2 Simple DirectMedia Layer
3 Copyright (C) 1997-2016 Sam Lantinga <slouken@libsdl.org>
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.
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:
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.
21 #include "../SDL_internal.h"
23 #ifndef _SDL_sysaudio_h
24 #define _SDL_sysaudio_h
26 #include "SDL_mutex.h"
27 #include "SDL_thread.h"
29 /* The SDL audio driver */
30 typedef struct SDL_AudioDevice SDL_AudioDevice;
31 #define _THIS SDL_AudioDevice *_this
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);
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);
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. */
46 extern void SDL_OpenedAudioDeviceDisconnected(SDL_AudioDevice *device);
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)
60 /* Used by apps that queue audio instead of using the callback. */
61 typedef struct SDL_AudioBufferQueue
63 Uint8 data[SDL_AUDIOBUFFERQUEUE_PACKETLEN]; /* packet data. */
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. */
67 } SDL_AudioBufferQueue;
69 typedef struct SDL_AudioDriverImpl
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);
85 /* !!! FIXME: add pause(), so we can optimize instead of mixing silence. */
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; /* !!! FIXME: do we need this anymore? */
91 int HasCaptureSupport;
92 int OnlyHasDefaultOutputDevice;
93 int OnlyHasDefaultInputDevice;
94 int AllowsArbitraryDeviceNames;
95 } SDL_AudioDriverImpl;
98 typedef struct SDL_AudioDeviceItem
101 struct SDL_AudioDeviceItem *next;
102 #if (defined(__GNUC__) && (__GNUC__ <= 2))
103 char name[1]; /* actually variable length. */
107 } SDL_AudioDeviceItem;
110 typedef struct SDL_AudioDriver
113 /* The name of this audio driver */
117 /* The description of this audio driver */
120 SDL_AudioDriverImpl impl;
122 /* A mutex for device detection */
123 SDL_mutex *detectionLock;
124 SDL_bool captureDevicesRemoved;
125 SDL_bool outputDevicesRemoved;
126 int outputDeviceCount;
127 int inputDeviceCount;
128 SDL_AudioDeviceItem *outputDevices;
129 SDL_AudioDeviceItem *inputDevices;
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 */
142 /* Define the SDL audio driver structure */
143 struct SDL_AudioDevice
146 /* Data common to all devices */
147 SDL_AudioDeviceID id;
149 /* The current audio specification (shared with audio thread) */
152 /* An audio conversion block for audio format emulation */
153 SDL_AudioCVT convert;
155 /* The streamer, if sample rate conversion necessitates it */
157 SDL_AudioStreamer streamer;
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. */
167 /* Fake audio buffer for when the audio hardware is busy */
170 /* A mutex for locking the mixing buffers */
171 SDL_mutex *mixer_lock;
173 /* A thread to feed the audio device */
175 SDL_threadID threadid;
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. */
184 /* Data private to this driver */
185 struct SDL_PrivateAudioData *hidden;
189 typedef struct AudioBootStrap
193 int (*init) (SDL_AudioDriverImpl * impl);
194 int demand_only; /* 1==request explicitly, or it won't be available. */
197 #endif /* _SDL_sysaudio_h */
199 /* vi: set ts=4 sw=4 expandtab: */