1 files changed, 102 insertions, 0 deletions
diff --git a/media/libvpx/libvpx/vp8/common/treecoder.c b/media/libvpx/libvpx/vp8/common/treecoder.c
new file mode 100644
index 0000000000..f1e78f4321
--- /dev/null
+++ b/media/libvpx/libvpx/vp8/common/treecoder.c
@@ -0,0 +1,102 @@
+/*
+ *  Copyright (c) 2010 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 <assert.h>
+#include <stdio.h>
+
+#include "vp8/common/treecoder.h"
+#include "vpx/vpx_integer.h"
+
+static void tree2tok(struct vp8_token_struct *const p, vp8_tree t, int i, int v,
+                     int L) {
+  v += v;
+  ++L;
+
+  do {
+    const vp8_tree_index j = t[i++];
+
+    if (j <= 0) {
+      p[-j].value = v;
+      p[-j].Len = L;
+    } else {
+      tree2tok(p, t, j, v, L);
+    }
+  } while (++v & 1);
+}
+
+void vp8_tokens_from_tree(struct vp8_token_struct *p, vp8_tree t) {
+  tree2tok(p, t, 0, 0, 0);
+}
+
+void vp8_tokens_from_tree_offset(struct vp8_token_struct *p, vp8_tree t,
+                                 int offset) {
+  tree2tok(p - offset, t, 0, 0, 0);
+}
+
+static void branch_counts(int n, /* n = size of alphabet */
+                          vp8_token tok[/* n */], vp8_tree tree,
+                          unsigned int branch_ct[/* n-1 */][2],
+                          const unsigned int num_events[/* n */]) {
+  const int tree_len = n - 1;
+  int t = 0;
+
+  assert(tree_len);
+
+  do {
+    branch_ct[t][0] = branch_ct[t][1] = 0;
+  } while (++t < tree_len);
+
+  t = 0;
+
+  do {
+    int L = tok[t].Len;
+    const int enc = tok[t].value;
+    const unsigned int ct = num_events[t];
+
+    vp8_tree_index i = 0;
+
+    do {
+      const int b = (enc >> --L) & 1;
+      const int j = i >> 1;
+      assert(j < tree_len && 0 <= L);
+
+      branch_ct[j][b] += ct;
+      i = tree[i + b];
+    } while (i > 0);
+
+    assert(!L);
+  } while (++t < n);
+}
+
+void vp8_tree_probs_from_distribution(int n, /* n = size of alphabet */
+                                      vp8_token tok[/* n */], vp8_tree tree,
+                                      vp8_prob probs[/* n-1 */],
+                                      unsigned int branch_ct[/* n-1 */][2],
+                                      const unsigned int num_events[/* n */],
+                                      unsigned int Pfactor, int Round) {
+  const int tree_len = n - 1;
+  int t = 0;
+
+  branch_counts(n, tok, tree, branch_ct, num_events);
+
+  do {
+    const unsigned int *const c = branch_ct[t];
+    const unsigned int tot = c[0] + c[1];
+
+    if (tot) {
+      const unsigned int p =
+          (unsigned int)(((uint64_t)c[0] * Pfactor) + (Round ? tot >> 1 : 0)) /
+          tot;
+      probs[t] = p < 256 ? (p ? p : 1) : 255; /* agree w/old version for now */
+    } else {
+      probs[t] = vp8_prob_half;
+    }
+  } while (++t < tree_len);
+}