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* hdlc.h -- General purpose ISDN HDLC decoder.
* Implementation of a HDLC decoder/encoder in software.
* Necessary because some ISDN devices don't have HDLC
* controllers.
* Copyright (C)
* 2009 Karsten Keil <>
* 2002 Wolfgang Mües <>
* 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;
u16 crc;
u8 cbin;
u8 shift_reg;
u8 ffvalue;
/* set if transferring data */
u32 data_received:1;
/* set if D channel (send idle instead of flags) */
u32 dchannel:1;
/* set if 56K adaptation */
u32 do_adapt56:1;
/* set if in closing phase (need to send CRC + flag) */
u32 do_closing:1;
/* set if data is bitreverse */
u32 do_bitreverse:1;
/* Feature Flags */
#define HDLC_56KBIT 0x01
#define HDLC_DCHANNEL 0x02
#define HDLC_BITREVERSE 0x04
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, u32 features);
extern int isdnhdlc_decode(struct isdnhdlc_vars *hdlc, const u8 *src,
int slen, int *count, u8 *dst, int dsize);
extern void isdnhdlc_out_init(struct isdnhdlc_vars *hdlc, u32 features);
extern int isdnhdlc_encode(struct isdnhdlc_vars *hdlc, const u8 *src,
u16 slen, int *count, u8 *dst, int dsize);
#endif /* __ISDNHDLC_H__ */