/**
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* \addtogroup uip
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* @{
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*/
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/**
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* \defgroup slip Serial Line IP (SLIP) protocol
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* @{
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*
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* The SLIP protocol is a very simple way to transmit IP packets over
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* a serial line. It does not provide any framing or error control,
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* and is therefore not very widely used today.
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*
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* This SLIP implementation requires two functions for accessing the
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* serial device: slipdev_char_poll() and slipdev_char_put(). These
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* must be implemented specifically for the system on which the SLIP
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* protocol is to be run.
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*/
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/**
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* \file
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* SLIP protocol implementation
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* \author Adam Dunkels <adam@dunkels.com>
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*/
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/*
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* Copyright (c) 2001, Adam Dunkels.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote
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* products derived from this software without specific prior
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* written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
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* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
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* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* This file is part of the uIP TCP/IP stack.
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*
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*
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*/
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/*
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* This is a generic implementation of the SLIP protocol over an RS232
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* (serial) device.
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*
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* Huge thanks to Ullrich von Bassewitz <uz@cc65.org> of cc65 fame for
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* and endless supply of bugfixes, insightsful comments and
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* suggestions, and improvements to this code!
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*/
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#include "uip.h"
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#include "uip-fw.h"
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#include "slipdev.h"
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#include <string.h> /* For memcpy() */
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#define SLIP_END 0300
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#define SLIP_ESC 0333
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#define SLIP_ESC_END 0334
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#define SLIP_ESC_ESC 0335
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static uint8_t slip_buf[UIP_BUFSIZE];
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static uint16_t len, tmplen;
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static uint8_t lastc;
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/*-----------------------------------------------------------------------------------*/
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/**
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* Send the packet in the uip_buf and uip_appdata buffers using the
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* SLIP protocol.
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*
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* The first 40 bytes of the packet (the IP and TCP headers) are read
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* from the uip_buf buffer, and the following bytes (the application
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* data) are read from the uip_appdata buffer.
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*
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* \return This function will always return UIP_FW_OK.
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*/
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/*-----------------------------------------------------------------------------------*/
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uint8_t
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slipdev_send(void)
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{
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uint16_t i;
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uint8_t *ptr;
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uint8_t c;
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slipdev_char_put(SLIP_END);
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ptr = &uip_buf[UIP_LLH_LEN];
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for(i = 0; i < uip_len; ++i) {
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if(i == UIP_TCPIP_HLEN) {
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ptr = (char *)uip_appdata;
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}
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c = *ptr++;
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switch(c) {
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case SLIP_END:
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slipdev_char_put(SLIP_ESC);
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slipdev_char_put(SLIP_ESC_END);
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break;
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case SLIP_ESC:
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slipdev_char_put(SLIP_ESC);
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slipdev_char_put(SLIP_ESC_ESC);
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break;
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default:
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slipdev_char_put(c);
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break;
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}
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}
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slipdev_char_put(SLIP_END);
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return UIP_FW_OK;
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}
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/*-----------------------------------------------------------------------------------*/
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/**
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* Poll the SLIP device for an available packet.
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*
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* This function will poll the SLIP device to see if a packet is
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* available. It uses a buffer in which all avaliable bytes from the
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* RS232 interface are read into. When a full packet has been read
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* into the buffer, the packet is copied into the uip_buf buffer and
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* the length of the packet is returned.
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*
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* \return The length of the packet placed in the uip_buf buffer, or
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* zero if no packet is available.
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*/
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/*-----------------------------------------------------------------------------------*/
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uint16_t
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slipdev_poll(void)
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{
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uint8_t c;
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while(slipdev_char_poll(&c)) {
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switch(c) {
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case SLIP_ESC:
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lastc = c;
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break;
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case SLIP_END:
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lastc = c;
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/* End marker found, we copy our input buffer to the uip_buf
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buffer and return the size of the packet we copied. */
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memcpy(&uip_buf[UIP_LLH_LEN], slip_buf, len);
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tmplen = len;
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len = 0;
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return tmplen;
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default:
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if(lastc == SLIP_ESC) {
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lastc = c;
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/* Previous read byte was an escape byte, so this byte will be
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interpreted differently from others. */
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switch(c) {
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case SLIP_ESC_END:
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c = SLIP_END;
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break;
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case SLIP_ESC_ESC:
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c = SLIP_ESC;
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break;
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}
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} else {
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lastc = c;
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}
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slip_buf[len] = c;
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++len;
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if(len > UIP_BUFSIZE) {
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len = 0;
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}
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break;
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}
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}
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return 0;
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}
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/*-----------------------------------------------------------------------------------*/
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/**
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* Initialize the SLIP module.
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*
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* This function does not initialize the underlying RS232 device, but
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* only the SLIP part.
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*/
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/*-----------------------------------------------------------------------------------*/
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void
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slipdev_init(void)
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{
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lastc = len = 0;
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}
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/*-----------------------------------------------------------------------------------*/
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/** @} */
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/** @} */
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