add method availableOutputBuffer()

src/decode.c

@@ -425,8 +425,7 @@ static void decodeParent(PlayerControl * pc, DecoderControl * dc, OutputBuffer *
 	pc->play = 0;
 	wakeup_main_task();
 
-	while ((unsigned)cb->end - cb->begin < bbp &&
-	       cb->end != buffered_chunks - 1 &&
+	while (availableOutputBuffer(cb) < bbp &&
 	       dc->state != DECODE_STATE_STOP) {
 		processDecodeInput();
 		player_sleep();

src/outputBuffer.c

@@ -57,6 +57,14 @@ void flushOutputBuffer(OutputBuffer * cb)
 	}
 }
 
+unsigned availableOutputBuffer(const OutputBuffer * cb)
+{
+	if (cb->end >= cb->begin)
+		return cb->end - cb->begin;
+	else
+		return cb->end + buffered_chunks - cb->begin;
+}
+
 /**
  * Return the tail chunk has room for additional data.  If there is no
  * room in the queue, this function blocks until the player thread has

src/outputBuffer.h

@@ -55,6 +55,9 @@ void clearOutputBuffer(OutputBuffer * cb);
 
 void flushOutputBuffer(OutputBuffer * cb);
 
+/** determine the number of decoded chunks */
+unsigned availableOutputBuffer(const OutputBuffer * cb);
+
 /* we send inStream for buffering the inputStream while waiting to
    send the next chunk */
 int sendDataToOutputBuffer(OutputBuffer * cb,