381 lines
12 KiB
C
381 lines
12 KiB
C
/* www.mycal.com
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*---------------------------------------------------------------------------
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* ahdlc.c - Ahdlc receive and transmit processor for PPP engine.
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*
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*---------------------------------------------------------------------------
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* Version
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* 0.1 Original Version Jan 11, 1998
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*
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*---------------------------------------------------------------------------
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*
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* Copyright (C) 1998, Mycal Labs www.mycal.com
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*
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*---------------------------------------------------------------------------
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*/
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/*
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* Copyright (c) 2003, Mike Johnson, Mycal Labs, www.mycal.net
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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. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by Mike Johnson/Mycal Labs
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* www.mycal.net.
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* 4. 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 Mycal Modified uIP TCP/IP stack.
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*
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* $Id: ahdlc.c,v 1.1 2007/05/26 07:14:39 oliverschmidt Exp $
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*
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*/
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/* */
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/* include files */
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/* */
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#include "net/uip.h"
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#include "ppp.h"
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#if 0
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#define DEBUG1(x)
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#else
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#include <stdio.h>
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#define DEBUG1(x) debug_printf x
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#endif
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#define PACKET_TX_DEBUG 1
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/*---------------------------------------------------------------------------
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* ahdlc flags bit defins, for ahdlc_flags variable
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---------------------------------------------------------------------------*/
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/* Escaped mode bit */
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#define AHDLC_ESCAPED 0x1
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/* Frame is ready bit */
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#define AHDLC_RX_READY 0x2
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#define AHDLC_RX_ASYNC_MAP 0x4
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#define AHDLC_TX_ASYNC_MAP 0x8
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#define AHDLC_PFC 0x10
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#define AHDLC_ACFC 0x20
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/*---------------------------------------------------------------------------
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* Private Local Globals
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* 10 bytes - standard
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* - with counters
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---------------------------------------------------------------------------*/
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/* running tx CRC */
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u16_t ahdlc_tx_crc;
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/* running rx CRC */
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u16_t ahdlc_rx_crc;
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/* number of rx bytes processed, cur frame */
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u16_t ahdlc_rx_count;
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/* ahdlc state flags, see above */
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u8_t ahdlc_flags;
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u8_t ahdlc_tx_offline;
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/*
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* The following can be optimized out
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*/
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u8_t *ahdlc_rx_buffer; /* What to do here? +++ */
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u16_t ahdlc_max_rx_buffer_size;
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/*
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* Optional statistics counters.
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*/
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#ifdef AHDLC_COUNTERS
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u8_t ahdlc_rx_tobig_error;
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#endif
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/*---------------------------------------------------------------------------*/
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/* Simple and fast CRC16 routine for embedded processors.
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* Just slightly slower than the table lookup method but consumes
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* almost no space. Much faster and smaller than the loop and
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* shift method that is widely used in the embedded space.
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* Can be optimized even more in .ASM
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*
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* data = (crcvalue ^ inputchar) & 0xff;
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* data = (data ^ (data << 4)) & 0xff;
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* crc = (crc >> 8) ^ ((data << 8) ^ (data <<3) ^ (data >> 4))
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*/
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/*---------------------------------------------------------------------------*/
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static u16_t
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crcadd(u16_t crcvalue, u8_t c)
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{
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u16_t b;
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b = (crcvalue ^ c) & 0xFF;
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b = (b ^ (b << 4)) & 0xFF;
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b = (b << 8) ^ (b << 3) ^ (b >> 4);
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return ((crcvalue >> 8) ^ b);
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}
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/*---------------------------------------------------------------------------*/
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/* ahdlc_init(buffer, buffersize) - this initializes the ahdlc engine to
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* allow for rx frames.
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*/
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/*---------------------------------------------------------------------------*/
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void
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ahdlc_init(u8_t *buffer, u16_t maxrxbuffersize)
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{
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ahdlc_flags = 0 | AHDLC_RX_ASYNC_MAP;
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ahdlc_rx_buffer = buffer;
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ahdlc_max_rx_buffer_size = maxrxbuffersize;
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/* ahdlc_async_map = 0; */
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#ifdef AHDLC_COUNTERS
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ahdlc_rx_tobig_error = 0;
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ahdl_tx_offline = 0;
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#endif
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}
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/*---------------------------------------------------------------------------*/
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/* ahdlc_rx_ready() - resets the ahdlc engine to the beginning of frame
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* state.
