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contiki/core/net/ppp/ahdlc.c

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/* www.mycal.com
*---------------------------------------------------------------------------
* ahdlc.c - Ahdlc receive and transmit processor for PPP engine.
*
*---------------------------------------------------------------------------
* Version
* 0.1 Original Version Jan 11, 1998
*
*---------------------------------------------------------------------------
*
* Copyright (C) 1998, Mycal Labs www.mycal.com
*
*---------------------------------------------------------------------------
*/
/*
* Copyright (c) 2003, Mike Johnson, Mycal Labs, www.mycal.net
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by Mike Johnson/Mycal Labs
* www.mycal.net.
* 4. 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 Mycal Modified uIP TCP/IP stack.
*
* $Id: ahdlc.c,v 1.1 2006/06/17 22:48:09 adamdunkels Exp $
*
*/
/* */
/* include files */
/* */
#include "net/uip.h"
#include "ppp.h"
#if 0
#define DEBUG1(x)
#else
#include <stdio.h>
#define DEBUG1(x) debug_printf x
#endif
#define PACKET_TX_DEBUG 1
/*---------------------------------------------------------------------------
* ahdlc flags bit defins, for ahdlc_flags variable
---------------------------------------------------------------------------*/
/* Escaped mode bit */
#define AHDLC_ESCAPED 0x1
/* Frame is ready bit */
#define AHDLC_RX_READY 0x2
#define AHDLC_RX_ASYNC_MAP 0x4
#define AHDLC_TX_ASYNC_MAP 0x8
#define AHDLC_PFC 0x10
#define AHDLC_ACFC 0x20
/*---------------------------------------------------------------------------
* Private Local Globals
* 10 bytes - standard
* - with counters
---------------------------------------------------------------------------*/
/* running tx CRC */
u16_t ahdlc_tx_crc;
/* running rx CRC */
u16_t ahdlc_rx_crc;
/* number of rx bytes processed, cur frame */
u16_t ahdlc_rx_count;
/* ahdlc state flags, see above */
u8_t ahdlc_flags;
u8_t ahdlc_tx_offline;
/*
* The following can be optimized out
*/
u8_t *ahdlc_rx_buffer; /* What to do here? +++ */
u16_t ahdlc_max_rx_buffer_size;
/*
* Optional statistics counters.
*/
#ifdef AHDLC_COUNTERS
u8_t ahdlc_rx_tobig_error;
#endif
/*---------------------------------------------------------------------------*/
/* Simple and fast CRC16 routine for embedded processors.
* Just slightly slower than the table lookup method but consumes
* almost no space. Much faster and smaller than the loop and
* shift method that is widely used in the embedded space.
* Can be optimized even more in .ASM
*
* data = (crcvalue ^ inputchar) & 0xff;
* data = (data ^ (data << 4)) & 0xff;
* crc = (crc >> 8) ^ ((data << 8) ^ (data <<3) ^ (data >> 4))
*/
/*---------------------------------------------------------------------------*/
static u16_t
crcadd(u16_t crcvalue, u8_t c)
{
u16_t b;
b = (crcvalue ^ c) & 0xFF;
b = (b ^ (b << 4)) & 0xFF;
b = (b << 8) ^ (b << 3) ^ (b >> 4);
return ((crcvalue >> 8) ^ b);
}
/*---------------------------------------------------------------------------*/
/* ahdlc_init(buffer, buffersize) - this initializes the ahdlc engine to
* allow for rx frames.
*/
/*---------------------------------------------------------------------------*/
void
ahdlc_init(u8_t *buffer, u16_t maxrxbuffersize)
{
ahdlc_flags = 0 | AHDLC_RX_ASYNC_MAP;
ahdlc_rx_buffer = buffer;
ahdlc_max_rx_buffer_size = maxrxbuffersize;
/* ahdlc_async_map = 0; */
#ifdef AHDLC_COUNTERS
ahdlc_rx_tobig_error = 0;
ahdl_tx_offline = 0;
#endif
}
/*---------------------------------------------------------------------------*/
/* ahdlc_rx_ready() - resets the ahdlc engine to the beginning of frame
* state.
*/
/*---------------------------------------------------------------------------*/
void
ahdlc_rx_ready(void)
{
ahdlc_rx_count = 0;
ahdlc_rx_crc = 0xffff;
ahdlc_flags |= AHDLC_RX_READY;
}
/*---------------------------------------------------------------------------*/
/* ahdlc receive function - This routine processes incoming bytes and tries
* to build a PPP frame.
