1 files changed, 125 insertions, 0 deletions
diff --git a/vp9/common/vp9_treecoder.h b/vp9/common/vp9_treecoder.h
new file mode 100644
index 000000000..a79b1564a
--- /dev/null
+++ b/vp9/common/vp9_treecoder.h
@@ -0,0 +1,125 @@
+/*
+ *  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.
+ */
+
+#ifndef VP9_COMMON_VP9_TREECODER_H_
+#define VP9_COMMON_VP9_TREECODER_H_
+
+#include "./vpx_config.h"
+#include "vpx/vpx_integer.h"
+#include "vp9/common/vp9_common.h"
+
+typedef uint8_t vp9_prob;
+
+#define vp9_prob_half ((vp9_prob) 128)
+
+typedef int8_t vp9_tree_index;
+
+#define TREE_SIZE(leaf_count) (2 * (leaf_count) - 2)
+
+#define vp9_complement(x) (255 - x)
+
+/* We build coding trees compactly in arrays.
+   Each node of the tree is a pair of vp9_tree_indices.
+   Array index often references a corresponding probability table.
+   Index <= 0 means done encoding/decoding and value = -Index,
+   Index > 0 means need another bit, specification at index.
+   Nonnegative indices are always even;  processing begins at node 0. */
+
+typedef const vp9_tree_index vp9_tree[];
+
+struct vp9_token {
+  int value;
+  int len;
+};
+
+/* Construct encoding array from tree. */
+
+void vp9_tokens_from_tree(struct vp9_token*, vp9_tree);
+
+/* Convert array of token occurrence counts into a table of probabilities
+   for the associated binary encoding tree.  Also writes count of branches
+   taken for each node on the tree; this facilitiates decisions as to
+   probability updates. */
+
+void vp9_tree_probs_from_distribution(vp9_tree tree,
+                                      unsigned int branch_ct[ /* n - 1 */ ][2],
+                                      const unsigned int num_events[ /* n */ ]);
+
+
+static INLINE vp9_prob clip_prob(int p) {
+  return (p > 255) ? 255u : (p < 1) ? 1u : p;
+}
+
+// int64 is not needed for normal frame level calculations.
+// However when outputing entropy stats accumulated over many frames
+// or even clips we can overflow int math.
+#ifdef ENTROPY_STATS
+static INLINE vp9_prob get_prob(int num, int den) {
+  return (den == 0) ? 128u : clip_prob(((int64_t)num * 256 + (den >> 1)) / den);
+}
+#else
+static INLINE vp9_prob get_prob(int num, int den) {
+  return (den == 0) ? 128u : clip_prob((num * 256 + (den >> 1)) / den);
+}
+#endif
+
+static INLINE vp9_prob get_binary_prob(int n0, int n1) {
+  return get_prob(n0, n0 + n1);
+}
+
+/* this function assumes prob1 and prob2 are already within [1,255] range */
+static INLINE vp9_prob weighted_prob(int prob1, int prob2, int factor) {
+  return ROUND_POWER_OF_TWO(prob1 * (256 - factor) + prob2 * factor, 8);
+}
+
+static INLINE vp9_prob merge_probs(vp9_prob pre_prob,
+                                   const unsigned int ct[2],
+                                   unsigned int count_sat,
+                                   unsigned int max_update_factor) {
+  const vp9_prob prob = get_binary_prob(ct[0], ct[1]);
+  const unsigned int count = MIN(ct[0] + ct[1], count_sat);
+  const unsigned int factor = max_update_factor * count / count_sat;
+  return weighted_prob(pre_prob, prob, factor);
+}
+
+static unsigned int tree_merge_probs_impl(unsigned int i,
+                                          const vp9_tree_index *tree,
+                                          const vp9_prob *pre_probs,
+                                          const unsigned int *counts,
+                                          unsigned int count_sat,
+                                          unsigned int max_update_factor,
+                                          vp9_prob *probs) {
+  const int l = tree[i];
+  const unsigned int left_count = (l <= 0)
+                 ? counts[-l]
+                 : tree_merge_probs_impl(l, tree, pre_probs, counts,
+                                         count_sat, max_update_factor, probs);
+  const int r = tree[i + 1];
+  const unsigned int right_count = (r <= 0)
+                 ? counts[-r]
+                 : tree_merge_probs_impl(r, tree, pre_probs, counts,
+                                         count_sat, max_update_factor, probs);
+  const unsigned int ct[2] = { left_count, right_count };
+  probs[i >> 1] = merge_probs(pre_probs[i >> 1], ct,
+                              count_sat, max_update_factor);
+  return left_count + right_count;
+}
+
+static void tree_merge_probs(const vp9_tree_index *tree,
+                             const vp9_prob *pre_probs,
+                             const unsigned int *counts,
+                             unsigned int count_sat,
+                             unsigned int max_update_factor, vp9_prob *probs) {
+  tree_merge_probs_impl(0, tree, pre_probs, counts,
+                        count_sat, max_update_factor, probs);
+}
+
+
+#endif  // VP9_COMMON_VP9_TREECODER_H_