lc-addrlabels.h

Protothreads are extremely lightweight stackless threads designed for severely memory constrained s

/*
 * 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 protothreads library.
 * 
 * Author: Adam Dunkels <[e-mail]>
 *
 * $Id: lc-addrlabels.h,v 1.2 2005/02/24 10:36:59 adam Exp $
 */

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

/**
 * \file
 * Implementation of local continuations based on the "Labels as
 * values" feature of gcc
 * \author
 * Adam Dunkels <[e-mail]>
 *
 * This implementation of local continuations is based on a special
 * feature of the GCC C compiler called "labels as values". This
 * feature allows assigning pointers with the address of the code
 * corresponding to a particular C label.
 *
 * For more information, see the GCC documentation:
 *
 * http://gcc.gnu.org/onlinedocs/gcc/Labels-as-Values.html
 *
 */

#ifndef __LC_ADDRLABELS_H__
#define __LC_ADDRLABELS_H__

/** \hideinitializer */
typedef void * lc_t;

#define LC_CONCAT2(s1, s2) s1##s2
#define LC_CONCAT(s1, s2) LC_CONCAT2(s1, s2)

#define LC_SET(s)				\
  do {						\
    LC_CONCAT(LC_LABEL, __LINE__):   	        \
    (s) = &&LC_CONCAT(LC_LABEL, __LINE__);	\
  } while(0)

#define LC_RESUME(s)				\
  do {						\
    if(s != NULL) {				\
      goto *s;					\
    }						\
  } while(0)

#define LC_END(s)

#define LC_INIT(s) s = NULL

#endif /* __LC_ADDRLABELS_H__ */