libvpx: Pull from upstream

source/libvpx/vp9/encoder/vp9_subexp.c

 /*
  *  Copyright (c) 2013 The WebM project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #include "vp9/common/vp9_common.h"
 #include "vp9/common/vp9_entropy.h"
 
 #include "vp9/encoder/vp9_cost.h"
 #include "vp9/encoder/vp9_writer.h"
 
 #define vp9_cost_upd256  ((int)(vp9_cost_one(upd) - vp9_cost_zero(upd)))
 
-static int update_bits[255];
+static const int update_bits[255] = {
+   5,  5,  5,  5,  5,  5,  5,  5,  5,  5,  5,  5,  5,  5,  5,  5,
+   6,  6,  6,  6,  6,  6,  6,  6,  6,  6,  6,  6,  6,  6,  6,  6,
+   8,  8,  8,  8,  8,  8,  8,  8,  8,  8,  8,  8,  8,  8,  8,  8,
+   8,  8,  8,  8,  8,  8,  8,  8,  8,  8,  8,  8,  8,  8,  8,  8,
+  10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10,
+  10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10,
+  10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10,
+  10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10,
+  10, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
+  11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
+  11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
+  11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
+  11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
+  11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
+  11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
+  11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,  0,
+};
 
 static int recenter_nonneg(int v, int m) {
   if (v > (m << 1))
     return v;
   else if (v >= m)
     return ((v - m) << 1);
   else
     return ((m - v) << 1) - 1;
 }
 
@@ skipping 24 matching lines @@
   m--;
   if ((m << 1) <= MAX_PROB)
     i = recenter_nonneg(v, m) - 1;
   else
     i = recenter_nonneg(MAX_PROB - 1 - v, MAX_PROB - 1 - m) - 1;
 
   i = map_table[i];
   return i;
 }
 
-static int count_term_subexp(int word) {
-  if (word < 16)
-    return 5;
-  if (word < 32)
-    return 6;
-  if (word < 64)
-    return 8;
-  if (word < 129)
-    return 10;
-  return 11;
-}
-
 static int prob_diff_update_cost(vp9_prob newp, vp9_prob oldp) {
   int delp = remap_prob(newp, oldp);
   return update_bits[delp] * 256;
 }
 
 static void encode_uniform(vp9_writer *w, int v) {
   const int l = 8;
   const int m = (1 << l) - 191;
   if (v < m) {
     vp9_write_literal(w, v, l - 1);
@@ skipping 18 matching lines @@
   } else {
     encode_uniform(w, word - 64);
   }
 }
 
 void vp9_write_prob_diff_update(vp9_writer *w, vp9_prob newp, vp9_prob oldp) {
   const int delp = remap_prob(newp, oldp);
   encode_term_subexp(w, delp);
 }
 
-void vp9_compute_update_table() {
-  int i;
-  for (i = 0; i < 254; i++)
-    update_bits[i] = count_term_subexp(i);
-}
-
 int vp9_prob_diff_update_savings_search(const unsigned int *ct,
                                         vp9_prob oldp, vp9_prob *bestp,
                                         vp9_prob upd) {
   const int old_b = cost_branch256(ct, oldp);
   int bestsavings = 0;
   vp9_prob newp, bestnewp = oldp;
   const int step = *bestp > oldp ? -1 : 1;
 
   for (newp = *bestp; newp != oldp; newp += step) {
     const int new_b = cost_branch256(ct, newp);
@@ skipping 54 matching lines @@
                                                           upd);
   assert(newp >= 1);
   if (savings > 0) {
     vp9_write(w, 1, upd);
     vp9_write_prob_diff_update(w, newp, *oldp);
     *oldp = newp;
   } else {
     vp9_write(w, 0, upd);
   }
 }