Stopwatch

// System.Diagnostics.Stopwatch — System.Core (decompiled from Larva HIR)

import System;

into namespace System.Diagnostics
{
	/// Measures elapsed time, from the runtime's monotonic clock in nanoseconds.
	public final class Stopwatch
	{
		i64 started;
		i64 elapsed;
		bool running;

		static extern("time.precise") Now() : i64;

		/// Nanoseconds so far.
		Nanoseconds() : i64 => running ? elapsed + Now() - started : elapsed;

		public:
			/// The clock now, in ticks of Frequency.
			static GetTimestamp() : i64 => Now();

			/// The time from a timestamp to now, and between two.
			static GetElapsedTime(i64 start) : TimeSpan => new TimeSpan((Now() - start) / 100);

			static GetElapsedTime(i64 start, i64 end) : TimeSpan => new TimeSpan((end - start) / 100);

			static StartNew() : Stopwatch
			{
				Stopwatch watch = new Stopwatch();
				watch.Start();
				return watch;
			}

			Start()
			{
				if (!running)
				{
					started = Now();
					running = true;
				}
			}

			Stop()
			{
				if (running)
				{
					elapsed += Now() - started;
					running = false;
				}
			}

			Reset()
			{
				elapsed = 0;
				running = false;
			}

			Restart()
			{
				elapsed = 0;
				started = Now();
				running = true;
			}

			/// Ticks of GetTimestamp and ElapsedTicks per second (they are nanoseconds).
			static i64 Frequency
			{
				get => 1000000000;
			}

			static bool IsHighResolution
			{
				get => true;
			}

			bool IsRunning
			{
				get => running;
			}

			TimeSpan Elapsed
			{
				get => new TimeSpan(Nanoseconds() / 100);
			}

			i64 ElapsedMilliseconds
			{
				get => Nanoseconds() / 1000000;
			}

			i64 ElapsedTicks
			{
				get => Nanoseconds();
			}
	}
}