El 02/04/14 09:08, Michael Van Canneyt ha escrit:
Show quoted text 21 lines
On Tue, 1 Apr 2014, Mattias Gaertner wrote:
> On Tue, 01 Apr 2014 12:20:53 +0200
> Luca Olivetti wrote:
>
>> [...]
>> function GetTickCount64: QWord;
>> var
>> tp: timespec;
>> begin
>> clock_gettime(CLOCK_MONOTONIC, @tp);
>> Result := (Int64(tp.tv_sec) * 1000) + (tp.tv_nsec div 1000000);
>> end;
>> [...]
>
> Thanks. GetTickCount64 now uses it on Linux.
The implementation in Sysutils now does so too, and uses a fallback
using gettimeofday.
I checked the revision and it looks wrong: fpgettimeofday uses a TTimeVal (resolution microseconds), while clock_gettime uses TTimeSpec (resolution nanoseconds). A suitable (I think) fallback could be CLOCK_REALTIME, e.g.
var
ts:TTimeSpec;
begin
{$IFDEF HAVECLOCKGETTIME}
if clock_gettime(CLOCK_MONOTONIC, @ts)<0 then
{$ENDIF}
clock_gettime(CLOCK_REALTIME, at ts);
Result := (Int64(ts.tv_sec) * 1000) + (ts.tv_nsec div 1000000);
end;
The problem is that the clock_gettime function is only defined for linux (isn't it supposed to be available in any posix system?) so maybe:
var
tv:TTimeVal;
{$IFDEF HAVECLOCKGETTIME}
ts:TTimeSpec;
{$ENDIF}
begin
{$IFDEF HAVECLOCKGETTIME}
if clock_gettime(CLOCK_MONOTONIC, @ts)=0 then
begin
Result := (Int64(ts.tv_sec) * 1000) + (ts.tv_nsec div 1000000);
exit;
end;
{$ENDIF}
clock_gettime(CLOCK_REALTIME, at tv);
Result := (Int64(tv.tv_sec) * 1000) + (tv.tv_usec div 1000);
end;
Btw, in theory CLOCK_MONOTONIC_RAW should be even better, though it's only available from linux 2.6.28
var
tv:TTimeVal;
{$IFDEF HAVECLOCKGETTIME}
r:cint;
ts:TTimeSpec;
{$ENDIF}
begin
{$IFDEF HAVECLOCKGETTIME}
r:=clock_gettime(CLOCK_MONOTONIC_RAW, @ts);
if r<0 then
r:=clock_gettime(CLOCK_MONOTONIC, @ts)=0;
if r=0 then
begin
Result := (Int64(ts.tv_sec) * 1000) + (ts.tv_nsec div 1000000);
exit;
end;
{$ENDIF}
clock_gettime(CLOCK_REALTIME, at tv);
Result := (Int64(tv.tv_sec) * 1000) + (tv.tv_usec div 1000);
end;
and then there's CLOCK_MONOTONIC_COARSE......
Bye
Luca Olivetti
Wetron Automation Technology
http://www.wetron.es
Tel. +34 935883004 Fax +34 935883007
