SDL  2.0
SDL_sysaudio.h
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1 /*
2  Simple DirectMedia Layer
3  Copyright (C) 1997-2016 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 
29 /* The SDL audio driver */
30 typedef struct SDL_AudioDevice SDL_AudioDevice;
31 #define _THIS SDL_AudioDevice *_this
32 
33 /* Audio targets should call this as devices are added to the system (such as
34  a USB headset being plugged in), and should also be called for
35  for every device found during DetectDevices(). */
36 extern void SDL_AddAudioDevice(const int iscapture, const char *name, void *handle);
37 
38 /* Audio targets should call this as devices are removed, so SDL can update
39  its list of available devices. */
40 extern void SDL_RemoveAudioDevice(const int iscapture, void *handle);
41 
42 /* Audio targets should call this if an opened audio device is lost while
43  being used. This can happen due to i/o errors, or a device being unplugged,
44  etc. If the device is totally gone, please also call SDL_RemoveAudioDevice()
45  as appropriate so SDL's list of devices is accurate. */
47 
48 
49 /* This is the size of a packet when using SDL_QueueAudio(). We allocate
50  these as necessary and pool them, under the assumption that we'll
51  eventually end up with a handful that keep recycling, meeting whatever
52  the app needs. We keep packing data tightly as more arrives to avoid
53  wasting space, and if we get a giant block of data, we'll split them
54  into multiple packets behind the scenes. My expectation is that most
55  apps will have 2-3 of these in the pool. 8k should cover most needs, but
56  if this is crippling for some embedded system, we can #ifdef this.
57  The system preallocates enough packets for 2 callbacks' worth of data. */
58 #define SDL_AUDIOBUFFERQUEUE_PACKETLEN (8 * 1024)
59 
60 /* Used by apps that queue audio instead of using the callback. */
61 typedef struct SDL_AudioBufferQueue
62 {
64  Uint32 datalen; /* bytes currently in use in this packet. */
65  Uint32 startpos; /* bytes currently consumed in this packet. */
66  struct SDL_AudioBufferQueue *next; /* next item in linked list. */
68 
69 typedef struct SDL_AudioDriverImpl
70 {
71  void (*DetectDevices) (void);
72  int (*OpenDevice) (_THIS, void *handle, const char *devname, int iscapture);
73  void (*ThreadInit) (_THIS); /* Called by audio thread at start */
74  void (*WaitDevice) (_THIS);
75  void (*PlayDevice) (_THIS);
76  int (*GetPendingBytes) (_THIS);
77  Uint8 *(*GetDeviceBuf) (_THIS);
78  void (*WaitDone) (_THIS);
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 */
90  int SkipMixerLock; /* !!! FIXME: do we need this anymore? */
96 
97 
98 typedef struct SDL_AudioDeviceItem
99 {
100  void *handle;
102  #if (defined(__GNUC__) && (__GNUC__ <= 2))
103  char name[1]; /* actually variable length. */
104  #else
105  char name[];
106  #endif
108 
109 
110 typedef struct SDL_AudioDriver
111 {
112  /* * * */
113  /* The name of this audio driver */
114  const char *name;
115 
116  /* * * */
117  /* The description of this audio driver */
118  const char *desc;
119 
121 
122  /* A mutex for device detection */
131 
132 
133 /* Streamer */
134 typedef struct
135 {
137  int max_len; /* the maximum length in bytes */
138  int read_pos, write_pos; /* the position of the write and read heads in bytes */
140 
141 
142 /* Define the SDL audio driver structure */
144 {
145  /* * * */
146  /* Data common to all devices */
148 
149  /* The current audio specification (shared with audio thread) */
151 
152  /* An audio conversion block for audio format emulation */
154 
155  /* The streamer, if sample rate conversion necessitates it */
158 
159  /* Current state flags */
160  /* !!! FIXME: should be SDL_bool */
162  int enabled; /* true if device is functioning and connected. */
163  int shutdown; /* true if we are signaling the play thread to end. */
164  int paused;
165  int opened;
166 
167  /* Fake audio buffer for when the audio hardware is busy */
169 
170  /* A mutex for locking the mixing buffers */
172 
173  /* A thread to feed the audio device */
176 
177  /* Queued buffers (if app not using callback). */
178  SDL_AudioBufferQueue *buffer_queue_head; /* device fed from here. */
179  SDL_AudioBufferQueue *buffer_queue_tail; /* queue fills to here. */
180  SDL_AudioBufferQueue *buffer_queue_pool; /* these are unused packets. */
181  Uint32 queued_bytes; /* number of bytes of audio data in the queue. */
182 
183  /* * * */
184  /* Data private to this driver */
186 };
187 #undef _THIS
188 
189 typedef struct AudioBootStrap
190 {
191  const char *name;
192  const char *desc;
193  int (*init) (SDL_AudioDriverImpl * impl);
194  int demand_only; /* 1==request explicitly, or it won't be available. */
196 
197 #endif /* _SDL_sysaudio_h */
198 
199 /* vi: set ts=4 sw=4 expandtab: */
struct SDL_PrivateAudioData * hidden
Definition: SDL_sysaudio.h:185
SDL_AudioDeviceID id
Definition: SDL_sysaudio.h:147
SDL_mutex * mixer_lock
Definition: SDL_sysaudio.h:171
SDL_bool captureDevicesRemoved
Definition: SDL_sysaudio.h:124
const char * name
Definition: SDL_sysaudio.h:114
uint32_t Uint32
An unsigned 32-bit integer type.
