SLA Calculation needed to exclude Holidays, Weekends and Off business hours

Hello all,

I am to create a function that will calculate the minutes between two dates for company work hours, excluding the weekends. 

The function here from RSingh() is ideal for this purpose; however I am now asked to excluded company holidays also.

http://social.msdn.microsoft.com/Forums/sqlserver/en-US/de4f7661-c702-4a10-ad06-3e28e4e0a83c/sla-calculation-help-needed-in-excluding-weekends-and-off-business-hours-for-calculation?forum=transactsql

With a table called 'holidays' that contains holiday dates. I would hope to modify the function to exclude these.

Please, how can this be accomplished?