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
39    /* Variables used to track bit costs without outputing to the bitstream */
40    unsigned int  measure_cost;
41    unsigned long bit_counter;
42} BOOL_CODER;
43
44extern void vp8_start_encode(BOOL_CODER *bc, unsigned char *buffer, unsigned char *buffer_end);
45
46extern void vp8_encode_value(BOOL_CODER *br, int data, int bits);
47extern void vp8_stop_encode(BOOL_CODER *bc);
48extern const unsigned int vp8_prob_cost[256];
49
50
51DECLARE_ALIGNED(16, extern const unsigned char, vp8_norm[256]);
52
53static int validate_buffer(const unsigned char *start,
54                           size_t               len,
55                           const unsigned char *end,
56                           struct vpx_internal_error_info *error)
57{
58    if (start + len > start && start + len < end)
59        return 1;
60    else
61        vpx_internal_error(error, VPX_CODEC_CORRUPT_FRAME,
62            "Truncated packet or corrupt partition ");
63
64    return 0;
65}
66static void vp8_encode_bool(BOOL_CODER *br, int bit, int probability)
67{
68    unsigned int split;
69    int count = br->count;
70    unsigned int range = br->range;
71    unsigned int lowvalue = br->lowvalue;
72    register unsigned int shift;
73
74#ifdef VP8_ENTROPY_STATS
75#if defined(SECTIONBITS_OUTPUT)
76
77    if (bit)
78        Sectionbits[active_section] += vp8_prob_cost[255-probability];
79    else
80        Sectionbits[active_section] += vp8_prob_cost[probability];
81
82#endif
83#endif
84
85    split = 1 + (((range - 1) * probability) >> 8);
86
87    range = split;
88
89    if (bit)
90    {
91        lowvalue += split;
92        range = br->range - split;
93    }
94
95    shift = vp8_norm[range];
96
97    range <<= shift;
98    count += shift;
99
100    if (count >= 0)
101    {
102        int offset = shift - count;
103
104        if ((lowvalue << (offset - 1)) & 0x80000000)
105        {
106            int x = br->pos - 1;
107
108            while (x >= 0 && br->buffer[x] == 0xff)
109            {
110                br->buffer[x] = (unsigned char)0;
111                x--;
112            }
113
114            br->buffer[x] += 1;
115        }
116
117        validate_buffer(br->buffer + br->pos, 1, br->buffer_end, br->error);
118        br->buffer[br->pos++] = (lowvalue >> (24 - offset));
119
120        lowvalue <<= offset;
121        shift = count;
122        lowvalue &= 0xffffff;
123        count -= 8 ;
124    }
125
126    lowvalue <<= shift;
127    br->count = count;
128    br->lowvalue = lowvalue;
129    br->range = range;
130}
131
132#ifdef __cplusplus
133}  // extern "C"
134#endif
135
136#endif  // VP8_ENCODER_BOOLHUFF_H_
137