1 /**
2 * Copyright (C) 2022 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include <ImsMediaBitWriter.h>
18 #include <ImsMediaTrace.h>
19 #include <string.h>
20
ImsMediaBitWriter()21 ImsMediaBitWriter::ImsMediaBitWriter()
22 {
23 mBuffer = nullptr;
24 mMaxBufferSize = 0;
25 mBytePos = 0;
26 mBitPos = 0;
27 mBitBuffer = 0;
28 mBufferFull = false;
29 }
30
~ImsMediaBitWriter()31 ImsMediaBitWriter::~ImsMediaBitWriter() {}
32
SetBuffer(uint8_t * pbBuffer,uint32_t nBufferSize)33 void ImsMediaBitWriter::SetBuffer(uint8_t* pbBuffer, uint32_t nBufferSize)
34 {
35 mBytePos = 0;
36 mBitPos = 0;
37 mBitBuffer = 0;
38 mBufferFull = false;
39 mBuffer = pbBuffer;
40 mMaxBufferSize = nBufferSize;
41 }
42
Write(uint32_t nValue,uint32_t nSize)43 bool ImsMediaBitWriter::Write(uint32_t nValue, uint32_t nSize)
44 {
45 if (nSize == 0)
46 {
47 return false;
48 }
49
50 if (mBuffer == nullptr || nSize > 24 || mBufferFull)
51 {
52 IMLOGE2("[Write] nSize[%d], BufferFull[%d]", nSize, mBufferFull);
53 return false;
54 }
55
56 // write to bit buffer
57 mBitBuffer += (nValue << (32 - nSize) >> mBitPos);
58 mBitPos += nSize;
59
60 // write to byte buffer
61 while (mBitPos >= 8)
62 {
63 mBuffer[mBytePos++] = (uint8_t)(mBitBuffer >> 24);
64 mBitBuffer <<= 8;
65 mBitPos -= 8;
66 }
67
68 if (mBytePos >= mMaxBufferSize)
69 {
70 mBufferFull = true;
71 }
72
73 return true;
74 }
75
WriteByteBuffer(uint8_t * pbSrc,uint32_t nBitSize)76 bool ImsMediaBitWriter::WriteByteBuffer(uint8_t* pbSrc, uint32_t nBitSize)
77 {
78 uint32_t nByteSize;
79 uint32_t nRemainBitSize;
80 nByteSize = nBitSize >> 3;
81 nRemainBitSize = nBitSize & 0x07;
82
83 if (mBitPos == 0)
84 {
85 memcpy(mBuffer + mBytePos, pbSrc, nByteSize);
86 mBytePos += nByteSize;
87 }
88 else
89 {
90 uint32_t i;
91
92 for (i = 0; i < nByteSize; i++)
93 {
94 if (!Write(pbSrc[i], 8))
95 {
96 return false;
97 }
98 }
99 }
100
101 if (nRemainBitSize > 0)
102 {
103 uint32_t v = pbSrc[nByteSize];
104 v >>= (8 - nRemainBitSize);
105
106 if (!Write(v, nRemainBitSize))
107 {
108 return false;
109 }
110 }
111
112 return true;
113 }
114
WriteByteBuffer(uint32_t value)115 bool ImsMediaBitWriter::WriteByteBuffer(uint32_t value)
116 {
117 uint32_t nRemainBitSize = 32;
118
119 for (int32_t i = 0; i < 4; i++)
120 {
121 nRemainBitSize -= 8;
122 uint8_t v = (value >> nRemainBitSize) & 0x00ff;
123
124 if (!Write(v, 8))
125 {
126 return false;
127 }
128 }
129
130 return true;
131 }
132
Seek(uint32_t nSize)133 void ImsMediaBitWriter::Seek(uint32_t nSize)
134 {
135 Flush();
136 mBitPos += nSize;
137
138 while (mBitPos >= 8)
139 {
140 mBytePos++;
141 mBitPos -= 8;
142 }
143 }
144
AddPadding()145 void ImsMediaBitWriter::AddPadding()
146 {
147 if (mBitPos > 0)
148 {
149 Write(0, 8 - mBitPos);
150 }
151 }
152
GetBufferSize()153 uint32_t ImsMediaBitWriter::GetBufferSize()
154 {
155 uint32_t nSize;
156 nSize = (mBitPos + 7) >> 3;
157 nSize += mBytePos;
158 return nSize;
159 }
160
Flush()161 void ImsMediaBitWriter::Flush()
162 {
163 if (mBitPos > 0)
164 {
165 mBuffer[mBytePos] += (uint8_t)(mBitBuffer >> 24);
166 mBitBuffer = 0;
167 }
168 }