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lc-addrlabels.h
1 /*
2  * Copyright (c) 2004-2005, Swedish Institute of Computer Science.
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  * notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  * notice, this list of conditions and the following disclaimer in the
12  * documentation and/or other materials provided with the distribution.
13  * 3. Neither the name of the Institute nor the names of its contributors
14  * may be used to endorse or promote products derived from this software
15  * without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  *
29  * This file is part of the Contiki operating system.
30  *
31  * Author: Adam Dunkels <adam@sics.se>
32  *
33  * $Id: lc-addrlabels.h,v 1.4 2006/06/03 11:29:43 adam Exp $
34  */
35 
36 /*
37  * \file
38  * Implementation of local continuations based on the "Labels as
39  * values" feature of gcc
40  * \author
41  * Adam Dunkels <adam@sics.se>
42  *
43  * This implementation of local continuations is based on a special
44  * feature of the GCC C compiler called "labels as values". This
45  * feature allows assigning pointers with the address of the code
46  * corresponding to a particular C label.
47  *
48  * For more information, see the GCC documentation:
49  * http://gcc.gnu.org/onlinedocs/gcc/Labels-as-Values.html
50  *
51  */
52 
53 #ifndef __LC_ADDRLABELS_H__
54 #define __LC_ADDRLABELS_H__
55 
56 /** \hideinitializer */
57 typedef void * lc_t;
58 
59 #define LC_INIT(s) s = NULL
60 
61 #define LC_IS_INITED(s) (s==NULL)
62 
63 #define LC_RESUME(s) \
64  do { \
65  if(s != NULL) { \
66  goto *s; \
67  } \
68  } while(0)
69 
70 #define LC_CONCAT2(s1, s2) s1##s2
71 #define LC_CONCAT(s1, s2) LC_CONCAT2(s1, s2)
72 
73 #define LC_SET(s) \
74  do { \
75  LC_CONCAT(LC_LABEL, __LINE__): \
76  (s) = &&LC_CONCAT(LC_LABEL, __LINE__); \
77  } while(0)
78 
79 #define LC_END(s)
80 
81 #endif /* __LC_ADDRLABELS_H__ */
82 /** @} */