Add SDL2 backend for playback, fix #173

5 files changed, 293 insertions, 1 deletions

diff --git a/Alc/ALc.c b/Alc/ALc.c
index 0cde449e..c72a1833 100644
--- a/Alc/ALc.c
+++ b/Alc/ALc.c
@@ -100,6 +100,9 @@ static struct BackendInfo BackendList[] = {
 #ifdef HAVE_OPENSL
     { "opensl", ALCopenslBackendFactory_getFactory },
 #endif
+#ifdef HAVE_SDL2
+    { "sdl2", ALCsdl2BackendFactory_getFactory },
+#endif
 
     { "null", ALCnullBackendFactory_getFactory },
 #ifdef HAVE_WAVE
diff --git a/Alc/backends/base.h b/Alc/backends/base.h
index 177f6869..b05523b2 100644
--- a/Alc/backends/base.h
+++ b/Alc/backends/base.h
@@ -147,6 +147,7 @@ ALCbackendFactory *ALCportBackendFactory_getFactory(void);
 ALCbackendFactory *ALCopenslBackendFactory_getFactory(void);
 ALCbackendFactory *ALCnullBackendFactory_getFactory(void);
 ALCbackendFactory *ALCwaveBackendFactory_getFactory(void);
+ALCbackendFactory *ALCsdl2BackendFactory_getFactory(void);
 ALCbackendFactory *ALCloopbackFactory_getFactory(void);
 
