_LARGE_INTEGER til Int64 med lowpart og highpart

Jeg har posted et spørgsmål før men her er der et andet problem..
jeg kan ikke gennemskue hvordan man skal komme uden om
QueryPerformancefrequency(p);
da p er _LARGE_INTEGER; og QuweyPerformancefrequency skal bruge Int64 men Int64 understøtter ikke Lowpart og highpart.
er der nogen måde at konvertere dette eller hvad skal man gøre?

function wintimefloat:extended;
var
  p:_LARGE_INTEGER;
  e:extended;
begin
  if performancecountfreq = 0 then begin
    QueryPerformancefrequency(p);
    e := p.lowpart;
    if e < 0 then e := e + highdwordconst;
    performancecountfreq := ((p.highpart*highdwordconst)+e);
  end;
  if queryperformancecounter(p) then begin
    e := p.lowpart;
    if e < 0 then e := e + highdwordconst;
    result := ((p.highpart*highdwordconst)+e)/performancecountfreq;
  end else begin
    result := timegettime/1000;
  end;
end;
function wintimefloat:extended;
var
  p:_LARGE_INTEGER;
  e:extended;
begin
  if performancecountfreq = 0 then begin
    function wintimefloat:extended;
var
  p:_LARGE_INTEGER;
  e:extended;
begin
  if performancecountfreq = 0 then begin
    QueryPerformancefrequency(p);
    e := p.lowpart;
    if e < 0 then e := e + highdwordconst;
    performancecountfreq := ((p.highpart*highdwordconst)+e);
  end;
  if queryperformancecounter(p) then begin
    e := p.lowpart;
    if e < 0 then e := e + highdwordconst;
    result := ((p.highpart*highdwordconst)+e)/performancecountfreq;
  end else begin
    result := timegettime/1000;
  end;
end;
    e := p.lowpart;
    if e < 0 then e := e + highdwordconst;
    performancecountfreq := ((p.highpart*highdwordconst)+e);
  end;
  if queryperformancecounter(p) then begin
    e := p.lowpart;
    if e < 0 then e := e + highdwordconst;
    result := ((p.highpart*highdwordconst)+e)/performancecountfreq;
  end else begin
    result := timegettime/1000;
  end;
end;