lc-switch.h 2.73 KB
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/*
 * Copyright (c) 2004-2005, Swedish Institute of Computer Science.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the Institute nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * This file is part of the uIP TCP/IP stack
 *
 * Author: Adam Dunkels <adam@sics.se>
 *
 * $Id: lc-switch.h,v 1.2 2006/06/12 08:00:30 adam Exp $
 */

/**
 * \addtogroup lc
 * @{
 */

/**
 * \file
 * Implementation of local continuations based on switch() statment
 * \author Adam Dunkels <adam@sics.se>
 *
 * This implementation of local continuations uses the C switch()
 * statement to resume execution of a function somewhere inside the
 * function's body. The implementation is based on the fact that
 * switch() statements are able to jump directly into the bodies of
 * control structures such as if() or while() statmenets.
 *
 * This implementation borrows heavily from Simon Tatham's coroutines
 * implementation in C:
 * http://www.chiark.greenend.org.uk/~sgtatham/coroutines.html
 */

#ifndef __LC_SWITCH_H__
#define __LC_SWTICH_H__

/* WARNING! lc implementation using switch() does not work if an
   LC_SET() is done within another switch() statement! */

/** \hideinitializer */
typedef unsigned short lc_t;

#define LC_INIT(s) s = 0;

#define LC_RESUME(s) switch(s) { case 0:

#define LC_SET(s) s = __LINE__; case __LINE__:

#define LC_END(s) }

#endif /* __LC_SWITCH_H__ */

/** @} */