/* * align.{cc,hh} -- element aligns passing packets * Eddie Kohler * * Copyright (c) 1999-2000 Massachusetts Institute of Technology * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the "Software"), * to deal in the Software without restriction, subject to the conditions * listed in the Click LICENSE file. These conditions include: you must * preserve this copyright notice, and you cannot mention the copyright * holders in advertising related to the Software without their permission. * The Software is provided WITHOUT ANY WARRANTY, EXPRESS OR IMPLIED. This * notice is a summary of the Click LICENSE file; the license in that file is * legally binding. */ #include #include "align.hh" #include #include #include CLICK_DECLS Align::Align() { } Align::~Align() { } int Align::configure(Vector &conf, ErrorHandler *errh) { unsigned modulus; if (cp_va_kparse(conf, this, errh, "MODULUS", cpkP+cpkM, cpUnsigned, &modulus, "OFFSET", cpkP+cpkM, cpUnsigned, &_offset, cpEnd) < 0) return -1; if (modulus != 2 && modulus != 4 && modulus != 8) return errh->error("align modulus must be 2, 4, or 8"); if (_offset >= (int)modulus) return errh->error("align offset must be smaller than modulus"); _mask = modulus - 1; return 0; } Packet * Align::smaction(Packet *p) { int delta = _offset - (reinterpret_cast(p->data()) & _mask); if (delta == 0) return p; if (delta < 0) delta += _mask + 1; return p->shift_data(delta); } void Align::push(int, Packet *p) { output(0).push(smaction(p)); } Packet * Align::pull(int) { Packet *p = input(0).pull(); return (p ? smaction(p) : 0); } CLICK_ENDDECLS EXPORT_ELEMENT(Align) ELEMENT_MT_SAFE(Align)
