mjpegdec: Fill raw huffman tables with default values too

These may be used by hwaccel decoders when the standard tables are not
otherwise available.  At the same time, clean up that code into an array
so it's a little less repetitive.

libavcodec/mjpegdec.c

@@ -73,34 +73,45 @@ static int build_vlc(VLC *vlc, const uint8_t *bits_table,
                               huff_code, 2, 2, huff_sym, 2, 2, use_static);
 }
 
-static int build_basic_mjpeg_vlc(MJpegDecodeContext *s)
+static int init_default_huffman_tables(MJpegDecodeContext *s)
 {
-    int ret;
-
-    if ((ret = build_vlc(&s->vlcs[0][0], avpriv_mjpeg_bits_dc_luminance,
-                         avpriv_mjpeg_val_dc, 12, 0, 0)) < 0)
-        return ret;
-
-    if ((ret = build_vlc(&s->vlcs[0][1], avpriv_mjpeg_bits_dc_chrominance,
-                         avpriv_mjpeg_val_dc, 12, 0, 0)) < 0)
-        return ret;
-
-    if ((ret = build_vlc(&s->vlcs[1][0], avpriv_mjpeg_bits_ac_luminance,
-                         avpriv_mjpeg_val_ac_luminance, 251, 0, 1)) < 0)
-        return ret;
-
-    if ((ret = build_vlc(&s->vlcs[1][1], avpriv_mjpeg_bits_ac_chrominance,
-                         avpriv_mjpeg_val_ac_chrominance, 251, 0, 1)) < 0)
-        return ret;
-
-    if ((ret = build_vlc(&s->vlcs[2][0], avpriv_mjpeg_bits_ac_luminance,
-                         avpriv_mjpeg_val_ac_luminance, 251, 0, 0)) < 0)
-        return ret;
-
-    if ((ret = build_vlc(&s->vlcs[2][1], avpriv_mjpeg_bits_ac_chrominance,
-                         avpriv_mjpeg_val_ac_chrominance, 251, 0, 0)) < 0)
-        return ret;
+    static const struct {
+        int class;
+        int index;
+        const uint8_t *bits;
+        const uint8_t *values;
+        int codes;
+        int length;
+    } ht[] = {
+        { 0, 0, avpriv_mjpeg_bits_dc_luminance,
+                avpriv_mjpeg_val_dc, 12, 12 },
+        { 0, 1, avpriv_mjpeg_bits_dc_chrominance,
+                avpriv_mjpeg_val_dc, 12, 12 },
+        { 1, 0, avpriv_mjpeg_bits_ac_luminance,
+                avpriv_mjpeg_val_ac_luminance,   251, 162 },
+        { 1, 1, avpriv_mjpeg_bits_ac_chrominance,
+                avpriv_mjpeg_val_ac_chrominance, 251, 162 },
+        { 2, 0, avpriv_mjpeg_bits_ac_luminance,
+                avpriv_mjpeg_val_ac_luminance,   251, 162 },
+        { 2, 1, avpriv_mjpeg_bits_ac_chrominance,
+                avpriv_mjpeg_val_ac_chrominance, 251, 162 },
+    };
+    int i, ret;
+
+    for (i = 0; i < FF_ARRAY_ELEMS(ht); i++) {
+        ret = build_vlc(&s->vlcs[ht[i].class][ht[i].index],
+                        ht[i].bits, ht[i].values, ht[i].codes,
+                        0, ht[i].class == 1);
+        if (ret < 0)
+            return ret;
 
+        if (ht[i].class < 2) {
+            memcpy(s->raw_huffman_lengths[ht[i].class][ht[i].index],
+                   ht[i].bits + 1, 16);
+            memcpy(s->raw_huffman_values[ht[i].class][ht[i].index],
+                   ht[i].values, ht[i].length);
+        }
+    }
 
     return 0;
 }
@@ -151,7 +162,7 @@ av_cold int ff_mjpeg_decode_init(AVCodecContext *avctx)
     avctx->colorspace = AVCOL_SPC_BT470BG;
     s->hwaccel_pix_fmt = s->hwaccel_sw_pix_fmt = AV_PIX_FMT_NONE;
 
-    if ((ret = build_basic_mjpeg_vlc(s)) < 0)
+    if ((ret = init_default_huffman_tables(s)) < 0)
         return ret;
 
     if (s->extern_huff) {
@@ -161,7 +172,7 @@ av_cold int ff_mjpeg_decode_init(AVCodecContext *avctx)
         if (ff_mjpeg_decode_dht(s)) {
             av_log(avctx, AV_LOG_ERROR,
                    "error using external huffman table, switching back to internal\n");
-            build_basic_mjpeg_vlc(s);
+            init_default_huffman_tables(s);
         }
     }
     if (avctx->field_order == AV_FIELD_BB) { /* quicktime icefloe 019 */