1 files changed, 47 insertions, 48 deletions

diff --git a/libavcodec/vble.c b/libavcodec/vble.c
index 5e8543bec0..43c7d55d9c 100644
--- a/libavcodec/vble.c
+++ b/libavcodec/vble.c
@@ -2,20 +2,20 @@
  * VBLE Decoder
  * Copyright (c) 2011 Derek Buitenhuis
  *
- * This file is part of Libav.
+ * This file is part of FFmpeg.
  *
- * Libav is free software; you can redistribute it and/or
+ * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
- * Libav is distributed in the hope that it will be useful,
+ * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
- * License along with Libav; if not, write to the Free Software
+ * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
@@ -35,55 +35,51 @@ typedef struct {
     DSPContext dsp;
 
     int            size;
-    uint8_t        *val; /* First holds the lengths of vlc symbols and then their values */
+    uint8_t        *val; ///< This array first holds the lengths of vlc symbols and then their value.
 } VBLEContext;
 
-static uint8_t vble_read_reverse_unary(GetBitContext *gb)
-{
-    /* At most we need to read 9 bits total to get indices up to 8 */
-    uint8_t val = show_bits(gb, 8);
-
-    if (val) {
-        val = 7 - av_log2_16bit(av_reverse[val]);
-        skip_bits(gb, val + 1);
-        return val;
-    } else {
-        skip_bits(gb, 8);
-        if (get_bits1(gb))
-            return 8;
-    }
-
-    /* Return something larger than 8 on error */
-    return UINT8_MAX;
-}
-
 static int vble_unpack(VBLEContext *ctx, GetBitContext *gb)
 {
     int i;
+    int allbits = 0;
+    static const uint8_t LUT[256] = {
+        8,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,
+        5,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,
+        6,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,
+        5,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,
+        7,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,
+        5,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,
+        6,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,
+        5,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,
+    };
 
     /* Read all the lengths in first */
     for (i = 0; i < ctx->size; i++) {
-        ctx->val[i] = vble_read_reverse_unary(gb);
-
-        if (ctx->val[i] == UINT8_MAX)
-            return -1;
-    }
-
-    for (i = 0; i < ctx->size; i++) {
-        /* Check we have enough bits left */
-        if (get_bits_left(gb) < ctx->val[i])
-            return -1;
-
-        /* get_bits can't take a length of 0 */
-        if (ctx->val[i])
-            ctx->val[i] = (1 << ctx->val[i]) + get_bits(gb, ctx->val[i]) - 1;
+        /* At most we need to read 9 bits total to get indices up to 8 */
+        int val = show_bits(gb, 8);
+
+        // read reverse unary
+        if (val) {
+            val = LUT[val];
+            skip_bits(gb, val + 1);
+            ctx->val[i] = val;
+        } else {
+            skip_bits(gb, 8);
+            if (!get_bits1(gb))
+                return -1;
+            ctx->val[i] = 8;
+        }
+        allbits += ctx->val[i];
     }
 
+    /* Check we have enough bits left */
+    if (get_bits_left(gb) < allbits)
+        return -1;
     return 0;
 }
 
-static void vble_restore_plane(VBLEContext *ctx, int plane, int offset,
-                              int width, int height)
+static void vble_restore_plane(VBLEContext *ctx, GetBitContext *gb, int plane,
+                               int offset, int width, int height)
 {
     AVFrame *pic = ctx->avctx->coded_frame;
     uint8_t *dst = pic->data[plane];
@@ -92,14 +88,17 @@ static void vble_restore_plane(VBLEContext *ctx, int plane, int offset,
     int i, j, left, left_top;
 
     for (i = 0; i < height; i++) {
-        for (j = 0; j < width; j++)
-            val[j] = (val[j] >> 1) ^ -(val[j] & 1);
-
+        for (j = 0; j < width; j++) {
+            /* get_bits can't take a length of 0 */
+            if (val[j]) {
+                int v = (1 << val[j]) + get_bits(gb, val[j]) - 1;
+                val[j] = (v >> 1) ^ -(v & 1);
+            }
+        }
         if (i) {
             left = 0;
             left_top = dst[-stride];
-            ctx->dsp.add_hfyu_median_prediction(dst, dst-stride, val,
-                                                width, &left, &left_top);
+            ctx->dsp.add_hfyu_median_prediction(dst, dst-stride, val, width, &left, &left_top);
         } else {
             dst[0] = val[0];
             for (j = 1; j < width; j++)
@@ -154,15 +153,15 @@ static int vble_decode_frame(AVCodecContext *avctx, void *data, int *data_size,
     }
 
     /* Restore planes. Should be almost identical to Huffyuv's. */
-    vble_restore_plane(ctx, 0, offset, avctx->width, avctx->height);
+    vble_restore_plane(ctx, &gb, 0, offset, avctx->width, avctx->height);
 
     /* Chroma */
     if (!(ctx->avctx->flags & CODEC_FLAG_GRAY)) {
         offset += avctx->width * avctx->height;
-        vble_restore_plane(ctx, 1, offset, width_uv, height_uv);
+        vble_restore_plane(ctx, &gb, 1, offset, width_uv, height_uv);
 
         offset += width_uv * height_uv;
-        vble_restore_plane(ctx, 2, offset, width_uv, height_uv);
+        vble_restore_plane(ctx, &gb, 2, offset, width_uv, height_uv);
     }
 
     *data_size = sizeof(AVFrame);