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 VPX_VP8_ENCODER_BOOLHUFF_H_
19 #define VPX_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 void vp8_start_encode(BOOL_CODER *bc, unsigned char *source,
39 unsigned char *source_end);
40
41 void vp8_encode_value(BOOL_CODER *bc, int data, int bits);
42 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 * bc,int bit,int probability)59 static void vp8_encode_bool(BOOL_CODER *bc, int bit, int probability) {
60 unsigned int split;
61 int count = bc->count;
62 unsigned int range = bc->range;
63 unsigned int lowvalue = bc->lowvalue;
64 int shift;
65
66 split = 1 + (((range - 1) * probability) >> 8);
67
68 range = split;
69
70 if (bit) {
71 lowvalue += split;
72 range = bc->range - split;
73 }
74
75 shift = vp8_norm[range];
76
77 range <<= shift;
78 count += shift;
79
80 if (count >= 0) {
81 int offset = shift - count;
82
83 if ((lowvalue << (offset - 1)) & 0x80000000) {
84 int x = bc->pos - 1;
85
86 while (x >= 0 && bc->buffer[x] == 0xff) {
87 bc->buffer[x] = (unsigned char)0;
88 x--;
89 }
90
91 bc->buffer[x] += 1;
92 }
93
94 validate_buffer(bc->buffer + bc->pos, 1, bc->buffer_end, bc->error);
95 bc->buffer[bc->pos++] = (lowvalue >> (24 - offset));
96
97 lowvalue <<= offset;
98 shift = count;
99 lowvalue &= 0xffffff;
100 count -= 8;
101 }
102
103 lowvalue <<= shift;
104 bc->count = count;
105 bc->lowvalue = lowvalue;
106 bc->range = range;
107 }
108
109 #ifdef __cplusplus
110 } // extern "C"
111 #endif
112
113 #endif // VPX_VP8_ENCODER_BOOLHUFF_H_
114