AudioTrackShared.h revision c26741598a840f7c1d12ee457fb26f68fcdbcc70 
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
45// Important: do not add any virtual methods, including ~
46struct audio_track_cblk_t
47{
48
49    // The data members are grouped so that members accessed frequently and in the same context
50    // are in the same line of data cache.
51                Mutex       lock;           // sizeof(int)
52                Condition   cv;             // sizeof(int)
53
54                // next 4 are offsets within "buffers"
55    volatile    uint32_t    user;
56    volatile    uint32_t    server;
57                uint32_t    userBase;
58                uint32_t    serverBase;
59
60                // if there is a shared buffer, "buffers" is the value of pointer() for the shared
61                // buffer, otherwise "buffers" points immediately after the control block
62                void*       buffers;
63                uint32_t    frameCount;
64
65                // Cache line boundary
66
67                uint32_t    loopStart;
68                uint32_t    loopEnd;        // read-only for server, read/write for client
69                int         loopCount;      // read/write for client
70
71                // Channel volumes are fixed point U4.12, so 0x1000 means 1.0.
72                // Left channel is in [0:15], right channel is in [16:31].
73                // Always read and write the combined pair atomically.
74                // For AudioTrack only, not used by AudioRecord.
75private:
76                uint32_t    mVolumeLR;
77public:
78
79                uint32_t    sampleRate;
80
81                // NOTE: audio_track_cblk_t::frameSize is not equal to AudioTrack::frameSize() for
82                // 8 bit PCM data: in this case,  mCblk->frameSize is based on a sample size of
83                // 16 bit because data is converted to 16 bit before being stored in buffer
84
85                // read-only for client, server writes once at initialization and is then read-only
86                uint8_t     frameSize;       // would normally be size_t, but 8 bits is plenty
87                uint8_t     mName;           // normal tracks: track name, fast tracks: track index
88
89                // used by client only
90                uint16_t    bufferTimeoutMs; // Maximum cumulated timeout before restarting
91                                             // audioflinger
92
93                uint16_t    waitTimeMs;      // Cumulated wait time, used by client only
94private:
95                // client write-only, server read-only
96                uint16_t    mSendLevel;      // Fixed point U4.12 so 0x1000 means 1.0
97public:
98    volatile    int32_t     flags;
99
100                // Cache line boundary (32 bytes)
101
102                // Since the control block is always located in shared memory, this constructor
103                // is only used for placement new().  It is never used for regular new() or stack.
104                            audio_track_cblk_t();
105                uint32_t    stepUser(uint32_t frameCount);      // called by client only, where
106                // client includes regular AudioTrack and AudioFlinger::PlaybackThread::OutputTrack
107                bool        stepServer(uint32_t frameCount);    // called by server only
108                void*       buffer(uint32_t offset) const;
109                uint32_t    framesAvailable();
110                uint32_t    framesAvailable_l();
111                uint32_t    framesReady();                      // called by server only
112                bool        tryLock();
113
114                // No barriers on the following operations, so the ordering of loads/stores
115                // with respect to other parameters is UNPREDICTABLE. That's considered safe.
116
117                // for AudioTrack client only, caller must limit to 0.0 <= sendLevel <= 1.0
118                void        setSendLevel(float sendLevel) {
119                    mSendLevel = uint16_t(sendLevel * 0x1000);
120                }
121
122                // for AudioFlinger only; the return value must be validated by the caller
123                uint16_t    getSendLevel_U4_12() const {
124                    return mSendLevel;
125                }
126
127                // for AudioTrack client only, caller must limit to 0 <= volumeLR <= 0x10001000
128                void        setVolumeLR(uint32_t volumeLR) {
129                    mVolumeLR = volumeLR;
130                }
131
132                // for AudioFlinger only; the return value must be validated by the caller
133                uint32_t    getVolumeLR() const {
134                    return mVolumeLR;
135                }
136
137};
138
139
140// ----------------------------------------------------------------------------
141
142}; // namespace android
143
144#endif // ANDROID_AUDIO_TRACK_SHARED_H
145