Added audio device buffer queueing API.

.hgignore

@@ -73,6 +73,7 @@ test/Makefile
 test/SDL2.dll
 test/checkkeys
 test/loopwave
+test/loopwavequeue
 test/testatomic
 test/testaudioinfo
 test/testautomation

include/SDL_audio.h

@@ -155,6 +155,9 @@ typedef Uint16 SDL_AudioFormat;
  *
  *  Once the callback returns, the buffer will no longer be valid.
  *  Stereo samples are stored in a LRLRLR ordering.
+ *
+ *  You can choose to avoid callbacks and use SDL_QueueAudio() instead, if
+ *  you like. Just open your audio device with a NULL callback.
  */
 typedef void (SDLCALL * SDL_AudioCallback) (void *userdata, Uint8 * stream,
                                             int len);
@@ -171,8 +174,8 @@ typedef struct SDL_AudioSpec
     Uint16 samples;             /**< Audio buffer size in samples (power of 2) */
     Uint16 padding;             /**< Necessary for some compile environments */
     Uint32 size;                /**< Audio buffer size in bytes (calculated) */
-    SDL_AudioCallback callback;
-    void *userdata;
+    SDL_AudioCallback callback; /**< Callback that feeds the audio device (NULL to use SDL_QueueAudio()). */
+    void *userdata;             /**< Userdata passed to callback (ignored for NULL callbacks). */
 } SDL_AudioSpec;
 
 
@@ -273,9 +276,11 @@ extern DECLSPEC const char *SDLCALL SDL_GetCurrentAudioDriver(void);
  *      to the audio buffer, and the length in bytes of the audio buffer.
  *      This function usually runs in a separate thread, and so you should
  *      protect data structures that it accesses by calling SDL_LockAudio()
- *      and SDL_UnlockAudio() in your code.
+ *      and SDL_UnlockAudio() in your code. Alternately, you may pass a NULL
+ *      pointer here, and call SDL_QueueAudio() with some frequency, to queue
+ *      more audio samples to be played.
  *    - \c desired->userdata is passed as the first parameter to your callback
- *      function.
+ *      function. If you passed a NULL callback, this value is ignored.
  *
  *  The audio device starts out playing silence when it's opened, and should
  *  be enabled for playing by calling \c SDL_PauseAudio(0) when you are ready
@@ -474,6 +479,100 @@ extern DECLSPEC void SDLCALL SDL_MixAudioFormat(Uint8 * dst,
                                                 SDL_AudioFormat format,
                                                 Uint32 len, int volume);
 
