> You can also use TDateTime, but if the clock on your computer is
changed
> during time-measuring, you would get the wrong values.
Which is a very good reason for not using it! And all the floating
point arithmetic and conversion from system time is much slower.
QueryPerformanceCounter can be used for periods longer than 49 days,
but it's 64-bit arithmetic which I think is the FPU again. Provided
GetTickCount is used with functions that check for wrap around, and you
don't want to measure more than 49 days, it's quite safe. And with a
special function that allows the wrap around to be tested!
Angus
function DiffTicks (const StartTick, EndTick: longword): longword ;
begin
if EndTick > StartTick then
Result := EndTick - StartTick
else
Result := (MaxLongWord - StartTick) + EndTick ;
end ;
function GetTickCountX: longword ;
var
newtick: Int64 ;
begin
result := GetTickCount ;
if TicksTestOffset = 0 then exit ; // no testing, byebye
// TicksTestOffset is set in initialization so that the counter wraps
// five mins after startup
newtick := Int64 (result) + Int64 (TicksTestOffset) ;
if newtick >= MaxLongWrd then
result := newtick - MaxLongWrd
else
result := newtick ;
end ;
// force GetTickCount wrap in 5 mins - next line normally commented out
TicksTestOffset := MaxLongWord - GetTickCount - (5 * 60 * 1000) ;
Angus
--
To unsubscribe or change your settings for TWSocket mailing list
please goto http://www.elists.org/mailman/listinfo/twsocket
Visit our website at http://www.overbyte.be
