drivers/isdn/hardware/mISDN/isdnhdlc.h

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 /*
   3  * hdlc.h  --  General purpose ISDN HDLC decoder.
   4  *
   5  * Implementation of a HDLC decoder/encoder in software.
   6  * Necessary because some ISDN devices don't have HDLC
   7  * controllers.
   8  *
   9  * Copyright (C)
  10  *      2009    Karsten Keil            <keil@b1-systems.de>
  11  *      2002    Wolfgang Mües          <wolfgang@iksw-muees.de>
  12  *      2001    Frode Isaksen           <fisaksen@bewan.com>
  13  *      2001    Kai Germaschewski       <kai.germaschewski@gmx.de>
  14  */
  15
  16 #ifndef __ISDNHDLC_H__
  17 #define __ISDNHDLC_H__
  18
  19 struct isdnhdlc_vars {
  20         int bit_shift;
  21         int hdlc_bits1;
  22         int data_bits;
  23         int ffbit_shift;        /* encoding only */
  24         int state;
  25         int dstpos;
  26
  27         u16 crc;
  28
  29         u8 cbin;
  30         u8 shift_reg;
  31         u8 ffvalue;
  32
  33         /* set if transferring data */
  34         u32 data_received:1;
  35         /* set if D channel (send idle instead of flags) */
  36         u32 dchannel:1;
  37         /* set if 56K adaptation */
  38         u32 do_adapt56:1;
  39         /* set if in closing phase (need to send CRC + flag) */
  40         u32 do_closing:1;
  41         /* set if data is bitreverse */
  42         u32 do_bitreverse:1;
  43 };
  44
  45 /* Feature Flags */
  46 #define HDLC_56KBIT     0x01
  47 #define HDLC_DCHANNEL   0x02
  48 #define HDLC_BITREVERSE 0x04
  49
  50 /*
  51   The return value from isdnhdlc_decode is
  52   the frame length, 0 if no complete frame was decoded,
  53   or a negative error number
  54 */
  55 #define HDLC_FRAMING_ERROR     1
  56 #define HDLC_CRC_ERROR         2
  57 #define HDLC_LENGTH_ERROR      3
  58
  59 extern void     isdnhdlc_rcv_init(struct isdnhdlc_vars *hdlc, u32 features);
  60
  61 extern int      isdnhdlc_decode(struct isdnhdlc_vars *hdlc, const u8 *src,
  62                         int slen, int *count, u8 *dst, int dsize);
  63
  64 extern void     isdnhdlc_out_init(struct isdnhdlc_vars *hdlc, u32 features);
  65
  66 extern int      isdnhdlc_encode(struct isdnhdlc_vars *hdlc, const u8 *src,
  67                         u16 slen, int *count, u8 *dst, int dsize);
  68
  69 #endif /* __ISDNHDLC_H__ */