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Refactored the audio queueing code to a generic SDL_DataQueue interface.

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This is not a public API (at the moment), but we will be needing this for
other internal things soon.
This commit is contained in:
Ryan C. Gordon
2016-12-06 02:23:54 -05:00
parent 8b960d4e0f
commit a0e003eebb
7 changed files with 330 additions and 179 deletions
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183
src/audio/SDL_audio.c
View File

@@ -418,136 +418,23 @@ SDL_RemoveAudioDevice(const int iscapture, void *handle)
/* buffer queueing support... */
/* this expects that you managed thread safety elsewhere. */
static void
free_audio_queue(SDL_AudioBufferQueue *packet)
{
while (packet) {
SDL_AudioBufferQueue *next = packet->next;
SDL_free(packet);
packet = next;
}
}
/* NOTE: This assumes you'll hold the mixer lock before calling! */
static int
queue_audio_to_device(SDL_AudioDevice *device, const Uint8 *data, Uint32 len)
{
SDL_AudioBufferQueue *orighead;
SDL_AudioBufferQueue *origtail;
Uint32 origlen;
Uint32 datalen;
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;
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;
}
return 0;
}
/* NOTE: This assumes you'll hold the mixer lock before calling! */
static Uint32
dequeue_audio_from_device(SDL_AudioDevice *device, Uint8 *stream, Uint32 len)
{
SDL_AudioBufferQueue *packet;
Uint8 *ptr = stream;
while ((len > 0) && ((packet = device->buffer_queue_head) != NULL)) {
const Uint32 avail = packet->datalen - packet->startpos;
const Uint32 cpy = SDL_min(len, avail);
SDL_assert(device->queued_bytes >= avail);
SDL_memcpy(ptr, packet->data + packet->startpos, cpy);
packet->startpos += cpy;
ptr += cpy;
device->queued_bytes -= cpy;
len -= cpy;
if (packet->startpos == packet->datalen) { /* packet is done, put it in the pool. */
device->buffer_queue_head = packet->next;
SDL_assert((packet->next != NULL) || (packet == device->buffer_queue_tail));
packet->next = device->buffer_queue_pool;
device->buffer_queue_pool = packet;
}
}
SDL_assert((device->buffer_queue_head != NULL) == (device->queued_bytes != 0));
if (device->buffer_queue_head == NULL) {
device->buffer_queue_tail = NULL; /* in case we drained the queue entirely. */
}
return (Uint32) (ptr - stream);
}
static void SDLCALL
SDL_BufferQueueDrainCallback(void *userdata, Uint8 *stream, int len)
{
/* this function always holds the mixer lock before being called. */
SDL_AudioDevice *device = (SDL_AudioDevice *) userdata;
Uint32 written;
size_t dequeued;
SDL_assert(device != NULL); /* this shouldn't ever happen, right?! */
SDL_assert(!device->iscapture); /* this shouldn't ever happen, right?! */
SDL_assert(len >= 0); /* this shouldn't ever happen, right?! */
written = dequeue_audio_from_device(device, stream, (Uint32) len);
stream += written;
len -= (int) written;
dequeued = SDL_ReadFromDataQueue(device->buffer_queue, stream, len);
stream += dequeued;
len -= (int) dequeued;
if (len > 0) { /* fill any remaining space in the stream with silence. */
SDL_assert(device->buffer_queue_head == NULL);
SDL_assert(SDL_CountDataQueue(device->buffer_queue) == 0);
SDL_memset(stream, device->spec.silence, len);
}
}
@@ -565,7 +452,7 @@ SDL_BufferQueueFillCallback(void *userdata, Uint8 *stream, int len)
/* note that if this needs to allocate more space and run out of memory,
we have no choice but to quietly drop the data and hope it works out
later, but you probably have bigger problems in this case anyhow. */
queue_audio_to_device(device, stream, (Uint32) len);
SDL_WriteToDataQueue(device->buffer_queue, stream, len);
}
int
@@ -584,7 +471,7 @@ SDL_QueueAudio(SDL_AudioDeviceID devid, const void *data, Uint32 len)
if (len > 0) {
current_audio.impl.LockDevice(device);
rc = queue_audio_to_device(device, data, len);
rc = SDL_WriteToDataQueue(device->buffer_queue, data, len);
current_audio.impl.UnlockDevice(device);
