LXR linux/include/linux/isdn/hdlc.h

   1/*
   2 * hdlc.h  --  General purpose ISDN HDLC decoder.
   3 *
   4 * Implementation of a HDLC decoder/encoder in software.
   5 * Necessary because some ISDN devices don't have HDLC
   6 * controllers.
   7 *
   8 * Copyright (C)
   9 *      2009    Karsten Keil            <keil@b1-systems.de>
  10 *      2002    Wolfgang Mües           <wolfgang@iksw-muees.de>
  11 *      2001    Frode Isaksen           <fisaksen@bewan.com>
  12 *      2001    Kai Germaschewski       <kai.germaschewski@gmx.de>
  13 *
  14 * This program is free software; you can redistribute it and/or modify
  15 * it under the terms of the GNU General Public License as published by
  16 * the Free Software Foundation; either version 2 of the License, or
  17 * (at your option) any later version.
  18 *
  19 * This program is distributed in the hope that it will be useful,
  20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22 * GNU General Public License for more details.
  23 *
  24 * You should have received a copy of the GNU General Public License
  25 * along with this program; if not, write to the Free Software
  26 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  27 */
  28
  29#ifndef __ISDNHDLC_H__
  30#define __ISDNHDLC_H__
  31
  32struct isdnhdlc_vars {
  33        int bit_shift;
  34        int hdlc_bits1;
  35        int data_bits;
  36        int ffbit_shift;        /* encoding only */
  37        int state;
  38        int dstpos;
  39
  40        u16 crc;
  41
  42        u8 cbin;
  43        u8 shift_reg;
  44        u8 ffvalue;
  45
  46        /* set if transferring data */
  47        u32 data_received:1;
  48        /* set if D channel (send idle instead of flags) */
  49        u32 dchannel:1;
  50        /* set if 56K adaptation */
  51        u32 do_adapt56:1;
  52        /* set if in closing phase (need to send CRC + flag) */
  53        u32 do_closing:1;
  54        /* set if data is bitreverse */
  55        u32 do_bitreverse:1;
  56};
  57
  58/* Feature Flags */
  59#define HDLC_56KBIT     0x01
  60#define HDLC_DCHANNEL   0x02
  61#define HDLC_BITREVERSE 0x04
  62
  63/*
  64  The return value from isdnhdlc_decode is
  65  the frame length, 0 if no complete frame was decoded,
  66  or a negative error number
  67*/
  68#define HDLC_FRAMING_ERROR     1
  69#define HDLC_CRC_ERROR         2
  70#define HDLC_LENGTH_ERROR      3
  71
  72extern void     isdnhdlc_rcv_init(struct isdnhdlc_vars *hdlc, u32 features);
  73
  74extern int      isdnhdlc_decode(struct isdnhdlc_vars *hdlc, const u8 *src,
  75                        int slen, int *count, u8 *dst, int dsize);
  76
  77extern void     isdnhdlc_out_init(struct isdnhdlc_vars *hdlc, u32 features);
  78
  79extern int      isdnhdlc_encode(struct isdnhdlc_vars *hdlc, const u8 *src,
  80                        u16 slen, int *count, u8 *dst, int dsize);
  81
  82#endif /* __ISDNHDLC_H__ */
  83