+/**
+ *  Queue more audio on non-callback devices.
+ *
+ *  SDL offers two ways to feed audio to the device: you can either supply a
+ *  callback that SDL triggers with some frequency to obtain more audio
+ *  (pull method), or you can supply no callback, and then SDL will expect
+ *  you to supply data at regular intervals (push method) with this function.
+ *
+ *  There are no limits on the amount of data you can queue, short of
+ *  exhaustion of address space. Queued data will drain to the device as
+ *  necessary without further intervention from you. If the device needs
+ *  audio but there is not enough queued, it will play silence to make up
+ *  the difference. This means you will have skips in your audio playback
+ *  if you aren't routinely queueing sufficient data.
+ *
+ *  This function copies the supplied data, so you are safe to free it when
+ *  the function returns. This function is thread-safe, but queueing to the
+ *  same device from two threads at once does not promise which buffer will
+ *  be queued first.
+ *
+ *  You may not queue audio on a device that is using an application-supplied
+ *  callback; doing so returns an error. You have to use the audio callback
+ *  or queue audio with this function, but not both.
+ *
+ *  You should not call SDL_LockAudio() on the device before queueing; SDL
+ *  handles locking internally for this function.
+ *
+ *  \param dev The device ID to which we will queue audio.
+ *  \param data The data to queue to the device for later playback.
+ *  \param len The number of bytes (not samples!) to which (data) points.
+ *  \return zero on success, -1 on error.
+ *
+ *  \sa SDL_GetQueuedAudioSize
+ *  \sa SDL_ClearQueuedAudio
+ */
+extern DECLSPEC int SDLCALL SDL_QueueAudio(SDL_AudioDeviceID dev, const void *data, Uint32 len);
+
+/**
+ *  Get the number of bytes of still-queued audio.
+ *
+ *  This is the number of bytes that have been queued for playback with
+ *  SDL_QueueAudio(), but have not yet been sent to the hardware.
+ *
+ *  Once we've sent it to the hardware, this function can not decide the exact
+ *  byte boundary of what has been played. It's possible that we just gave the
+ *  hardware several kilobytes right before you called this function, but it
+ *  hasn't played any of it yet, or maybe half of it, etc.
+ *
+ *  You may not queue audio on a device that is using an application-supplied
+ *  callback; calling this function on such a device always returns 0.
+ *  You have to use the audio callback or queue audio with SDL_QueueAudio(),
+ *  but not both.
+ *
+ *  You should not call SDL_LockAudio() on the device before querying; SDL
+ *  handles locking internally for this function.
+ *
+ *  \param dev The device ID of which we will query queued audio size.
+ *  \return Number of bytes (not samples!) of queued audio.
+ *
+ *  \sa SDL_QueueAudio
+ *  \sa SDL_ClearQueuedAudio
+ */
+extern DECLSPEC Uint32 SDLCALL SDL_GetQueuedAudioSize(SDL_AudioDeviceID dev);
+
+/**
+ *  Drop any queued audio data waiting to be sent to the hardware.
+ *
+ *  Immediately after this call, SDL_GetQueuedAudioSize() will return 0 and
+ *  the hardware will start playing silence if more audio isn't queued.
+ *
+ *  This will not prevent playback of queued audio that's already been sent
+ *  to the hardware, as we can not undo that, so expect there to be some
+ *  fraction of a second of audio that might still be heard. This can be
+ *  useful if you want to, say, drop any pending music during a level change
+ *  in your game.
+ *
+ *  You may not queue audio on a device that is using an application-supplied
+ *  callback; calling this function on such a device is always a no-op.
+ *  You have to use the audio callback or queue audio with SDL_QueueAudio(),
+ *  but not both.
+ *
+ *  You should not call SDL_LockAudio() on the device before clearing the
+ *  queue; SDL handles locking internally for this function.
+ *
+ *  This function always succeeds and thus returns void.
+ *
+ *  \param dev The device ID of which to clear the audio queue.
+ *
+ *  \sa SDL_QueueAudio
+ *  \sa SDL_GetQueuedAudioSize
+ */
+extern DECLSPEC void SDLCALL SDL_ClearQueuedAudio(SDL_AudioDeviceID dev);
+
+
 /**
  *  \name Audio lock functions
  *

