perfcounter.cs

功能：基于windows mobile 的地图查看器。使用vs2005开发

using System;
using System.Runtime.InteropServices;

namespace PInvokeLibrary
{
	/// <summary>
	/// Provides access to the Performance Counters.
	/// </summary>
	public class PerfCounter
	{
		/// <summary>
		/// This function retrieves the frequency of the high-resolution performance
		/// counter if one is provided by the OEM.
		/// </summary>
		/// <param name="lpFrequency">Pointer to a variable that the function sets,
		/// in counts per second, to the current performance-counter frequency. If
		/// the installed hardware does not support a high-resolution performance
		/// counter, this parameter can be set to zero.</param>
		/// <returns>Nonzero indicates that the installed hardware supports a high-
		/// resolution performance counter. Zero indicates that the installed hardware
		/// does not support a high-resolution performance counter.</returns>
		[DllImport("CoreDll.dll")]
		public static extern int QueryPerformanceFrequency(ref Int64 lpFrequency);

		/// <summary>
		/// This function retrieves the current value of the high-resolution performance
		/// counter if one is provided by the OEM.
		/// </summary>
		/// <param name="lpPerformanceCount">Pointer to a variable that the function sets,
		/// in counts, to the current performance-counter value. If the installed hardware
		/// does not support a high-resolution performance counter, this parameter can be
		/// set to zero.</param>
		/// <returns>QueryPerformanceFrequency will return 1000 if the hardware does not
		/// support a high frequency counter since the API defaults to a milliseconds
		/// GetTickCount implementation.</returns>
		[DllImport("CoreDll.dll")]
		public static extern int QueryPerformanceCounter(ref Int64 lpPerformanceCount);

		/// <summary>
		/// Run a test of the PerfCounter class.
		/// </summary>
		/// <param name="showLine">Delegate called to show debug information</param>
		public static void TestProc(MainTest.DisplayLineDelegate showLine)
		{
			System.Int64 freq = 0;
			if (QueryPerformanceFrequency(ref freq) != 0)
			{
				System.Int64 count1 = 0;
				System.Int64 count2 = 0;

				if (QueryPerformanceCounter(ref count1) != 0)
				{
					System.Threading.Thread.Sleep(1200);
					QueryPerformanceCounter(ref count2);
					showLine(String.Format("Timer Start: {0}", count1));
					showLine(String.Format("Timer Stop: {0}", count2));
					showLine(String.Format("Timer Freq: {0} Hz", freq));
					showLine(String.Format("Slept for {0} ms", (count2 - count1) * 1000 / freq));
				}
				else
				{
					showLine("FAILURE: QueryPerformanceCounter failed");
				}
			}
			else
			{
				showLine("FAILURE: QueryPerformanceFrequency failed");
			}
		}
	}
}