1 files changed, 227 insertions, 0 deletions
diff --git a/alc/backends/sdl2.cpp b/alc/backends/sdl2.cpp
new file mode 100644
index 00000000..25b5d4d9
--- /dev/null
+++ b/alc/backends/sdl2.cpp
@@ -0,0 +1,227 @@
+/**
+ * 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 "backends/sdl2.h"
+
+#include <cassert>
+#include <cstdlib>
+#include <cstring>
+#include <string>
+
+#include "AL/al.h"
+
+#include "alcmain.h"
+#include "alexcpt.h"
+#include "almalloc.h"
+#include "alu.h"
+#include "logging.h"
+
+#include <SDL2/SDL.h>
+
+
+namespace {
+
+#ifdef _WIN32
+#define DEVNAME_PREFIX "OpenAL Soft on "
+#else
+#define DEVNAME_PREFIX ""
+#endif
+
+constexpr ALCchar defaultDeviceName[] = DEVNAME_PREFIX "Default Device";
+
+struct Sdl2Backend final : public BackendBase {
+    Sdl2Backend(ALCdevice *device) noexcept : BackendBase{device} { }
+    ~Sdl2Backend() override;
+
+    void audioCallback(Uint8 *stream, int len) noexcept;
+    static void audioCallbackC(void *ptr, Uint8 *stream, int len) noexcept
+    { static_cast<Sdl2Backend*>(ptr)->audioCallback(stream, len); }
+
+    void open(const ALCchar *name) override;
+    bool reset() override;
+    bool start() override;
+    void stop() override;
+    void lock() override;
+    void unlock() override;
+
+    SDL_AudioDeviceID mDeviceID{0u};
+    ALuint mFrameSize{0};
+
+    ALuint mFrequency{0u};
+    DevFmtChannels mFmtChans{};
+    DevFmtType     mFmtType{};
+    ALuint mUpdateSize{0u};
+
+    DEF_NEWDEL(Sdl2Backend)
+};
+
+Sdl2Backend::~Sdl2Backend()
+{
+    if(mDeviceID)
+        SDL_CloseAudioDevice(mDeviceID);
+    mDeviceID = 0;
+}
+
+void Sdl2Backend::audioCallback(Uint8 *stream, int len) noexcept
+{
+    const auto ulen = static_cast<unsigned int>(len);
+    assert((ulen % mFrameSize) == 0);
+    aluMixData(mDevice, stream, ulen / mFrameSize);
+}
+
+void Sdl2Backend::open(const ALCchar *name)
+{
+    SDL_AudioSpec want{}, have{};
+
+    want.freq = static_cast<int>(mDevice->Frequency);
+    switch(mDevice->FmtType)
+    {
+    case DevFmtUByte: want.format = AUDIO_U8; break;
+    case DevFmtByte: want.format = AUDIO_S8; break;
+    case DevFmtUShort: want.format = AUDIO_U16SYS; break;
+    case DevFmtShort: want.format = AUDIO_S16SYS; break;
+    case DevFmtUInt: /* fall-through */
+    case DevFmtInt: want.format = AUDIO_S32SYS; break;
+    case DevFmtFloat: want.format = AUDIO_F32; break;
+    }
+    want.channels = (mDevice->FmtChans == DevFmtMono) ? 1 : 2;
+    want.samples = static_cast<Uint16>(mDevice->UpdateSize);
+    want.callback = &Sdl2Backend::audioCallbackC;
+    want.userdata = this;
+
+    /* Passing nullptr to SDL_OpenAudioDevice opens a default, which isn't
+     * necessarily the first in the list.