src/audio/SDL_audio.c

@@ -324,6 +324,181 @@ SDL_StreamDeinit(SDL_AudioStreamer * stream)
 }
 #endif
 
+
+/* buffer queueing support... */
+
+/* this expects that you managed thread safety elsewhere. */
+static void
+free_audio_queue(SDL_AudioBufferQueue *buffer)
+{
+    while (buffer) {
+        SDL_AudioBufferQueue *next = buffer->next;
+        SDL_free(buffer);
+        buffer = next;
+    }
+}
+
+static void SDLCALL
+SDL_BufferQueueDrainCallback(void *userdata, Uint8 *stream, int _len)
+{
+    /* this function always holds the mixer lock before being called. */
+    Uint32 len = (Uint32) _len;
+    SDL_AudioDevice *device = (SDL_AudioDevice *) userdata;
+    SDL_AudioBufferQueue *buffer;
+
+    SDL_assert(device != NULL);  /* this shouldn't ever happen, right?! */
+    SDL_assert(_len >= 0);  /* this shouldn't ever happen, right?! */
+
+    while ((len > 0) && ((buffer = device->buffer_queue_head) != NULL)) {
+        const Uint32 avail = buffer->datalen - buffer->startpos;
+        const Uint32 cpy = SDL_min(len, avail);
+        SDL_assert(device->queued_bytes >= avail);
+
+        SDL_memcpy(stream, buffer->data + buffer->startpos, cpy);
+        buffer->startpos += cpy;
+        stream += cpy;
+        device->queued_bytes -= cpy;
+        len -= cpy;
+
+        if (buffer->startpos == buffer->datalen) {  /* packet is done, put it in the pool. */
+            device->buffer_queue_head = buffer->next;
+            SDL_assert((buffer->next != NULL) || (buffer == device->buffer_queue_tail));
+            buffer->next = device->buffer_queue_pool;
+            device->buffer_queue_pool = buffer;
+        }
+    }
+
+    SDL_assert((device->buffer_queue_head != NULL) == (device->queued_bytes != 0));
+
+    if (len > 0) {  /* fill any remaining space in the stream with silence. */
+        SDL_assert(device->buffer_queue_head == NULL);
+        SDL_memset(stream, device->spec.silence, len);
+    }
+
+    if (device->buffer_queue_head == NULL) {
+        device->buffer_queue_tail = NULL;  /* in case we drained the queue entirely. */
+    }
+}
+
+int
+SDL_QueueAudio(SDL_AudioDeviceID devid, const void *_data, Uint32 len)
+{
+    SDL_AudioDevice *device = get_audio_device(devid);
+    const Uint8 *data = (const Uint8 *) _data;
+    SDL_AudioBufferQueue *orighead;
+    SDL_AudioBufferQueue *origtail;
+    Uint32 origlen;
+    Uint32 datalen;
+
+    if (!device) {
+        return -1;  /* get_audio_device() will have set the error state */
+    }
+
+    if (device->spec.callback != SDL_BufferQueueDrainCallback) {
+        return SDL_SetError("Audio device has a callback, queueing not allowed");
+    }
+
+    current_audio.impl.LockDevice(device);
+
+    orighead = device->buffer_queue_head;
+    origtail = device->buffer_queue_tail;
+    origlen = origtail ? origtail->datalen : 0;
+
+    while (len > 0) {
+        SDL_AudioBufferQueue *packet = device->buffer_queue_tail;
+        SDL_assert(!packet || (packet->datalen <= SDL_AUDIOBUFFERQUEUE_PACKETLEN));
+        if (!packet || (packet->datalen >= SDL_AUDIOBUFFERQUEUE_PACKETLEN)) {
+            /* tail packet missing or completely full; we need a new packet. */
+            packet = device->buffer_queue_pool;
+            if (packet != NULL) {
+                /* we have one available in the pool. */
+                device->buffer_queue_pool = packet->next;
+            } else {
+                /* Have to allocate a new one! */
+                packet = (SDL_AudioBufferQueue *) SDL_malloc(sizeof (SDL_AudioBufferQueue));
+                if (packet == NULL) {
+                    /* uhoh, reset so we've queued nothing new, free what we can. */
+                    if (!origtail) {
+                        packet = device->buffer_queue_head;  /* whole queue. */
+                    } else {
+                        packet = origtail->next;  /* what we added to existing queue. */
+                        origtail->next = NULL;
+                        origtail->datalen = origlen;
+                    }
+                    device->buffer_queue_head = orighead;
+                    device->buffer_queue_tail = origtail;
+                    device->buffer_queue_pool = NULL;
+
+                    current_audio.impl.UnlockDevice(device);
+
+                    free_audio_queue(packet);  /* give back what we can. */
+
+                    return SDL_OutOfMemory();
+                }
+            }
+            packet->datalen = 0;
+            packet->startpos = 0;
+            packet->next = NULL;
+
+            SDL_assert((device->buffer_queue_head != NULL) == (device->queued_bytes != 0));
+            if (device->buffer_queue_tail == NULL) {
+                device->buffer_queue_head = packet;
+            } else {
+                device->buffer_queue_tail->next = packet;
+            }
+            device->buffer_queue_tail = packet;
+        }
+
+        datalen = SDL_min(len, SDL_AUDIOBUFFERQUEUE_PACKETLEN - packet->datalen);
+        SDL_memcpy(packet->data + packet->datalen, data, datalen);
+        data += datalen;
+        len -= datalen;
+        packet->datalen += datalen;
+        device->queued_bytes += datalen;
+    }
+
+    current_audio.impl.UnlockDevice(device);
+
+    return 0;
+}
+
+Uint32
+SDL_GetQueuedAudioSize(SDL_AudioDeviceID devid)
+{
+    /* this happens to work for non-queueing devices, since we memset()
+       the device to zero at init time, and these devices should return 0. */
+    Uint32 retval = 0;
+    SDL_AudioDevice *device = get_audio_device(devid);
+    if (device) {
+        current_audio.impl.LockDevice(device);
+        retval = device->queued_bytes;
+        current_audio.impl.UnlockDevice(device);
+    }
+
+    return retval;
+}
+
+void
+SDL_ClearQueuedAudio(SDL_AudioDeviceID devid)
+{
+    SDL_AudioDevice *device = get_audio_device(devid);
+    SDL_AudioBufferQueue *buffer = NULL;
+    if (!device) {
+        return;  /* nothing to do. */
+    }
+
+    /* Blank out the device and release the mutex. Free it afterwards. */
+    current_audio.impl.LockDevice(device);
+    buffer = device->buffer_queue_head;
+    device->buffer_queue_tail = NULL;
+    device->buffer_queue_head = NULL;
+    device->queued_bytes = 0;
+    current_audio.impl.UnlockDevice(device);
+
+    free_audio_queue(buffer);
+}
+
+
 #if defined(__ANDROID__)
 #include <android/log.h>
 #endif
@@ -800,6 +975,10 @@ close_audio_device(SDL_AudioDevice * device)
         current_audio.impl.CloseDevice(device);
         device->opened = 0;
     }
+
+    free_audio_queue(device->buffer_queue_head);
+    free_audio_queue(device->buffer_queue_pool);
+
     SDL_FreeAudioMem(device);
 }
 
