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c38fc3bc2e
The original isdnhdlc code was developed for devices which had reversed bitorder in the byte stream. Adding code to handle normal bitstreams as well. Signed-off-by: Karsten Keil <keil@b1-systems.de>
83 lines
2.3 KiB
C
83 lines
2.3 KiB
C
/*
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* hdlc.h -- General purpose ISDN HDLC decoder.
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*
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* Implementation of a HDLC decoder/encoder in software.
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* Neccessary because some ISDN devices don't have HDLC
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* controllers.
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*
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* Copyright (C)
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* 2009 Karsten Keil <keil@b1-systems.de>
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* 2002 Wolfgang Mües <wolfgang@iksw-muees.de>
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* 2001 Frode Isaksen <fisaksen@bewan.com>
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* 2001 Kai Germaschewski <kai.germaschewski@gmx.de>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#ifndef __ISDNHDLC_H__
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#define __ISDNHDLC_H__
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struct isdnhdlc_vars {
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int bit_shift;
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int hdlc_bits1;
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int data_bits;
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int ffbit_shift; /* encoding only */
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int state;
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int dstpos;
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u16 crc;
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u8 cbin;
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u8 shift_reg;
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u8 ffvalue;
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/* set if transferring data */
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u32 data_received:1;
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/* set if D channel (send idle instead of flags) */
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u32 dchannel:1;
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/* set if 56K adaptation */
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u32 do_adapt56:1;
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/* set if in closing phase (need to send CRC + flag) */
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u32 do_closing:1;
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/* set if data is bitreverse */
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u32 do_bitreverse:1;
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};
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/* Feature Flags */
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#define HDLC_56KBIT 0x01
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#define HDLC_DCHANNEL 0x02
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#define HDLC_BITREVERSE 0x04
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/*
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The return value from isdnhdlc_decode is
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the frame length, 0 if no complete frame was decoded,
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or a negative error number
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*/
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#define HDLC_FRAMING_ERROR 1
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#define HDLC_CRC_ERROR 2
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#define HDLC_LENGTH_ERROR 3
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extern void isdnhdlc_rcv_init(struct isdnhdlc_vars *hdlc, u32 features);
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extern int isdnhdlc_decode(struct isdnhdlc_vars *hdlc, const u8 *src,
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int slen, int *count, u8 *dst, int dsize);
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extern void isdnhdlc_out_init(struct isdnhdlc_vars *hdlc, u32 features);
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extern int isdnhdlc_encode(struct isdnhdlc_vars *hdlc, const u8 *src,
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u16 slen, int *count, u8 *dst, int dsize);
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#endif /* __ISDNHDLC_H__ */
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