Calcular o número de dias úteis entre duas datas

The following formula counts the number of weekdays (but not weekend days):

diffDays := (EndDate - StartDate) / 86400 + 1;
strtDay := @Modulo(@Weekday(StartDate); 7);
endDay := @Modulo(@c(EndDate); 7);
result := (diffDays - endDay + strtDay - 8) * 5 / 7 - @Max(-2; -strtDay) - @Min(1; endDay) + 5 - strtDay + endDay