SDL  2.0
SDL_sysaudio.h
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1 /*
2  Simple DirectMedia Layer
3  Copyright (C) 1997-2018 Sam Lantinga <slouken@libsdl.org>
4 
5  This software is provided 'as-is', without any express or implied
6  warranty. In no event will the authors be held liable for any damages
7  arising from the use of this software.
8 
9  Permission is granted to anyone to use this software for any purpose,
10  including commercial applications, and to alter it and redistribute it
11  freely, subject to the following restrictions:
12 
13  1. The origin of this software must not be misrepresented; you must not
14  claim that you wrote the original software. If you use this software
15  in a product, an acknowledgment in the product documentation would be
16  appreciated but is not required.
17  2. Altered source versions must be plainly marked as such, and must not be
18  misrepresented as being the original software.
19  3. This notice may not be removed or altered from any source distribution.
20 */
21 #include "../SDL_internal.h"
22 
23 #ifndef SDL_sysaudio_h_
24 #define SDL_sysaudio_h_
25 
26 #include "SDL_mutex.h"
27 #include "SDL_thread.h"
28 #include "../SDL_dataqueue.h"
29 #include "./SDL_audio_c.h"
30 
31 /* !!! FIXME: These are wordy and unlocalized... */
32 #define DEFAULT_OUTPUT_DEVNAME "System audio output device"
33 #define DEFAULT_INPUT_DEVNAME "System audio capture device"
34 
35 /* The SDL audio driver */
36 typedef struct SDL_AudioDevice SDL_AudioDevice;
37 #define _THIS SDL_AudioDevice *_this
38 
39 /* Audio targets should call this as devices are added to the system (such as
40  a USB headset being plugged in), and should also be called for
41  for every device found during DetectDevices(). */
42 extern void SDL_AddAudioDevice(const int iscapture, const char *name, void *handle);
43 
44 /* Audio targets should call this as devices are removed, so SDL can update
45  its list of available devices. */
46 extern void SDL_RemoveAudioDevice(const int iscapture, void *handle);
47 
48 /* Audio targets should call this if an opened audio device is lost while
49  being used. This can happen due to i/o errors, or a device being unplugged,
50  etc. If the device is totally gone, please also call SDL_RemoveAudioDevice()
51  as appropriate so SDL's list of devices is accurate. */
52 extern void SDL_OpenedAudioDeviceDisconnected(SDL_AudioDevice *device);
53 
54 /* This is the size of a packet when using SDL_QueueAudio(). We allocate
55  these as necessary and pool them, under the assumption that we'll
56  eventually end up with a handful that keep recycling, meeting whatever
57  the app needs. We keep packing data tightly as more arrives to avoid
58  wasting space, and if we get a giant block of data, we'll split them
59  into multiple packets behind the scenes. My expectation is that most
60  apps will have 2-3 of these in the pool. 8k should cover most needs, but
61  if this is crippling for some embedded system, we can #ifdef this.
62  The system preallocates enough packets for 2 callbacks' worth of data. */
63 #define SDL_AUDIOBUFFERQUEUE_PACKETLEN (8 * 1024)
64 
65 typedef struct SDL_AudioDriverImpl
66 {
67  void (*DetectDevices) (void);
68  int (*OpenDevice) (_THIS, void *handle, const char *devname, int iscapture);
69  void (*ThreadInit) (_THIS); /* Called by audio thread at start */
70  void (*ThreadDeinit) (_THIS); /* Called by audio thread at end */
71  void (*BeginLoopIteration)(_THIS); /* Called by audio thread at top of loop */
72  void (*WaitDevice) (_THIS);
73  void (*PlayDevice) (_THIS);
74  int (*GetPendingBytes) (_THIS);
75  Uint8 *(*GetDeviceBuf) (_THIS);
76  int (*CaptureFromDevice) (_THIS, void *buffer, int buflen);
77  void (*FlushCapture) (_THIS);
78  void (*PrepareToClose) (_THIS); /**< Called between run and draining wait for playback devices */
79  void (*CloseDevice) (_THIS);
80  void (*LockDevice) (_THIS);
81  void (*UnlockDevice) (_THIS);
82  void (*FreeDeviceHandle) (void *handle); /**< SDL is done with handle from SDL_AddAudioDevice() */
