1 /*
2 * Copyright 2014, 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 #define LOG_TAG "AudioSPDIF"
18
19 #include <string.h>
20 #include <assert.h>
21
22 #include <utils/Log.h>
23 #include <audio_utils/spdif/FrameScanner.h>
24
25 namespace android {
26
FrameScanner(int dataType,const uint8_t * syncBytes,uint32_t syncLength,uint32_t headerLength)27 FrameScanner::FrameScanner(int dataType,
28 const uint8_t *syncBytes,
29 uint32_t syncLength,
30 uint32_t headerLength)
31 : mBytesSkipped(0)
32 , mSyncBytes(syncBytes)
33 , mSyncLength(syncLength)
34 , mHeaderLength(headerLength)
35 , mCursor(0)
36 , mFormatDumpCount(0)
37 , mSampleRate(0)
38 , mRateMultiplier(1)
39 , mFrameSizeBytes(0)
40 , mDataType(dataType)
41 , mDataTypeInfo(0)
42 {
43 }
44
~FrameScanner()45 FrameScanner::~FrameScanner()
46 {
47 }
48
49 // State machine that scans for headers in a byte stream.
50 // @return true if we have detected a complete and valid header.
scan(uint8_t byte)51 bool FrameScanner::scan(uint8_t byte)
52 {
53 bool result = false;
54 ALOGV("FrameScanner: byte = 0x%02X, mCursor = %d", byte, mCursor);
55 assert(mCursor < sizeof(mHeaderBuffer));
56 if (mCursor < mSyncLength) {
57 // match sync word
58 if (byte == mSyncBytes[mCursor]) {
59 mHeaderBuffer[mCursor++] = byte;
60 } else {
61 mBytesSkipped += 1; // skip unsynchronized data
62 mCursor = 0;
63 }
64 } else if (mCursor < mHeaderLength) {
65 // gather header for parsing
66 mHeaderBuffer[mCursor++] = byte;
67 if (mCursor >= mHeaderLength) {
68 if (parseHeader()) {
69 result = true;
70 } else {
71 ALOGE("FrameScanner: ERROR - parseHeader() failed.");
72 }
73 mCursor = 0;
74 }
75 }
76 return result;
77 }
78
79 } // namespace android
80