do not forget - your own addition :-)

play_queue.cpp

 #include "play_queue.h"
 #include "utility/dspinst.h"
 
+bool AudioPlayQueue::available(void)
+{
+        if (userblock) return true;
+        userblock = allocate();
+        if (userblock) return true;
+        return false;
+}
 
 int16_t * AudioPlayQueue::getBuffer(void)
 {
+	if (userblock) return userblock->data;
 	while (1) {
 		userblock = allocate();
 		if (userblock) return userblock->data;

play_queue.h

 		userblock(NULL), head(0), tail(0) { }
 	void play(int16_t data);
 	void play(const int16_t *data, uint32_t len);
+	bool available(void);
 	int16_t * getBuffer(void);
 	void playBuffer(void);
 	void stop(void);