Definition: SDL_stdinc.h:155
const char * name
Definition: SDL_sysaudio.h:191
struct SDL_AudioDeviceItem * next
Definition: SDL_sysaudio.h:101
GLint GLenum GLsizei GLsizei GLsizei GLint GLsizei const GLvoid * data
Definition: SDL_opengl.h:1967
SDL_threadID threadid
Definition: SDL_sysaudio.h:175
SDL_AudioBufferQueue * buffer_queue_pool
Definition: SDL_sysaudio.h:180
SDL_AudioSpec spec
Definition: SDL_sysaudio.h:150
void SDL_AddAudioDevice(const int iscapture, const char *name, void *handle)
Definition: SDL_audio.c:347
GLuint const GLchar * name
SDL_mutex * detectionLock
Definition: SDL_sysaudio.h:123
SDL_AudioBufferQueue * buffer_queue_head
Definition: SDL_sysaudio.h:178
SDL_bool
Definition: SDL_stdinc.h:126
void SDL_RemoveAudioDevice(const int iscapture, void *handle)
Definition: SDL_audio.c:405
SDL_AudioBufferQueue * buffer_queue_tail
Definition: SDL_sysaudio.h:179
struct SDL_AudioBufferQueue * next
Definition: SDL_sysaudio.h:66
uint8_t Uint8
An unsigned 8-bit integer type.
Definition: SDL_stdinc.h:139
const char * desc
Definition: SDL_sysaudio.h:118
#define _THIS
Definition: SDL_sysaudio.h:31
Uint8 * fake_stream
Definition: SDL_sysaudio.h:168
SDL_AudioDeviceItem * outputDevices
Definition: SDL_sysaudio.h:128
SDL_AudioStreamer streamer
Definition: SDL_sysaudio.h:157
SDL_bool outputDevicesRemoved
Definition: SDL_sysaudio.h:125
SDL_PRINTF_FORMAT_STRING const char int SDL_PRINTF_FORMAT_STRING const char int SDL_PRINTF_FORMAT_STRING const char int SDL_PRINTF_FORMAT_STRING const char const char SDL_SCANF_FORMAT_STRING const char return SDL_ThreadFunction const char void return Uint32 return Uint32 void
Uint32 SDL_AudioDeviceID
Definition: SDL_audio.h:303
SDL_AudioDriverImpl impl
Definition: SDL_sysaudio.h:120
void SDL_OpenedAudioDeviceDisconnected(SDL_AudioDevice *device)
Definition: SDL_audio.c:364
const char * desc
Definition: SDL_sysaudio.h:192
SDL_Thread * thread
Definition: SDL_sysaudio.h:174
#define SDL_AUDIOBUFFERQUEUE_PACKETLEN
Definition: SDL_sysaudio.h:58
SDL_AudioCVT convert
Definition: SDL_sysaudio.h:153
SDL_AudioDeviceItem * inputDevices
Definition: SDL_sysaudio.h:129
unsigned long SDL_threadID
Definition: SDL_thread.h:49