Added SDL 1c0f6952e65e.

libs/SDL2/src/audio/SDL_sysaudio.h

@@ -33,6 +33,26 @@ typedef struct SDL_AudioDevice SDL_AudioDevice;
 /* Used by audio targets during DetectDevices() */
 typedef void (*SDL_AddAudioDevice)(const char *name);
 
+/* This is the size of a packet when using SDL_QueueAudio(). We allocate
+   these as necessary and pool them, under the assumption that we'll
+   eventually end up with a handful that keep recycling, meeting whatever
+   the app needs. We keep packing data tightly as more arrives to avoid
+   wasting space, and if we get a giant block of data, we'll split them
+   into multiple packets behind the scenes. My expectation is that most
+   apps will have 2-3 of these in the pool. 8k should cover most needs, but
+   if this is crippling for some embedded system, we can #ifdef this.
+   The system preallocates enough packets for 2 callbacks' worth of data. */
+#define SDL_AUDIOBUFFERQUEUE_PACKETLEN (8 * 1024)
+
+/* Used by apps that queue audio instead of using the callback. */
+typedef struct SDL_AudioBufferQueue
+{
+    Uint8 data[SDL_AUDIOBUFFERQUEUE_PACKETLEN];  /* packet data. */
+    Uint32 datalen;  /* bytes currently in use in this packet. */
+    Uint32 startpos;  /* bytes currently consumed in this packet. */
+    struct SDL_AudioBufferQueue *next;  /* next item in linked list. */
+} SDL_AudioBufferQueue;
+
 typedef struct SDL_AudioDriverImpl
 {
     void (*DetectDevices) (int iscapture, SDL_AddAudioDevice addfn);
@@ -40,6 +60,7 @@ typedef struct SDL_AudioDriverImpl
     void (*ThreadInit) (_THIS); /* Called by audio thread at start */
     void (*WaitDevice) (_THIS);
     void (*PlayDevice) (_THIS);
+    int (*GetPendingBytes) (_THIS);
     Uint8 *(*GetDeviceBuf) (_THIS);
     void (*WaitDone) (_THIS);
     void (*CloseDevice) (_THIS);
@@ -119,6 +140,12 @@ struct SDL_AudioDevice
     SDL_Thread *thread;
     SDL_threadID threadid;
 
+    /* Queued buffers (if app not using callback). */
+    SDL_AudioBufferQueue *buffer_queue_head; /* device fed from here. */
+    SDL_AudioBufferQueue *buffer_queue_tail; /* queue fills to here. */
+    SDL_AudioBufferQueue *buffer_queue_pool; /* these are unused packets. */
+    Uint32 queued_bytes;  /* number of bytes of audio data in the queue. */
+
     /* * * */
     /* Data private to this driver */
     struct SDL_PrivateAudioData *hidden;