def parse_int(self, buff, start, end):
        '''
            parse an integer from the buffer given the interval of bytes
        :param buff:
        :param start:
        :param end:
        '''
#         num = self.parse_uint(buff, start, end)
#         l = (end - start)
#         return self.twos_comp(num, l * 8)
        return struct.unpack_from(self.structmap[end - start], buff, start)[0]