h264: move q0 scan tables into context

This fixes out of global array reads.
The alternative solutions of checking the index or modifying the VLC tables
to prevent the index going outside are each about 1-2 cpu cyclces slower
per coded 4x4 block.
The alternative of padding the global tables directly is more ugly and
moving them to the context should benefit cache locality.

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

1 files changed, 12 insertions, 12 deletions

diff --git a/libavcodec/h264.c b/libavcodec/h264.c
index 85787f40d1..7ebe3521b0 100644
--- a/libavcodec/h264.c
+++ b/libavcodec/h264.c
@@ -2719,19 +2719,19 @@ static void init_scan_tables(H264Context *h)
 #undef T
     }
     if (h->sps.transform_bypass) { // FIXME same ugly
-        h->zigzag_scan_q0          = zigzag_scan;
-        h->zigzag_scan8x8_q0       = ff_zigzag_direct;
-        h->zigzag_scan8x8_cavlc_q0 = zigzag_scan8x8_cavlc;
-        h->field_scan_q0           = field_scan;
-        h->field_scan8x8_q0        = field_scan8x8;
-        h->field_scan8x8_cavlc_q0  = field_scan8x8_cavlc;
+        memcpy(h->zigzag_scan_q0          , zigzag_scan             , sizeof(h->zigzag_scan_q0         ));
+        memcpy(h->zigzag_scan8x8_q0       , ff_zigzag_direct        , sizeof(h->zigzag_scan8x8_q0      ));
+        memcpy(h->zigzag_scan8x8_cavlc_q0 , zigzag_scan8x8_cavlc    , sizeof(h->zigzag_scan8x8_cavlc_q0));
+        memcpy(h->field_scan_q0           , field_scan              , sizeof(h->field_scan_q0          ));
+        memcpy(h->field_scan8x8_q0        , field_scan8x8           , sizeof(h->field_scan8x8_q0       ));
+        memcpy(h->field_scan8x8_cavlc_q0  , field_scan8x8_cavlc     , sizeof(h->field_scan8x8_cavlc_q0 ));
     } else {
-        h->zigzag_scan_q0          = h->zigzag_scan;
-        h->zigzag_scan8x8_q0       = h->zigzag_scan8x8;
-        h->zigzag_scan8x8_cavlc_q0 = h->zigzag_scan8x8_cavlc;
-        h->field_scan_q0           = h->field_scan;
-        h->field_scan8x8_q0        = h->field_scan8x8;
-        h->field_scan8x8_cavlc_q0  = h->field_scan8x8_cavlc;
+        memcpy(h->zigzag_scan_q0          , h->zigzag_scan          , sizeof(h->zigzag_scan_q0         ));
+        memcpy(h->zigzag_scan8x8_q0       , h->zigzag_scan8x8       , sizeof(h->zigzag_scan8x8_q0      ));
+        memcpy(h->zigzag_scan8x8_cavlc_q0 , h->zigzag_scan8x8_cavlc , sizeof(h->zigzag_scan8x8_cavlc_q0));
+        memcpy(h->field_scan_q0           , h->field_scan           , sizeof(h->field_scan_q0          ));
+        memcpy(h->field_scan8x8_q0        , h->field_scan8x8        , sizeof(h->field_scan8x8_q0       ));
+        memcpy(h->field_scan8x8_cavlc_q0  , h->field_scan8x8_cavlc  , sizeof(h->field_scan8x8_cavlc_q0 ));
     }
 }