Arithmetic shift accumulator right

def instruction_ASR_register(self, opcode, register):
        """ Arithmetic shift accumulator right """
        a = register.value
        r = self.ASR(a)
#        log.debug("$%x ASR %s value $%x >> 1 | Carry = $%x" % (
#            self.program_counter,
#            register.name, a, r
#        ))
        register.set(r)