avcodec/sheervideo: Reduce the size of static arrays

The SheerVideo decoder uses VLC tables which are currently stored in
large arrays that contain the length of each leaf of the corresponding
tree from left to right, taking 15.5KB of space. But all these arrays
follow a common pattern: First the entries are ascending and then they
are descending with lots of successive entries have the same value.
Therefore it makes sense to use a run-length encoding to store them, as
this commit does. Notice that the length 16 has to be treated specially
because there are arrays with more than 256 consecutive entries with
value 16 and because the length of the entries start to descend from
this length onward.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>

1 files changed, 69 insertions, 58 deletions

diff --git a/libavcodec/sheervideo.c b/libavcodec/sheervideo.c
index 099e5fdf22..3471fdcff9 100644
--- a/libavcodec/sheervideo.c
+++ b/libavcodec/sheervideo.c
@@ -1781,21 +1781,32 @@ static void decode_rgb(AVCodecContext *avctx, AVFrame *p, GetBitContext *gb)
     }
 }
 
-static int build_vlc(VLC *vlc, const uint8_t *len, int count)
+static int build_vlc(VLC *vlc, const SheerTable *table)
 {
+    const uint8_t *cur = table->lens;
     uint16_t codes[1024];
-    unsigned index;
-    int i;
+    uint8_t  lens[1024];
+    unsigned count = 0;
 
-    index = 0;
-    for (i = 0; i < count; i++) {
-        codes[i] = index >> (32 - len[i]);
-        index   += 1U    << (32 - len[i]);
+    for (unsigned step = 1, len = 1, index = 0; len > 0; len += step) {
+        unsigned new_count = count;
+
+        if (len == 16) {
+            new_count += table->nb_16s;
+            step       = -1;
+        } else
+            new_count += *cur++;
+
+        for (; count < new_count; count++) {
+            codes[count] = index >> (32 - len);
+            index       += 1U    << (32 - len);
+            lens[count]  = len;
+        }
     }
 
     ff_free_vlc(vlc);
     return init_vlc(vlc, SHEER_VLC_BITS, count,
-                    len,   sizeof(*len),   sizeof(*len),
+                    lens,  sizeof(*lens),  sizeof(*lens),
                     codes, sizeof(*codes), sizeof(*codes), 0);
 }
 
