libvpx: Pull from upstream

source/libvpx/vp9/encoder/vp9_subexp.c

Index: source/libvpx/vp9/encoder/vp9_subexp.c
===================================================================
--- source/libvpx/vp9/encoder/vp9_subexp.c	(revision 251189)
+++ source/libvpx/vp9/encoder/vp9_subexp.c	(working copy)
@@ -18,17 +18,6 @@
 
 static int update_bits[255];
 
-static int count_uniform(int v, int n) {
-  int l = get_unsigned_bits(n);
-  int m;
-  if (l == 0) return 0;
-  m = (1 << l) - n;
-  if (v < m)
-    return l - 1;
-  else
-    return l;
-}
-
 static int split_index(int i, int n, int modulus) {
   int max1 = (n - 1 - modulus / 2) / modulus + 1;
   if (i % modulus == modulus / 2)
@@ -81,29 +70,16 @@
   return i;
 }
 
-static int count_term_subexp(int word, int k, int num_syms) {
-  int count = 0;
-  int i = 0;
-  int mk = 0;
-  while (1) {
-    int b = (i ? k + i - 1 : k);
-    int a = (1 << b);
-    if (num_syms <= mk + 3 * a) {
-      count += count_uniform(word - mk, num_syms - mk);
-      break;
-    } else {
-      int t = (word >= mk + a);
-      count++;
-      if (t) {
-        i = i + 1;
-        mk += a;
-      } else {
-        count += b;
-        break;
-      }
-    }
-  }
-  return count;
+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) {
@@ -111,12 +87,9 @@
   return update_bits[delp] * 256;
 }
 
-static void encode_uniform(vp9_writer *w, int v, int n) {
-  int l = get_unsigned_bits(n);
-  int m;
-  if (l == 0)
-    return;
-  m = (1 << l) - n;
+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);
   } else {
@@ -125,38 +98,32 @@
   }
 }
 
-static void encode_term_subexp(vp9_writer *w, int word, int k, int num_syms) {
-  int i = 0;
-  int mk = 0;
-  while (1) {
-    int b = (i ? k + i - 1 : k);
-    int a = (1 << b);
-    if (num_syms <= mk + 3 * a) {
-      encode_uniform(w, word - mk, num_syms - mk);
-      break;
-    } else {
-      int t = (word >= mk + a);
-      vp9_write_literal(w, t, 1);
-      if (t) {
-        i = i + 1;
-        mk += a;
-      } else {
-        vp9_write_literal(w, word - mk, b);
-        break;
-      }
-    }
+static INLINE int write_bit_gte(vp9_writer *w, int word, int test) {
+  vp9_write_literal(w, word >= test, 1);
+  return word >= test;
+}
+
+static void encode_term_subexp(vp9_writer *w, int word) {
+  if (!write_bit_gte(w, word, 16)) {
+    vp9_write_literal(w, word, 4);
+  } else if (!write_bit_gte(w, word, 32)) {
+    vp9_write_literal(w, word - 16, 4);
+  } else if (!write_bit_gte(w, word, 64)) {
+    vp9_write_literal(w, word - 32, 5);
+  } 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, SUBEXP_PARAM, 255);
+  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, SUBEXP_PARAM, 255);
+    update_bits[i] = count_term_subexp(i);
 }
 
 int vp9_prob_diff_update_savings_search(const unsigned int *ct,