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 */
10
11
12/****************************************************************************
13*
14*   Module Title :     boolhuff.h
15*
16*   Description  :     Bool Coder header file.
17*
18****************************************************************************/
19#ifndef VP8_ENCODER_BOOLHUFF_H_
20#define VP8_ENCODER_BOOLHUFF_H_
21
22#include "vpx_ports/mem.h"
23#include "vpx/internal/vpx_codec_internal.h"
24
25#ifdef __cplusplus
26extern "C" {
27#endif
28
29typedef struct
30{
31    unsigned int lowvalue;
32    unsigned int range;
33    int count;
34    unsigned int pos;
35    unsigned char *buffer;
36    unsigned char *buffer_end;
37    struct vpx_internal_error_info *error;
38} BOOL_CODER;
39
40extern void vp8_start_encode(BOOL_CODER *bc, unsigned char *buffer, unsigned char *buffer_end);
41
42extern void vp8_encode_value(BOOL_CODER *br, int data, int bits);
43extern void vp8_stop_encode(BOOL_CODER *bc);
44extern const unsigned int vp8_prob_cost[256];
45
46
47DECLARE_ALIGNED(16, extern const unsigned char, vp8_norm[256]);
48
49static 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 ");
59
60    return 0;
61}
62static 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;
69
70#ifdef VP8_ENTROPY_STATS
71#if defined(SECTIONBITS_OUTPUT)
72
73    if (bit)
74        Sectionbits[active_section] += vp8_prob_cost[255-probability];
75    else
76        Sectionbits[active_section] += vp8_prob_cost[probability];
77
78#endif
79#endif
80
81    split = 1 + (((range - 1) * probability) >> 8);
82
83    range = split;
84
85    if (bit)
86    {
87        lowvalue += split;
88        range = br->range - split;
89    }
90
91    shift = vp8_norm[range];
92
93    range <<= shift;
94    count += shift;
95
96    if (count >= 0)
97    {
98        int offset = shift - count;
99
100        if ((lowvalue << (offset - 1)) & 0x80000000)
101        {
102            int x = br->pos - 1;
103
104            while (x >= 0 && br->buffer[x] == 0xff)
105            {
106                br->buffer[x] = (unsigned char)0;
107                x--;
108            }
109
110            br->buffer[x] += 1;
111        }
112
113        validate_buffer(br->buffer + br->pos, 1, br->buffer_end, br->error);
114        br->buffer[br->pos++] = (lowvalue >> (24 - offset));
115
116        lowvalue <<= offset;
117        shift = count;
118        lowvalue &= 0xffffff;
119        count -= 8 ;
120    }
121
122    lowvalue <<= shift;
123    br->count = count;
124    br->lowvalue = lowvalue;
125    br->range = range;
126}
127
128#ifdef __cplusplus
129}  // extern "C"
130#endif
131
132#endif  // VP8_ENCODER_BOOLHUFF_H_
133