@@ -1825,64 +1836,64 @@ static int decode_frame(AVCodecContext *avctx,
         avctx->pix_fmt = AV_PIX_FMT_RGB0;
         s->decode_frame = decode_rgb;
         if (s->format != format) {
-            ret  = build_vlc(&s->vlc[0], l_r_rgb, 256);
-            ret |= build_vlc(&s->vlc[1], l_g_rgb, 256);
+            ret  = build_vlc(&s->vlc[0], &l_r_rgb);
+            ret |= build_vlc(&s->vlc[1], &l_g_rgb);
         }
         break;
     case MKTAG(' ', 'r', 'G', 'B'):
         avctx->pix_fmt = AV_PIX_FMT_RGB0;
         s->decode_frame = decode_rgbi;
         if (s->format != format) {
-            ret  = build_vlc(&s->vlc[0], l_r_rgbi, 256);
-            ret |= build_vlc(&s->vlc[1], l_g_rgbi, 256);
+            ret  = build_vlc(&s->vlc[0], &l_r_rgbi);
+            ret |= build_vlc(&s->vlc[1], &l_g_rgbi);
         }
         break;
     case MKTAG('A', 'R', 'G', 'X'):
         avctx->pix_fmt = AV_PIX_FMT_GBRAP10;
         s->decode_frame = decode_argx;
         if (s->format != format) {
-            ret  = build_vlc(&s->vlc[0], l_r_rgbx, 1024);
-            ret |= build_vlc(&s->vlc[1], l_g_rgbx, 1024);
+            ret  = build_vlc(&s->vlc[0], &l_r_rgbx);
+            ret |= build_vlc(&s->vlc[1], &l_g_rgbx);
         }
         break;
     case MKTAG('A', 'r', 'G', 'X'):
         avctx->pix_fmt = AV_PIX_FMT_GBRAP10;
         s->decode_frame = decode_argxi;
         if (s->format != format) {
-            ret  = build_vlc(&s->vlc[0], l_r_rgbxi, 1024);
-            ret |= build_vlc(&s->vlc[1], l_g_rgbxi, 1024);
+            ret  = build_vlc(&s->vlc[0], &l_r_rgbxi);
+            ret |= build_vlc(&s->vlc[1], &l_g_rgbxi);
         }
         break;
     case MKTAG('R', 'G', 'B', 'X'):
         avctx->pix_fmt = AV_PIX_FMT_GBRP10;
         s->decode_frame = decode_rgbx;
         if (s->format != format) {
-            ret  = build_vlc(&s->vlc[0], l_r_rgbx, 1024);
-            ret |= build_vlc(&s->vlc[1], l_g_rgbx, 1024);
+            ret  = build_vlc(&s->vlc[0], &l_r_rgbx);
+            ret |= build_vlc(&s->vlc[1], &l_g_rgbx);
         }
         break;
     case MKTAG('r', 'G', 'B', 'X'):
         avctx->pix_fmt = AV_PIX_FMT_GBRP10;
         s->decode_frame = decode_rgbxi;
         if (s->format != format) {
-            ret  = build_vlc(&s->vlc[0], l_r_rgbxi, 1024);
-            ret |= build_vlc(&s->vlc[1], l_g_rgbxi, 1024);
+            ret  = build_vlc(&s->vlc[0], &l_r_rgbxi);
+            ret |= build_vlc(&s->vlc[1], &l_g_rgbxi);
         }
         break;
     case MKTAG('A', 'R', 'G', 'B'):
         avctx->pix_fmt = AV_PIX_FMT_ARGB;
         s->decode_frame = decode_argb;
         if (s->format != format) {
-            ret  = build_vlc(&s->vlc[0], l_r_rgb, 256);
-            ret |= build_vlc(&s->vlc[1], l_g_rgb, 256);
+            ret  = build_vlc(&s->vlc[0], &l_r_rgb);
+            ret |= build_vlc(&s->vlc[1], &l_g_rgb);
         }
         break;
     case MKTAG('A', 'r', 'G', 'B'):
         avctx->pix_fmt = AV_PIX_FMT_ARGB;
         s->decode_frame = decode_argbi;
         if (s->format != format) {
-            ret  = build_vlc(&s->vlc[0], l_r_rgbi, 256);
-            ret |= build_vlc(&s->vlc[1], l_g_rgbi, 256);
+            ret  = build_vlc(&s->vlc[0], &l_r_rgbi);
+            ret |= build_vlc(&s->vlc[1], &l_g_rgbi);
         }
         break;
     case MKTAG('A', 'Y', 'B', 'R'):
@@ -1891,8 +1902,8 @@ static int decode_frame(AVCodecContext *avctx,
         avctx->pix_fmt = AV_PIX_FMT_YUVA444P;
         s->decode_frame = decode_aybr;
         if (s->format != format) {
