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 * Module Title : boolhuff.h
14 *
15 * Description : Bool Coder header file.
16 *
17 ****************************************************************************/
18 #ifndef VP8_ENCODER_BOOLHUFF_H_
19 #define VP8_ENCODER_BOOLHUFF_H_
20
21 #include "vpx_ports/mem.h"
22 #include "vpx/internal/vpx_codec_internal.h"
23
24 #ifdef __cplusplus
25 extern "C" {
26 #endif
27
28 typedef struct {
29 unsigned int lowvalue;
30 unsigned int range;
31 int count;
32 unsigned int pos;
33 unsigned char *buffer;
34 unsigned char *buffer_end;
35 struct vpx_internal_error_info *error;
36 } BOOL_CODER;
37
38 extern void vp8_start_encode(BOOL_CODER *bc, unsigned char *buffer,
39 unsigned char *buffer_end);
40
41 extern void vp8_encode_value(BOOL_CODER *br, int data, int bits);
42 extern void vp8_stop_encode(BOOL_CODER *bc);
43 extern const unsigned int vp8_prob_cost[256];
44
45 DECLARE_ALIGNED(16, extern const unsigned char, vp8_norm[256]);
46
validate_buffer(const unsigned char * start,size_t len,const unsigned char * end,struct vpx_internal_error_info * error)47 static int validate_buffer(const unsigned char *start, size_t len,
48 const unsigned char *end,
49 struct vpx_internal_error_info *error) {
50 if (start + len > start && start + len < end) {
51 return 1;
52 } else {
53 vpx_internal_error(error, VPX_CODEC_CORRUPT_FRAME,
54 "Truncated packet or corrupt partition ");
55 }
56
57 return 0;
58 }
vp8_encode_bool(BOOL_CODER * br,int bit,int probability)59 static void vp8_encode_bool(BOOL_CODER *br, int bit, int probability) {
60 unsigned int split;
61 int count = br->count;
62 unsigned int range = br->range;
63 unsigned int lowvalue = br->lowvalue;
64 register int shift;
65
66 #ifdef VP8_ENTROPY_STATS
67 #if defined(SECTIONBITS_OUTPUT)
68
69 if (bit)
70 Sectionbits[active_section] += vp8_prob_cost[255 - probability];
71 else
72 Sectionbits[active_section] += vp8_prob_cost[probability];
73
74 #endif
75 #endif
76
77 split = 1 + (((range - 1) * probability) >> 8);
78
79 range = split;
80
81 if (bit) {
82 lowvalue += split;
83 range = br->range - split;
84 }
85
86 shift = vp8_norm[range];
87
88 range <<= shift;
89 count += shift;
90
91 if (count >= 0) {
92 int offset = shift - count;
93
94 if ((lowvalue << (offset - 1)) & 0x80000000) {
95 int x = br->pos - 1;
96
97 while (x >= 0 && br->buffer[x] == 0xff) {
98 br->buffer[x] = (unsigned char)0;
99 x--;
100 }
101
102 br->buffer[x] += 1;
103 }
104
105 validate_buffer(br->buffer + br->pos, 1, br->buffer_end, br->error);
106 br->buffer[br->pos++] = (lowvalue >> (24 - offset));
107
108 lowvalue <<= offset;
109 shift = count;
110 lowvalue &= 0xffffff;
111 count -= 8;
112 }
113
114 lowvalue <<= shift;
115 br->count = count;
116 br->lowvalue = lowvalue;
117 br->range = range;
118 }
119
120 #ifdef __cplusplus
121 } // extern "C"
122 #endif
123
124 #endif // VP8_ENCODER_BOOLHUFF_H_
125