From: Josh Coalson <jcoalson@users.sourceforce.net>
Date: Mon, 12 Mar 2007 07:23:22 +0000 (+0000)
Subject: slight optimization to conversion of M/S->L/R
X-Git-Tag: 1.2.0~111
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=3847879a5519959a225a273b935384c562a1a52e;p=platform%2Fupstream%2Fflac.git

slight optimization to conversion of M/S->L/R
---

diff --git a/src/libFLAC/stream_decoder.c b/src/libFLAC/stream_decoder.c
index e09db2f..0da4661 100644
--- a/src/libFLAC/stream_decoder.c
+++ b/src/libFLAC/stream_decoder.c
@@ -1981,7 +1981,7 @@ FLAC__bool read_frame_(FLAC__StreamDecoder *decoder, FLAC__bool *got_a_frame, FL
 {
 	unsigned channel;
 	unsigned i;
-	FLAC__int32 mid, side, left, right;
+	FLAC__int32 mid, side;
 	unsigned frame_crc; /* the one we calculate from the input stream */
 	FLAC__uint32 x;
 
@@ -2063,15 +2063,19 @@ FLAC__bool read_frame_(FLAC__StreamDecoder *decoder, FLAC__bool *got_a_frame, FL
 				case FLAC__CHANNEL_ASSIGNMENT_MID_SIDE:
 					FLAC__ASSERT(decoder->private_->frame.header.channels == 2);
 					for(i = 0; i < decoder->private_->frame.header.blocksize; i++) {
+#if 1
 						mid = decoder->private_->output[0][i];
 						side = decoder->private_->output[1][i];
 						mid <<= 1;
-						if(side & 1) /* i.e. if 'side' is odd... */
-							mid++;
-						left = mid + side;
-						right = mid - side;
-						decoder->private_->output[0][i] = left >> 1;
-						decoder->private_->output[1][i] = right >> 1;
+						mid |= (side & 1); /* i.e. if 'side' is odd... */
+						decoder->private_->output[0][i] = (mid + side) >> 1;
+						decoder->private_->output[1][i] = (mid - side) >> 1;
+#else
+						//@@@@@@ OPT: try without 'side' temp variable
+						mid = (decoder->private_->output[0][i] << 1) | (decoder->private_->output[1][i] & 1); /* i.e. if 'side' is odd... */
+						decoder->private_->output[0][i] = (mid + decoder->private_->output[1][i]) >> 1;
+						decoder->private_->output[1][i] = (mid - decoder->private_->output[1][i]) >> 1;
+#endif
 					}
 					break;
 				default: