Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.ServiceModel.Internals/System/Runtime/Ticks.cs

@@ -0,0 +1,68 @@
+//----------------------------------------------------------------------------
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+//----------------------------------------------------------------------------
+
+namespace System.Runtime
+{
+    using System.Security;
+    using System.Runtime.Interop;
+
+    static class Ticks
+    {
+        public static long Now
+        {
+            [Fx.Tag.SecurityNote(Miscellaneous = "Why isn't the SuppressUnmanagedCodeSecurity attribute working in this case?")]
+            [SecuritySafeCritical]
+            get
+            {
+                long time;
+#pragma warning disable 1634
+#pragma warning suppress 56523 // function has no error return value
+#pragma warning restore 1634
+                UnsafeNativeMethods.GetSystemTimeAsFileTime(out time);
+                return time;
+            }
+        }
+
+        public static long FromMilliseconds(int milliseconds)
+        {
+            return checked((long)milliseconds * TimeSpan.TicksPerMillisecond);
+        }
+
+        public static int ToMilliseconds(long ticks)
+        {
+            return checked((int)(ticks / TimeSpan.TicksPerMillisecond));
+        }
+
+        public static long FromTimeSpan(TimeSpan duration)
+        {
+            return duration.Ticks;
+        }
+
+        public static TimeSpan ToTimeSpan(long ticks)
+        {
+            return new TimeSpan(ticks);
+        }
+
+        public static long Add(long firstTicks, long secondTicks)
+        {
+            if (firstTicks == long.MaxValue || firstTicks == long.MinValue)
+            {
+                return firstTicks;
+            }
+            if (secondTicks == long.MaxValue || secondTicks == long.MinValue)
+            {
+                return secondTicks;
+            }
+            if (firstTicks >= 0 && long.MaxValue - firstTicks <= secondTicks)
+            {
+                return long.MaxValue - 1;
+            }
+            if (firstTicks <= 0 && long.MinValue - firstTicks >= secondTicks)
+            {
+                return long.MinValue + 1;
+            }
+            return checked(firstTicks + secondTicks);
+        }
+    }
+}