@@ -814,11 +993,6 @@ prepare_audiospec(const SDL_AudioSpec * orig, SDL_AudioSpec * prepared)
 {
     SDL_memcpy(prepared, orig, sizeof(SDL_AudioSpec));
 
-    if (orig->callback == NULL) {
-        SDL_SetError("SDL_OpenAudio() passed a NULL callback");
-        return 0;
-    }
-
     if (orig->freq == 0) {
         const char *env = SDL_getenv("SDL_AUDIO_FREQUENCY");
         if ((!env) || ((prepared->freq = SDL_atoi(env)) == 0)) {
@@ -871,7 +1045,6 @@ prepare_audiospec(const SDL_AudioSpec * orig, SDL_AudioSpec * prepared)
     return 1;
 }
 
-
 static SDL_AudioDeviceID
 open_audio_device(const char *devname, int iscapture,
                   const SDL_AudioSpec * desired, SDL_AudioSpec * obtained,
@@ -950,7 +1123,7 @@ open_audio_device(const char *devname, int iscapture,
         SDL_OutOfMemory();
         return 0;
     }
-    SDL_memset(device, '\0', sizeof(SDL_AudioDevice));
+    SDL_zerop(device);
     device->spec = *obtained;
     device->enabled = 1;
     device->paused = 1;
@@ -968,8 +1141,9 @@ open_audio_device(const char *devname, int iscapture,
 
     /* force a device detection if we haven't done one yet. */
     if ( ((iscapture) && (current_audio.inputDevices == NULL)) ||
-         ((!iscapture) && (current_audio.outputDevices == NULL)) )
+         ((!iscapture) && (current_audio.outputDevices == NULL)) ) {
         SDL_GetNumAudioDevices(iscapture);
+    }
 
     if (current_audio.impl.OpenDevice(device, devname, iscapture) < 0) {
         close_audio_device(device);
@@ -1043,6 +1217,25 @@ open_audio_device(const char *devname, int iscapture,
         }
     }
 