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*/
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/*---------------------------------------------------------------------------*/
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void
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ahdlc_rx_ready(void)
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{
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ahdlc_rx_count = 0;
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ahdlc_rx_crc = 0xffff;
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ahdlc_flags |= AHDLC_RX_READY;
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}
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/*---------------------------------------------------------------------------*/
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/* ahdlc receive function - This routine processes incoming bytes and tries
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* to build a PPP frame.
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*
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* Two possible reasons that ahdlc_rx will not process characters:
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* o Buffer is locked - in this case ahdlc_rx returns 1, char
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* sending routing should retry.
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*/
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/*---------------------------------------------------------------------------*/
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u8_t
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ahdlc_rx(u8_t c)
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{
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static u16_t protocol;
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/* check to see if PPP packet is useable, we should have hardware
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flow control set, but if host ignores it and sends us a char when
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the PPP Receive packet is in use, discard the character. +++ */
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if(ahdlc_flags & AHDLC_RX_READY) {
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/* check to see if character is less than 0x20 hex we really
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should set AHDLC_RX_ASYNC_MAP on by default and only turn it
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off when it is negotiated off to handle some buggy stacks. */
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if((c < 0x20) &&
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((ahdlc_flags & AHDLC_RX_ASYNC_MAP) == 0)) {
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/* discard character */
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DEBUG1(("Discard because char is < 0x20 hex and asysnc map is 0\n"));
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return 0;
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}
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/* are we in escaped mode? */
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if(ahdlc_flags & AHDLC_ESCAPED) {
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/* set escaped to FALSE */
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ahdlc_flags &= ~AHDLC_ESCAPED;
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/* if value is 0x7e then silently discard and reset receive packet */
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if(c == 0x7e) {
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ahdlc_rx_ready();
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return 0;
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}
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/* incomming char = itself xor 20 */
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c = c ^ 0x20;
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} else if(c == 0x7e) {
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/* handle frame end */
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if(ahdlc_rx_crc == CRC_GOOD_VALUE) {
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DEBUG1(("\nReceiving packet with good crc value, len %d\n",ahdlc_rx_count));
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/* we hae a good packet, turn off CTS until we are done with
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this packet */
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/*CTS_OFF();*/
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/* remove CRC bytes from packet */
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ahdlc_rx_count -= 2;
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/* lock PPP buffer */
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ahdlc_flags &= ~AHDLC_RX_READY;
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/*
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* upcall routine must fully process frame before return
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* as returning signifies that buffer belongs to AHDLC again.
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*/
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if((c & 0x1) && (ahdlc_flags & PPP_PFC)) {
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/* Send up packet */
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ppp_upcall((u16_t)ahdlc_rx_buffer[0],
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(u8_t *)&ahdlc_rx_buffer[1],
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(u16_t)(ahdlc_rx_count - 1));
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} else {
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/* Send up packet */
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ppp_upcall((u16_t)(ahdlc_rx_buffer[0] << 8 | ahdlc_rx_buffer[1]),
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(u8_t *)&ahdlc_rx_buffer[2], (u16_t)(ahdlc_rx_count - 2));
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}
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ahdlc_tx_offline = 0; // The remote side is alive
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ahdlc_rx_ready();
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return 0;
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} else if(ahdlc_rx_count > 3) {
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DEBUG1(("\nReceiving packet with bad crc value, was 0x%04x len %d\n",ahdlc_rx_crc, ahdlc_rx_count));
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#ifdef AHDLC_COUNTERS
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++ahdlc_crc_error;
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#endif
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/* Shouldn't we dump the packet and not pass it up? */
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/*ppp_upcall((u16_t)ahdlc_rx_buffer[0],
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(u8_t *)&ahdlc_rx_buffer[0], (u16_t)(ahdlc_rx_count+2));
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dump_ppp_packet(&ahdlc_rx_buffer[0],ahdlc_rx_count);*/
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}
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ahdlc_rx_ready();
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return 0;
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} else if(c == 0x7d) {
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/* handle escaped chars*/
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ahdlc_flags |= PPP_ESCAPED;
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return 0;
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}
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/* try to store char if not to big */
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if(ahdlc_rx_count >= ahdlc_max_rx_buffer_size /*PPP_RX_BUFFER_SIZE*/) {
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#ifdef AHDLC_COUNTERS
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++ahdlc_rx_tobig_error;
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#endif
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ahdlc_rx_ready();
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} else {
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/* Add CRC in */
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ahdlc_rx_crc = crcadd(ahdlc_rx_crc, c);
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/* do auto ACFC, if packet len is zero discard 0xff and 0x03 */
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if(ahdlc_rx_count == 0) {
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if((c == 0xff) || (c == 0x03))
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return 0;
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}
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/* Store char */
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ppp_rx_buffer[ahdlc_rx_count++] = c;
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}
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} else {
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/* we are busy and didn't process the character. */
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DEBUG1(("Busy/not active\n"));
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return 1;
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}
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return 0;
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}
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/*---------------------------------------------------------------------------*/
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/* ahdlc_tx_char(char) - write a character to the serial device,
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* escape if necessary.
