The Tor Browser: media/libvpx/vp8/common/treecoder.h@b8a032363ba2

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 #ifndef __INC_TREECODER_H

    13 #define __INC_TREECODER_H

    15 typedef unsigned char vp8bc_index_t; /* probability index */

    18 typedef unsigned char vp8_prob;

    20 #define vp8_prob_half ( (vp8_prob) 128)

    22 typedef signed char vp8_tree_index;

    23 struct bool_coder_spec;

    25 typedef struct bool_coder_spec bool_coder_spec;

    26 typedef struct bool_writer bool_writer;

    27 typedef struct bool_reader bool_reader;

    29 typedef const bool_coder_spec c_bool_coder_spec;

    30 typedef const bool_writer c_bool_writer;

    31 typedef const bool_reader c_bool_reader;

    35 # define vp8_complement( x) (255 - x)

    38 /* We build coding trees compactly in arrays.

    39    Each node of the tree is a pair of vp8_tree_indices.

    40    Array index often references a corresponding probability table.

    41    Index <= 0 means done encoding/decoding and value = -Index,

    42    Index > 0 means need another bit, specification at index.

    43    Nonnegative indices are always even;  processing begins at node 0. */

    45 typedef const vp8_tree_index vp8_tree[], *vp8_tree_p;

    48 typedef const struct vp8_token_struct

    49 {

    50     int value;

    51     int Len;

    52 } vp8_token;

    54 /* Construct encoding array from tree. */

    56 void vp8_tokens_from_tree(struct vp8_token_struct *, vp8_tree);

    57 void vp8_tokens_from_tree_offset(struct vp8_token_struct *, vp8_tree,

    58                                  int offset);

    61 /* Convert array of token occurrence counts into a table of probabilities

    62    for the associated binary encoding tree.  Also writes count of branches

    63    taken for each node on the tree; this facilitiates decisions as to

    64    probability updates. */

    66 void vp8_tree_probs_from_distribution(

    67     int n,                      /* n = size of alphabet */

    68     vp8_token tok               [ /* n */ ],

    69     vp8_tree tree,

    70     vp8_prob probs          [ /* n-1 */ ],

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

    72     const unsigned int num_events[ /* n */ ],

    73     unsigned int Pfactor,

    74     int Round

    75 );

    77 /* Variant of above using coder spec rather than hardwired 8-bit probs. */

    79 void vp8bc_tree_probs_from_distribution(

    80     int n,                      /* n = size of alphabet */

    81     vp8_token tok               [ /* n */ ],

    82     vp8_tree tree,

    83     vp8_prob probs          [ /* n-1 */ ],

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

    85     const unsigned int num_events[ /* n */ ],

    86     c_bool_coder_spec *s

    87 );

    90 #endif

The Tor Browser / file revision