1 files changed, 104 insertions, 0 deletions
diff --git a/src/Ryujinx.Common/PreciseSleep/PreciseSleepHelper.cs b/src/Ryujinx.Common/PreciseSleep/PreciseSleepHelper.cs
new file mode 100644
index 00000000..3c30a7f6
--- /dev/null
+++ b/src/Ryujinx.Common/PreciseSleep/PreciseSleepHelper.cs
@@ -0,0 +1,104 @@
+using Ryujinx.Common.SystemInterop;
+using System;
+using System.Threading;
+
+namespace Ryujinx.Common.PreciseSleep
+{
+    public static class PreciseSleepHelper
+    {
+        /// <summary>
+        /// Create a precise sleep event for the current platform.
+        /// </summary>
+        /// <returns>A precise sleep event</returns>
+        public static IPreciseSleepEvent CreateEvent()
+        {
+            if (OperatingSystem.IsLinux() || OperatingSystem.IsMacOS() || OperatingSystem.IsIOS() || OperatingSystem.IsAndroid())
+            {
+                return new NanosleepEvent();
+            }
+            else if (OperatingSystem.IsWindows())
+            {
+                return new WindowsSleepEvent();
+            }
+            else
+            {
+                return new SleepEvent();
+            }
+        }
+
+        /// <summary>
+        /// Sleeps up to the closest point to the timepoint that the OS reasonably allows.
+        /// The provided event is used by the timer to wake the current thread, and should not be signalled from any other source.
+        /// </summary>
+        /// <param name="evt">Event used to wake this thread</param>
+        /// <param name="timePoint">Target timepoint in host ticks</param>
+        public static void SleepUntilTimePoint(EventWaitHandle evt, long timePoint)
+        {
+            if (OperatingSystem.IsWindows())
+            {
+                WindowsGranularTimer.Instance.SleepUntilTimePointWithoutExternalSignal(evt, timePoint);
+            }
+            else
+            {
+                // Events might oversleep by a little, depending on OS.
+                // We don't want to miss the timepoint, so bias the wait to be lower.
+                // Nanosleep can possibly handle it better, too.
+                long accuracyBias = PerformanceCounter.TicksPerMillisecond / 2;
+                long now = PerformanceCounter.ElapsedTicks + accuracyBias;
+                long ms = Math.Min((timePoint - now) / PerformanceCounter.TicksPerMillisecond, int.MaxValue);
+
+                if (ms > 0)
+                {
+                    evt.WaitOne((int)ms);
+                }
+
+                if (OperatingSystem.IsLinux() || OperatingSystem.IsMacOS() || OperatingSystem.IsIOS() || OperatingSystem.IsAndroid())
+                {
+                    // Do a nanosleep.
+                    now = PerformanceCounter.ElapsedTicks;
+                    long ns = ((timePoint - now) * 1_000_000) / PerformanceCounter.TicksPerMillisecond;
+
+                    Nanosleep.SleepAtMost(ns);
+                }
+            }
+        }
+
+        /// <summary>
+        /// Spinwait until the given timepoint. If wakeSignal is or becomes 1, return early.
+        /// Thread is allowed to yield.
+        /// </summary>
+        /// <param name="timePoint">Target timepoint in host ticks</param>
+        /// <param name="wakeSignal">Returns early if this is set to 1</param>
+        public static void SpinWaitUntilTimePoint(long timePoint, ref long wakeSignal)
+        {
+            SpinWait spinWait = new();
+
+            while (Interlocked.Read(ref wakeSignal) != 1 && PerformanceCounter.ElapsedTicks < timePoint)
+            {
+                // Our time is close - don't let SpinWait go off and potentially Thread.Sleep().
+                if (spinWait.NextSpinWillYield)
+                {
+                    Thread.Yield();
+
+                    spinWait.Reset();
+                }
+                else
+                {
+                    spinWait.SpinOnce();
+                }
+            }
+        }
+
+        /// <summary>
+        /// Spinwait until the given timepoint, with no opportunity to wake early.
+        /// </summary>
+        /// <param name="timePoint">Target timepoint in host ticks</param>
+        public static void SpinWaitUntilTimePoint(long timePoint)
+        {
+            while (PerformanceCounter.ElapsedTicks < timePoint)
+            {
+                Thread.SpinWait(5);
+            }
+        }
+    }
+}