A former state representative from Salem, N.H., has agreed to plead guilty to charges of selling drugs. Ronald ‘‘Tony’’ Giordano, 54, was scheduled to go to trial next week on charges he sold the painkiller oxycodone. He said he has reached a plea agreement with prosecutors and is scheduled to plead guilty Feb. 14. His attorney said final details of the agreement are being worked out. Giordano was a state representative from 2000 to 2002 and was chairman of the Salem Zoning Board of Adjustment at the time of his arrest on felony drug charges in December 2011. Police said they found more than 100 oxycodone pills while searching Giordano’s home.