Day of week in structured text

(*  Day of Week Routine - 
    This version compensates for leap years and non-leap years, as well as the oddball leap century.

To use this routine, create a DINT array of 12 elements called "MonthValue", and assign it as follows:
MonthValue[0] := 0, 3, 3, 6, 1, 4, 6, 2, 5, 0, 3, 5
The final value, DayOfWeek is just that, Sunday = 0, Monday = 1, etc.
*)

Year         := GL_WC_Time[0];
Month         := GL_WC_Time[1];
DayOfMonth     := GL_WC_Time[2];
Curr_Hour    := GL_WC_Time[3];
Curr_Minute    := GL_WC_Time[4];


IF (((Year MOD 4) = 0) AND NOT ((Year MOD 100) = 0)) OR ((Year MOD 400) = 0)
THEN 
    MonthValue[0] := 6;
    MonthValue[1] := 2;
ELSE
    MonthValue[0] := 0;
    MonthValue[1] := 3;
End_If;

DayOfWeek := (DayOfMonth + MonthValue[Month-1] + (Year MOD 100) + ((Year MOD 100) / 4) + 6) MOD 7;