The Tor Browser: media/libvpx/vp8/encoder/boolhuff.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 /****************************************************************************

    13 *

    14 *   Module Title :     boolhuff.h

    15 *

    16 *   Description  :     Bool Coder header file.

    17 *

    18 ****************************************************************************/

    19 #ifndef __INC_BOOLHUFF_H

    20 #define __INC_BOOLHUFF_H

    22 #include "vpx_ports/mem.h"

    23 #include "vpx/internal/vpx_codec_internal.h"

    25 typedef struct

    26 {

    27     unsigned int lowvalue;

    28     unsigned int range;

    29     int count;

    30     unsigned int pos;

    31     unsigned char *buffer;

    32     unsigned char *buffer_end;

    33     struct vpx_internal_error_info *error;

    35     /* Variables used to track bit costs without outputing to the bitstream */

    36     unsigned int  measure_cost;

    37     unsigned long bit_counter;

    38 } BOOL_CODER;

    40 extern void vp8_start_encode(BOOL_CODER *bc, unsigned char *buffer, unsigned char *buffer_end);

    42 extern void vp8_encode_value(BOOL_CODER *br, int data, int bits);

    43 extern void vp8_stop_encode(BOOL_CODER *bc);

    44 extern const unsigned int vp8_prob_cost[256];

    47 DECLARE_ALIGNED(16, extern const unsigned char, vp8_norm[256]);

    49 static int validate_buffer(const unsigned char *start,

    50                            size_t               len,

    51                            const unsigned char *end,

    52                            struct vpx_internal_error_info *error)

    53 {

    54     if (start + len > start && start + len < end)

    55         return 1;

    56     else

    57         vpx_internal_error(error, VPX_CODEC_CORRUPT_FRAME,

    58             "Truncated packet or corrupt partition ");

    60     return 0;

    61 }

    62 static void vp8_encode_bool(BOOL_CODER *br, int bit, int probability)

    63 {

    64     unsigned int split;

    65     int count = br->count;

    66     unsigned int range = br->range;

    67     unsigned int lowvalue = br->lowvalue;

    68     register unsigned int shift;

    70 #ifdef VP8_ENTROPY_STATS

    71 #if defined(SECTIONBITS_OUTPUT)

    73     if (bit)

    74         Sectionbits[active_section] += vp8_prob_cost[255-probability];

    75     else

    76         Sectionbits[active_section] += vp8_prob_cost[probability];

    78 #endif

    79 #endif

    81     split = 1 + (((range - 1) * probability) >> 8);

    83     range = split;

    85     if (bit)

    86     {

    87         lowvalue += split;

    88         range = br->range - split;

    89     }

    91     shift = vp8_norm[range];

    93     range <<= shift;

    94     count += shift;

    96     if (count >= 0)

    97     {

    98         int offset = shift - count;

   100         if ((lowvalue << (offset - 1)) & 0x80000000)

   101         {

   102             int x = br->pos - 1;

   104             while (x >= 0 && br->buffer[x] == 0xff)

   105             {

   106                 br->buffer[x] = (unsigned char)0;

   107                 x--;

   108             }

   110             br->buffer[x] += 1;

   111         }

   113         validate_buffer(br->buffer + br->pos, 1, br->buffer_end, br->error);

   114         br->buffer[br->pos++] = (lowvalue >> (24 - offset));

   116         lowvalue <<= offset;

   117         shift = count;

   118         lowvalue &= 0xffffff;

   119         count -= 8 ;

   120     }

   122     lowvalue <<= shift;

   123     br->count = count;

   124     br->lowvalue = lowvalue;

   125     br->range = range;

   126 }

   128 #endif

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