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 } BOOL_CODER;
39
40 extern void vp8_start_encode(BOOL_CODER *bc, unsigned char *buffer, unsigned char *buffer_end);
41
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];
45
46
47 DECLARE_ALIGNED(16, extern const unsigned char, vp8_norm[256]);
48
validate_buffer(const unsigned char * start,size_t len,const unsigned char * end,struct vpx_internal_error_info * error)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 ");
59
60 return 0;
61 }
vp8_encode_bool(BOOL_CODER * br,int bit,int probability)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;
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