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contiki/core/dev/slip.c

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/* -*- C -*- */
/*
* Copyright (c) 2005, Swedish Institute of Computer Science
* 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. Neither the name of the Institute nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``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 INSTITUTE OR CONTRIBUTORS 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 operating system.
*
* @(#)$Id: slip.c,v 1.4 2007/02/01 14:04:06 bg- Exp $
*/
#include <stdio.h>
#include <string.h>
#include "contiki.h"
#include "net/uip.h"
#include "net/uip-fw.h"
#define BUF ((struct uip_tcpip_hdr *)&uip_buf[UIP_LLH_LEN])
#include "dev/slip.h"
#define SLIP_END 0300
#define SLIP_ESC 0333
#define SLIP_ESC_END 0334
#define SLIP_ESC_ESC 0335
PROCESS(slip_process, "SLIP driver");
u8_t slip_active;
#if 1
#define SLIP_STATISTICS(statement)
#else
u16_t slip_rubbish, slip_twopackets, slip_overflow, slip_ip_drop;
#define SLIP_STATISTICS(statement) statement
#endif
/* Must be at least one byte larger than UIP_BUFSIZE! */
#define RX_BUFSIZE (UIP_BUFSIZE - UIP_LLH_LEN + 16)
enum {
STATE_TWOPACKETS = 0, /* We have 2 packets and drop incoming data. */
STATE_OK = 1,
STATE_ESC = 2,
STATE_RUBBISH = 3,
};
/*
* Variables begin and end manage the buffer space in a cyclic
* fashion. The first used byte is at begin and end is one byte past
* the last. I.e. [begin, end) is the actively used space.
*
* If begin != pkt_end we have a packet at [begin, pkt_end),
* furthermore, if state == STATE_TWOPACKETS we have one more packet at
* [pkt_end, end). If more bytes arrive in state STATE_TWOPACKETS
* they are discarded.
*/
static u8_t state = STATE_TWOPACKETS;
static u16_t begin, end;
static u8_t rxbuf[RX_BUFSIZE];
static u16_t pkt_end; /* SLIP_END tracker. */
/*---------------------------------------------------------------------------*/
u8_t
slip_send(void)
{
u16_t i;
u8_t *ptr;
u8_t c;
slip_arch_writeb(SLIP_END);
ptr = &uip_buf[UIP_LLH_LEN];
for(i = 0; i < uip_len; ++i) {
if(i == UIP_TCPIP_HLEN) {
ptr = (u8_t *)uip_appdata;
}
c = *ptr++;
if(c == SLIP_END) {
slip_arch_writeb(SLIP_ESC);
c = SLIP_ESC_END;
} else if(c == SLIP_ESC) {
slip_arch_writeb(SLIP_ESC);
c = SLIP_ESC_ESC;
}
slip_arch_writeb(c);
}
slip_arch_writeb(SLIP_END);
return UIP_FW_OK;
}
u8_t
slip_write(const void *_ptr, int len)
{
const u8_t *ptr = _ptr;
u16_t i;
u8_t c;
slip_arch_writeb(SLIP_END);
for(i = 0; i < len; ++i) {
c = *ptr++;
if(c == SLIP_END) {
slip_arch_writeb(SLIP_ESC);
c = SLIP_ESC_END;
} else if(c == SLIP_ESC) {
slip_arch_writeb(SLIP_ESC);
c = SLIP_ESC_ESC;
}
slip_arch_writeb(c);
}
slip_arch_writeb(SLIP_END);
return len;
}
/*---------------------------------------------------------------------------*/
static void
rxbuf_init(void)
{
begin = end = pkt_end = 0;
state = STATE_OK;
}
/*---------------------------------------------------------------------------*/
/* Upper half does the polling. */
static u16_t
slip_poll_handler(u8_t *outbuf, u16_t blen)
{
/* This is a hack and won't work across buffer edge! */
if(rxbuf[begin] == 'C') {
int i;
if(begin < end && (end - begin) >= 6
&& memcmp(&rxbuf[begin], "CLIENT", 6) == 0) {
state = STATE_TWOPACKETS; /* Interrupts do nothing. */
memset(&rxbuf[begin], 0x0, 6);
rxbuf_init();
for(i = 0; i < 13; i++) {
slip_arch_writeb("CLIENTSERVER\300"[i]);
}
return 0;
}
}
/*
* Interrupt can not change begin but may change pkt_end.
