SDL: vitaaudio: Untested attempt to move Vita audio to SDL3's audio API.

https://github.com/libsdl-org/SDL/commit/ba27176106682be6aaf266ee678ac8b0a2aa4935

From ba27176106682be6aaf266ee678ac8b0a2aa4935 Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <[EMAIL REDACTED]>
Date: Thu, 20 Jul 2023 20:09:25 -0400
Subject: [PATCH] vitaaudio: Untested attempt to move Vita audio to SDL3's
 audio API.

---
 src/audio/vita/SDL_vitaaudio.c | 150 ++++++++++++++++++---------------
 1 file changed, 84 insertions(+), 66 deletions(-)

diff --git a/src/audio/vita/SDL_vitaaudio.c b/src/audio/vita/SDL_vitaaudio.c
index 5cd40e69960d..314f423027a3 100644
--- a/src/audio/vita/SDL_vitaaudio.c
+++ b/src/audio/vita/SDL_vitaaudio.c
@@ -38,41 +38,41 @@
 #define SCE_AUDIO_SAMPLE_ALIGN(s) (((s) + 63) & ~63)
 #define SCE_AUDIO_MAX_VOLUME      0x8000
 
-static int VITAAUD_OpenCaptureDevice(SDL_AudioDevice *_this)
+static int VITAAUD_OpenCaptureDevice(SDL_AudioDevice *device)
 {
-    _this->spec.freq = 16000;
-    _this->spec.samples = 512;
-    _this->spec.channels = 1;
+    device->spec.freq = 16000;
+    device->spec.channels = 1;
+    device->sample_frames = 512;
 
-    SDL_CalculateAudioSpec(&_this->spec);
+    SDL_UpdatedAudioDeviceFormat(device);
 
-    _this->hidden->port = sceAudioInOpenPort(SCE_AUDIO_IN_PORT_TYPE_VOICE, 512, 16000, SCE_AUDIO_IN_PARAM_FORMAT_S16_MONO);
+    device->hidden->port = sceAudioInOpenPort(SCE_AUDIO_IN_PORT_TYPE_VOICE, 512, 16000, SCE_AUDIO_IN_PARAM_FORMAT_S16_MONO);
 
-    if (_this->hidden->port < 0) {
-        return SDL_SetError("Couldn't open audio in port: %x", _this->hidden->port);
+    if (device->hidden->port < 0) {
+        return SDL_SetError("Couldn't open audio in port: %x", device->hidden->port);
     }
 
     return 0;
 }
 
-static int VITAAUD_OpenDevice(SDL_AudioDevice *_this, const char *devname)
+static int VITAAUD_OpenDevice(SDL_AudioDevice *device, const char *devname)
 {
     int format, mixlen, i, port = SCE_AUDIO_OUT_PORT_TYPE_MAIN;
     int vols[2] = { SCE_AUDIO_MAX_VOLUME, SCE_AUDIO_MAX_VOLUME };
     SDL_AudioFormat test_format;
     const SDL_AudioFormat *closefmts;
 
-    _this->hidden = (struct SDL_PrivateAudioData *)
-        SDL_malloc(sizeof(*_this->hidden));
-    if (_this->hidden == NULL) {
+    device->hidden = (struct SDL_PrivateAudioData *)
+        SDL_malloc(sizeof(*device->hidden));
+    if (device->hidden == NULL) {
         return SDL_OutOfMemory();
     }
-    SDL_memset(_this->hidden, 0, sizeof(*_this->hidden));
+    SDL_memset(device->hidden, 0, sizeof(*device->hidden));
 
-    closefmts = SDL_ClosestAudioFormats(_this->spec.format);
+    closefmts = SDL_ClosestAudioFormats(device->spec.format);
     while ((test_format = *(closefmts++)) != 0) {
         if (test_format == SDL_AUDIO_S16LSB) {
-            _this->spec.format = test_format;
+            device->spec.format = test_format;
             break;
         }
     }
@@ -81,106 +81,125 @@ static int VITAAUD_OpenDevice(SDL_AudioDevice *_this, const char *devname)
         return SDL_SetError("Unsupported audio format");
     }
 
-    if (_this->iscapture) {
-        return VITAAUD_OpenCaptureDevice(_this);
+    if (device->iscapture) {
+        return VITAAUD_OpenCaptureDevice(device);
     }
 
-    /* The sample count must be a multiple of 64. */
-    _this->spec.samples = SCE_AUDIO_SAMPLE_ALIGN(_this->spec.samples);
+    // The sample count must be a multiple of 64.
+    device->sample_frames = SCE_AUDIO_SAMPLE_ALIGN(device->sample_frames);
 
