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lc-addrlabels.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-addrlabels.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 the "Labels as
00044  * values" feature of gcc
00045  * \author
00046  * Adam Dunkels <adam@sics.se>
00047  *
00048  * This implementation of local continuations is based on a special
00049  * feature of the GCC C compiler called "labels as values". This
00050  * feature allows assigning pointers with the address of the code
00051  * corresponding to a particular C label.
00052  *
00053  * For more information, see the GCC documentation:
00054  *
00055  * http://gcc.gnu.org/onlinedocs/gcc/Labels-as-Values.html
00056  *
00057  */
00058 
00059 #ifndef __LC_ADDRLABELS_H__
00060 #define __LC_ADDRLABELS_H__
00061 
00062 /** \hideinitializer */
00063 typedef void * lc_t;
00064 
00065 #define LC_CONCAT2(s1, s2) s1##s2
00066 #define LC_CONCAT(s1, s2) LC_CONCAT2(s1, s2)
00067 
00068 #define LC_SET(s)                               \
00069   do {                                          \
00070     LC_CONCAT(LC_LABEL, __LINE__):              \
00071     (s) = &&LC_CONCAT(LC_LABEL, __LINE__);      \
00072   } while(0)
00073 
00074 #define LC_RESUME(s)                            \
00075   do {                                          \
00076     if(s != NULL) {                             \
00077       goto *s;                                  \
00078     }                                           \
00079   } while(0)
00080 
00081 #define LC_END(s)
00082 
00083 #define LC_INIT(s) s = NULL
00084 
00085 #endif /* __LC_ADDRLABELS_H__ */

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