From d8278bab79ffc82f449522766fbd505dd64b6c1c Mon Sep 17 00:00:00 2001
From: Mike Melanson <mike@multimedia.cx>
Date: Wed, 18 May 2005 00:11:49 +0000
Subject: [PATCH] replace get_superblock_run_length() with a VLC table

Originally committed as revision 4267 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
 libavcodec/vp3.c     | 18 ++++++++++++++++++
 libavcodec/vp3data.h | 21 +++++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/libavcodec/vp3.c b/libavcodec/vp3.c
index ad72965e4c..9e9939abb9 100644
--- a/libavcodec/vp3.c
+++ b/libavcodec/vp3.c
@@ -1182,7 +1182,14 @@ static int unpack_superblocks(Vp3DecodeContext *s, GetBitContext *gb)
         while (current_superblock < s->superblock_count) {
             if (current_run == 0) {
                 bit ^= 1;
+#if 1
+                current_run = get_vlc2(gb, 
+                    s->superblock_run_length_vlc.table, 6, 2) + 1;
+                if (current_run == 34)
+                    current_run += get_bits(gb, 12);
+#else
                 current_run = get_superblock_run_length(gb);
+#endif
                 debug_block_coding("      setting superblocks %d..%d to %s\n",
                     current_superblock,
                     current_superblock + current_run - 1,
@@ -1221,7 +1228,14 @@ static int unpack_superblocks(Vp3DecodeContext *s, GetBitContext *gb)
 
                     if (current_run == 0) {
                         bit ^= 1;
+#if 1
+                        current_run = get_vlc2(gb, 
+                            s->superblock_run_length_vlc.table, 6, 2) + 1;
+                        if (current_run == 34)
+                            current_run += get_bits(gb, 12);
+#else
                         current_run = get_superblock_run_length(gb);
+#endif
                     }
 
                     debug_block_coding("      setting superblock %d to %s\n",
@@ -2630,6 +2644,10 @@ static int vp3_decode_init(AVCodecContext *avctx)
             &ac_bias_3[i][0][0], 4, 2, 0);
     }
 
+    init_vlc(&s->superblock_run_length_vlc, 6, 34,
+        &superblock_run_length_vlc_table[0][1], 4, 2,
+        &superblock_run_length_vlc_table[0][0], 4, 2, 0);
+
     init_vlc(&s->fragment_run_length_vlc, 5, 31,
         &fragment_run_length_vlc_table[0][1], 4, 2,
         &fragment_run_length_vlc_table[0][0], 4, 2, 0);
diff --git a/libavcodec/vp3data.h b/libavcodec/vp3data.h
index 5a5ff9cac5..893a5873a0 100644
--- a/libavcodec/vp3data.h
+++ b/libavcodec/vp3data.h
@@ -72,6 +72,27 @@ static const uint32_t vp31_filter_limit_values[64] =
     0,  0,  0,  0,  0,  0,  0,  0
 };
 
+static const uint16_t superblock_run_length_vlc_table[34][2] = {
+    { 0, 1 },
+
+    { 4, 3 },    { 5, 3 },
+
+    { 0xC, 4 },  { 0xD, 4 },
+
+    { 0x38, 6 },    { 0x39, 6 },    { 0x3A, 6 },    { 0x3B, 6 },
+
+    { 0xF0, 8 },    { 0xF1, 8 },    { 0xF2, 8 },    { 0xF3, 8 },
+    { 0xF4, 8 },    { 0xF5, 8 },    { 0xF6, 8 },    { 0xF7, 8 },
+
+    { 0x3E0, 10 },    { 0x3E1, 10 },    { 0x3E2, 10 },    { 0x3E3, 10 },
+    { 0x3E4, 10 },    { 0x3E5, 10 },    { 0x3E6, 10 },    { 0x3E7, 10 },
+    { 0x3E8, 10 },    { 0x3E9, 10 },    { 0x3EA, 10 },    { 0x3EB, 10 },
+    { 0x3EC, 10 },    { 0x3ED, 10 },    { 0x3EE, 10 },    { 0x3EF, 10 },
+    
+    { 0x3F, 6 }  /* this last VLC is a special case for reading 12 more
+                    bits from stream and adding the value 34 */
+};
+
 static const uint16_t fragment_run_length_vlc_table[30][2] = {
     /* 1 -> 2 */
     { 0x0, 2 },    { 0x1, 2 },