*
* Two possible reasons that ahdlc_rx will not process characters:
* o Buffer is locked - in this case ahdlc_rx returns 1, char
* sending routing should retry.
*/
/*---------------------------------------------------------------------------*/
u8_t
ahdlc_rx(u8_t c)
{
static u16_t protocol;
/* check to see if PPP packet is useable, we should have hardware
flow control set, but if host ignores it and sends us a char when
the PPP Receive packet is in use, discard the character. +++ */
if(ahdlc_flags & AHDLC_RX_READY) {
/* check to see if character is less than 0x20 hex we really
should set AHDLC_RX_ASYNC_MAP on by default and only turn it
off when it is negotiated off to handle some buggy stacks. */
if((c < 0x20) &&
((ahdlc_flags & AHDLC_RX_ASYNC_MAP) == 0)) {
/* discard character */
DEBUG1(("Discard because char is < 0x20 hex and asysnc map is 0\n"));
return 0;
}
/* are we in escaped mode? */
if(ahdlc_flags & AHDLC_ESCAPED) {
/* set escaped to FALSE */
ahdlc_flags &= ~AHDLC_ESCAPED;
/* if value is 0x7e then silently discard and reset receive packet */
if(c == 0x7e) {
ahdlc_rx_ready();
return 0;
}
/* incomming char = itself xor 20 */
c = c ^ 0x20;
} else if(c == 0x7e) {
/* handle frame end */
if(ahdlc_rx_crc == CRC_GOOD_VALUE) {
DEBUG1(("\nReceiving packet with good crc value, len %d\n",ahdlc_rx_count));
/* we hae a good packet, turn off CTS until we are done with
this packet */
/*CTS_OFF();*/
/* remove CRC bytes from packet */
ahdlc_rx_count -= 2;
/* lock PPP buffer */
ahdlc_flags &= ~AHDLC_RX_READY;
/*
* upcall routine must fully process frame before return
* as returning signifies that buffer belongs to AHDLC again.
*/
if((c & 0x1) && (ahdlc_flags & PPP_PFC)) {
/* Send up packet */
ppp_upcall((u16_t)ahdlc_rx_buffer[0],
(u8_t *)&ahdlc_rx_buffer[1],
(u16_t)(ahdlc_rx_count - 1));
} else {
/* Send up packet */
ppp_upcall((u16_t)(ahdlc_rx_buffer[0] << 8 | ahdlc_rx_buffer[1]),
(u8_t *)&ahdlc_rx_buffer[2], (u16_t)(ahdlc_rx_count - 2));
}
ahdlc_tx_offline = 0; // The remote side is alive
ahdlc_rx_ready();
return 0;
} else if(ahdlc_rx_count > 3) {
DEBUG1(("\nReceiving packet with bad crc value, was 0x%04x len %d\n",ahdlc_rx_crc, ahdlc_rx_count));
#ifdef AHDLC_COUNTERS
++ahdlc_crc_error;
#endif
/* Shouldn't we dump the packet and not pass it up? */
/*ppp_upcall((u16_t)ahdlc_rx_buffer[0],
(u8_t *)&ahdlc_rx_buffer[0], (u16_t)(ahdlc_rx_count+2));
dump_ppp_packet(&ahdlc_rx_buffer[0],ahdlc_rx_count);*/
}
ahdlc_rx_ready();
return 0;
} else if(c == 0x7d) {
/* handle escaped chars*/
ahdlc_flags |= PPP_ESCAPED;
return 0;
}
/* try to store char if not to big */
if(ahdlc_rx_count >= ahdlc_max_rx_buffer_size /*PPP_RX_BUFFER_SIZE*/) {
#ifdef AHDLC_COUNTERS
++ahdlc_rx_tobig_error;
#endif
ahdlc_rx_ready();
} else {
/* Add CRC in */
ahdlc_rx_crc = crcadd(ahdlc_rx_crc, c);
/* do auto ACFC, if packet len is zero discard 0xff and 0x03 */
if(ahdlc_rx_count == 0) {
if((c == 0xff) || (c == 0x03))
return 0;
}
/* Store char */
ppp_rx_buffer[ahdlc_rx_count++] = c;
}
} else {
/* we are busy and didn't process the character. */
DEBUG1(("Busy/not active\n"));
return 1;
}
return 0;
}
/*---------------------------------------------------------------------------*/
/* ahdlc_tx_char(char) - write a character to the serial device,
* escape if necessary.
