1 files changed, 58 insertions, 0 deletions
diff --git a/alc/backends/base.cpp b/alc/backends/base.cpp
new file mode 100644
index 00000000..a7d47c6d
--- /dev/null
+++ b/alc/backends/base.cpp
@@ -0,0 +1,58 @@
+
+#include "config.h"
+
+#include <cstdlib>
+
+#include <thread>
+
+#include "alcmain.h"
+#include "alu.h"
+
+#include "backends/base.h"
+
+
+ClockLatency GetClockLatency(ALCdevice *device)
+{
+    BackendBase *backend{device->Backend.get()};
+    ClockLatency ret{backend->getClockLatency()};
+    ret.Latency += device->FixedLatency;
+    return ret;
+}
+
+
+/* BackendBase method implementations. */
+BackendBase::BackendBase(ALCdevice *device) noexcept : mDevice{device}
+{ }
+
+BackendBase::~BackendBase() = default;
+
+ALCboolean BackendBase::reset()
+{ return ALC_FALSE; }
+
+ALCenum BackendBase::captureSamples(void*, ALCuint)
+{ return ALC_INVALID_DEVICE; }
+
+ALCuint BackendBase::availableSamples()
+{ return 0; }
+
+ClockLatency BackendBase::getClockLatency()
+{
+    ClockLatency ret;
+
+    ALuint refcount;
+    do {
+        while(((refcount=mDevice->MixCount.load(std::memory_order_acquire))&1))
+            std::this_thread::yield();
+        ret.ClockTime = GetDeviceClockTime(mDevice);
+        std::atomic_thread_fence(std::memory_order_acquire);
+    } while(refcount != mDevice->MixCount.load(std::memory_order_relaxed));
+
+    /* NOTE: The device will generally have about all but one periods filled at
+     * any given time during playback. Without a more accurate measurement from
+     * the output, this is an okay approximation.
+     */
+    ret.Latency  = std::chrono::seconds{maxi(mDevice->BufferSize-mDevice->UpdateSize, 0)};
+    ret.Latency /= mDevice->Frequency;
+
+    return ret;
+}