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580 lines
13 KiB
580 lines
13 KiB
/*
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* Driver for ST5481 USB ISDN modem
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*
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* Author Frode Isaksen
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* Copyright 2001 by Frode Isaksen <fisaksen@bewan.com>
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* 2001 by Kai Germaschewski <kai.germaschewski@gmx.de>
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*
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* This software may be used and distributed according to the terms
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* of the GNU General Public License, incorporated herein by reference.
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*
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*/
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#include <linux/crc-ccitt.h>
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#include "st5481_hdlc.h"
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enum {
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HDLC_FAST_IDLE,HDLC_GET_FLAG_B0,HDLC_GETFLAG_B1A6,HDLC_GETFLAG_B7,
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HDLC_GET_DATA,HDLC_FAST_FLAG
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};
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enum {
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HDLC_SEND_DATA,HDLC_SEND_CRC1,HDLC_SEND_FAST_FLAG,
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HDLC_SEND_FIRST_FLAG,HDLC_SEND_CRC2,HDLC_SEND_CLOSING_FLAG,
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HDLC_SEND_IDLE1,HDLC_SEND_FAST_IDLE,HDLC_SENDFLAG_B0,
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HDLC_SENDFLAG_B1A6,HDLC_SENDFLAG_B7,STOPPED
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};
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void
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hdlc_rcv_init(struct hdlc_vars *hdlc, int do_adapt56)
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{
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hdlc->bit_shift = 0;
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hdlc->hdlc_bits1 = 0;
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hdlc->data_bits = 0;
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hdlc->ffbit_shift = 0;
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hdlc->data_received = 0;
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hdlc->state = HDLC_GET_DATA;
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hdlc->do_adapt56 = do_adapt56;
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hdlc->dchannel = 0;
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hdlc->crc = 0;
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hdlc->cbin = 0;
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hdlc->shift_reg = 0;
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hdlc->ffvalue = 0;
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hdlc->dstpos = 0;
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}
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void
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hdlc_out_init(struct hdlc_vars *hdlc, int is_d_channel, int do_adapt56)
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{
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hdlc->bit_shift = 0;
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hdlc->hdlc_bits1 = 0;
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hdlc->data_bits = 0;
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hdlc->ffbit_shift = 0;
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hdlc->data_received = 0;
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hdlc->do_closing = 0;
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hdlc->ffvalue = 0;
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if (is_d_channel) {
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hdlc->dchannel = 1;
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hdlc->state = HDLC_SEND_FIRST_FLAG;
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} else {
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hdlc->dchannel = 0;
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hdlc->state = HDLC_SEND_FAST_FLAG;
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hdlc->ffvalue = 0x7e;
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}
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hdlc->cbin = 0x7e;
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hdlc->bit_shift = 0;
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if(do_adapt56){
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hdlc->do_adapt56 = 1;
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hdlc->data_bits = 0;
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hdlc->state = HDLC_SENDFLAG_B0;
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} else {
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hdlc->do_adapt56 = 0;
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hdlc->data_bits = 8;
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}
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hdlc->shift_reg = 0;
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}
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/*
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hdlc_decode - decodes HDLC frames from a transparent bit stream.
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The source buffer is scanned for valid HDLC frames looking for
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flags (01111110) to indicate the start of a frame. If the start of
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the frame is found, the bit stuffing is removed (0 after 5 1's).
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When a new flag is found, the complete frame has been received
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and the CRC is checked.
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If a valid frame is found, the function returns the frame length
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excluding the CRC with the bit HDLC_END_OF_FRAME set.
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If the beginning of a valid frame is found, the function returns
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the length.
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If a framing error is found (too many 1s and not a flag) the function
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returns the length with the bit HDLC_FRAMING_ERROR set.
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If a CRC error is found the function returns the length with the
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bit HDLC_CRC_ERROR set.
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If the frame length exceeds the destination buffer size, the function
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returns the length with the bit HDLC_LENGTH_ERROR set.
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src - source buffer
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slen - source buffer length
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count - number of bytes removed (decoded) from the source buffer
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dst _ destination buffer
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dsize - destination buffer size
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returns - number of decoded bytes in the destination buffer and status
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flag.
