file(nullptr),
+    _req_buff(nullptr),
+    _req_btr(0),
+    _req_br(nullptr),
+    _req_result(FatFs::FR_OK),
+    _eof(false),
+    _force_eof(false),
+    _execute(false)
+{ }
+
+void sd_reader_task::start(FatFs * fs, FatFs::FILE * file) {
+    _fs        = fs;
+    _file      = file;
+    _eof       = false;
+    _force_eof = false;
+    _execute   = false;
+    task::start();
+}
+
+FatFs::FRESULT sd_reader_task::read_data(uint8_t* buff, uint16_t btr, uint16_t* br) {
+    // Copy request parameters
+    _req_buff = buff;
+    _req_btr  = btr;
+    _req_br   = br;
+    // Trigger task execution
+    _execute_mutex.lock();
+    _execute = true;
+    _execute_mutex.unlock();
+    _execute_cv.notify_one();
+    // Wait for execution to complete
+    _caller_cv.wait(_caller_mutex, [this]() {return !_execute;});
+    // Return the result of the execution
+    return _req_result;
+}
+
+void sd_reader_task::run() {
+    do {
+        // Wait for a new request
+        _execute_cv.wait(_execute_mutex, [this]() {return _execute;});
+        // Read in the requested bytes
+        _req_result = _fs->read(_file, _req_buff, _req_btr, _req_br);
+        _eof = f_eof (_file);
+        // Notify end of execution
+        _execute = false;
+        _caller_cv.notify_one();
+    } while (!_eof && !_force_eof);
+}