Besides calling _get_next_addr, we will check if data locates at that address seems to be code or not. If not, 
        we'll move on to request for next valid address.

def _get_next_code_addr(self, initial_state):
        """
        Besides calling _get_next_addr, we will check if data locates at that address seems to be code or not. If not, 
        we'll move on to request for next valid address.
        """
        next_addr = self._get_next_addr_to_search()
        if next_addr is None:
            return None

        start_addr = next_addr
        sz = ""
        is_sz = True
        while is_sz:
            # Get data until we meet a 0
            while next_addr in initial_state.memory:
                try:
                    l.debug("Searching address %x", next_addr)
                    val = initial_state.mem_concrete(next_addr, 1)
                    if val == 0:
                        if len(sz) < 4:
                            is_sz = False
                        else:
                            reach_end = True
                        break
                    if chr(val) not in string.printable:
                        is_sz = False
                        break
                    sz += chr(val)
                    next_addr += 1
                except SimValueError:
                    # Not concretizable
                    l.debug("Address 0x%08x is not concretizable!", next_addr)
                    break

            if len(sz) > 0 and is_sz:
                l.debug("Got a string of %d chars: [%s]", len(sz), sz)
                # l.debug("Occpuy %x - %x", start_addr, start_addr + len(sz) + 1)
                self._seg_list.occupy(start_addr, len(sz) + 1)
                sz = ""
                next_addr = self._get_next_addr_to_search()
                if next_addr is None:
                    return None
                # l.debug("next addr = %x", next_addr)
                start_addr = next_addr

            if is_sz:
                next_addr += 1

        instr_alignment = initial_state.arch.instruction_alignment
        if start_addr % instr_alignment > 0:
            start_addr = start_addr - start_addr % instr_alignment + \
                instr_alignment

        l.debug('_get_next_code_addr() returns 0x%x', start_addr)
        return start_addr