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 /* !!! FIXME: These are wordy and unlocalized... */ 30 #define DEFAULT_OUTPUT_DEVNAME "System audio output device" 31 #define DEFAULT_INPUT_DEVNAME "System audio capture device" 32 33 /* The SDL audio driver */ 34 typedef struct SDL_AudioDevice SDL_AudioDevice; 35 #define _THIS SDL_AudioDevice *_this 36 37 /* Audio targets should call this as devices are added to the system (such as 38 a USB headset being plugged in), and should also be called for 39 for every device found during DetectDevices(). */ 40 extern void SDL_AddAudioDevice(const int iscapture, const char *name, void *handle); 41 42 /* Audio targets should call this as devices are removed, so SDL can update 43 its list of available devices. */ 44 extern void SDL_RemoveAudioDevice(const int iscapture, void *handle); 45 46 /* Audio targets should call this if an opened audio device is lost while 47 being used. This can happen due to i/o errors, or a device being unplugged, 48 etc. If the device is totally gone, please also call SDL_RemoveAudioDevice() 49 as appropriate so SDL's list of devices is accurate. */ 50 extern void SDL_OpenedAudioDeviceDisconnected(SDL_AudioDevice *device); 51 52 53 /* This is the size of a packet when using SDL_QueueAudio(). We allocate 54 these as necessary and pool them, under the assumption that we'll 55 eventually end up with a handful that keep recycling, meeting whatever 56 the app needs. We keep packing data tightly as more arrives to avoid 57 wasting space, and if we get a giant block of data, we'll split them 58 into multiple packets behind the scenes. My expectation is that most 59 apps will have 2-3 of these in the pool. 8k should cover most needs, but 60 if this is crippling for some embedded system, we can #ifdef this. 61 The system preallocates enough packets for 2 callbacks' worth of data. */ 62 #define SDL_AUDIOBUFFERQUEUE_PACKETLEN (8 * 1024) 63 64 /* Used by apps that queue audio instead of using the callback. */ 65 typedef struct SDL_AudioBufferQueue 66 { 67 Uint8 data[SDL_AUDIOBUFFERQUEUE_PACKETLEN]; /* packet data. */ 68 Uint32 datalen; /* bytes currently in use in this packet. */ 69 Uint32 startpos; /* bytes currently consumed in this packet. */ 70 struct SDL_AudioBufferQueue *next; /* next item in linked list. */ 71 } SDL_AudioBufferQueue; 72 73 typedef struct SDL_AudioDriverImpl 74 { 75 void (*DetectDevices) (void); 76 int (*OpenDevice) (_THIS, void *handle, const char *devname, int iscapture); 77 void (*ThreadInit) (_THIS); /* Called by audio thread at start */ 78 void (*WaitDevice) (_THIS); 79 void (*PlayDevice) (_THIS); 80 int (*GetPendingBytes) (_THIS); 81 Uint8 *(*GetDeviceBuf) (_THIS); 82 int (*CaptureFromDevice) (_THIS, void *buffer, int buflen); 83 void (*FlushCapture) (_THIS); 84 void (*PrepareToClose) (_THIS); /**< Called between run and draining wait for playback devices */ 85 void (*CloseDevice) (_THIS); 86 void (*LockDevice) (_THIS); 87 void (*UnlockDevice) (_THIS); 88 void (*FreeDeviceHandle) (void *handle); /**< SDL is done with handle from SDL_AddAudioDevice() */ 89 void (*Deinitialize) (void); 90 91 /* !!! FIXME: add pause(), so we can optimize instead of mixing silence. */ 92 93 /* Some flags to push duplicate code into the core and reduce #ifdefs. */ 94 /* !!! FIXME: these should be SDL_bool */ 95 int ProvidesOwnCallbackThread; 96 int SkipMixerLock; 97 int HasCaptureSupport; 98 int OnlyHasDefaultOutputDevice; 99 int OnlyHasDefaultCaptureDevice; 100 int AllowsArbitraryDeviceNames; 101 } SDL_AudioDriverImpl; 102 103 104 typedef struct SDL_AudioDeviceItem 105 { 106 void *handle; 107 struct SDL_AudioDeviceItem *next; 108 #if (defined(__GNUC__) && (__GNUC__ <= 2)) 109 char name[1]; /* actually variable length. */ 110 #else 111 char name[]; 112 #endif 113 } SDL_AudioDeviceItem; 114 115 116 typedef struct SDL_AudioDriver 117 { 118 /* * * */ 119 /* The name of this audio driver */ 120 const char *name; 121 122 /* * * */ 123 /* The description of this audio driver */ 124 const char *desc; 125 126 SDL_AudioDriverImpl impl; 127 128 /* A mutex for device detection */ 129 SDL_mutex *detectionLock; 130 SDL_bool captureDevicesRemoved; 131 SDL_bool outputDevicesRemoved; 132 int outputDeviceCount; 133 int inputDeviceCount; 134 SDL_AudioDeviceItem *outputDevices; 135 SDL_AudioDeviceItem *inputDevices; 136 } SDL_AudioDriver; 137 138 139 /* Streamer */ 140 typedef struct 141 { 142 Uint8 *buffer; 143 int max_len; /* the maximum length in bytes */ 144 int read_pos, write_pos; /* the position of the write and read heads in bytes */ 145 } SDL_AudioStreamer; 146 147 148 /* Define the SDL audio driver structure */ 149 struct SDL_AudioDevice 150 { 151 /* * * */ 152 /* Data common to all devices */ 153 SDL_AudioDeviceID id; 154 155 /* The current audio specification (shared with audio thread) */ 156 SDL_AudioSpec spec; 157 158 /* An audio conversion block for audio format emulation */ 159 SDL_AudioCVT convert; 160 161 /* The streamer, if sample rate conversion necessitates it */ 162 int use_streamer; 163 SDL_AudioStreamer streamer; 164 165 /* Current state flags */ 166 SDL_atomic_t shutdown; /* true if we are signaling the play thread to end. */ 167 SDL_atomic_t enabled; /* true if device is functioning and connected. */ 168 SDL_atomic_t paused; 169 SDL_bool iscapture; 170 171 /* Fake audio buffer for when the audio hardware is busy */ 172 Uint8 *fake_stream; 173 174 /* A mutex for locking the mixing buffers */ 175 SDL_mutex *mixer_lock; 176 177 /* A thread to feed the audio device */ 178 SDL_Thread *thread; 179 SDL_threadID threadid; 180 181 /* Queued buffers (if app not using callback). */ 182 SDL_AudioBufferQueue *buffer_queue_head; /* device fed from here. */ 183 SDL_AudioBufferQueue *buffer_queue_tail; /* queue fills to here. */ 184 SDL_AudioBufferQueue *buffer_queue_pool; /* these are unused packets. */ 185 Uint32 queued_bytes; /* number of bytes of audio data in the queue. */ 186 187 /* * * */ 188 /* Data private to this driver */ 189 struct SDL_PrivateAudioData *hidden; 190 191 void *handle; 192 }; 193 #undef _THIS 194 195 typedef struct AudioBootStrap 196 { 197 const char *name; 198 const char *desc; 199 int (*init) (SDL_AudioDriverImpl * impl); 200 int demand_only; /* 1==request explicitly, or it won't be available. */ 201 } AudioBootStrap; 202 203 #endif /* _SDL_sysaudio_h */ 204 205 /* vi: set ts=4 sw=4 expandtab: */ 206