blob: 705b2ca93c21c39325661063888704f6de55aa8a (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
|
// Copyright 2016 The Draco Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// File provides direct encoding of bits with arithmetic encoder interface.
#ifndef DRACO_COMPRESSION_BIT_CODERS_DIRECT_BIT_ENCODER_H_
#define DRACO_COMPRESSION_BIT_CODERS_DIRECT_BIT_ENCODER_H_
#include <vector>
#include "draco/core/encoder_buffer.h"
namespace draco {
class DirectBitEncoder {
public:
DirectBitEncoder();
~DirectBitEncoder();
// Must be called before any Encode* function is called.
void StartEncoding();
// Encode one bit. If |bit| is true encode a 1, otherwise encode a 0.
void EncodeBit(bool bit) {
if (bit) {
local_bits_ |= 1 << (31 - num_local_bits_);
}
num_local_bits_++;
if (num_local_bits_ == 32) {
bits_.push_back(local_bits_);
num_local_bits_ = 0;
local_bits_ = 0;
}
}
// Encode |nbits| of |value|, starting from the least significant bit.
// |nbits| must be > 0 and <= 32.
void EncodeLeastSignificantBits32(int nbits, uint32_t value) {
DRACO_DCHECK_EQ(true, nbits <= 32);
DRACO_DCHECK_EQ(true, nbits > 0);
const int remaining = 32 - num_local_bits_;
// Make sure there are no leading bits that should not be encoded and
// start from here.
value = value << (32 - nbits);
if (nbits <= remaining) {
value = value >> num_local_bits_;
local_bits_ = local_bits_ | value;
num_local_bits_ += nbits;
if (num_local_bits_ == 32) {
bits_.push_back(local_bits_);
local_bits_ = 0;
num_local_bits_ = 0;
}
} else {
value = value >> (32 - nbits);
num_local_bits_ = nbits - remaining;
const uint32_t value_l = value >> num_local_bits_;
local_bits_ = local_bits_ | value_l;
bits_.push_back(local_bits_);
local_bits_ = value << (32 - num_local_bits_);
}
}
// Ends the bit encoding and stores the result into the target_buffer.
void EndEncoding(EncoderBuffer *target_buffer);
private:
void Clear();
std::vector<uint32_t> bits_;
uint32_t local_bits_;
uint32_t num_local_bits_;
};
} // namespace draco
#endif // DRACO_COMPRESSION_BIT_CODERS_DIRECT_BIT_ENCODER_H_
|
