private static int Calibrate()
{
const int referenceCount = 1000;
return(Enumerable.Range(0, referenceCount)
.Aggregate(
(long)0,
(a, i) =>
{
var t1 = new Interop.timespec();
var t2 = new Interop.timespec();
t1.tv_sec = (IntPtr)0;
t1.tv_nsec = (IntPtr)1000000;
var start = DateTime.UtcNow.Ticks;
Interop.nanosleep(ref t1, ref t2);
return a + ((DateTime.UtcNow.Ticks - start) * 100 - 1000000);
},
a => (int)(a / referenceCount)));
}
/// <summary>
/// Sleeps the specified delay.
/// </summary>
/// <param name="delay">The delay.</param>
public static void Sleep(TimeSpan delay)
{
// Based on [BCM2835 C library](http://www.open.com.au/mikem/bcm2835/)
// Calling nanosleep() takes at least 100-200 us, so use it for
// long waits and use a busy wait on the hires timer for the rest.
var start = DateTime.UtcNow.Ticks;
var millisecondDelay = (decimal)delay.TotalMilliseconds;
if (millisecondDelay >= 100)
{
// Do not use high resolution timer for long interval (>= 100ms)
Thread.Sleep(delay);
}
else if (millisecondDelay > 0.450m)
{
var t1 = new Interop.timespec();
var t2 = new Interop.timespec();
// Use nanosleep if interval is higher than 450µs
t1.tv_sec = (IntPtr)0;
t1.tv_nsec = (IntPtr)((long)(millisecondDelay * 1000000) - nanoSleepOffset);
Interop.nanosleep(ref t1, ref t2);
}
else
{
while (true)
{
if ((DateTime.UtcNow.Ticks - start) * 0.0001m >= millisecondDelay)
{
break;
}
}
}
}