hdlc.h

Go to the documentation of this file.

/*
 * 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        <[email protected]>
 *  2002    Wolfgang Mües      <[email protected]>
 *  2001    Frode Isaksen       <[email protected]>
 *  2001    Kai Germaschewski   <[email protected]>
 *
 * 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
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * 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_FRAMING_ERROR     1
#define HDLC_CRC_ERROR         2
#define HDLC_LENGTH_ERROR      3

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__ */