 
diff --git a/Alc/backends/sdl2.c b/Alc/backends/sdl2.c
new file mode 100644
index 00000000..4b2d3acd
--- /dev/null
+++ b/Alc/backends/sdl2.c
@@ -0,0 +1,265 @@
+/**
+ * OpenAL cross platform audio library
+ * Copyright (C) 2018 by authors.
+ * This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Library General Public
+ *  License as published by the Free Software Foundation; either
+ *  version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ *  License along with this library; if not, write to the
+ *  Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ * Or go to http://www.gnu.org/copyleft/lgpl.html
+ */
+
+#include "config.h"
+
+#include <stdlib.h>
+#include <SDL2/SDL.h>
+
+#include "alMain.h"
+#include "alu.h"
+#include "threads.h"
+#include "compat.h"
+
+#include "backends/base.h"
+
+
+typedef struct ALCsdl2Backend {
+    DERIVE_FROM_TYPE(ALCbackend);
+
+    SDL_AudioDeviceID deviceID;
+    ALvoid *mBuffer;
+    ALuint mSize;
+    ALCboolean quit;
+    ATOMIC(int) killNow;
+    althrd_t thread;
+} ALCsdl2Backend;
+
+static int ALCsdl2Backend_mixerProc(void *ptr);
+
+static void ALCsdl2Backend_Construct(ALCsdl2Backend *self, ALCdevice *device);
+static DECLARE_FORWARD(ALCsdl2Backend, ALCbackend, void, Destruct)
+static ALCenum ALCsdl2Backend_open(ALCsdl2Backend *self, const ALCchar *name);
+static ALCboolean ALCsdl2Backend_reset(ALCsdl2Backend *self);
+static ALCboolean ALCsdl2Backend_start(ALCsdl2Backend *self);
+static void ALCsdl2Backend_stop(ALCsdl2Backend *self);
+static DECLARE_FORWARD2(ALCsdl2Backend, ALCbackend, ALCenum, captureSamples, void*, ALCuint)
+static DECLARE_FORWARD(ALCsdl2Backend, ALCbackend, ALCuint, availableSamples)
+static DECLARE_FORWARD(ALCsdl2Backend, ALCbackend, ClockLatency, getClockLatency)
+static DECLARE_FORWARD(ALCsdl2Backend, ALCbackend, void, lock)
+static DECLARE_FORWARD(ALCsdl2Backend, ALCbackend, void, unlock)
+DECLARE_DEFAULT_ALLOCATORS(ALCsdl2Backend)
+
+DEFINE_ALCBACKEND_VTABLE(ALCsdl2Backend);
+
+static void ALCsdl2Backend_Construct(ALCsdl2Backend *self, ALCdevice *device)
+{
+    ALCbackend_Construct(STATIC_CAST(ALCbackend, self), device);
+    SET_VTABLE2(ALCsdl2Backend, ALCbackend, self);
+
+    self->mBuffer = NULL;
+    self->mSize = 0;
+    self->quit = ALC_FALSE;
+    if(SDL_WasInit(0) == 0) // Is SDL2 initialized at all?
+    {
+        SDL_Init(SDL_INIT_AUDIO);
+        self->quit = ALC_TRUE;
+    }
+    else if(!SDL_WasInit(SDL_INIT_AUDIO))
+        SDL_InitSubSystem(SDL_INIT_AUDIO);
+
+    ATOMIC_INIT(&self->killNow, AL_TRUE);
+}
+
+
+static int ALCsdl2Backend_mixerProc(void *ptr)
+{
+    ALCsdl2Backend *self = (ALCsdl2Backend*)ptr;
+    ALCdevice *device = STATIC_CAST(ALCbackend, self)->mDevice;
+    struct timespec now, start;
+    ALuint64 avail, done;
+    const long restTime = (long)((ALuint64)device->UpdateSize * 1000000000 /
+                                 device->Frequency / 2);
+
+    SetRTPriority();
+    althrd_setname(althrd_current(), MIXER_THREAD_NAME);
+
+    done = 0;
+    if(altimespec_get(&start, AL_TIME_UTC) != AL_TIME_UTC)
+    {
+        ERR("Failed to get starting time\n");
+        return 1;
+    }
+    while(!ATOMIC_LOAD(&self->killNow, almemory_order_acquire) &&
+          ATOMIC_LOAD(&device->Connected, almemory_order_acquire))
+    {
+        if(altimespec_get(&now, AL_TIME_UTC) != AL_TIME_UTC)
+        {
+            ERR("Failed to get current time\n");
+            return 1;
+        }
+
+        avail  = (now.tv_sec - start.tv_sec) * device->Frequency;
+        avail += (ALint64)(now.tv_nsec - start.tv_nsec) * device->Frequency / 1000000000;
+        if(avail < done)
+        {
+            /* Oops, time skipped backwards. Reset the number of samples done
+             * with one update available since we (likely) just came back from
+             * sleeping. */
+            done = avail - device->UpdateSize;
+        }
+
+        if(avail-done < device->UpdateSize)
+            al_nssleep(restTime);
+        else while(avail-done >= device->UpdateSize)
+        {
+            ALCsdl2Backend_lock(self);
+            aluMixData(device, self->mBuffer, device->UpdateSize);
+            SDL_QueueAudio(self->deviceID, self->mBuffer, self->mSize);
+            ALCsdl2Backend_unlock(self);
+            done += device->UpdateSize;
+        }
+    }
+
+    return 0;
+}
+
+static ALCenum ALCsdl2Backend_open(ALCsdl2Backend *self, const ALCchar *name)
