moved check to outputBufferAbsolute()

decoderParent() uses a lot of OutputBuffer internals to see whether
cross-fading should be started.  Move these checks to outputBuffer.c,
which also simplifies decoderParent().

git-svn-id: https://svn.musicpd.org/mpd/trunk@7262 09075e82-0dd4-0310-85a5-a0d7c8717e4f

3 files changed, 27 insertions, 17 deletions

diff --git a/src/decode.c b/src/decode.c
index 05e4c4a56..fd65dc5ae 100644
--- a/src/decode.c
+++ b/src/decode.c
@@ -503,7 +503,6 @@ static void decodeParent(PlayerControl * pc, DecoderControl * dc, OutputBuffer *
 			      (fadePosition = next - cb->begin +
 			       buffered_chunks) <= crossFadeChunks))) {
 				/* perform cross fade */
-				unsigned int test = end;
 				if (nextChunk < 0) {
 					/* beginning of the cross fade
 					   - adjust crossFadeChunks
@@ -512,13 +511,8 @@ static void decodeParent(PlayerControl * pc, DecoderControl * dc, OutputBuffer *
 					   chunks in the old song */
 					crossFadeChunks = fadePosition;
 				}
-				if (end < cb->begin)
-					test += buffered_chunks;
-				nextChunk = cb->begin + crossFadeChunks;
-				if ((unsigned)nextChunk < test) {
-					if ((unsigned)nextChunk >= buffered_chunks) {
-						nextChunk -= buffered_chunks;
-					}
+				nextChunk = outputBufferAbsolute(cb, crossFadeChunks);
+				if (nextChunk >= 0) {
 					pcm_mix(cb->chunks +
 						cb->begin * CHUNK_SIZE,
 						cb->chunks +
@@ -575,16 +569,9 @@ static void decodeParent(PlayerControl * pc, DecoderControl * dc, OutputBuffer *
 				/* the cross-fade is finished; skip
 				   the section which was cross-faded
 				   (and thus already played) */
-				unsigned int test = end;
-				nextChunk = cb->begin + crossFadeChunks;
-				if (end < cb->begin)
-					test += buffered_chunks;
-				if ((unsigned)nextChunk < test) {
-					if ((unsigned)nextChunk >= buffered_chunks) {
-						nextChunk -= buffered_chunks;
-					}
+				nextChunk = outputBufferAbsolute(cb, crossFadeChunks);
+				if (nextChunk >= 0)
 					advanceOutputBufferTo(cb, nextChunk);
-				}
 			}
 
 			/* wait for the decoder to work on the new song */
diff --git a/src/outputBuffer.c b/src/outputBuffer.c
index f5a6dbf51..b5fddd98d 100644
--- a/src/outputBuffer.c
+++ b/src/outputBuffer.c
@@ -65,6 +65,23 @@ unsigned availableOutputBuffer(const OutputBuffer * cb)
 		return cb->end + buffered_chunks - cb->begin;
 }
 
+int outputBufferAbsolute(const OutputBuffer * cb, unsigned relative)
+{
+	unsigned i, max;
+
+	max = cb->end;
+	if (max < cb->begin)
+		max += buffered_chunks;
+	i = (unsigned)cb->begin + relative;
+	if (i >= max)
+		return -1;
+
+	if (i >= buffered_chunks)
+		i -= buffered_chunks;
+
+	return (int)i;
+}
+
 /**
  * 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
diff --git a/src/outputBuffer.h b/src/outputBuffer.h
index 08124dffa..06ec60d19 100644
--- a/src/outputBuffer.h
+++ b/src/outputBuffer.h
@@ -58,6 +58,12 @@ void flushOutputBuffer(OutputBuffer * cb);
 /** determine the number of decoded chunks */
 unsigned availableOutputBuffer(const OutputBuffer * cb);
 
+/**
+ * Get the absolute index of the nth used chunk after the first one.
+ * Returns -1 if there is no such chunk.
+ */
+int outputBufferAbsolute(const OutputBuffer * cb, unsigned relative);
+
 /* we send inStream for buffering the inputStream while waiting to
    send the next chunk */
 int sendDataToOutputBuffer(OutputBuffer * cb,