-    /* Update the fragment size as size in bytes. */
-    SDL_CalculateAudioSpec(&_this->spec);
+    // Update the fragment size as size in bytes.
+    SDL_UpdatedAudioDeviceFormat(device);
 
     /* Allocate the mixing buffer.  Its size and starting address must
        be a multiple of 64 bytes.  Our sample count is already a multiple of
        64, so spec->size should be a multiple of 64 as well. */
-    mixlen = _this->spec.size * NUM_BUFFERS;
-    _this->hidden->rawbuf = (Uint8 *)SDL_aligned_alloc(64, mixlen);
-    if (_this->hidden->rawbuf == NULL) {
+    mixlen = device->buffer_size * NUM_BUFFERS;
+    device->hidden->rawbuf = (Uint8 *)SDL_aligned_alloc(64, mixlen);
+    if (device->hidden->rawbuf == NULL) {
         return SDL_SetError("Couldn't allocate mixing buffer");
     }
 
-    /* Setup the hardware channel. */
-    if (_this->spec.channels == 1) {
+    // Setup the hardware channel.
+    if (device->spec.channels == 1) {
         format = SCE_AUDIO_OUT_MODE_MONO;
     } else {
         format = SCE_AUDIO_OUT_MODE_STEREO;
     }
 
-    if (_this->spec.freq < 48000) {
+    // the main port requires 48000Hz audio, so this drops to the background music port if necessary
+    if (device->spec.freq < 48000) {
         port = SCE_AUDIO_OUT_PORT_TYPE_BGM;
     }
 
-    _this->hidden->port = sceAudioOutOpenPort(port, _this->spec.samples, _this->spec.freq, format);
-    if (_this->hidden->port < 0) {
-        SDL_aligned_free(_this->hidden->rawbuf);
-        _this->hidden->rawbuf = NULL;
-        return SDL_SetError("Couldn't open audio out port: %x", _this->hidden->port);
+    device->hidden->port = sceAudioOutOpenPort(port, device->sample_frames, device->spec.freq, format);
+    if (device->hidden->port < 0) {
+        SDL_aligned_free(device->hidden->rawbuf);
+        device->hidden->rawbuf = NULL;
+        return SDL_SetError("Couldn't open audio out port: %x", device->hidden->port);
     }
 
-    sceAudioOutSetVolume(_this->hidden->port, SCE_AUDIO_VOLUME_FLAG_L_CH | SCE_AUDIO_VOLUME_FLAG_R_CH, vols);
+    sceAudioOutSetVolume(device->hidden->port, SCE_AUDIO_VOLUME_FLAG_L_CH | SCE_AUDIO_VOLUME_FLAG_R_CH, vols);
 
-    SDL_memset(_this->hidden->rawbuf, 0, mixlen);
+    SDL_memset(device->hidden->rawbuf, 0, mixlen);
     for (i = 0; i < NUM_BUFFERS; i++) {
-        _this->hidden->mixbufs[i] = &_this->hidden->rawbuf[i * _this->spec.size];
+        device->hidden->mixbufs[i] = &device->hidden->rawbuf[i * device->buffer_size];
     }
 
-    _this->hidden->next_buffer = 0;
+    device->hidden->next_buffer = 0;
     return 0;
 }
 
-static void VITAAUD_PlayDevice(SDL_AudioDevice *_this)
+static void VITAAUD_PlayDevice(SDL_AudioDevice *device)
 {
-    Uint8 *mixbuf = _this->hidden->mixbufs[_this->hidden->next_buffer];
+    Uint8 *mixbuf = device->hidden->mixbufs[device->hidden->next_buffer];
 
-    sceAudioOutOutput(_this->hidden->port, mixbuf);
+    sceAudioOutOutput(device->hidden->port, mixbuf);
 
-    _this->hidden->next_buffer = (_this->hidden->next_buffer + 1) % NUM_BUFFERS;
+    device->hidden->next_buffer = (device->hidden->next_buffer + 1) % NUM_BUFFERS;
 }
 
-/* This function waits until it is possible to write a full sound buffer */
-static void VITAAUD_WaitDevice(SDL_AudioDevice *_this)
+// This function waits until it is possible to write a full sound buffer
+static void VITAAUD_WaitDevice(SDL_AudioDevice *device)
 {
-    /* Because we block when sending audio, there's no need for this function to do anything. */
+    // !!! FIXME: we might just need to sleep roughly as long as playback buffers take to process, based on sample rate, etc.
+    while (!SDL_AtomicGet(&device->shutdown) && (sceAudioOutGetRestSample(device->hidden->port) >= device->buffer_size)) {
+        SDL_Delay(1);
+    }
 }
 