-            ret  = build_vlc(&s->vlc[0], l_y_ybr, 256);
-            ret |= build_vlc(&s->vlc[1], l_u_ybr, 256);
+            ret  = build_vlc(&s->vlc[0], &l_y_ybr);
+            ret |= build_vlc(&s->vlc[1], &l_u_ybr);
         }
         break;
     case MKTAG('A', 'y', 'B', 'R'):
@@ -1901,8 +1912,8 @@ static int decode_frame(AVCodecContext *avctx,
         avctx->pix_fmt = AV_PIX_FMT_YUVA444P;
         s->decode_frame = decode_aybri;
         if (s->format != format) {
-            ret  = build_vlc(&s->vlc[0], l_y_ybri, 256);
-            ret |= build_vlc(&s->vlc[1], l_u_ybri, 256);
+            ret  = build_vlc(&s->vlc[0], &l_y_ybri);
+            ret |= build_vlc(&s->vlc[1], &l_u_ybri);
         }
         break;
     case MKTAG(' ', 'Y', 'B', 'R'):
@@ -1911,8 +1922,8 @@ static int decode_frame(AVCodecContext *avctx,
         avctx->pix_fmt = AV_PIX_FMT_YUV444P;
         s->decode_frame = decode_ybr;
         if (s->format != format) {
-            ret  = build_vlc(&s->vlc[0], l_y_ybr, 256);
-            ret |= build_vlc(&s->vlc[1], l_u_ybr, 256);
+            ret  = build_vlc(&s->vlc[0], &l_y_ybr);
+            ret |= build_vlc(&s->vlc[1], &l_u_ybr);
         }
         break;
     case MKTAG(' ', 'y', 'B', 'R'):
@@ -1921,112 +1932,112 @@ static int decode_frame(AVCodecContext *avctx,
         avctx->pix_fmt = AV_PIX_FMT_YUV444P;
         s->decode_frame = decode_ybri;
         if (s->format != format) {
-            ret  = build_vlc(&s->vlc[0], l_y_ybri, 256);
-            ret |= build_vlc(&s->vlc[1], l_u_ybri, 256);
+            ret  = build_vlc(&s->vlc[0], &l_y_ybri);
+            ret |= build_vlc(&s->vlc[1], &l_u_ybri);
         }
         break;
     case MKTAG('Y', 'B', 'R', 0x0a):
         avctx->pix_fmt = AV_PIX_FMT_YUV444P10;
         s->decode_frame = decode_ybr10;
         if (s->format != format) {
-            ret  = build_vlc(&s->vlc[0], l_y_ybr10, 1024);
-            ret |= build_vlc(&s->vlc[1], l_u_ybr10, 1024);
+            ret  = build_vlc(&s->vlc[0], &l_y_ybr10);
+            ret |= build_vlc(&s->vlc[1], &l_u_ybr10);
         }
         break;
     case MKTAG('y', 'B', 'R', 0x0a):
         avctx->pix_fmt = AV_PIX_FMT_YUV444P10;
         s->decode_frame = decode_ybr10i;
         if (s->format != format) {
-            ret  = build_vlc(&s->vlc[0], l_y_ybr10i, 1024);
-            ret |= build_vlc(&s->vlc[1], l_u_ybr10i, 1024);
+            ret  = build_vlc(&s->vlc[0], &l_y_ybr10i);
+            ret |= build_vlc(&s->vlc[1], &l_u_ybr10i);
         }
         break;
     case MKTAG('C', 'A', '4', 'p'):
         avctx->pix_fmt = AV_PIX_FMT_YUVA444P10;
         s->decode_frame = decode_ca4p;
         if (s->format != format) {
-            ret  = build_vlc(&s->vlc[0], l_y_ybr10, 1024);
-            ret |= build_vlc(&s->vlc[1], l_u_ybr10, 1024);
+            ret  = build_vlc(&s->vlc[0], &l_y_ybr10);
+            ret |= build_vlc(&s->vlc[1], &l_u_ybr10);
         }
         break;
     case MKTAG('C', 'A', '4', 'i'):
         avctx->pix_fmt = AV_PIX_FMT_YUVA444P10;
         s->decode_frame = decode_ca4i;
         if (s->format != format) {
-            ret  = build_vlc(&s->vlc[0], l_y_ybr10i, 1024);
-            ret |= build_vlc(&s->vlc[1], l_u_ybr10i, 1024);
+            ret  = build_vlc(&s->vlc[0], &l_y_ybr10i);
+            ret |= build_vlc(&s->vlc[1], &l_u_ybr10i);
         }
         break;
     case MKTAG('B', 'Y', 'R', 'Y'):
         avctx->pix_fmt = AV_PIX_FMT_YUV422P;
         s->decode_frame = decode_byry;
         if (s->format != format) {
-            ret  = build_vlc(&s->vlc[0], l_y_byry, 256);