+    if (device->spec.callback == NULL) {  /* use buffer queueing? */
+        /* pool a few packets to start. Enough for two callbacks. */
+        const int packetlen = SDL_AUDIOBUFFERQUEUE_PACKETLEN;
+        const int wantbytes = ((device->convert.needed) ? device->convert.len : device->spec.size) * 2;
+        const int wantpackets = (wantbytes / packetlen) + ((wantbytes % packetlen) ? packetlen : 0);
+        for (i = 0; i < wantpackets; i++) {
+            SDL_AudioBufferQueue *packet = (SDL_AudioBufferQueue *) SDL_malloc(sizeof (SDL_AudioBufferQueue));
+            if (packet) { /* don't care if this fails, we'll deal later. */
+                packet->datalen = 0;
+                packet->startpos = 0;
+                packet->next = device->buffer_queue_pool;
+                device->buffer_queue_pool = packet;
+            }
+        }
+
+        device->spec.callback = SDL_BufferQueueDrainCallback;
+        device->spec.userdata = device;
+    }
+
     /* Find an available device ID and store the structure... */
     for (id = min_id - 1; id < SDL_arraysize(open_devices); id++) {
         if (open_devices[id] == NULL) {

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);
@@ -119,6 +139,12 @@ 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;

src/dynapi/SDL_dynapi_overrides.h

@@ -588,3 +588,6 @@
 #define SDL_SetWindowHitTest SDL_SetWindowHitTest_REAL
 #define SDL_GetGlobalMouseState SDL_GetGlobalMouseState_REAL
 #define SDL_HasAVX2 SDL_HasAVX2_REAL
+#define SDL_QueueAudio SDL_QueueAudio_REAL
+#define SDL_GetQueuedAudioSize SDL_GetQueuedAudioSize_REAL
+#define SDL_ClearQueuedAudio SDL_ClearQueuedAudio_REAL

src/dynapi/SDL_dynapi_procs.h

@@ -620,3 +620,6 @@ SDL_DYNAPI_PROC(int,SDL_CaptureMouse,(SDL_bool a),(a),return)
 SDL_DYNAPI_PROC(int,SDL_SetWindowHitTest,(SDL_Window *a, SDL_HitTest b, void *c),(a,b,c),return)
 SDL_DYNAPI_PROC(Uint32,SDL_GetGlobalMouseState,(int *a, int *b),(a,b),return)
 SDL_DYNAPI_PROC(SDL_bool,SDL_HasAVX2,(void),(),return)
+SDL_DYNAPI_PROC(int,SDL_QueueAudio,(SDL_AudioDeviceID a, const void *b, Uint32 c),(a,b,c),return)
+SDL_DYNAPI_PROC(Uint32,SDL_GetQueuedAudioSize,(SDL_AudioDeviceID a),(a),return)
+SDL_DYNAPI_PROC(void,SDL_ClearQueuedAudio,(SDL_AudioDeviceID a),(a),)

test/Makefile.in

@@ -10,6 +10,7 @@ LIBS	= @LIBS@
 TARGETS = \
 	checkkeys$(EXE) \
 	loopwave$(EXE) \
+	loopwavequeue$(EXE) \
 	testatomic$(EXE) \
 	testaudioinfo$(EXE) \
 	testautomation$(EXE) \
@@ -71,6 +72,9 @@ checkkeys$(EXE): $(srcdir)/checkkeys.c
 loopwave$(EXE): $(srcdir)/loopwave.c
 	$(CC) -o $@ $^ $(CFLAGS) $(LIBS)
 
+loopwavequeue$(EXE): $(srcdir)/loopwavequeue.c
+	$(CC) -o $@ $^ $(CFLAGS) $(LIBS)
+
 testresample$(EXE): $(srcdir)/testresample.c
 	$(CC) -o $@ $^ $(CFLAGS) $(LIBS)
 

test/README

@@ -3,6 +3,7 @@ These are test programs for the SDL library:
 
 	checkkeys	Watch the key events to check the keyboard
 	loopwave	Audio test -- loop playing a WAV file
+	loopwavequeue	Audio test -- loop playing a WAV file with SDL_QueueAudio
 	testaudioinfo	Lists audio device capabilities
 	testcdrom	Sample audio CD control program
 	testerror	Tests multi-threaded error handling