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*/
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int hdlc_decode(struct hdlc_vars *hdlc, const unsigned char *src,
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int slen, int *count, unsigned char *dst, int dsize)
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{
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int status=0;
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static const unsigned char fast_flag[]={
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0x00,0x00,0x00,0x20,0x30,0x38,0x3c,0x3e,0x3f
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};
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static const unsigned char fast_flag_value[]={
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0x00,0x7e,0xfc,0xf9,0xf3,0xe7,0xcf,0x9f,0x3f
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};
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static const unsigned char fast_abort[]={
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0x00,0x00,0x80,0xc0,0xe0,0xf0,0xf8,0xfc,0xfe,0xff
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};
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*count = slen;
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while(slen > 0){
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if(hdlc->bit_shift==0){
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hdlc->cbin = *src++;
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slen--;
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hdlc->bit_shift = 8;
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if(hdlc->do_adapt56){
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hdlc->bit_shift --;
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}
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}
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switch(hdlc->state){
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case STOPPED:
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return 0;
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case HDLC_FAST_IDLE:
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if(hdlc->cbin == 0xff){
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hdlc->bit_shift = 0;
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break;
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}
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hdlc->state = HDLC_GET_FLAG_B0;
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hdlc->hdlc_bits1 = 0;
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hdlc->bit_shift = 8;
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break;
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case HDLC_GET_FLAG_B0:
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if(!(hdlc->cbin & 0x80)) {
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hdlc->state = HDLC_GETFLAG_B1A6;
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hdlc->hdlc_bits1 = 0;
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} else {
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if(!hdlc->do_adapt56){
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if(++hdlc->hdlc_bits1 >=8 ) if(hdlc->bit_shift==1)
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hdlc->state = HDLC_FAST_IDLE;
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}
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}
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hdlc->cbin<<=1;
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hdlc->bit_shift --;
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break;
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case HDLC_GETFLAG_B1A6:
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if(hdlc->cbin & 0x80){
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hdlc->hdlc_bits1++;
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if(hdlc->hdlc_bits1==6){
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hdlc->state = HDLC_GETFLAG_B7;
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}
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} else {
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hdlc->hdlc_bits1 = 0;
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}
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hdlc->cbin<<=1;
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hdlc->bit_shift --;
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break;
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case HDLC_GETFLAG_B7:
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if(hdlc->cbin & 0x80) {
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hdlc->state = HDLC_GET_FLAG_B0;
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} else {
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hdlc->state = HDLC_GET_DATA;
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hdlc->crc = 0xffff;
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hdlc->shift_reg = 0;
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hdlc->hdlc_bits1 = 0;
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hdlc->data_bits = 0;
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hdlc->data_received = 0;
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}
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hdlc->cbin<<=1;
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hdlc->bit_shift --;
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break;
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case HDLC_GET_DATA:
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if(hdlc->cbin & 0x80){
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hdlc->hdlc_bits1++;
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switch(hdlc->hdlc_bits1){
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case 6:
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break;
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case 7:
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if(hdlc->data_received) {
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// bad frame
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status = -HDLC_FRAMING_ERROR;
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}
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if(!hdlc->do_adapt56){
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if(hdlc->cbin==fast_abort[hdlc->bit_shift+1]){
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hdlc->state = HDLC_FAST_IDLE;
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hdlc->bit_shift=1;
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break;
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}
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} else {
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hdlc->state = HDLC_GET_FLAG_B0;
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}
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break;
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default:
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hdlc->shift_reg>>=1;
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hdlc->shift_reg |= 0x80;
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hdlc->data_bits++;
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break;
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}
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} else {
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switch(hdlc->hdlc_bits1){
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case 5:
