From 4531b85a252265e299602e15e35696420dd76e01 Mon Sep 17 00:00:00 2001
From: "Nathan E. Egge" <negge@mozilla.com>
Date: Sun, 19 Jun 2016 14:38:04 -0400
Subject: [PATCH] Add code to compute in-order mappings for tokens.
Add av1_indices_from_tree() function that computes a forward and inverse
mapping of the tree leaf-node symbols to their in-order traversal.
This is necessary because many of the aom_tree binary trees have their
leaf nodes out of order (e.g., an in-order traversal of a tree with n
nodes does not start at symbol 0 and go to symbol n - 1), but the CDFs
created by tree_to_cdf() are indexed in-order.
Change-Id: Icd0dbed4c171a67c9e84a634106c4fdb5b1b3488
---
av1/encoder/treewriter.c | 16 ++++++++++++++++
av1/encoder/treewriter.h | 2 ++
2 files changed, 18 insertions(+)
diff --git a/av1/encoder/treewriter.c b/av1/encoder/treewriter.c
index 50be72413b..742ffca237 100644
--- a/av1/encoder/treewriter.c
+++ b/av1/encoder/treewriter.c
@@ -32,6 +32,22 @@ void av1_tokens_from_tree(struct av1_token *tokens,
tree2tok(tokens, tree, 0, 0, 0);
}
+/* This code assumes that tree contains as unique leaf nodes the integer values
+ 0 to len - 1 and produces the forward and inverse mapping tables in ind[]
+ and inv[] respectively. */
+void av1_indices_from_tree(int *ind, int *inv, int len,
+ const aom_tree_index *tree) {
+ int i;
+ int index;
+ for (i = index = 0; i < TREE_SIZE(len); i++) {
+ const aom_tree_index j = tree[i];
+ if (j <= 0) {
+ inv[index] = -j;
+ ind[-j] = index++;
+ }
+ }
+}
+
static unsigned int convert_distribution(unsigned int i, aom_tree tree,
unsigned int branch_ct[][2],
const unsigned int num_events[]) {
diff --git a/av1/encoder/treewriter.h b/av1/encoder/treewriter.h
index 9a4cb86cb2..e16b43fcd8 100644
--- a/av1/encoder/treewriter.h
+++ b/av1/encoder/treewriter.h
@@ -28,6 +28,8 @@ struct av1_token {
};
void av1_tokens_from_tree(struct av1_token *, const aom_tree_index *);
+void av1_indices_from_tree(int *ind, int *inv, int len,
+ const aom_tree_index *tree);
static INLINE void av1_write_token(aom_writer *w, const aom_tree_index *tree,
const aom_prob *probs,
--
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