test/loopwavequeue.c

@@ -0,0 +1,127 @@
+/*
+  Copyright (C) 1997-2014 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely.
+*/
+
+/* Program to load a wave file and loop playing it using SDL sound queueing */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#if HAVE_SIGNAL_H
+#include <signal.h>
+#endif
+
+#include "SDL.h"
+
+struct
+{
+    SDL_AudioSpec spec;
+    Uint8 *sound;               /* Pointer to wave data */
+    Uint32 soundlen;            /* Length of wave data */
+    int soundpos;               /* Current play position */
+} wave;
+
+
+/* Call this instead of exit(), so we can clean up SDL: atexit() is evil. */
+static void
+quit(int rc)
+{
+    SDL_Quit();
+    exit(rc);
+}
+
+static int done = 0;
+void
+poked(int sig)
+{
+    done = 1;
+}
+
+int
+main(int argc, char *argv[])
+{
+    int i;
+    char filename[4096];
+
+	/* Enable standard application logging */
+	SDL_LogSetPriority(SDL_LOG_CATEGORY_APPLICATION, SDL_LOG_PRIORITY_INFO);
+
+    /* Load the SDL library */
+    if (SDL_Init(SDL_INIT_AUDIO) < 0) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Couldn't initialize SDL: %s\n", SDL_GetError());
+        return (1);
+    }
+
+    if (argc > 1) {
+        SDL_strlcpy(filename, argv[1], sizeof(filename));
+    } else {
+        SDL_strlcpy(filename, "sample.wav", sizeof(filename));
+    }
+    /* Load the wave file into memory */
+    if (SDL_LoadWAV(filename, &wave.spec, &wave.sound, &wave.soundlen) == NULL) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Couldn't load %s: %s\n", filename, SDL_GetError());
+        quit(1);
+    }
+
+    wave.spec.callback = NULL;  /* we'll push audio. */
+
+#if HAVE_SIGNAL_H
+    /* Set the signals */
+#ifdef SIGHUP
+    signal(SIGHUP, poked);
+#endif
+    signal(SIGINT, poked);
+#ifdef SIGQUIT
+    signal(SIGQUIT, poked);
+#endif
+    signal(SIGTERM, poked);
+#endif /* HAVE_SIGNAL_H */
+
+    /* Initialize fillerup() variables */
+    if (SDL_OpenAudio(&wave.spec, NULL) < 0) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Couldn't open audio: %s\n", SDL_GetError());
+        SDL_FreeWAV(wave.sound);
+        quit(2);
+    }
+
+    /*static x[99999]; SDL_QueueAudio(1, x, sizeof (x));*/
+
+    /* Let the audio run */
+    SDL_PauseAudio(0);
+
+    /* Note that we stuff the entire audio buffer into the queue in one
+       shot. Most apps would want to feed it a little at a time, as it
+       plays, but we're going for simplicity here. */
+    
+    while (!done && (SDL_GetAudioStatus() == SDL_AUDIO_PLAYING))
+    {
+        /* The device from SDL_OpenAudio() is always device #1. */
+        const Uint32 queued = SDL_GetQueuedAudioSize(1);
+        SDL_Log("Device has %u bytes queued.\n", (unsigned int) queued);
+        if (queued <= 8192) {  /* time to requeue the whole thing? */
+            if (SDL_QueueAudio(1, wave.sound, wave.soundlen) == 0) {
+                SDL_Log("Device queued %u more bytes.\n", (unsigned int) wave.soundlen);
+            } else {
+                SDL_Log("Device FAILED to queue %u more bytes: %s\n", (unsigned int) wave.soundlen, SDL_GetError());
+            }
+        }
+
+        SDL_Delay(100);  /* let it play for awhile. */
+    }
+
+    /* Clean up on signal */
+    SDL_CloseAudio();
+    SDL_FreeWAV(wave.sound);
+    SDL_Quit();
+    return 0;
+}
+
+/* vi: set ts=4 sw=4 expandtab: */