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break;
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case 6:
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if(hdlc->data_received){
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if (hdlc->dstpos < 2) {
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status = -HDLC_FRAMING_ERROR;
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} else if (hdlc->crc != 0xf0b8){
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// crc error
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status = -HDLC_CRC_ERROR;
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} else {
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// remove CRC
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hdlc->dstpos -= 2;
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// good frame
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status = hdlc->dstpos;
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}
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}
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hdlc->crc = 0xffff;
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hdlc->shift_reg = 0;
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hdlc->data_bits = 0;
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if(!hdlc->do_adapt56){
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if(hdlc->cbin==fast_flag[hdlc->bit_shift]){
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hdlc->ffvalue = fast_flag_value[hdlc->bit_shift];
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hdlc->state = HDLC_FAST_FLAG;
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hdlc->ffbit_shift = hdlc->bit_shift;
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hdlc->bit_shift = 1;
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} else {
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hdlc->state = HDLC_GET_DATA;
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hdlc->data_received = 0;
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}
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} else {
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hdlc->state = HDLC_GET_DATA;
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hdlc->data_received = 0;
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}
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break;
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default:
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hdlc->shift_reg>>=1;
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hdlc->data_bits++;
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break;
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}
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hdlc->hdlc_bits1 = 0;
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}
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if (status) {
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hdlc->dstpos = 0;
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*count -= slen;
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hdlc->cbin <<= 1;
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hdlc->bit_shift--;
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return status;
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}
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if(hdlc->data_bits==8){
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hdlc->data_bits = 0;
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hdlc->data_received = 1;
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hdlc->crc = crc_ccitt_byte(hdlc->crc, hdlc->shift_reg);
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// good byte received
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if (dsize--) {
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dst[hdlc->dstpos++] = hdlc->shift_reg;
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} else {
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// frame too long
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status = -HDLC_LENGTH_ERROR;
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hdlc->dstpos = 0;
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}
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}
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hdlc->cbin <<= 1;
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hdlc->bit_shift--;
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break;
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case HDLC_FAST_FLAG:
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if(hdlc->cbin==hdlc->ffvalue){
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hdlc->bit_shift = 0;
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break;
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} else {
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if(hdlc->cbin == 0xff){
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hdlc->state = HDLC_FAST_IDLE;
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hdlc->bit_shift=0;
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} else if(hdlc->ffbit_shift==8){
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hdlc->state = HDLC_GETFLAG_B7;
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break;
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} else {
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hdlc->shift_reg = fast_abort[hdlc->ffbit_shift-1];
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hdlc->hdlc_bits1 = hdlc->ffbit_shift-2;
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if(hdlc->hdlc_bits1<0)hdlc->hdlc_bits1 = 0;
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hdlc->data_bits = hdlc->ffbit_shift-1;
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hdlc->state = HDLC_GET_DATA;
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hdlc->data_received = 0;
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}
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}
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break;
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default:
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break;
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}
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}
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*count -= slen;
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return 0;
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}
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/*
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hdlc_encode - encodes HDLC frames to a transparent bit stream.
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The bit stream starts with a beginning flag (01111110). After
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that each byte is added to the bit stream with bit stuffing added
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(0 after 5 1's).
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When the last byte has been removed from the source buffer, the
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CRC (2 bytes is added) and the frame terminates with the ending flag.
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For the dchannel, the idle character (all 1's) is also added at the end.
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If this function is called with empty source buffer (slen=0), flags or
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idle character will be generated.