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*
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* Relies on local global vars : ahdlc_tx_crc, ahdlc_flags.
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* Modifies local global vars : ahdlc_tx_crc.
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*/
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/*---------------------------------------------------------------------------*/
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void
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ahdlc_tx_char(u16_t protocol, u8_t c)
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{
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/* add in crc */
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ahdlc_tx_crc = crcadd(ahdlc_tx_crc, c);
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/*
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* See if we need to escape char, we always escape 0x7d and 0x7e, in the case
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* of char < 0x20 we only support async map of default or none, so escape if
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* ASYNC map is not set. We may want to modify this to support a bitmap set
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* ASYNC map.
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*/
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if((c == 0x7d) || (c == 0x7e) ||
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((c < 0x20) && ((protocol == LCP) ||
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(ahdlc_flags & PPP_TX_ASYNC_MAP) == 0))) {
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/* send escape char and xor byte by 0x20 */
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ppp_arch_putchar(0x7d);
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c ^= 0x20;
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}
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ppp_arch_putchar(c);
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}
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/*---------------------------------------------------------------------------*/
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/* ahdlc_tx(protocol,buffer,len) - Transmit a PPP frame.
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* Buffer contains protocol data, ahdlc_tx addes address, control and
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* protocol data.
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*
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* Relies on local global vars : ahdlc_tx_crc, ahdlc_flags.
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* Modifies local global vars : ahdlc_tx_crc.
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*/
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/*---------------------------------------------------------------------------*/
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u8_t
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ahdlc_tx(u16_t protocol, u8_t *header, u8_t *buffer,
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u16_t headerlen, u16_t datalen)
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{
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u16_t i;
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u8_t c;
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DEBUG1(("\nAHDLC_TX - transmit frame, protocol 0x%04x, length %d offline %d\n",protocol,datalen+headerlen,ahdlc_tx_offline));
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if (AHDLC_TX_OFFLINE && (ahdlc_tx_offline++ > AHDLC_TX_OFFLINE)) {
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ahdlc_tx_offline = 0;
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DEBUG1(("\nAHDLC_TX to many outstanding TX packets => ppp_reconnect()\n"));
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ppp_reconnect();
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return 0;
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}
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#if PACKET_TX_DEBUG
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DEBUG1(("\n"));
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for(i = 0; i < headerlen; ++i) {
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DEBUG1(("0x%02x ", header[i]));
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}
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for(i = 0; i < datalen; ++i) {
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DEBUG1(("0x%02x ", buffer[i]));
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}
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DEBUG1(("\n\n"));
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#endif
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/* Check to see that physical layer is up, we can assume is some
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cases */
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/* write leading 0x7e */
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ppp_arch_putchar(0x7e);
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/* set initial CRC value */
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ahdlc_tx_crc = 0xffff;
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/* send HDLC control and address if not disabled or of LCP frame type */
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/*if((0==(ahdlc_flags & PPP_ACFC)) || ((0xc0==buffer[0]) && (0x21==buffer[1]))) */
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if((0 == (ahdlc_flags & PPP_ACFC)) || (protocol == LCP)) {
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ahdlc_tx_char(protocol, 0xff);
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ahdlc_tx_char(protocol, 0x03);
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}
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/* Write Protocol */
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ahdlc_tx_char(protocol,(u8_t)(protocol >> 8));
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ahdlc_tx_char(protocol,(u8_t)(protocol & 0xff));
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/* write header if it exists */
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for(i = 0; i < headerlen; ++i) {
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/* Get next byte from buffer */
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c = header[i];
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/* Write it...*/
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ahdlc_tx_char(protocol, c);
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}
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/* Write frame bytes */
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for(i = 0; i < datalen; ++i) {
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/* Get next byte from buffer */
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c = buffer[i];
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/* Write it...*/
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ahdlc_tx_char(protocol, c);
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}
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/* send crc, lsb then msb */
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i = ahdlc_tx_crc ^ 0xffff;
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ahdlc_tx_char(protocol, (u8_t)(i & 0xff));
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ahdlc_tx_char(protocol, (u8_t)((i >> 8) & 0xff));
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/* write trailing 0x7e, probably not needed but it doesn't hurt*/
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ppp_arch_putchar(0x7e);
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return 0;
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}
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/*---------------------------------------------------------------------------*/
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