}
@@ -605,7 +492,7 @@ SDL_DequeueAudio(SDL_AudioDeviceID devid, void *data, Uint32 len)
}
current_audio.impl.LockDevice(device);
rc = dequeue_audio_from_device(device, data, len);
rc = (Uint32) SDL_ReadFromDataQueue(device->buffer_queue, data, len);
current_audio.impl.UnlockDevice(device);
return rc;
}
@@ -623,11 +510,11 @@ SDL_GetQueuedAudioSize(SDL_AudioDeviceID devid)
/* Nothing to do unless we're set up for queueing. */
if (device->spec.callback == SDL_BufferQueueDrainCallback) {
current_audio.impl.LockDevice(device);
retval = device->queued_bytes + current_audio.impl.GetPendingBytes(device);
retval = SDL_CountDataQueue(device->buffer_queue) + current_audio.impl.GetPendingBytes(device);
current_audio.impl.UnlockDevice(device);
} else if (device->spec.callback == SDL_BufferQueueFillCallback) {
current_audio.impl.LockDevice(device);
retval = device->queued_bytes;
retval = SDL_CountDataQueue(device->buffer_queue);
current_audio.impl.UnlockDevice(device);
}
@@ -638,7 +525,6 @@ void
SDL_ClearQueuedAudio(SDL_AudioDeviceID devid)
{
SDL_AudioDevice *device = get_audio_device(devid);
SDL_AudioBufferQueue *packet;
if (!device) {
return; /* nothing to do. */
@@ -647,35 +533,10 @@ SDL_ClearQueuedAudio(SDL_AudioDeviceID devid)
/* Blank out the device and release the mutex. Free it afterwards. */
current_audio.impl.LockDevice(device);
/* merge the available pool and the current queue into one list. */
packet = device->buffer_queue_head;
if (packet) {
device->buffer_queue_tail->next = device->buffer_queue_pool;
} else {
packet = device->buffer_queue_pool;
}
/* Remove the queued packets from the device. */
device->buffer_queue_tail = NULL;
device->buffer_queue_head = NULL;
device->queued_bytes = 0;
device->buffer_queue_pool = packet;
/* Keep up to two packets in the pool to reduce future malloc pressure. */
if (packet) {
if (!packet->next) {
packet = NULL; /* one packet (the only one) for the pool. */
} else {
SDL_AudioBufferQueue *next = packet->next->next;
packet->next->next = NULL; /* two packets for the pool. */
packet = next; /* rest will be freed. */
}
}
SDL_ClearDataQueue(device->buffer_queue, SDL_AUDIOBUFFERQUEUE_PACKETLEN * 2);
current_audio.impl.UnlockDevice(device);
/* free any extra packets we didn't keep in the pool. */
free_audio_queue(packet);
}
@@ -1076,9 +937,7 @@ close_audio_device(SDL_AudioDevice * device)
current_audio.impl.CloseDevice(device);
}
free_audio_queue(device->buffer_queue_head);
free_audio_queue(device->buffer_queue_pool);
SDL_FreeDataQueue(device->buffer_queue);
SDL_free(device);
}
@@ -1348,19 +1207,13 @@ 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;
}
const size_t slack = ((device->convert.needed) ? device->convert.len : device->spec.size) * 2;
device->buffer_queue = SDL_NewDataQueue(SDL_AUDIOBUFFERQUEUE_PACKETLEN, slack);
if (!device->buffer_queue) {
close_audio_device(device);
SDL_SetError("Couldn't create audio buffer queue");
return 0;
}
device->spec.callback = iscapture ? SDL_BufferQueueFillCallback : SDL_BufferQueueDrainCallback;
device->spec.userdata = device;
}

16
src/audio/SDL_sysaudio.h
View File

@@ -25,6 +25,7 @@
#include "SDL_mutex.h"
#include "SDL_thread.h"
#include "../SDL_dataqueue.h"
/* !!! FIXME: These are wordy and unlocalized... */
#define DEFAULT_OUTPUT_DEVNAME "System audio output device"
@@ -49,7 +50,6 @@ extern void SDL_RemoveAudioDevice(const int iscapture, void *handle);
as appropriate so SDL's list of devices is accurate. */
extern void SDL_OpenedAudioDeviceDisconnected(SDL_AudioDevice *device);
/* 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
@@ -61,15 +61,6 @@ extern void SDL_OpenedAudioDeviceDisconnected(SDL_AudioDevice *device);
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) (void);
@@ -175,10 +166,7 @@ struct SDL_AudioDevice
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. */
SDL_DataQueue *buffer_queue;
/* * * */
/* Data private to this driver */