AudioTrackShared.h revision d12b033552585cd8761ba6241f21e4cea4a21878 
1/*
2 * Copyright (C) 2007 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#ifndef ANDROID_AUDIO_TRACK_SHARED_H
18#define ANDROID_AUDIO_TRACK_SHARED_H
19
20#include <stdint.h>
21#include <sys/types.h>
22
23#include <utils/threads.h>
24
25namespace android {
26
27// ----------------------------------------------------------------------------
28
29// Maximum cumulated timeout milliseconds before restarting audioflinger thread
30#define MAX_STARTUP_TIMEOUT_MS  3000    // Longer timeout period at startup to cope with A2DP
31                                        // init time
32#define MAX_RUN_TIMEOUT_MS      1000
33#define WAIT_PERIOD_MS          10
34#define RESTORE_TIMEOUT_MS      5000    // Maximum waiting time for a track to be restored
35
36#define CBLK_UNDERRUN   0x01 // set: underrun (out) or overrrun (in), clear: no underrun or overrun
37#define CBLK_DIRECTION  0x02 // set: cblk is for an AudioTrack, clear: for AudioRecord
38#define CBLK_FORCEREADY 0x04 // set: track is considered ready immediately by AudioFlinger,
39                             // clear: track is ready when buffer full
40#define CBLK_INVALID    0x08 // track buffer invalidated by AudioFlinger, need to re-create
41#define CBLK_DISABLED   0x10 // track disabled by AudioFlinger due to underrun, need to re-start
42#define CBLK_RESTORING  0x20 // track is being restored after invalidation by AudioFlinger
43#define CBLK_RESTORED   0x40 // track has been restored after invalidation by AudioFlinger
44#define CBLK_FAST       0x80 // AudioFlinger successfully created a fast track
45
46// Important: do not add any virtual methods, including ~
47struct audio_track_cblk_t
48{
49
50    // The data members are grouped so that members accessed frequently and in the same context
51    // are in the same line of data cache.
52                Mutex       lock;           // sizeof(int)
53                Condition   cv;             // sizeof(int)
54
55                // next 4 are offsets within "buffers"
56    volatile    uint32_t    user;
57    volatile    uint32_t    server;
58                uint32_t    userBase;
59                uint32_t    serverBase;
60
61                // if there is a shared buffer, "buffers" is the value of pointer() for the shared
62                // buffer, otherwise "buffers" points immediately after the control block
63                void*       buffers;
64                uint32_t    frameCount;
65
66                // Cache line boundary
67
68                uint32_t    loopStart;
69                uint32_t    loopEnd;        // read-only for server, read/write for client
70                int         loopCount;      // read/write for client
71
72                // Channel volumes are fixed point U4.12, so 0x1000 means 1.0.
73                // Left channel is in [0:15], right channel is in [16:31].
74                // Always read and write the combined pair atomically.
75                // For AudioTrack only, not used by AudioRecord.
76private:
77                uint32_t    mVolumeLR;
78public:
79
80                uint32_t    sampleRate;
81
82                // NOTE: audio_track_cblk_t::frameSize is not equal to AudioTrack::frameSize() for
83                // 8 bit PCM data: in this case,  mCblk->frameSize is based on a sample size of
84                // 16 bit because data is converted to 16 bit before being stored in buffer
85
86                // read-only for client, server writes once at initialization and is then read-only
87                uint8_t     frameSize;       // would normally be size_t, but 8 bits is plenty
88                uint8_t     mName;           // normal tracks: track name, fast tracks: track index
89
90                // used by client only
91                uint16_t    bufferTimeoutMs; // Maximum cumulated timeout before restarting
92                                             // audioflinger
93
94                uint16_t    waitTimeMs;      // Cumulated wait time, used by client only
95private:
96                // client write-only, server read-only
97                uint16_t    mSendLevel;      // Fixed point U4.12 so 0x1000 means 1.0
98public:
99    volatile    int32_t     flags;
100
101                // Cache line boundary (32 bytes)
102
103                // Since the control block is always located in shared memory, this constructor
104                // is only used for placement new().  It is never used for regular new() or stack.
105                            audio_track_cblk_t();
106                uint32_t    stepUser(uint32_t frameCount);      // called by client only, where
107                // client includes regular AudioTrack and AudioFlinger::PlaybackThread::OutputTrack
108                bool        stepServer(uint32_t frameCount);    // called by server only
109                void*       buffer(uint32_t offset) const;
110                uint32_t    framesAvailable();
111                uint32_t    framesAvailable_l();
112                uint32_t    framesReady();                      // called by server only
113                bool        tryLock();
114
115                // No barriers on the following operations, so the ordering of loads/stores
116                // with respect to other parameters is UNPREDICTABLE. That's considered safe.
117
118                // for AudioTrack client only, caller must limit to 0.0 <= sendLevel <= 1.0
119                void        setSendLevel(float sendLevel) {
120                    mSendLevel = uint16_t(sendLevel * 0x1000);
121                }
122
123                // for AudioFlinger only; the return value must be validated by the caller
124                uint16_t    getSendLevel_U4_12() const {
125                    return mSendLevel;
126                }
127
128                // for AudioTrack client only, caller must limit to 0 <= volumeLR <= 0x10001000
129                void        setVolumeLR(uint32_t volumeLR) {
130                    mVolumeLR = volumeLR;
131                }
132
133                // for AudioFlinger only; the return value must be validated by the caller
134                uint32_t    getVolumeLR() const {
135                    return mVolumeLR;
136                }
137
138};
139
140
141// ----------------------------------------------------------------------------
142
143}; // namespace android
144
145#endif // ANDROID_AUDIO_TRACK_SHARED_H
146