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src - source buffer
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slen - source buffer length
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count - number of bytes removed (encoded) from source buffer
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dst _ destination buffer
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dsize - destination buffer size
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returns - number of encoded bytes in the destination buffer
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*/
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int hdlc_encode(struct hdlc_vars *hdlc, const unsigned char *src,
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unsigned short slen, int *count,
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unsigned char *dst, int dsize)
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{
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static const unsigned char xfast_flag_value[] = {
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0x7e,0x3f,0x9f,0xcf,0xe7,0xf3,0xf9,0xfc,0x7e
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};
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int len = 0;
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*count = slen;
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while (dsize > 0) {
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if(hdlc->bit_shift==0){
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if(slen && !hdlc->do_closing){
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hdlc->shift_reg = *src++;
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slen--;
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if (slen == 0)
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hdlc->do_closing = 1; /* closing sequence, CRC + flag(s) */
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hdlc->bit_shift = 8;
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} else {
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if(hdlc->state == HDLC_SEND_DATA){
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if(hdlc->data_received){
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hdlc->state = HDLC_SEND_CRC1;
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hdlc->crc ^= 0xffff;
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hdlc->bit_shift = 8;
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hdlc->shift_reg = hdlc->crc & 0xff;
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} else if(!hdlc->do_adapt56){
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hdlc->state = HDLC_SEND_FAST_FLAG;
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} else {
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hdlc->state = HDLC_SENDFLAG_B0;
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}
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}
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}
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}
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switch(hdlc->state){
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case STOPPED:
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while (dsize--)
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*dst++ = 0xff;
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return dsize;
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case HDLC_SEND_FAST_FLAG:
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hdlc->do_closing = 0;
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if(slen == 0){
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*dst++ = hdlc->ffvalue;
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len++;
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dsize--;
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break;
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}
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if(hdlc->bit_shift==8){
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hdlc->cbin = hdlc->ffvalue>>(8-hdlc->data_bits);
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hdlc->state = HDLC_SEND_DATA;
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hdlc->crc = 0xffff;
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hdlc->hdlc_bits1 = 0;
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hdlc->data_received = 1;
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}
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break;
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case HDLC_SENDFLAG_B0:
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hdlc->do_closing = 0;
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hdlc->cbin <<= 1;
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hdlc->data_bits++;
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hdlc->hdlc_bits1 = 0;
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hdlc->state = HDLC_SENDFLAG_B1A6;
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break;
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case HDLC_SENDFLAG_B1A6:
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hdlc->cbin <<= 1;
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hdlc->data_bits++;
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hdlc->cbin++;
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if(++hdlc->hdlc_bits1 == 6)
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hdlc->state = HDLC_SENDFLAG_B7;
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break;
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case HDLC_SENDFLAG_B7:
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hdlc->cbin <<= 1;
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hdlc->data_bits++;
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if(slen == 0){
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hdlc->state = HDLC_SENDFLAG_B0;
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break;
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}
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if(hdlc->bit_shift==8){
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hdlc->state = HDLC_SEND_DATA;
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hdlc->crc = 0xffff;
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hdlc->hdlc_bits1 = 0;
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hdlc->data_received = 1;
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}
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break;
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case HDLC_SEND_FIRST_FLAG:
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hdlc->data_received = 1;
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if(hdlc->data_bits==8){
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hdlc->state = HDLC_SEND_DATA;
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hdlc->crc = 0xffff;
