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
26 extern "C" {
27 #endif
28
29 typedef 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
44 extern void vp8_start_encode(BOOL_CODER *bc, unsigned char *buffer, unsigned char *buffer_end);
45
46 extern void vp8_encode_value(BOOL_CODER *br, int data, int bits);
47 extern void vp8_stop_encode(BOOL_CODER *bc);
48 extern const unsigned int vp8_prob_cost[256];
49
50
51 DECLARE_ALIGNED(16, extern const unsigned char, vp8_norm[256]);
52
validate_buffer(const unsigned char * start,size_t len,const unsigned char * end,struct vpx_internal_error_info * error)53 static 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 }
vp8_encode_bool(BOOL_CODER * br,int bit,int probability)66 static 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