Contiki-NG
lc-addrlabels.h
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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  */
34 
35 /**
36  * \addtogroup lc
37  * @{
38  */
39 
40 /**
41  * \file
42  * Implementation of local continuations based on the "Labels as
43  * values" feature of gcc
44  * \author
45  * Adam Dunkels <adam@sics.se>
46  *
47  * This implementation of local continuations is based on a special
48  * feature of the GCC C compiler called "labels as values". This
49  * feature allows assigning pointers with the address of the code
50  * corresponding to a particular C label.
51  *
52  * For more information, see the GCC documentation:
53  * http://gcc.gnu.org/onlinedocs/gcc/Labels-as-Values.html
54  *
55  * Thanks to dividuum for finding the nice local scope label
56  * implementation.
57  */
58 
59 #ifndef LC_ADDRLABELS_H_
60 #define LC_ADDRLABELS_H_
61 
62 /** \hideinitializer */
63 typedef void * lc_t;
64 
65 #define LC_INIT(s) s = NULL
66 
67 
68 #define LC_RESUME(s) \
69  do { \
70  if(s != NULL) { \
71  goto *s; \
72  } \
73  } while(0)
74 
75 #define LC_SET(s) \
76  do { \
77  __label__ resume; \
78  resume: \
79  (s) = &&resume; \
80  } while(0)
81 
82 #define LC_END(s)
83 
84 #endif /* LC_ADDRLABELS_H_ */
85 /** @} */
void * lc_t
The local continuation type.
Definition: lc-addrlabels.h:63