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hdlc->hdlc_bits1 = 0;
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break;
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}
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hdlc->cbin <<= 1;
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hdlc->data_bits++;
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if(hdlc->shift_reg & 0x01)
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hdlc->cbin++;
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hdlc->shift_reg >>= 1;
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hdlc->bit_shift--;
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if(hdlc->bit_shift==0){
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hdlc->state = HDLC_SEND_DATA;
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hdlc->crc = 0xffff;
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hdlc->hdlc_bits1 = 0;
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}
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break;
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case HDLC_SEND_DATA:
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hdlc->cbin <<= 1;
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hdlc->data_bits++;
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if(hdlc->hdlc_bits1 == 5){
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hdlc->hdlc_bits1 = 0;
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break;
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}
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if(hdlc->bit_shift==8){
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hdlc->crc = crc_ccitt_byte(hdlc->crc, hdlc->shift_reg);
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}
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if(hdlc->shift_reg & 0x01){
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hdlc->hdlc_bits1++;
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hdlc->cbin++;
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hdlc->shift_reg >>= 1;
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hdlc->bit_shift--;
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} else {
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hdlc->hdlc_bits1 = 0;
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hdlc->shift_reg >>= 1;
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hdlc->bit_shift--;
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}
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break;
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case HDLC_SEND_CRC1:
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hdlc->cbin <<= 1;
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hdlc->data_bits++;
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if(hdlc->hdlc_bits1 == 5){
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hdlc->hdlc_bits1 = 0;
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break;
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}
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if(hdlc->shift_reg & 0x01){
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hdlc->hdlc_bits1++;
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hdlc->cbin++;
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hdlc->shift_reg >>= 1;
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hdlc->bit_shift--;
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} else {
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hdlc->hdlc_bits1 = 0;
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hdlc->shift_reg >>= 1;
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hdlc->bit_shift--;
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}
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if(hdlc->bit_shift==0){
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hdlc->shift_reg = (hdlc->crc >> 8);
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hdlc->state = HDLC_SEND_CRC2;
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hdlc->bit_shift = 8;
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}
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break;
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case HDLC_SEND_CRC2:
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hdlc->cbin <<= 1;
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hdlc->data_bits++;
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if(hdlc->hdlc_bits1 == 5){
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hdlc->hdlc_bits1 = 0;
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break;
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}
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if(hdlc->shift_reg & 0x01){
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hdlc->hdlc_bits1++;
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|
hdlc->cbin++;
|
|
hdlc->shift_reg >>= 1;
|
|
hdlc->bit_shift--;
|
|
} else {
|
|
hdlc->hdlc_bits1 = 0;
|
|
hdlc->shift_reg >>= 1;
|
|
hdlc->bit_shift--;
|
|
}
|
|
if(hdlc->bit_shift==0){
|
|
hdlc->shift_reg = 0x7e;
|
|
hdlc->state = HDLC_SEND_CLOSING_FLAG;
|
|
hdlc->bit_shift = 8;
|
|
}
|
|
break;
|
|
case HDLC_SEND_CLOSING_FLAG:
|
|
hdlc->cbin <<= 1;
|
|
hdlc->data_bits++;
|
|
if(hdlc->hdlc_bits1 == 5){
|
|
hdlc->hdlc_bits1 = 0;
|
|
break;
|
|
}
|
|
if(hdlc->shift_reg & 0x01){
|
|
hdlc->cbin++;
|
|
}
|
|
hdlc->shift_reg >>= 1;
|
|
hdlc->bit_shift--;
|
|
if(hdlc->bit_shift==0){
|
|
hdlc->ffvalue = xfast_flag_value[hdlc->data_bits];
|
|
if(hdlc->dchannel){
|
|
hdlc->ffvalue = 0x7e;
|
|
hdlc->state = HDLC_SEND_IDLE1;
|
|
hdlc->bit_shift = 8-hdlc->data_bits;
|
|
if(hdlc->bit_shift==0)
|
|
hdlc->state = HDLC_SEND_FAST_IDLE;
|
|
} else {
|
|
if(!hdlc->do_adapt56){
|
|
hdlc->state = HDLC_SEND_FAST_FLAG;
|
|
hdlc->data_received = 0;
|
|
} else {
|
|
hdlc->state = HDLC_SENDFLAG_B0;
|
|
hdlc->data_received = 0;
|
|
}
|
|
// Finished with this frame, send flags
|
|
if (dsize > 1) dsize = 1;
|
|
}
|
|
}
|
|
break;
|
|
case HDLC_SEND_IDLE1:
|
|
hdlc->do_closing = 0;
|
|
hdlc->cbin <<= 1;
|
|
hdlc->cbin++;
|
|
hdlc->data_bits++;
|
|
hdlc->bit_shift--;
|
|
if(hdlc->bit_shift==0){
|
|
hdlc->state = HDLC_SEND_FAST_IDLE;
|
|
hdlc->bit_shift = 0;
|
|
}
|
|
break;
|
|
case HDLC_SEND_FAST_IDLE:
|
|
hdlc->do_closing = 0;
|
|
hdlc->cbin = 0xff;
|
|
hdlc->data_bits = 8;
|
|
if(hdlc->bit_shift == 8){
|
|
hdlc->cbin = 0x7e;
|
|
hdlc->state = HDLC_SEND_FIRST_FLAG;
|
|
} else {
|
|
*dst++ = hdlc->cbin;
|
|
hdlc->bit_shift = hdlc->data_bits = 0;
|
|
len++;
|
|
dsize = 0;
|
|
}
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
if(hdlc->do_adapt56){
|
|
if(hdlc->data_bits==7){
|
|
hdlc->cbin <<= 1;
|
|
hdlc->cbin++;
|
|
hdlc->data_bits++;
|
|
}
|
|
}
|
|
if(hdlc->data_bits==8){
|
|
*dst++ = hdlc->cbin;
|
|
hdlc->data_bits = 0;
|
|
len++;
|
|
dsize--;
|
|
}
|
|
}
|
|
*count -= slen;
|
|
|
|
return len;
|
|
}
|
|
|
|
|