83  void (*Deinitialize) (void);
84 
85  /* !!! FIXME: add pause(), so we can optimize instead of mixing silence. */
86 
87  /* Some flags to push duplicate code into the core and reduce #ifdefs. */
88  /* !!! FIXME: these should be SDL_bool */
89  int ProvidesOwnCallbackThread;
90  int SkipMixerLock;
91  int HasCaptureSupport;
92  int OnlyHasDefaultOutputDevice;
93  int OnlyHasDefaultCaptureDevice;
94  int AllowsArbitraryDeviceNames;
95 } SDL_AudioDriverImpl;
96 
97 
98 typedef struct SDL_AudioDeviceItem
99 {
100  void *handle;
101  char *name;
102  char *original_name;
103  int dupenum;
104  struct SDL_AudioDeviceItem *next;
105 } SDL_AudioDeviceItem;
106 
107 
108 typedef struct SDL_AudioDriver
109 {
110  /* * * */
111  /* The name of this audio driver */
112  const char *name;
113 
114  /* * * */
115  /* The description of this audio driver */
116  const char *desc;
117 
118  SDL_AudioDriverImpl impl;
119 
120  /* A mutex for device detection */
121  SDL_mutex *detectionLock;
122  SDL_bool captureDevicesRemoved;
123  SDL_bool outputDevicesRemoved;
124  int outputDeviceCount;
125  int inputDeviceCount;
126  SDL_AudioDeviceItem *outputDevices;
127  SDL_AudioDeviceItem *inputDevices;
128 } SDL_AudioDriver;
129 
130 
131 /* Define the SDL audio driver structure */
132 struct SDL_AudioDevice
133 {
134  /* * * */
135  /* Data common to all devices */
136  SDL_AudioDeviceID id;
137 
138  /* The device's current audio specification */
139  SDL_AudioSpec spec;
140 
141  /* The callback's expected audio specification (converted vs device's spec). */
142  SDL_AudioSpec callbackspec;
143 
144  /* Stream that converts and resamples. NULL if not needed. */
145  SDL_AudioStream *stream;
146 
147  /* Current state flags */
148  SDL_atomic_t shutdown; /* true if we are signaling the play thread to end. */
149  SDL_atomic_t enabled; /* true if device is functioning and connected. */
150  SDL_atomic_t paused;
151  SDL_bool iscapture;
152 
153  /* Scratch buffer used in the bridge between SDL and the user callback. */
154  Uint8 *work_buffer;
155 
156  /* Size, in bytes, of work_buffer. */
157  Uint32 work_buffer_len;
158 
159  /* A mutex for locking the mixing buffers */
160  SDL_mutex *mixer_lock;
161 
162  /* A thread to feed the audio device */
163  SDL_Thread *thread;
164  SDL_threadID threadid;
165 
166  /* Queued buffers (if app not using callback). */
167  SDL_DataQueue *buffer_queue;
168 
169  /* * * */
170  /* Data private to this driver */
171  struct SDL_PrivateAudioData *hidden;
172 
173  void *handle;
174 };
175 #undef _THIS
176 
177 typedef struct AudioBootStrap
178 {
179  const char *name;
180  const char *desc;
181  int (*init) (SDL_AudioDriverImpl * impl);
182  int demand_only; /* 1==request explicitly, or it won't be available. */
183 } AudioBootStrap;
184 
185 /* Not all of these are available in a given build. Use #ifdefs, etc. */
186 extern AudioBootStrap PULSEAUDIO_bootstrap;
187 extern AudioBootStrap ALSA_bootstrap;
188 extern AudioBootStrap JACK_bootstrap;
189 extern AudioBootStrap SNDIO_bootstrap;
190 extern AudioBootStrap NETBSDAUDIO_bootstrap;
191 extern AudioBootStrap DSP_bootstrap;
192 extern AudioBootStrap QSAAUDIO_bootstrap;
193 extern AudioBootStrap SUNAUDIO_bootstrap;
194 extern AudioBootStrap ARTS_bootstrap;
195 extern AudioBootStrap ESD_bootstrap;
196 extern AudioBootStrap NACLAUDIO_bootstrap;
197 extern AudioBootStrap NAS_bootstrap;
198 extern AudioBootStrap WASAPI_bootstrap;
199 extern AudioBootStrap DSOUND_bootstrap;
200 extern AudioBootStrap WINMM_bootstrap;
201 extern AudioBootStrap PAUDIO_bootstrap;
202 extern AudioBootStrap HAIKUAUDIO_bootstrap;
203 extern AudioBootStrap COREAUDIO_bootstrap;
204 extern AudioBootStrap DISKAUDIO_bootstrap;
205 extern AudioBootStrap DUMMYAUDIO_bootstrap;
206 extern AudioBootStrap FUSIONSOUND_bootstrap;
207 extern AudioBootStrap ANDROIDAUDIO_bootstrap;
208 extern AudioBootStrap PSPAUDIO_bootstrap;
209 extern AudioBootStrap EMSCRIPTENAUDIO_bootstrap;
210 
211 #endif /* SDL_sysaudio_h_ */
212 
213 /* vi: set ts=4 sw=4 expandtab: */