procedure Delay1us;
var pc1, pc0,pf:LARGE_INTEGER;
    ticks:int64;
begin
     if (QueryPerformanceFrequency(int64(pf))) then
     begin
          ticks:= pf.QuadPart * dwNumCycles div 1000000;
          QueryPerformanceCounter(int64(pc0));
          repeat
                QueryPerformanceCounter(int64(pc1));
          until not (pc1.QuadPart - pc0.QuadPart < ticks);
     end;
end;