1 files changed, 51 insertions, 29 deletions

diff --git a/audio/decoders/adpcm.cpp b/audio/decoders/adpcm.cpp
index ffb61a49c0..7f578ddbae 100644
--- a/audio/decoders/adpcm.cpp
+++ b/audio/decoders/adpcm.cpp
@@ -334,67 +334,89 @@ int MS_ADPCMStream::readBuffer(int16 *buffer, const int numSamples) {
 
 #pragma mark -
 
-
-#define DK3_READ_NIBBLE() \
+#define DK3_READ_NIBBLE(channelNo) \
 do { \
 	if (_topNibble) { \
 		_nibble = _lastByte >> 4; \
 		_topNibble = false; \
 	} else { \
-		if (_stream->pos() >= _endpos) \
-			break; \
-		if ((_stream->pos() % _blockAlign) == 0) \
-			continue; \
 		_lastByte = _stream->readByte(); \
 		_nibble = _lastByte & 0xf; \
 		_topNibble = true; \
+		--blockBytesLeft; \
+		--audioBytesLeft; \
 	} \
-} while (0)
-
+	decodeIMA(_nibble, channelNo); \
+} while(0)
 
 int DK3_ADPCMStream::readBuffer(int16 *buffer, const int numSamples) {
+	assert((numSamples % 4) == 0);
+
+	const uint startOffset = _stream->pos() % _blockAlign;
+	uint audioBytesLeft = _endpos - _stream->pos();
+	uint blockBytesLeft;
+	if (startOffset != 0) {
+		blockBytesLeft = _blockAlign - startOffset;
+	} else {
+		blockBytesLeft = 0;
+	}
+
 	int samples = 0;
+	while (samples < numSamples && audioBytesLeft) {
+		if (blockBytesLeft == 0) {
+			blockBytesLeft = MIN(_blockAlign, audioBytesLeft);
+			_topNibble = false;
 
-	assert((numSamples % 4) == 0);
+			if (blockBytesLeft < 16) {
+				warning("Truncated DK3 ADPCM block header");
+				break;
+			}
+
+			_stream->skip(2);
+			const uint16 rate = _stream->readUint16LE();
+			assert(rate == getRate());
+			_stream->skip(6);
 
-	while (samples < numSamples && !_stream->eos() && _stream->pos() < _endpos) {
-		if ((_stream->pos() % _blockAlign) == 0) {
-			_stream->readUint16LE(); // Unknown
-			uint16 rate = _stream->readUint16LE(); // Copy of rate
-			_stream->skip(6); // Unknown
 			// Get predictor for both sum/diff channels
 			_status.ima_ch[0].last = _stream->readSint16LE();
 			_status.ima_ch[1].last = _stream->readSint16LE();
+
 			// Get index for both sum/diff channels
 			_status.ima_ch[0].stepIndex = _stream->readByte();
 			_status.ima_ch[1].stepIndex = _stream->readByte();
+			assert(_status.ima_ch[0].stepIndex < ARRAYSIZE(_imaTable));
+			assert(_status.ima_ch[1].stepIndex < ARRAYSIZE(_imaTable));
 
-			if (_stream->eos())
-				break;
-
-			// Sanity check
-			assert(rate == getRate());
+			blockBytesLeft -= 16;
+			audioBytesLeft -= 16;
 		}
 
-		DK3_READ_NIBBLE();
-		decodeIMA(_nibble, 0);
+		DK3_READ_NIBBLE(0);
+		DK3_READ_NIBBLE(1);
 
-		DK3_READ_NIBBLE();
-		decodeIMA(_nibble, 1);
+		*buffer++ = _status.ima_ch[0].last + _status.ima_ch[1].last;
+		*buffer++ = _status.ima_ch[0].last - _status.ima_ch[1].last;
 
-		buffer[samples++] = _status.ima_ch[0].last + _status.ima_ch[1].last;
-		buffer[samples++] = _status.ima_ch[0].last - _status.ima_ch[1].last;
+		DK3_READ_NIBBLE(0);
 
-		DK3_READ_NIBBLE();
-		decodeIMA(_nibble, 0);
+		*buffer++ = _status.ima_ch[0].last + _status.ima_ch[1].last;
+		*buffer++ = _status.ima_ch[0].last - _status.ima_ch[1].last;
 
-		buffer[samples++] = _status.ima_ch[0].last + _status.ima_ch[1].last;
-		buffer[samples++] = _status.ima_ch[0].last - _status.ima_ch[1].last;
+		samples += 4;
+
+		// if the last sample of a block ends on an odd byte, the encoder adds
+		// an extra alignment byte
+		if (!_topNibble && blockBytesLeft == 1) {
+			_stream->skip(1);
+			--blockBytesLeft;
+			--audioBytesLeft;
+		}
 	}
 
 	return samples;
 }
 
+#undef DK3_READ_NIBBLE
 
 #pragma mark -