+{
+    ALCdevice *device = STATIC_CAST(ALCbackend, self)->mDevice;
+    SDL_AudioSpec want;
+    SDL_zero(want);
+    want.freq = device->Frequency;
+    want.format = AUDIO_F32;
+    want.channels = 2;
+    want.samples = device->UpdateSize;
+
+    if(!name)
+        name = SDL_GetAudioDeviceName(0, 0);
+    self->deviceID = SDL_OpenAudioDevice(name, 0, &want, NULL, 0);
+    if(self->deviceID == 0) {
+        ERR("Could not open device\n");
+        return ALC_INVALID_VALUE;
+    }
+    alstr_copy_cstr(&STATIC_CAST(ALCbackend, self)->mDevice->DeviceName, name);
+
+    return ALC_NO_ERROR;
+}
+
+static ALCboolean ALCsdl2Backend_reset(ALCsdl2Backend *self)
+{
+    SetDefaultWFXChannelOrder(STATIC_CAST(ALCbackend, self)->mDevice);
+    return ALC_TRUE;
+}
+
+static ALCboolean ALCsdl2Backend_start(ALCsdl2Backend *self)
+{
+    ALCdevice *device = STATIC_CAST(ALCbackend, self)->mDevice;
+    self->mSize = device->UpdateSize * FrameSizeFromDevFmt(
+        device->FmtChans, device->FmtType, device->AmbiOrder
+    );
+    self->mBuffer = malloc(self->mSize);
+    if(!self->mBuffer)
+    {
+        ERR("Buffer malloc failed\n");
+        return ALC_FALSE;
+    }
+
+    ATOMIC_STORE(&self->killNow, AL_FALSE, almemory_order_release);
+    if(althrd_create(&self->thread, ALCsdl2Backend_mixerProc, self) != althrd_success)
+    {
+        free(self->mBuffer);
+        self->mBuffer = NULL;
+        self->mSize = 0;
+        return ALC_FALSE;
+    }
+    SDL_PauseAudioDevice(self->deviceID, 0);
+    return ALC_TRUE;
+}
+
+static void ALCsdl2Backend_stop(ALCsdl2Backend *self)
+{
+    int res;
+
+    if(ATOMIC_EXCHANGE(&self->killNow, AL_TRUE, almemory_order_acq_rel))
+        return;
+    althrd_join(self->thread, &res);
+
+    free(self->mBuffer);
+    self->mBuffer = NULL;
+    if(self->quit)
+        SDL_Quit();
+}
+
+
+typedef struct ALCsdl2BackendFactory {
+    DERIVE_FROM_TYPE(ALCbackendFactory);
+} ALCsdl2BackendFactory;
+#define ALCsdl2BACKENDFACTORY_INITIALIZER { { GET_VTABLE2(ALCsdl2BackendFactory, ALCbackendFactory) } }
+
+ALCbackendFactory *ALCsdl2BackendFactory_getFactory(void);
+
+static ALCboolean ALCsdl2BackendFactory_init(ALCsdl2BackendFactory *self);
+static DECLARE_FORWARD(ALCsdl2BackendFactory, ALCbackendFactory, void, deinit)
+static ALCboolean ALCsdl2BackendFactory_querySupport(ALCsdl2BackendFactory *self, ALCbackend_Type type);
+static void ALCsdl2BackendFactory_probe(ALCsdl2BackendFactory *self, enum DevProbe type);
+static ALCbackend* ALCsdl2BackendFactory_createBackend(ALCsdl2BackendFactory *self, ALCdevice *device, ALCbackend_Type type);
+DEFINE_ALCBACKENDFACTORY_VTABLE(ALCsdl2BackendFactory);
+
+
+ALCbackendFactory *ALCsdl2BackendFactory_getFactory(void)
+{
+    static ALCsdl2BackendFactory factory = ALCsdl2BACKENDFACTORY_INITIALIZER;
+    return STATIC_CAST(ALCbackendFactory, &factory);
+}
+
+
+static ALCboolean ALCsdl2BackendFactory_init(ALCsdl2BackendFactory* UNUSED(self))
+{
+    return ALC_TRUE;
+}
+
+static ALCboolean ALCsdl2BackendFactory_querySupport(ALCsdl2BackendFactory* UNUSED(self), ALCbackend_Type type)
+{
+    if(type == ALCbackend_Playback)
+        return ALC_TRUE;
+    return ALC_FALSE;
+}
+
+static void ALCsdl2BackendFactory_probe(ALCsdl2BackendFactory* UNUSED(self), enum DevProbe type)
+{
+    if(type != ALL_DEVICE_PROBE)
+        return;
+    ALCboolean quit = ALC_FALSE;
+    if(SDL_WasInit(0) == 0) // Is SDL2 initialized at all?
+    {
+        SDL_Init(SDL_INIT_AUDIO);
+        quit = ALC_TRUE;
+    }
+    else if(!SDL_WasInit(SDL_INIT_AUDIO))
+        SDL_InitSubSystem(SDL_INIT_AUDIO);
+    for(int i = 0; i < SDL_GetNumAudioDevices(0); ++i)
+        AppendAllDevicesList(SDL_GetAudioDeviceName(i, 0));
+    if(quit)
+        SDL_Quit();
+}
+
+static ALCbackend* ALCsdl2BackendFactory_createBackend(ALCsdl2BackendFactory* UNUSED(self), ALCdevice *device, ALCbackend_Type type)
+{
+    if(type == ALCbackend_Playback)
+    {
+        ALCsdl2Backend *backend;
+        NEW_OBJ(backend, ALCsdl2Backend)(device);
+        if(!backend) return NULL;
+        return STATIC_CAST(ALCbackend, backend);
+    }
+
+    return NULL;
+}
diff --git a/CMakeLists.txt b/CMakeLists.txt
index bd531128..0c6196f1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -759,6 +759,7 @@ SET(HAVE_PULSEAUDIO 0)
 SET(HAVE_COREAUDIO  0)
 SET(HAVE_OPENSL     0)
 SET(HAVE_WAVE       0)
+SET(HAVE_SDL2       0)
 
