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lc-switch.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 switch() statement
43 * \author Adam Dunkels <adam@sics.se>
44 *
45 * This implementation of local continuations uses the C switch()
46 * statement to resume execution of a function somewhere inside the
47 * function's body. The implementation is based on the fact that
48 * switch() statements are able to jump directly into the bodies of
49 * control structures such as if() or while() statements.
50 *
51 * This implementation borrows heavily from Simon Tatham's coroutines
52 * implementation in C:
53 * http://www.chiark.greenend.org.uk/~sgtatham/coroutines.html
54 */
55
56#ifndef LC_SWITCH_H_
57#define LC_SWITCH_H_
58
59/* WARNING! lc implementation using switch() does not work if an
60 LC_SET() is done within another switch() statement! */
61
62/** \hideinitializer */
63typedef unsigned short lc_t;
64
65#define LC_INIT(s) s = 0;
66
67#define LC_RESUME(s) switch(s) { case 0:
68
69#define LC_SET(s) s = __LINE__; case __LINE__:
70
71#define LC_END(s) }
72
73#endif /* LC_SWITCH_H_ */
74
75/** @} */
void * lc_t
The local continuation type.