function DAY_OF_WEEK( Time : int64 ) : integer ;

var DOW : int64 ;

begin
    DOW := 0 ;
    LIB_DAY_OF_WEEK( int64( @Time ), int64( @DOW ) ) ;
    Result := DOW ;
end ;

procedure LIB_DAY_OF_WEEK( Time, Res : int64 ) ;

begin
    if( Res = 0 ) then
    begin
        exit ; // No place to write result
    end ;
    if( Time = 0 ) then
    begin
        Time := LIB_Get_Timestamp ;
    end else
    begin
        Time := pint64( Time )^ ;
        if( Time = 0 ) then
        begin
            Time := LIB_Get_Timestamp ;
        end ;
    end ;
    Time := DOW( Time ) ;
    pint64( Res )^ := Time ;
end ;

function DOW( Time : int64 ) : int64 ;

begin
    Time := Time div One_Day - 1 ; // Convert to day (-1 since day 0 is Sunday, and Monday=1 on VMS)
    Result := ( Time mod 7 ) + 1 ; // Make 1-based instead of 0-based
end ;

function CVT_FROM_INTERNAL_TIME( Operation, Time : int64 ) : int64 ;

begin
    LIB_CVT_FROM_INTERNAL_TIME( int64( @Result ), int64( @Operation ), int64( @Time ) ) ;
end ;

const VMS_Julian : int64 = 586604160000000000 ;

function LIB_CVT_FROM_INTERNAL_TIME( ResultTime, Operation : int64 ; Time : int64 = 0 ) : int64 ;

var ResValue : int64 ;
    Y, Mo, D, H, M, S : word ;
    NS : longint ;
    Weekday : integer ;

begin
    Result := 0 ;
    if( Time = 0 ) then
    begin
        Time := LIB_Get_Timestamp ;
    end else
    begin
        Time := Pint64( Time )^ ;
    end ;
    Operation := pint64( Operation )^ ;
    case Operation of
        LIB_K_DELTA_WEEKS,
        LIB_K_DELTA_DAYS,
        LIB_K_DELTA_HOURS,
        LIB_K_DELTA_MINUTES,
        LIB_K_DELTA_SECONDS : ;
        else if( Time < 0 ) then // Delta time
             begin
                 Result := LIB_ABSTIMREQ ;
                 exit ;
             end ;
    end ;
    if( Time < 0 ) then
    begin
        Time := -Time ;
    end ;
    if( ResultTime = 0 ) then // No place to write result...
    begin
        exit ;
    end ;

    Parse_Sirius_Timestamp( Time, Y, Mo, D, H, M, S, NS ) ;
    Weekday := DOW( Time ) ;
    case Operation of
        LIB_K_MONTH_OF_YEAR : ResValue := M ; // 1 to 12
        LIB_K_DAY_OF_YEAR : ResValue := Julian( M, D, Y ) ; // 1 to 366
        LIB_K_HOUR_OF_YEAR : ResValue := ( Julian( M, D, Y ) - 1 ) * 24 + H ; // 1 to 8784
        LIB_K_MINUTE_OF_YEAR : ResValue := ( Julian( M, D, Y ) - 1 ) * 24 * 60 + H * 60 + M ; 
            // 1 to 527,040
        LIB_K_SECOND_OF_YEAR : ResValue := ( Julian( M, D, Y ) - 1 ) * 24 * 60 * 60 + H * 60 * 60 + 
            M * 60 + S ;
        LIB_K_DAY_OF_MONTH : ResValue := D ; // 1 to 31
        LIB_K_HOUR_OF_MONTH : ResValue := ( D - 1 ) * 24 + H ; // 1 to 744
        LIB_K_MINUTE_OF_MONTH : ResValue := ( D - 1 ) * 24 * 60 + H * 60 + M ; // 1 to 44,640
        LIB_K_SECOND_OF_MONTH : ResValue := ( D - 1 ) * 24 * 60 * 60 + H * 60 * 60 + M * 60 + S ; 
            // 1 to 2,678,400
        LIB_K_DAY_OF_WEEK : ResValue := Weekday ; // 1 to 7
        LIB_K_HOUR_OF_WEEK : ResValue := ( Weekday - 1 ) * 24 + H ; // 1 to 168
        LIB_K_MINUTE_OF_WEEK : ResValue := ( Weekday - 1 ) + 24 * 60 + H * 60 + M ; // 1 to 10,080
        LIB_K_SECOND_OF_WEEK : ResValue := ( Weekday - 1 ) + 24 * 60 * 60 + H * 60 * 60 + M * 60 + 
            S ; // 1 to 604,800
        LIB_K_HOUR_OF_DAY : ResValue := H ; // 0 to 23
        LIB_K_MINUTE_OF_DAY : ResValue := H * 60 + M ; // 0 to 1439
        LIB_K_SECOND_OF_DAY : ResValue := H * 60 + M * 60 + S ; // 0 to 86,399
        LIB_K_MINUTE_OF_HOUR : ResValue := M ; // 0 to 59
        LIB_K_SECOND_OF_HOUR : ResValue := M * 60 + S ; // 0 to 3599
        LIB_K_SECOND_OF_MINUTE : ResValue := S ; // 0 to 59
        LIB_K_NANOSECOND_OF_SECOND : ResValue := NS ;
        LIB_K_JULIAN_DATE : ResValue := ( Time - VMS_Julian ) div One_Day ; 
            // Julian date (days since 17�Nov�1858)
        LIB_K_DELTA_WEEKS : ResValue := Time div One_Week ;
        LIB_K_DELTA_DAYS : ResValue := Time div One_Day ;
        LIB_K_DELTA_HOURS : ResValue := Time div One_Hour ;
        LIB_K_DELTA_MINUTES : ResValue := Time div One_Minute ;
        LIB_K_DELTA_SECONDS : ResValue := Time div One_Second ;
        else
        begin
            Result := LIB_INVOPER ; // Invalid operation
            exit ;
        end ;
    end ;
    pint64( ResultTime )^ := ResValue ;
end ; // LIB_CVT_FROM_INTERNAL_TIME