replace read() by readBuffer() in CopyRateConverter

svn-id: r12102

1 files changed, 38 insertions, 10 deletions

diff --git a/sound/rate.cpp b/sound/rate.cpp
index 45046cb80b..352243bc79 100644
--- a/sound/rate.cpp
+++ b/sound/rate.cpp
@@ -192,26 +192,54 @@ the_end:
 
 /**
  * Simple audio rate converter for the case that the inrate equals the outrate.
- * @todo This is inefficient, it would be better if this used readBuffer()
- *       instead of read().
  */
 template<bool stereo, bool reverseStereo>
 class CopyRateConverter : public RateConverter {
+	st_sample_t *_buffer;
+	st_size_t _bufferSize;
 public:
+	CopyRateConverter() : _buffer(0), _bufferSize(0) {}
+	~CopyRateConverter() {
+		free(_buffer);
+	}
+
 	virtual int flow(AudioInputStream &input, st_sample_t *obuf, st_size_t osamp, st_volume_t vol_l, st_volume_t vol_r) {
-		int16 tmp[2];
-		st_size_t len = osamp;
 		assert(input.isStereo() == stereo);
-		while (!input.endOfData() && len--) {
-			tmp[0] = tmp[1] = input.read();
-			if (stereo)
-				tmp[reverseStereo ? 0 : 1] = input.read();
+		
+		st_sample_t *ptr;
+		st_size_t len;
+		
+		if (stereo)
+			osamp *= 2;
+
+		// Reallocate temp buffer, if necessary
+		if (osamp > _bufferSize) {
+			free(_buffer);
+			_buffer = (st_sample_t *)malloc(osamp * 2);
+			_bufferSize = osamp;
+		}
+
+		// Read up to 'osamp' samples into our temporary buffer
+		len = input.readBuffer(_buffer, osamp);
+		
+		// Mix the data into the output buffer
+		ptr = _buffer;
+		while (len--) {
+			st_sample_t tmp0, tmp1;
+			tmp0 = tmp1 = *ptr++;
+			if (stereo) {
+				if (reverseStereo)
+					tmp0 = *ptr++;
+				else
+					tmp1 = *ptr++;
+				len--;
+			}
 
 			// output left channel
-			clampedAdd(*obuf++, (tmp[0] * (int)vol_l) >> 8);
+			clampedAdd(*obuf++, (tmp0 * (int)vol_l) >> 8);
 	
 			// output right channel
-			clampedAdd(*obuf++, (tmp[1] * (int)vol_r) >> 8);
+			clampedAdd(*obuf++, (tmp1 * (int)vol_r) >> 8);
 		}
 		return (ST_SUCCESS);
 	}