Decoding Dates and Times

The date code is a 32 bit value specifying the start time of the block. Bits 0-16 contain the number of seconds since midnight, and bits 17-31 the number of days since 17th November 1989.

function DecodeTime(time : dword) : string;
begin
  result := IntTo2str(time div 3600)+':'+
            IntTo2Str((Time mod 3600) div 60)+':'+
            IntTo2Str(Time mod 60);
end;


function DecodeDate(days : dword) : string;
const
  daycount : array[0..11] of integer =
    (31,28,31,30,31,30,31,31,30,31,30,31);
var
  year,month,day : word;

  function IsLeapYear(year : word) : boolean;
  begin
    IsLeapYear := (Year mod 4 = 0) and
                  ((Year mod 100 <> 0) or (Year mod 400 = 0));
  end;

begin
  year := 1989;
  month := 10;  { note that month and day are zero referenced }
  day := 0;
  inc(days,16); { The number of ‘days’ is referenced from 17 Nov 1989 }

  { Account for leap years }
  if IsLeapYear(Year) then
    daycount[1] := 29;

  while days>=daycount[month] do
  begin
    days := days - daycount[month];

    year := year + (month + 1) div 12;
    month := (month + 1) mod 12;

    if IsLeapYear(year) then
      daycount[1] := 29
    else
      daycount[1] := 28;
  end;

  Result := IntToStr(days+1)+'/'+IntToStr(month+1)+'/'+IntToStr(year);

end;