FreeRTOS/Common/ethernet/FreeTCPIP/net/lc-switch.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 uIP TCP/IP stack
  30  *
  31  * Author: Adam Dunkels <adam@sics.se>
  32  *
  33  * $Id: lc-switch.h,v 1.2 2006/06/12 08:00:30 adam Exp $
  34  */
  35
  36 /**
  37  * \addtogroup lc
  38  * @{
  39  */
  40
  41 /**
  42  * \file
  43  * Implementation of local continuations based on switch() statment
  44  * \author Adam Dunkels <adam@sics.se>
  45  *
  46  * This implementation of local continuations uses the C switch()
  47  * statement to resume execution of a function somewhere inside the
  48  * function's body. The implementation is based on the fact that
  49  * switch() statements are able to jump directly into the bodies of
  50  * control structures such as if() or while() statmenets.
  51  *
  52  * This implementation borrows heavily from Simon Tatham's coroutines
  53  * implementation in C:
  54  * http://www.chiark.greenend.org.uk/~sgtatham/coroutines.html
  55  */
  56
  57 #ifndef __LC_SWITCH_H__
  58 #define __LC_SWTICH_H__
  59
  60 /* WARNING! lc implementation using switch() does not work if an
  61    LC_SET() is done within another switch() statement! */
  62
  63 /** \hideinitializer */
  64 typedef unsigned short lc_t;
  65
  66 #define LC_INIT(s) s = 0;
  67
  68 #define LC_RESUME(s) switch(s) { case 0:
  69
  70 #define LC_SET(s) s = __LINE__; case __LINE__:
  71
  72 #define LC_END(s) }
  73
  74 #endif /* __LC_SWITCH_H__ */
  75
  76 /** @} */