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# uip/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 uIP TCP/IP stack
    00030  *
    00031  * Author: Adam Dunkels <adam@sics.se>
    00032  *
    00033  * $Id: lc-switch.h,v 1.2 2006/06/12 08:00:30 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  * http://www.chiark.greenend.org.uk/~sgtatham/coroutines.html
    00055  */
    00056
    00057 #ifndef __LC_SWITCH_H__
    00058 #define __LC_SWTICH_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 /** @} */