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 : vp9_boolhuff.h
15 *
16 * Description : Bool Coder header file.
17 *
18 ****************************************************************************/
19 #ifndef VP9_ENCODER_VP9_BOOLHUFF_H_
20 #define VP9_ENCODER_VP9_BOOLHUFF_H_
21
22 #include "vpx_ports/mem.h"
23
24 typedef struct {
25 unsigned int lowvalue;
26 unsigned int range;
27 unsigned int value;
28 int count;
29 unsigned int pos;
30 uint8_t *buffer;
31
32 // Variables used to track bit costs without outputing to the bitstream
33 unsigned int measure_cost;
34 unsigned long bit_counter;
35 } vp9_writer;
36
37 extern const unsigned int vp9_prob_cost[256];
38
39 void vp9_start_encode(vp9_writer *bc, uint8_t *buffer);
40 void vp9_stop_encode(vp9_writer *bc);
41
42 DECLARE_ALIGNED(16, extern const unsigned char, vp9_norm[256]);
43
vp9_write(vp9_writer * br,int bit,int probability)44 static void vp9_write(vp9_writer *br, int bit, int probability) {
45 unsigned int split;
46 int count = br->count;
47 unsigned int range = br->range;
48 unsigned int lowvalue = br->lowvalue;
49 register unsigned int shift;
50
51 #ifdef ENTROPY_STATS
52 #if defined(SECTIONBITS_OUTPUT)
53
54 if (bit)
55 Sectionbits[active_section] += vp9_prob_cost[255 - probability];
56 else
57 Sectionbits[active_section] += vp9_prob_cost[probability];
58
59 #endif
60 #endif
61
62 split = 1 + (((range - 1) * probability) >> 8);
63
64 range = split;
65
66 if (bit) {
67 lowvalue += split;
68 range = br->range - split;
69 }
70
71 shift = vp9_norm[range];
72
73 range <<= shift;
74 count += shift;
75
76 if (count >= 0) {
77 int offset = shift - count;
78
79 if ((lowvalue << (offset - 1)) & 0x80000000) {
80 int x = br->pos - 1;
81
82 while (x >= 0 && br->buffer[x] == 0xff) {
83 br->buffer[x] = 0;
84 x--;
85 }
86
87 br->buffer[x] += 1;
88 }
89
90 br->buffer[br->pos++] = (lowvalue >> (24 - offset));
91 lowvalue <<= offset;
92 shift = count;
93 lowvalue &= 0xffffff;
94 count -= 8;
95 }
96
97 lowvalue <<= shift;
98 br->count = count;
99 br->lowvalue = lowvalue;
100 br->range = range;
101 }
102
vp9_write_bit(vp9_writer * w,int bit)103 static void vp9_write_bit(vp9_writer *w, int bit) {
104 vp9_write(w, bit, 128); // vp9_prob_half
105 }
106
vp9_write_literal(vp9_writer * w,int data,int bits)107 static void vp9_write_literal(vp9_writer *w, int data, int bits) {
108 int bit;
109
110 for (bit = bits - 1; bit >= 0; bit--)
111 vp9_write_bit(w, 1 & (data >> bit));
112 }
113
114
115 #endif // VP9_ENCODER_VP9_BOOLHUFF_H_
116