[FFmpeg-devel] [PATCH 1/2] avcodec/lcldec: Optimize YUV422 case

[Michael Niedermayer]

This merges several byte operations and avoids some shifts inside the loop

Improves: Timeout (330sec -> 134sec)
Improves: 15599/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MSZH_fuzzer-5658127116009472

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
---
 libavcodec/lcldec.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/libavcodec/lcldec.c b/libavcodec/lcldec.c
index 104defa5f5..c3787b3cbe 100644
--- a/libavcodec/lcldec.c
+++ b/libavcodec/lcldec.c
@@ -391,13 +391,13 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPac
         break;
     case IMGTYPE_YUV422:
         for (row = 0; row < height; row++) {
-            for (col = 0; col < width - 3; col += 4) {
+            for (col = 0; col < (width - 2)>>1; col += 2) {
                 memcpy(y_out + col, encoded, 4);
                 encoded += 4;
-                u_out[ col >> 1     ] = *encoded++ + 128;
-                u_out[(col >> 1) + 1] = *encoded++ + 128;
-                v_out[ col >> 1     ] = *encoded++ + 128;
-                v_out[(col >> 1) + 1] = *encoded++ + 128;
+                AV_WN16(u_out + col, AV_RN16(encoded) ^ 0x8080);
+                encoded += 2;
+                AV_WN16(v_out + col, AV_RN16(encoded) ^ 0x8080);
+                encoded += 2;
             }
             y_out -= frame->linesize[0];
             u_out -= frame->linesize[1];
-- 
2.22.0