contiki/core/sys/arg.c

134 lines
4.2 KiB
C

/**
* \file
* Argument buffer for passing arguments when starting processes
* \author Adam Dunkels <adam@dunkels.com>
*/
/**
* \addtogroup sys
* @{
*/
/**
* \defgroup arg Argument buffer
* @{
*
* The argument buffer can be used when passing an argument from an
* exiting process to a process that has not been created yet. Since
* the exiting process will have exited when the new process is
* started, the argument cannot be passed in any of the processes'
* addres spaces. In such situations, the argument buffer can be used.
*
* The argument buffer is statically allocated in memory and is
* globally accessible to all processes.
*
* An argument buffer is allocated with the arg_alloc() function and
* deallocated with the arg_free() function. The arg_free() function
* is designed so that it can take any pointer, not just an argument
* buffer pointer. If the pointer to arg_free() is not an argument
* buffer, the function does nothing.
*/
/*
* Copyright (c) 2003, Adam Dunkels.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided
* with the distribution.
* 3. The name of the author may not be used to endorse or promote
* products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* This file is part of the Contiki desktop OS
*
* $Id: arg.c,v 1.1 2006/06/17 22:41:19 adamdunkels Exp $
*
*/
#include "sys/arg.h"
/**
* \internal Structure used for holding an argument buffer.
*/
struct argbuf {
char buf[128];
char used;
};
static struct argbuf bufs[1];
/*-----------------------------------------------------------------------------------*/
/**
* \internal Initalizer, called by the dispatcher module.
*/
/*-----------------------------------------------------------------------------------*/
void
arg_init(void)
{
bufs[0].used = 0;
}
/*-----------------------------------------------------------------------------------*/
/**
* Allocates an argument buffer.
*
* \param size The requested size of the buffer, in bytes.
*
* \return Pointer to allocated buffer, or NULL if no buffer could be
* allocated.
*
* \note It currently is not possible to allocate argument buffers of
* any other size than 128 bytes.
*
*/
/*-----------------------------------------------------------------------------------*/
char *
arg_alloc(char size)
{
if(bufs[0].used == 0) {
bufs[0].used = 1;
return bufs[0].buf;
}
return 0;
}
/*-----------------------------------------------------------------------------------*/
/**
* Deallocates an argument buffer.
*
* This function deallocates the argument buffer pointed to by the
* parameter, but only if the buffer actually is an argument buffer
* and is allocated. It is perfectly safe to call this function with
* any pointer.
*
* \param arg A pointer.
*/
/*-----------------------------------------------------------------------------------*/
void
arg_free(char *arg)
{
if(arg == bufs[0].buf) {
bufs[0].used = 0;
}
}
/*-----------------------------------------------------------------------------------*/
/** @} */
/** @} */