linux/include/linux/ppp-comp.h
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   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
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