 # Check for SSE support
 OPTION(ALSOFT_REQUIRE_SSE "Require SSE support" OFF)
@@ -1123,6 +1124,23 @@ IF(ALSOFT_REQUIRE_OPENSL AND NOT HAVE_OPENSL)
     MESSAGE(FATAL_ERROR "Failed to enabled required OpenSL backend")
 ENDIF()
 
+# Check for SDL2 backend
+OPTION(ALSOFT_REQUIRE_SDL2 "Require SDL2 backend" OFF)
+FIND_PACKAGE(SDL2)
+IF(SDL2_FOUND)
+    # Off by default, since it adds a runtime dependency
+    OPTION(ALSOFT_BACKEND_SDL2 "Enable SDL2 backend" OFF)
+    IF(ALSOFT_BACKEND_SDL2)
+        SET(HAVE_SDL2 1)
+        SET(ALC_OBJS  ${ALC_OBJS} Alc/backends/sdl2.c)
+        SET(BACKENDS  "${BACKENDS} SDL2,")
+        SET(EXTRA_LIBS ${SDL2_LIBRARY} ${EXTRA_LIBS})
+    ENDIF()
+ENDIF()
+IF(ALSOFT_REQUIRE_SDL2 AND NOT SDL2_FOUND)
+    MESSAGE(FATAL_ERROR "Failed to enabled required SDL2 backend")
+ENDIF()
+
 # Optionally enable the Wave Writer backend
 OPTION(ALSOFT_BACKEND_WAVE "Enable Wave Writer backend" ON)
 IF(ALSOFT_BACKEND_WAVE)
@@ -1206,7 +1224,9 @@ IF(ALSOFT_UTILS AND NOT ALSOFT_NO_CONFIG_UTIL)
     add_subdirectory(utils/alsoft-config)
 ENDIF()
 IF(ALSOFT_EXAMPLES)
-    FIND_PACKAGE(SDL2)
+    IF(NOT SDL2_FOUND)
+        FIND_PACKAGE(SDL2)
+    ENDIF()
     IF(SDL2_FOUND)
         FIND_PACKAGE(SDL_sound)
         FIND_PACKAGE(FFmpeg COMPONENTS AVFORMAT AVCODEC AVUTIL SWSCALE SWRESAMPLE)
diff --git a/config.h.in b/config.h.in
index 2abeedfd..345e8408 100644
--- a/config.h.in
+++ b/config.h.in
@@ -77,6 +77,9 @@
 /* Define if we have the Wave Writer backend */
 #cmakedefine HAVE_WAVE
 
+/* Define if we have the SDL2 backend */
+#cmakedefine HAVE_SDL2
+
 /* Define if we have the stat function */
 #cmakedefine HAVE_STAT