The Tor Browser: media/libvpx/vp9/common/vp9

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

     1 /*

     2  *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.

     3  *

     4  *  Use of this source code is governed by a BSD-style license

     5  *  that can be found in the LICENSE file in the root of the source

     6  *  tree. An additional intellectual property rights grant can be found

     7  *  in the file PATENTS.  All contributing project authors may

     8  *  be found in the AUTHORS file in the root of the source tree.

     9  */

    12 #include <assert.h>

    14 #include "./vpx_config.h"

    15 #include "vp9/common/vp9_treecoder.h"

    17 static void tree2tok(struct vp9_token *const p, vp9_tree t,

    18                     int i, int v, int l) {

    19   v += v;

    20   ++l;

    22   do {

    23     const vp9_tree_index j = t[i++];

    25     if (j <= 0) {

    26       p[-j].value = v;

    27       p[-j].len = l;

    28     } else {

    29       tree2tok(p, t, j, v, l);

    30     }

    31   } while (++v & 1);

    32 }

    34 void vp9_tokens_from_tree(struct vp9_token *p, vp9_tree t) {

    35   tree2tok(p, t, 0, 0, 0);

    36 }

    38 static unsigned int convert_distribution(unsigned int i, vp9_tree tree,

    39                                          unsigned int branch_ct[][2],

    40                                          const unsigned int num_events[]) {

    41   unsigned int left, right;

    43   if (tree[i] <= 0)

    44     left = num_events[-tree[i]];

    45   else

    46     left = convert_distribution(tree[i], tree, branch_ct, num_events);

    48   if (tree[i + 1] <= 0)

    49     right = num_events[-tree[i + 1]];

    50   else

    51     right = convert_distribution(tree[i + 1], tree, branch_ct, num_events);

    53   branch_ct[i >> 1][0] = left;

    54   branch_ct[i >> 1][1] = right;

    55   return left + right;

    56 }

    58 void vp9_tree_probs_from_distribution(vp9_tree tree,

    59                                       unsigned int branch_ct[/* n-1 */][2],

    60                                       const unsigned int num_events[/* n */]) {

    61   convert_distribution(0, tree, branch_ct, num_events);

    62 }

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