using System;
using System.Runtime.InteropServices;

namespace ExceptionPerformance
{
    class PerfCounter
    {
        [DllImport("kernel32.dll")]
        extern static short QueryPerformanceCounter(ref long x);
        [DllImport("kernel32.dll")]
        extern static short QueryPerformanceFrequency(ref long x);

        private long m_frequency;
        private long m_start;
        private long m_stop;

        public PerfCounter()
        {
            QueryPerformanceFrequency(ref m_frequency);
        }

        public void Start()
        {
            m_start = GetCurrentValue();
        }

        public void Stop()
        {
            m_stop = GetCurrentValue();
        }

        public double GetElapsedTimeInSeconds()
        {
            return (double)(m_stop - m_start) * (1.0 / m_frequency);
        }

        public double GetElapsedTimeInMilliseconds()
        {
            return (double)(m_stop - m_start) * (1000.0 / m_frequency);
        }

        private long GetCurrentValue()
        {
            long time = 0;
            QueryPerformanceCounter(ref time);
            return time;
        }

    }
}