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* isdnhdlc.h -- General purpose ISDN HDLC decoder.
* Implementation of a HDLC decoder/encoder in software.
* Neccessary because some ISDN devices don't have HDLC
* controllers. Also included: a bit reversal table.
*Copyright (C) 2002 Wolfgang M├╝es <>
* 2001 Frode Isaksen <>
* 2001 Kai Germaschewski <>
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
#ifndef __ISDNHDLC_H__
#define __ISDNHDLC_H__
struct isdnhdlc_vars {
int bit_shift;
int hdlc_bits1;
int data_bits;
int ffbit_shift; // encoding only
int state;
int dstpos;
unsigned short crc;
unsigned char cbin;
unsigned char shift_reg;
unsigned char ffvalue;
unsigned int data_received:1; // set if transferring data
unsigned int dchannel:1; // set if D channel (send idle instead of flags)
unsigned int do_adapt56:1; // set if 56K adaptation
unsigned int do_closing:1; // set if in closing phase (need to send CRC + flag
The return value from isdnhdlc_decode is
the frame length, 0 if no complete frame was decoded,
or a negative error number
#define HDLC_CRC_ERROR 2
extern void isdnhdlc_rcv_init (struct isdnhdlc_vars *hdlc, int do_adapt56);
extern int isdnhdlc_decode (struct isdnhdlc_vars *hdlc, const unsigned char *src, int slen,int *count,
unsigned char *dst, int dsize);
extern void isdnhdlc_out_init (struct isdnhdlc_vars *hdlc,int is_d_channel,int do_adapt56);
extern int isdnhdlc_encode (struct isdnhdlc_vars *hdlc,const unsigned char *src,unsigned short slen,int *count,
unsigned char *dst,int dsize);
#endif /* __ISDNHDLC_H__ */