program Timezone;

{ The PC emulator internet derived time appears to be accurate, but obviously does not
 suit all time zones. To fix this, I wrote this little utility TIMEZONE in Turbo Pascal. 
 Use TIMEZONE once from within AUTOEXEC.BAT to apply a fixed correction to the system clock
 e.g. TIMEZONE -1 17 2 will permanently subtract 1hr 17min and 2s from the system time
        TIMEZONE 1 34 5 will add 1hr 34min 5s to the system time
}

uses Dos;

var Hour, Minute, Second, Sec100, Code : word;
    STime, Correction : longint ;

function Seconds ( hour, minute, second: word ) : longint ;
         begin
              Seconds := longint(second)+((longint(hour)*60)+longint(minute))*60;
         end;

function twodigits ( number: word ) : String ;
         var S : String[2] ;
         begin
              Str ( number, S );
              if number < 10 then
                 twodigits := '0'+ S
              else
                 twodigits := S
         end;

procedure Time ( var hour, minute, second: word; seconds: longint ) ;
         begin
              second := seconds mod 60;
              minute := (seconds div 60) mod 60;
              hour   := (seconds div 3600) mod 60;
         end;

function CMDLN_to_TIME : longint ;
          var error1, error2, error3, hour, minute, second : integer;
          begin
               Val( ParamStr(1), hour, error1 );
               Val( ParamStr(2), minute, error2 );
               Val( ParamStr(3), second, error3 );
               If (error1=0) and (error2=0) and (error3=0) then
                  If hour>=0 then
                     CMDLN_to_TIME := second+minute*60+hour*3600
                  else
                     CMDLN_to_TIME := hour*3600-minute*60-second
               else
                  CMDLN_to_TIME := 0 ;
          end;

begin
     GetTime ( Hour, Minute, Second, Sec100 );
     Writeln ( 'Time from Internet is ', twodigits(Hour), ':', twodigits(Minute), ':',twodigits(Second) );
     Stime := Seconds ( Hour, Minute, Second );
     Correction := CMDLN_to_TIME;
     If (Correction <> 0) then
        begin
             Stime := (Stime + Correction) mod (60*60*24);
             Time ( Hour, Minute, Second, Stime );
             SetTime ( Hour, Minute, Second, Sec100 );
             Writeln( 'Corrected Time is     ', twodigits(Hour), ':', twodigits(Minute), ':', twodigits(Second) );
        end
     else
        Writeln( 'Error in command line parameters: Should be TIMEZONE <hour> <min> <sec>');

end.