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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 protothreads library.
00030  * 
00031  * Author: Adam Dunkels <adam@sics.se>
00032  *
00033  * $Id: lc-switch.h,v 1.2 2005/02/24 10:36:59 adam Exp $
00034  */
00035 
00036 /**
00037  * \addtogroup lc
00038  * @{
00039  */
00040 
00041 /**
00042  * \file
00043  * Implementation of local continuations based on switch() statment
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() statmenets.
00051  *
00052  * This implementation borrows heavily from Simon Tatham's coroutines
00053  * implementation in C:
00054  *
00055  * http://www.chiark.greenend.org.uk/~sgtatham/coroutines.html
00056  */
00057 
00058 #ifndef __LC_SWITCH_H__
00059 #define __LC_SWTICH_H__
00060 
00061 /* WARNING! lc implementation using switch() does not work if an
00062    LC_SET() is done within another switch() statement! */
00063 
00064 /** \hideinitializer */
00065 typedef unsigned short lc_t;
00066 
00067 #define LC_SET(s) case __LINE__: s = __LINE__
00068 
00069 #define LC_RESUME(s) switch(s) { case 0:
00070 
00071 #define LC_END(s) }
00072 
00073 #define LC_INIT(s) s = 0;
00074 
00075 #endif /* __LC_SWITCH_H__ */
00076 
00077 /** @} */

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