SDL_sysaudio.h (5439B)
1/* 2 Simple DirectMedia Layer 3 Copyright (C) 1997-2014 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 */ 30typedef struct SDL_AudioDevice SDL_AudioDevice; 31#define _THIS SDL_AudioDevice *_this 32 33/* Used by audio targets during DetectDevices() */ 34typedef void (*SDL_AddAudioDevice)(const char *name); 35 36/* This is the size of a packet when using SDL_QueueAudio(). We allocate 37 these as necessary and pool them, under the assumption that we'll 38 eventually end up with a handful that keep recycling, meeting whatever 39 the app needs. We keep packing data tightly as more arrives to avoid 40 wasting space, and if we get a giant block of data, we'll split them 41 into multiple packets behind the scenes. My expectation is that most 42 apps will have 2-3 of these in the pool. 8k should cover most needs, but 43 if this is crippling for some embedded system, we can #ifdef this. 44 The system preallocates enough packets for 2 callbacks' worth of data. */ 45#define SDL_AUDIOBUFFERQUEUE_PACKETLEN (8 * 1024) 46 47/* Used by apps that queue audio instead of using the callback. */ 48typedef struct SDL_AudioBufferQueue 49{ 50 Uint8 data[SDL_AUDIOBUFFERQUEUE_PACKETLEN]; /* packet data. */ 51 Uint32 datalen; /* bytes currently in use in this packet. */ 52 Uint32 startpos; /* bytes currently consumed in this packet. */ 53 struct SDL_AudioBufferQueue *next; /* next item in linked list. */ 54} SDL_AudioBufferQueue; 55 56typedef struct SDL_AudioDriverImpl 57{ 58 void (*DetectDevices) (int iscapture, SDL_AddAudioDevice addfn); 59 int (*OpenDevice) (_THIS, const char *devname, int iscapture); 60 void (*ThreadInit) (_THIS); /* Called by audio thread at start */ 61 void (*WaitDevice) (_THIS); 62 void (*PlayDevice) (_THIS); 63 int (*GetPendingBytes) (_THIS); 64 Uint8 *(*GetDeviceBuf) (_THIS); 65 void (*WaitDone) (_THIS); 66 void (*CloseDevice) (_THIS); 67 void (*LockDevice) (_THIS); 68 void (*UnlockDevice) (_THIS); 69 void (*Deinitialize) (void); 70 71 /* !!! FIXME: add pause(), so we can optimize instead of mixing silence. */ 72 73 /* Some flags to push duplicate code into the core and reduce #ifdefs. */ 74 int ProvidesOwnCallbackThread; 75 int SkipMixerLock; /* !!! FIXME: do we need this anymore? */ 76 int HasCaptureSupport; 77 int OnlyHasDefaultOutputDevice; 78 int OnlyHasDefaultInputDevice; 79} SDL_AudioDriverImpl; 80 81 82typedef struct SDL_AudioDriver 83{ 84 /* * * */ 85 /* The name of this audio driver */ 86 const char *name; 87 88 /* * * */ 89 /* The description of this audio driver */ 90 const char *desc; 91 92 SDL_AudioDriverImpl impl; 93 94 char **outputDevices; 95 int outputDeviceCount; 96 97 char **inputDevices; 98 int inputDeviceCount; 99} SDL_AudioDriver; 100 101 102/* Streamer */ 103typedef struct 104{ 105 Uint8 *buffer; 106 int max_len; /* the maximum length in bytes */ 107 int read_pos, write_pos; /* the position of the write and read heads in bytes */ 108} SDL_AudioStreamer; 109 110 111/* Define the SDL audio driver structure */ 112struct SDL_AudioDevice 113{ 114 /* * * */ 115 /* Data common to all devices */ 116 117 /* The current audio specification (shared with audio thread) */ 118 SDL_AudioSpec spec; 119 120 /* An audio conversion block for audio format emulation */ 121 SDL_AudioCVT convert; 122 123 /* The streamer, if sample rate conversion necessitates it */ 124 int use_streamer; 125 SDL_AudioStreamer streamer; 126 127 /* Current state flags */ 128 int iscapture; 129 int enabled; 130 int paused; 131 int opened; 132 133 /* Fake audio buffer for when the audio hardware is busy */ 134 Uint8 *fake_stream; 135 136 /* A semaphore for locking the mixing buffers */ 137 SDL_mutex *mixer_lock; 138 139 /* A thread to feed the audio device */ 140 SDL_Thread *thread; 141 SDL_threadID threadid; 142 143 /* Queued buffers (if app not using callback). */ 144 SDL_AudioBufferQueue *buffer_queue_head; /* device fed from here. */ 145 SDL_AudioBufferQueue *buffer_queue_tail; /* queue fills to here. */ 146 SDL_AudioBufferQueue *buffer_queue_pool; /* these are unused packets. */ 147 Uint32 queued_bytes; /* number of bytes of audio data in the queue. */ 148 149 /* * * */ 150 /* Data private to this driver */ 151 struct SDL_PrivateAudioData *hidden; 152}; 153#undef _THIS 154 155typedef struct AudioBootStrap 156{ 157 const char *name; 158 const char *desc; 159 int (*init) (SDL_AudioDriverImpl * impl); 160 int demand_only; /* 1==request explicitly, or it won't be available. */ 161} AudioBootStrap; 162 163#endif /* _SDL_sysaudio_h */ 164 165/* vi: set ts=4 sw=4 expandtab: */