How to calculate business days excluding saturdays and sundays given between two dates in Infopath (My Form is SharePoint List Form)

I am trying to get the business days excluding the weekends in between given dates. I found XPath formula over net to find the difference between two dates

number(substring(EndDate, 9, 2)) + floor((153 * (number(substring(EndDate, 6, 2)) + 12 * floor((14 - number(substring(EndDate, 6, 2))) div 12) - 3) + 2) div 5) + (number(substring(EndDate, 1, 4)) + 4800 - floor((14 - number(substring(EndDate, 6, 2))) div 12)) * 365 + floor((number(substring(EndDate, 1, 4)) + 4800 - floor((14 - number(substring(EndDate, 6, 2))) div 12)) div 4) - floor((number(substring(EndDate, 1, 4)) + 4800 - floor((14 - number(substring(EndDate, 6, 2))) div 12)) div 100) + floor((number(substring(EndDate, 1, 4)) + 4800 - floor((14 - number(substring(EndDate, 6, 2))) div 12)) div 400) - 32045 - (number(substring(StartDate, 9, 2)) + floor((153 * (number(substring(StartDate, 6, 2)) + 12 * floor((14 - number(substring(StartDate, 6, 2))) div 12) - 3) + 2) div 5)+ (number(substring(StartDate, 1, 4)) + 4800 - floor((14 - number(substring(StartDate, 6, 2))) div 12)) * 365 + floor((number(substring(StartDate, 1, 4)) + 4800 - floor((14 - number(substring(StartDate, 6, 2))) div 12)) div 4) - floor((number(substring(STartDate, 1, 4)) + 4800 - floor((14 - number(substring(StartDAte, 6, 2))) div 12)) div 100) + floor((number(substring(StartDate, 1, 4)) + 4800 - floor((14 - number(substring(StartDAte, 6, 2))) div 12)) div 400) - 32045) + 1

What i need to do exclude weekends in the above formula?

Thanks for your help!