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__ */