lc-switch.h

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00001 /*
00002  * Copyright (c) 2004-2005, Swedish Institute of Computer Science.
00003  * All rights reserved.
00004  *
00005  * Redistribution and use in source and binary forms, with or without
00006  * modification, are permitted provided that the following conditions
00007  * are met:
00008  * 1. Redistributions of source code must retain the above copyright
00009  *    notice, this list of conditions and the following disclaimer.
00010  * 2. Redistributions in binary form must reproduce the above copyright
00011  *    notice, this list of conditions and the following disclaimer in the
00012  *    documentation and/or other materials provided with the distribution.
00013  * 3. Neither the name of the Institute nor the names of its contributors
00014  *    may be used to endorse or promote products derived from this software
00015  *    without specific prior written permission.
00016  *
00017  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
00018  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
00019  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
00020  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
00021  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
00022  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
00023  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
00024  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
00025  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
00026  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
00027  * SUCH DAMAGE.
00028  *
00029  * This file is part of the Contiki operating system.
00030  *
00031  * Author: Adam Dunkels <adam@sics.se>
00032  *
00033  * $Id: lc-switch.h,v 1.3 2008/10/14 12:46:39 nvt-se Exp $
00034  */
00035 
00036 /**
00037  * \addtogroup lc
00038  * @{
00039  */
00040 
00041 /**
00042  * \file
00043  * Implementation of local continuations based on switch() statement
00044  * \author Adam Dunkels <adam@sics.se>
00045  *
00046  * This implementation of local continuations uses the C switch()
00047  * statement to resume execution of a function somewhere inside the
00048  * function's body. The implementation is based on the fact that
00049  * switch() statements are able to jump directly into the bodies of
00050  * control structures such as if() or while() statements.
00051  *
00052  * This implementation borrows heavily from Simon Tatham's coroutines
00053  * implementation in C:
00054  * http://www.chiark.greenend.org.uk/~sgtatham/coroutines.html
00055  */
00056 
00057 #ifndef __LC_SWITCH_H__
00058 #define __LC_SWITCH_H__
00059 
00060 /* WARNING! lc implementation using switch() does not work if an
00061    LC_SET() is done within another switch() statement! */
00062 
00063 /** \hideinitializer */
00064 typedef unsigned short lc_t;
00065 
00066 #define LC_INIT(s) s = 0;
00067 
00068 #define LC_RESUME(s) switch(s) { case 0:
00069 
00070 #define LC_SET(s) s = __LINE__; case __LINE__:
00071 
00072 #define LC_END(s) }
00073 
00074 #endif /* __LC_SWITCH_H__ */
00075 
00076 /** @} */

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