private UInt64 SubtractTimes(ComTypes.FILETIME a, ComTypes.FILETIME b)
{
UInt64 aInt = ((UInt64)(a.dwHighDateTime << 32)) | (UInt64)a.dwLowDateTime;
UInt64 bInt = ((UInt64)(b.dwHighDateTime << 32)) | (UInt64)b.dwLowDateTime;
return(aInt - bInt);
}
public short GetUsage()
{
short cpuCopy = _cpuUsage;
if (Interlocked.Increment(ref _runCount) == 1)
{
if (!EnoughTimePassed)
{
Interlocked.Decrement(ref _runCount);
return(cpuCopy);
}
ComTypes.FILETIME sysIdle, sysKernel, sysUser;
TimeSpan procTime;
Process process = Process.GetCurrentProcess();
procTime = process.TotalProcessorTime;
if (!GetSystemTimes(out sysIdle, out sysKernel, out sysUser))
{
Interlocked.Decrement(ref _runCount);
return(cpuCopy);
}
if (!IsFirstRun)
{
UInt64 sysKernelDiff = SubtractTimes(sysKernel, _prevSysKernel);
UInt64 sysUserDiff = SubtractTimes(sysUser, _prevSysUser);
UInt64 sysTotal = sysKernelDiff + sysUserDiff;
Int64 procTotal = procTime.Ticks - _prevProcTotal.Ticks;
if (sysTotal > 0)
{
_cpuUsage = (short)((100.0 * procTotal) / sysTotal);
}
}
_prevProcTotal = procTime;
_prevSysKernel = sysKernel;
_prevSysUser = sysUser;
_lastRun = DateTime.Now;
cpuCopy = _cpuUsage;
}
Interlocked.Decrement(ref _runCount);
return(cpuCopy);
}
private static extern bool GetSystemTimes(
out ComTypes.FILETIME lpIdleTime,
out ComTypes.FILETIME lpKernelTime,
out ComTypes.FILETIME lpUserTime
);
