Convert the null backend to C++

1 files changed, 232 insertions, 0 deletions

diff --git a/Alc/backends/null.cpp b/Alc/backends/null.cpp
new file mode 100644
index 00000000..2e1c6ac9
--- /dev/null
+++ b/Alc/backends/null.cpp
@@ -0,0 +1,232 @@
+/**
+ * OpenAL cross platform audio library
+ * Copyright (C) 2010 by Chris Robinson
+ * 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>
+#ifdef HAVE_WINDOWS_H
+#include <windows.h>
+#endif
+
+#include "alMain.h"
+#include "alu.h"
+#include "threads.h"
+#include "compat.h"
+
+#include "backends/base.h"
+
+
+namespace {
+
+constexpr ALCchar nullDevice[] = "No Output";
+
+} // namespace
+
+struct ALCnullBackend final : public ALCbackend {
+    ATOMIC(int) killNow;
+    althrd_t thread;
+};
+
+static int ALCnullBackend_mixerProc(void *ptr);
+
+static void ALCnullBackend_Construct(ALCnullBackend *self, ALCdevice *device);
+static void ALCnullBackend_Destruct(ALCnullBackend *self);
+static ALCenum ALCnullBackend_open(ALCnullBackend *self, const ALCchar *name);
+static ALCboolean ALCnullBackend_reset(ALCnullBackend *self);
+static ALCboolean ALCnullBackend_start(ALCnullBackend *self);
+static void ALCnullBackend_stop(ALCnullBackend *self);
+static DECLARE_FORWARD2(ALCnullBackend, ALCbackend, ALCenum, captureSamples, void*, ALCuint)
+static DECLARE_FORWARD(ALCnullBackend, ALCbackend, ALCuint, availableSamples)
+static DECLARE_FORWARD(ALCnullBackend, ALCbackend, ClockLatency, getClockLatency)
+static DECLARE_FORWARD(ALCnullBackend, ALCbackend, void, lock)
+static DECLARE_FORWARD(ALCnullBackend, ALCbackend, void, unlock)
+DECLARE_DEFAULT_ALLOCATORS(ALCnullBackend)
+
+DEFINE_ALCBACKEND_VTABLE(ALCnullBackend);
+
+
+static void ALCnullBackend_Construct(ALCnullBackend *self, ALCdevice *device)
+{
+    new (self) ALCnullBackend{};
+    ALCbackend_Construct(STATIC_CAST(ALCbackend, self), device);
+    SET_VTABLE2(ALCnullBackend, ALCbackend, self);
+
+    ATOMIC_INIT(&self->killNow, AL_TRUE);
+}
+
+static void ALCnullBackend_Destruct(ALCnullBackend *self)
+{
+    ALCbackend_Destruct(STATIC_CAST(ALCbackend, self));
+    self->~ALCnullBackend();
+}
+
+
+static int ALCnullBackend_mixerProc(void *ptr)
+{
+    ALCnullBackend *self = (ALCnullBackend*)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)
+        {
+            ALCnullBackend_lock(self);
+            aluMixData(device, NULL, device->UpdateSize);
+            ALCnullBackend_unlock(self);
+            done += device->UpdateSize;
+        }
+    }
+
+    return 0;
+}
+
+
+static ALCenum ALCnullBackend_open(ALCnullBackend *self, const ALCchar *name)
+{
+    ALCdevice *device;
+
+    if(!name)
+        name = nullDevice;
+    else if(strcmp(name, nullDevice) != 0)
+        return ALC_INVALID_VALUE;
+
+    device = STATIC_CAST(ALCbackend, self)->mDevice;
+    alstr_copy_cstr(&device->DeviceName, name);
+
+    return ALC_NO_ERROR;
+}
+
+static ALCboolean ALCnullBackend_reset(ALCnullBackend *self)
+{
+    SetDefaultWFXChannelOrder(STATIC_CAST(ALCbackend, self)->mDevice);
+    return ALC_TRUE;
+}
+
+static ALCboolean ALCnullBackend_start(ALCnullBackend *self)
+{
+    ATOMIC_STORE(&self->killNow, AL_FALSE, almemory_order_release);
+    if(althrd_create(&self->thread, ALCnullBackend_mixerProc, self) != althrd_success)
+        return ALC_FALSE;
+    return ALC_TRUE;
+}
+
+static void ALCnullBackend_stop(ALCnullBackend *self)
+{
+    int res;
+
+    if(ATOMIC_EXCHANGE(&self->killNow, AL_TRUE, almemory_order_acq_rel))
+        return;
+    althrd_join(self->thread, &res);
+}
+
+
+struct ALCnullBackendFactory final : public ALCbackendFactory {
+    ALCnullBackendFactory() noexcept;
+};
+
+ALCbackendFactory *ALCnullBackendFactory_getFactory(void);
+
+static ALCboolean ALCnullBackendFactory_init(ALCnullBackendFactory *self);
+static DECLARE_FORWARD(ALCnullBackendFactory, ALCbackendFactory, void, deinit)
+static ALCboolean ALCnullBackendFactory_querySupport(ALCnullBackendFactory *self, ALCbackend_Type type);
+static void ALCnullBackendFactory_probe(ALCnullBackendFactory *self, enum DevProbe type, al_string *outnames);
+static ALCbackend* ALCnullBackendFactory_createBackend(ALCnullBackendFactory *self, ALCdevice *device, ALCbackend_Type type);
+DEFINE_ALCBACKENDFACTORY_VTABLE(ALCnullBackendFactory);
+
+ALCnullBackendFactory::ALCnullBackendFactory() noexcept
+  : ALCbackendFactory{GET_VTABLE2(ALCnullBackendFactory, ALCbackendFactory)}
+{
+}
+
+
+ALCbackendFactory *ALCnullBackendFactory_getFactory(void)
+{
+    static ALCnullBackendFactory factory{};
+    return STATIC_CAST(ALCbackendFactory, &factory);
+}
+
+
+static ALCboolean ALCnullBackendFactory_init(ALCnullBackendFactory* UNUSED(self))
+{
+    return ALC_TRUE;
+}
+
+static ALCboolean ALCnullBackendFactory_querySupport(ALCnullBackendFactory* UNUSED(self), ALCbackend_Type type)
+{
+    if(type == ALCbackend_Playback)
+        return ALC_TRUE;
+    return ALC_FALSE;
+}
+
+static void ALCnullBackendFactory_probe(ALCnullBackendFactory* UNUSED(self), enum DevProbe type, al_string *outnames)
+{
+    switch(type)
+    {
+        case ALL_DEVICE_PROBE:
+        case CAPTURE_DEVICE_PROBE:
+            alstr_append_range(outnames, nullDevice, nullDevice+sizeof(nullDevice));
+            break;
+    }
+}
+
+static ALCbackend* ALCnullBackendFactory_createBackend(ALCnullBackendFactory* UNUSED(self), ALCdevice *device, ALCbackend_Type type)
+{
+    if(type == ALCbackend_Playback)
+    {
+        ALCnullBackend *backend;
+        NEW_OBJ(backend, ALCnullBackend)(device);
+        if(!backend) return NULL;
+        return STATIC_CAST(ALCbackend, backend);
+    }
+
+    return NULL;
+}