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
  32 struct 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
  72 extern void     isdnhdlc_rcv_init(struct isdnhdlc_vars *hdlc, u32 features);
  73
  74 extern int      isdnhdlc_decode(struct isdnhdlc_vars *hdlc, const u8 *src,
  75                         int slen, int *count, u8 *dst, int dsize);
  76
  77 extern void     isdnhdlc_out_init(struct isdnhdlc_vars *hdlc, u32 features);
  78
  79 extern int      isdnhdlc_encode(struct isdnhdlc_vars *hdlc, const u8 *src,
  80                         u16 slen, int *count, u8 *dst, int dsize);
  81
  82 #endif /* __ISDNHDLC_H__ */