* If pkt_end != begin it will not change again.
*/
if(begin != pkt_end) {
u16_t len;
if(begin < pkt_end) {
len = pkt_end - begin;
if(len > blen) {
len = 0;
} else {
memcpy(outbuf, &rxbuf[begin], len);
}
} else {
len = (RX_BUFSIZE - begin) + (pkt_end - 0);
if(len > blen) {
len = 0;
} else {
unsigned i;
for(i = begin; i < RX_BUFSIZE; i++)
*outbuf++ = rxbuf[i];
for(i = 0; i < pkt_end; i++)
*outbuf++ = rxbuf[i];
}
}
/* Remove data from buffer together with the copied packet. */
begin = pkt_end;
if(state == STATE_TWOPACKETS) {
pkt_end = end;
state = STATE_OK; /* Assume no bytes where lost! */
/* One more packet is buffered, need to be polled again! */
process_poll(&slip_process);
}
return len;
}
return 0;
}
/*---------------------------------------------------------------------------*/
PROCESS_THREAD(slip_process, ev, data)
{
PROCESS_BEGIN();
rxbuf_init();
while(1) {
PROCESS_YIELD();
slip_active = 1;
/* Move packet from rxbuf to buffer provided by uIP. */
uip_len = slip_poll_handler(&uip_buf[UIP_LLH_LEN],
UIP_BUFSIZE - UIP_LLH_LEN);
if(uip_len == 4 && strncmp(&uip_buf[UIP_LLH_LEN], "?IPA", 4) == 0) {
char buf[8];
memcpy(&buf[0], "=IPA", 4);
memcpy(&buf[4], &uip_hostaddr, 4);
slip_write(buf, 8);
} else if(uip_len > 0
&& uip_len == (((u16_t)(BUF->len[0]) << 8) + BUF->len[1])
&& uip_ipchksum() == 0xffff) {
#define IP_DF 0x40
if(BUF->ipid[0] == 0 && BUF->ipid[1] == 0 && BUF->ipoffset[0] & IP_DF) {
static u16_t ip_id;
u16_t nid = ip_id++;
BUF->ipid[0] = nid >> 8;
BUF->ipid[1] = nid;
nid = htons(nid);
nid = ~nid; /* negate */
BUF->ipchksum += nid; /* add */
if (BUF->ipchksum < nid) /* 1-complement overflow? */
BUF->ipchksum++;
}
tcpip_input();
} else {
uip_len = 0;
SLIP_STATISTICS(slip_ip_drop++);
}
}
PROCESS_END();
}
/*---------------------------------------------------------------------------*/
int
slip_input_byte(unsigned char c)
{
switch(state) {
case STATE_RUBBISH:
if(c == SLIP_END) {
state = STATE_OK;
}
return 0;
case STATE_TWOPACKETS: /* Two packets are already buffered! */
return 0;
case STATE_ESC:
if(c == SLIP_ESC_END) {
c = SLIP_END;
} else if(c == SLIP_ESC_ESC) {
c = SLIP_ESC;
} else {
state = STATE_RUBBISH;
SLIP_STATISTICS(slip_rubbish++);
end = pkt_end; /* remove rubbish */
return 0;
}
state = STATE_OK;
break;
case STATE_OK:
if(c == SLIP_ESC) {
state = STATE_ESC;
return 0;
} else if(c == SLIP_END) {
/*
* We have a new packet, possibly of zero length.
*
* There may already be one packet buffered.
*/
if(end != pkt_end) { /* Non zero length. */
if(begin == pkt_end) { /* None buffered. */
pkt_end = end;
} else {
state = STATE_TWOPACKETS;
SLIP_STATISTICS(slip_twopackets++);
}
process_poll(&slip_process);
return 1;
}
return 0;
}
break;
}
/* add_char: */
{
unsigned next;
next = end + 1;
if(next == RX_BUFSIZE) {
next = 0;
}
if(next == begin) { /* rxbuf is full */
state = STATE_RUBBISH;
SLIP_STATISTICS(slip_overflow++);
end = pkt_end; /* remove rubbish */
return 0;
}
rxbuf[end] = c;
end = next;
}
/* There could be a separate poll routine for this. */
if(c == 'T' && rxbuf[begin] == 'C') {
process_poll(&slip_process);
return 1;
}
return 0;
}
/*---------------------------------------------------------------------------*/
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