+     */
+    if(!name || strcmp(name, defaultDeviceName) == 0)
+        mDeviceID = SDL_OpenAudioDevice(nullptr, SDL_FALSE, &want, &have,
+            SDL_AUDIO_ALLOW_ANY_CHANGE);
+    else
+    {
+        const size_t prefix_len = strlen(DEVNAME_PREFIX);
+        if(strncmp(name, DEVNAME_PREFIX, prefix_len) == 0)
+            mDeviceID = SDL_OpenAudioDevice(name+prefix_len, SDL_FALSE, &want, &have,
+                SDL_AUDIO_ALLOW_ANY_CHANGE);
+        else
+            mDeviceID = SDL_OpenAudioDevice(name, SDL_FALSE, &want, &have,
+                SDL_AUDIO_ALLOW_ANY_CHANGE);
+    }
+    if(mDeviceID == 0)
+        throw al::backend_exception{ALC_INVALID_VALUE, "%s", SDL_GetError()};
+
+    mDevice->Frequency = static_cast<ALuint>(have.freq);
+
+    if(have.channels == 1)
+        mDevice->FmtChans = DevFmtMono;
+    else if(have.channels == 2)
+        mDevice->FmtChans = DevFmtStereo;
+    else
+        throw al::backend_exception{ALC_INVALID_VALUE, "Unhandled SDL channel count: %d",
+            int{have.channels}};
+
+    switch(have.format)
+    {
+    case AUDIO_U8:     mDevice->FmtType = DevFmtUByte;  break;
+    case AUDIO_S8:     mDevice->FmtType = DevFmtByte;   break;
+    case AUDIO_U16SYS: mDevice->FmtType = DevFmtUShort; break;
+    case AUDIO_S16SYS: mDevice->FmtType = DevFmtShort;  break;
+    case AUDIO_S32SYS: mDevice->FmtType = DevFmtInt;    break;
+    case AUDIO_F32SYS: mDevice->FmtType = DevFmtFloat;  break;
+    default:
+        throw al::backend_exception{ALC_INVALID_VALUE, "Unhandled SDL format: 0x%04x",
+            have.format};
+    }
+    mDevice->UpdateSize = have.samples;
+    mDevice->BufferSize = have.samples * 2; /* SDL always (tries to) use two periods. */
+
+    mFrameSize = mDevice->frameSizeFromFmt();
+    mFrequency = mDevice->Frequency;
+    mFmtChans = mDevice->FmtChans;
+    mFmtType = mDevice->FmtType;
+    mUpdateSize = mDevice->UpdateSize;
+
+    mDevice->DeviceName = name ? name : defaultDeviceName;
+}
+
+bool Sdl2Backend::reset()
+{
+    mDevice->Frequency = mFrequency;
+    mDevice->FmtChans = mFmtChans;
+    mDevice->FmtType = mFmtType;
+    mDevice->UpdateSize = mUpdateSize;
+    mDevice->BufferSize = mUpdateSize * 2;
+    SetDefaultWFXChannelOrder(mDevice);
+    return true;
+}
+
+bool Sdl2Backend::start()
+{
+    SDL_PauseAudioDevice(mDeviceID, 0);
+    return true;
+}
+
+void Sdl2Backend::stop()
+{ SDL_PauseAudioDevice(mDeviceID, 1); }
+
+void Sdl2Backend::lock()
+{ SDL_LockAudioDevice(mDeviceID); }
+
+void Sdl2Backend::unlock()
+{ SDL_UnlockAudioDevice(mDeviceID); }
+
+} // namespace
+
+BackendFactory &SDL2BackendFactory::getFactory()
+{
+    static SDL2BackendFactory factory{};
+    return factory;
+}
+
+bool SDL2BackendFactory::init()
+{ return (SDL_InitSubSystem(SDL_INIT_AUDIO) == 0); }
+
+bool SDL2BackendFactory::querySupport(BackendType type)
+{ return type == BackendType::Playback; }
+
+void SDL2BackendFactory::probe(DevProbe type, std::string *outnames)
+{
+    if(type != DevProbe::Playback)
+        return;
+
+    int num_devices{SDL_GetNumAudioDevices(SDL_FALSE)};
+
+    /* Includes null char. */
+    outnames->append(defaultDeviceName, sizeof(defaultDeviceName));
+    for(int i{0};i < num_devices;++i)
+    {
+        std::string name{DEVNAME_PREFIX};
+        name += SDL_GetAudioDeviceName(i, SDL_FALSE);
+        if(!name.empty())
+            outnames->append(name.c_str(), name.length()+1);
+    }
+}
+
+BackendPtr SDL2BackendFactory::createBackend(ALCdevice *device, BackendType type)
+{
+    if(type == BackendType::Playback)
+        return BackendPtr{new Sdl2Backend{device}};
+    return nullptr;
+}