1/*
2 * ppp-comp.h - Definitions for doing PPP packet compression.
3 *
4 * Copyright 1994-1998 Paul Mackerras.
5 *
6 *  This program is free software; you can redistribute it and/or
7 *  modify it under the terms of the GNU General Public License
8 *  version 2 as published by the Free Software Foundation.
9 */
10#ifndef _NET_PPP_COMP_H
11#define _NET_PPP_COMP_H
12
13#include <uapi/linux/ppp-comp.h>
14
15
16struct module;
17
18/*
19 * The following symbols control whether we include code for
20 * various compression methods.
21 */
22
23#ifndef DO_BSD_COMPRESS
24#define DO_BSD_COMPRESS	1	/* by default, include BSD-Compress */
25#endif
26#ifndef DO_DEFLATE
27#define DO_DEFLATE	1	/* by default, include Deflate */
28#endif
29#define DO_PREDICTOR_1	0
30#define DO_PREDICTOR_2	0
31
32/*
33 * Structure giving methods for compression/decompression.
34 */
35
36struct compressor {
37	int	compress_proto;	/* CCP compression protocol number */
38
39	/* Allocate space for a compressor (transmit side) */
40	void	*(*comp_alloc) (unsigned char *options, int opt_len);
41
42	/* Free space used by a compressor */
43	void	(*comp_free) (void *state);
44
45	/* Initialize a compressor */
46	int	(*comp_init) (void *state, unsigned char *options,
47			      int opt_len, int unit, int opthdr, int debug);
48
49	/* Reset a compressor */
50	void	(*comp_reset) (void *state);
51
52	/* Compress a packet */
53	int     (*compress) (void *state, unsigned char *rptr,
54			      unsigned char *obuf, int isize, int osize);
55
56	/* Return compression statistics */
57	void	(*comp_stat) (void *state, struct compstat *stats);
58
59	/* Allocate space for a decompressor (receive side) */
60	void	*(*decomp_alloc) (unsigned char *options, int opt_len);
61
62	/* Free space used by a decompressor */
63	void	(*decomp_free) (void *state);
64
65	/* Initialize a decompressor */
66	int	(*decomp_init) (void *state, unsigned char *options,
67				int opt_len, int unit, int opthdr, int mru,
68				int debug);
69
70	/* Reset a decompressor */
71	void	(*decomp_reset) (void *state);
72
73	/* Decompress a packet. */
74	int	(*decompress) (void *state, unsigned char *ibuf, int isize,
75				unsigned char *obuf, int osize);
76
77	/* Update state for an incompressible packet received */
78	void	(*incomp) (void *state, unsigned char *ibuf, int icnt);
79
80	/* Return decompression statistics */
81	void	(*decomp_stat) (void *state, struct compstat *stats);
82
83	/* Used in locking compressor modules */
84	struct module *owner;
85	/* Extra skb space needed by the compressor algorithm */
86	unsigned int comp_extra;
87};
88
89/*
90 * The return value from decompress routine is the length of the
91 * decompressed packet if successful, otherwise DECOMP_ERROR
92 * or DECOMP_FATALERROR if an error occurred.
93 *
94 * We need to make this distinction so that we can disable certain
95 * useful functionality, namely sending a CCP reset-request as a result
96 * of an error detected after decompression.  This is to avoid infringing
97 * a patent held by Motorola.
98 * Don't you just lurve software patents.
99 */
100
101#define DECOMP_ERROR		-1	/* error detected before decomp. */
102#define DECOMP_FATALERROR	-2	/* error detected after decomp. */
103
104extern int ppp_register_compressor(struct compressor *);
105extern void ppp_unregister_compressor(struct compressor *);
106#endif /* _NET_PPP_COMP_H */
107