*
* Relies on local global vars : ahdlc_tx_crc, ahdlc_flags.
* Modifies local global vars : ahdlc_tx_crc.
*/
/*---------------------------------------------------------------------------*/
void
ahdlc_tx_char(u16_t protocol, u8_t c)
{
/* add in crc */
ahdlc_tx_crc = crcadd(ahdlc_tx_crc, c);
/*
* See if we need to escape char, we always escape 0x7d and 0x7e, in the case
* of char < 0x20 we only support async map of default or none, so escape if
* ASYNC map is not set. We may want to modify this to support a bitmap set
* ASYNC map.
*/
if((c == 0x7d) || (c == 0x7e) ||
((c < 0x20) && ((protocol == LCP) ||
(ahdlc_flags & PPP_TX_ASYNC_MAP) == 0))) {
/* send escape char and xor byte by 0x20 */
ppp_arch_putchar(0x7d);
c ^= 0x20;
}
ppp_arch_putchar(c);
}
/*---------------------------------------------------------------------------*/
/* ahdlc_tx(protocol,buffer,len) - Transmit a PPP frame.
* Buffer contains protocol data, ahdlc_tx addes address, control and
* protocol data.
*
* Relies on local global vars : ahdlc_tx_crc, ahdlc_flags.
* Modifies local global vars : ahdlc_tx_crc.
*/
/*---------------------------------------------------------------------------*/
u8_t
ahdlc_tx(u16_t protocol, u8_t *header, u8_t *buffer,
u16_t headerlen, u16_t datalen)
{
u16_t i;
u8_t c;
DEBUG1(("\nAHDLC_TX - transmit frame, protocol 0x%04x, length %d offline %d\n",protocol,datalen+headerlen,ahdlc_tx_offline));
if (AHDLC_TX_OFFLINE && (ahdlc_tx_offline++ > AHDLC_TX_OFFLINE)) {
ahdlc_tx_offline = 0;
DEBUG1(("\nAHDLC_TX to many outstanding TX packets => ppp_reconnect()\n"));
ppp_reconnect();
return 0;
}
#if PACKET_TX_DEBUG
DEBUG1(("\n"));
for(i = 0; i < headerlen; ++i) {
DEBUG1(("0x%02x ", header[i]));
}
for(i = 0; i < datalen; ++i) {
DEBUG1(("0x%02x ", buffer[i]));
}
DEBUG1(("\n\n"));
#endif
/* Check to see that physical layer is up, we can assume is some
cases */
/* write leading 0x7e */
ppp_arch_putchar(0x7e);
/* set initial CRC value */
ahdlc_tx_crc = 0xffff;
/* send HDLC control and address if not disabled or of LCP frame type */
/*if((0==(ahdlc_flags & PPP_ACFC)) || ((0xc0==buffer[0]) && (0x21==buffer[1]))) */
if((0 == (ahdlc_flags & PPP_ACFC)) || (protocol == LCP)) {
ahdlc_tx_char(protocol, 0xff);
ahdlc_tx_char(protocol, 0x03);
}
/* Write Protocol */
ahdlc_tx_char(protocol,(u8_t)(protocol >> 8));
ahdlc_tx_char(protocol,(u8_t)(protocol & 0xff));
/* write header if it exists */
for(i = 0; i < headerlen; ++i) {
/* Get next byte from buffer */
c = header[i];
/* Write it...*/
ahdlc_tx_char(protocol, c);
}
/* Write frame bytes */
for(i = 0; i < datalen; ++i) {
/* Get next byte from buffer */
c = buffer[i];
/* Write it...*/
ahdlc_tx_char(protocol, c);
}
/* send crc, lsb then msb */
i = ahdlc_tx_crc ^ 0xffff;
ahdlc_tx_char(protocol, (u8_t)(i & 0xff));
ahdlc_tx_char(protocol, (u8_t)((i >> 8) & 0xff));
/* write trailing 0x7e, probably not needed but it doesn't hurt*/
ppp_arch_putchar(0x7e);
return 0;
}
/*---------------------------------------------------------------------------*/
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