-static Uint8 *VITAAUD_GetDeviceBuf(SDL_AudioDevice *_this)
+static Uint8 *VITAAUD_GetDeviceBuf(SDL_AudioDevice *device)
 {
-    return _this->hidden->mixbufs[_this->hidden->next_buffer];
+    return device->hidden->mixbufs[device->hidden->next_buffer];
 }
 
-static void VITAAUD_CloseDevice(SDL_AudioDevice *_this)
+static void VITAAUD_CloseDevice(SDL_AudioDevice *device)
 {
-    if (_this->hidden->port >= 0) {
-        if (_this->iscapture) {
-            sceAudioInReleasePort(_this->hidden->port);
+    if (device->hidden->port >= 0) {
+        if (device->iscapture) {
+            sceAudioInReleasePort(device->hidden->port);
         } else {
-            sceAudioOutReleasePort(_this->hidden->port);
+            sceAudioOutReleasePort(device->hidden->port);
         }
-        _this->hidden->port = -1;
+        device->hidden->port = -1;
     }
 
-    if (!_this->iscapture && _this->hidden->rawbuf != NULL) {
-        SDL_aligned_free(_this->hidden->rawbuf);
-        _this->hidden->rawbuf = NULL;
+    if (!device->iscapture && device->hidden->rawbuf != NULL) {
+        SDL_aligned_free(device->hidden->rawbuf);
+        device->hidden->rawbuf = NULL;
+    }
+}
+
+static void VITAAUD_WaitCaptureDevice(SDL_AudioDevice *device)
+{
+    // there's only a blocking call to obtain more data, so we'll just sleep as
+    //  long as a buffer would run.
+    const Uint64 endticks = SDL_GetTicks() + ((device->sample_frames * 1000) / device->spec.freq);
+    while (!SDL_AtomicGet(&device->shutdown) && (SDL_GetTicks() < endticks)) {
+        SDL_Delay(1);
     }
 }
 
-static int VITAAUD_CaptureFromDevice(SDL_AudioDevice *_this, void *buffer, int buflen)
+static int VITAAUD_CaptureFromDevice(SDL_AudioDevice *device, void *buffer, int buflen)
 {
     int ret;
-    SDL_assert(buflen == _this->spec.size);
-    ret = sceAudioInInput(_this->hidden->port, buffer);
+    SDL_assert(buflen == device->buffer_size);
+    ret = sceAudioInInput(device->hidden->port, buffer);
     if (ret < 0) {
         return SDL_SetError("Failed to capture from device: %x", ret);
     }
-    return _this->spec.size;
+    return device->buffer_size;
 }
 
-static void VITAAUD_ThreadInit(SDL_AudioDevice *_this)
+static void PULSEAUDIO_FlushCapture(SDL_AudioDevice *device)
 {
-    /* Increase the priority of this audio thread by 1 to put it
-       ahead of other SDL threads. */
+    // just grab the latest and dump it.
+    sceAudioInInput(device->hidden->port, device->work_buffer);
+}
+
+static void VITAAUD_ThreadInit(SDL_AudioDevice *device)
+{
+    // Increase the priority of this audio thread by 1 to put it ahead of other SDL threads.
     SceUID thid;
     SceKernelThreadInfo info;
     thid = sceKernelGetThreadId();
@@ -192,26 +211,25 @@ static void VITAAUD_ThreadInit(SDL_AudioDevice *_this)
 
 static SDL_bool VITAAUD_Init(SDL_AudioDriverImpl *impl)
 {
-    /* Set the function pointers */
     impl->OpenDevice = VITAAUD_OpenDevice;
     impl->PlayDevice = VITAAUD_PlayDevice;
     impl->WaitDevice = VITAAUD_WaitDevice;
     impl->GetDeviceBuf = VITAAUD_GetDeviceBuf;
     impl->CloseDevice = VITAAUD_CloseDevice;
     impl->ThreadInit = VITAAUD_ThreadInit;
-
+    impl->WaitCaptureDevice = VITAAUD_WaitCaptureDevice;
+    impl->FlushCapture = VITAAUD_FlushCapture;
     impl->CaptureFromDevice = VITAAUD_CaptureFromDevice;
 
-    /* and the capabilities */
     impl->HasCaptureSupport = SDL_TRUE;
     impl->OnlyHasDefaultOutputDevice = SDL_TRUE;
     impl->OnlyHasDefaultCaptureDevice = SDL_TRUE;
 
-    return SDL_TRUE; /* this audio target is available. */
+    return SDL_TRUE;
 }
 
 AudioBootStrap VITAAUD_bootstrap = {
     "vita", "VITA audio driver", VITAAUD_Init, SDL_FALSE
 };
 
-#endif /* SDL_AUDIO_DRIVER_VITA */
+#endif // SDL_AUDIO_DRIVER_VITA