-            ret |= build_vlc(&s->vlc[1], l_u_byry, 256);
+            ret  = build_vlc(&s->vlc[0], &l_y_byry);
+            ret |= build_vlc(&s->vlc[1], &l_u_byry);
         }
         break;
     case MKTAG('B', 'Y', 'R', 'y'):
         avctx->pix_fmt = AV_PIX_FMT_YUV422P;
         s->decode_frame = decode_byryi;
         if (s->format != format) {
-            ret  = build_vlc(&s->vlc[0], l_y_byryi, 256);
-            ret |= build_vlc(&s->vlc[1], l_u_byryi, 256);
+            ret  = build_vlc(&s->vlc[0], &l_y_byryi);
+            ret |= build_vlc(&s->vlc[1], &l_u_byryi);
         }
         break;
     case MKTAG('Y', 'b', 'Y', 'r'):
         avctx->pix_fmt = AV_PIX_FMT_YUV422P;
         s->decode_frame = decode_ybyr;
         if (s->format != format) {
-            ret  = build_vlc(&s->vlc[0], l_y_ybyr, 256);
-            ret |= build_vlc(&s->vlc[1], l_u_ybyr, 256);
+            ret  = build_vlc(&s->vlc[0], &l_y_ybyr);
+            ret |= build_vlc(&s->vlc[1], &l_u_ybyr);
         }
         break;
     case MKTAG('C', '8', '2', 'p'):
         avctx->pix_fmt = AV_PIX_FMT_YUVA422P;
         s->decode_frame = decode_c82p;
         if (s->format != format) {
-            ret  = build_vlc(&s->vlc[0], l_y_byry, 256);
-            ret |= build_vlc(&s->vlc[1], l_u_byry, 256);
+            ret  = build_vlc(&s->vlc[0], &l_y_byry);
+            ret |= build_vlc(&s->vlc[1], &l_u_byry);
         }
         break;
     case MKTAG('C', '8', '2', 'i'):
         avctx->pix_fmt = AV_PIX_FMT_YUVA422P;
         s->decode_frame = decode_c82i;
         if (s->format != format) {
-            ret  = build_vlc(&s->vlc[0], l_y_byryi, 256);
-            ret |= build_vlc(&s->vlc[1], l_u_byryi, 256);
+            ret  = build_vlc(&s->vlc[0], &l_y_byryi);
+            ret |= build_vlc(&s->vlc[1], &l_u_byryi);
         }
         break;
     case MKTAG(0xa2, 'Y', 'R', 'Y'):
         avctx->pix_fmt = AV_PIX_FMT_YUV422P10;
         s->decode_frame = decode_yry10;
         if (s->format != format) {
-            ret  = build_vlc(&s->vlc[0], l_y_yry10, 1024);
-            ret |= build_vlc(&s->vlc[1], l_u_yry10, 1024);
+            ret  = build_vlc(&s->vlc[0], &l_y_yry10);
+            ret |= build_vlc(&s->vlc[1], &l_u_yry10);
         }
         break;
     case MKTAG(0xa2, 'Y', 'R', 'y'):
         avctx->pix_fmt = AV_PIX_FMT_YUV422P10;
         s->decode_frame = decode_yry10i;
         if (s->format != format) {
-            ret  = build_vlc(&s->vlc[0], l_y_yry10i, 1024);
-            ret |= build_vlc(&s->vlc[1], l_u_yry10i, 1024);
+            ret  = build_vlc(&s->vlc[0], &l_y_yry10i);
+            ret |= build_vlc(&s->vlc[1], &l_u_yry10i);
         }
         break;
     case MKTAG('C', 'A', '2', 'p'):
         avctx->pix_fmt = AV_PIX_FMT_YUVA422P10;
         s->decode_frame = decode_ca2p;
         if (s->format != format) {
-            ret  = build_vlc(&s->vlc[0], l_y_yry10, 1024);
-            ret |= build_vlc(&s->vlc[1], l_u_yry10, 1024);
+            ret  = build_vlc(&s->vlc[0], &l_y_yry10);
+            ret |= build_vlc(&s->vlc[1], &l_u_yry10);
         }
         break;
     case MKTAG('C', 'A', '2', 'i'):
         avctx->pix_fmt = AV_PIX_FMT_YUVA422P10;
         s->decode_frame = decode_ca2i;
         if (s->format != format) {
-            ret  = build_vlc(&s->vlc[0], l_y_yry10i, 1024);
-            ret |= build_vlc(&s->vlc[1], l_u_yry10i, 1024);
+            ret  = build_vlc(&s->vlc[0], &l_y_yry10i);
+            ret |= build_vlc(&s->vlc[1], &l_u_yry10i);
         }
         break;
     default: