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1170 lines
29 KiB
1170 lines
29 KiB
/* |
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* Update: The Berkeley copyright was changed, and the change |
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* is retroactive to all "true" BSD software (ie everything |
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* from UCB as opposed to other peoples code that just carried |
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* the same license). The new copyright doesn't clash with the |
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* GPL, so the module-only restriction has been removed.. |
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*/ |
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|
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/* Because this code is derived from the 4.3BSD compress source: |
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* |
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* Copyright (c) 1985, 1986 The Regents of the University of California. |
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* All rights reserved. |
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* |
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* This code is derived from software contributed to Berkeley by |
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* James A. Woods, derived from original work by Spencer Thomas |
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* and Joseph Orost. |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions |
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* are met: |
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* 1. Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in the |
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* documentation and/or other materials provided with the distribution. |
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* 3. All advertising materials mentioning features or use of this software |
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* must display the following acknowledgement: |
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* This product includes software developed by the University of |
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* California, Berkeley and its contributors. |
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* 4. Neither the name of the University nor the names of its contributors |
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* may be used to endorse or promote products derived from this software |
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* without specific prior written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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* SUCH DAMAGE. |
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*/ |
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|
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/* |
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* This version is for use with contiguous buffers on Linux-derived systems. |
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* |
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* ==FILEVERSION 20000226== |
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* |
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* NOTE TO MAINTAINERS: |
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* If you modify this file at all, please set the number above to the |
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* date of the modification as YYMMDD (year month day). |
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* bsd_comp.c is shipped with a PPP distribution as well as with |
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* the kernel; if everyone increases the FILEVERSION number above, |
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* then scripts can do the right thing when deciding whether to |
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* install a new bsd_comp.c file. Don't change the format of that |
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* line otherwise, so the installation script can recognize it. |
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* |
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* From: bsd_comp.c,v 1.3 1994/12/08 01:59:58 paulus Exp |
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*/ |
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|
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#include <linux/module.h> |
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#include <linux/init.h> |
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#include <linux/slab.h> |
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#include <linux/vmalloc.h> |
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#include <linux/string.h> |
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|
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#include <linux/ppp_defs.h> |
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|
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#undef PACKETPTR |
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#define PACKETPTR 1 |
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#include <linux/ppp-comp.h> |
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#undef PACKETPTR |
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|
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#include <asm/byteorder.h> |
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|
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/* |
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* PPP "BSD compress" compression |
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* The differences between this compression and the classic BSD LZW |
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* source are obvious from the requirement that the classic code worked |
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* with files while this handles arbitrarily long streams that |
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* are broken into packets. They are: |
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* |
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* When the code size expands, a block of junk is not emitted by |
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* the compressor and not expected by the decompressor. |
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* |
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* New codes are not necessarily assigned every time an old |
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* code is output by the compressor. This is because a packet |
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* end forces a code to be emitted, but does not imply that a |
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* new sequence has been seen. |
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* |
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* The compression ratio is checked at the first end of a packet |
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* after the appropriate gap. Besides simplifying and speeding |
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* things up, this makes it more likely that the transmitter |
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* and receiver will agree when the dictionary is cleared when |
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* compression is not going well. |
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*/ |
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|
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/* |
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* Macros to extract protocol version and number of bits |
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* from the third byte of the BSD Compress CCP configuration option. |
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*/ |
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|
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#define BSD_VERSION(x) ((x) >> 5) |
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#define BSD_NBITS(x) ((x) & 0x1F) |
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|
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#define BSD_CURRENT_VERSION 1 |
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|
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/* |
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* A dictionary for doing BSD compress. |
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*/ |
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|
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struct bsd_dict { |
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union { /* hash value */ |
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unsigned long fcode; |
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struct { |
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#if defined(__LITTLE_ENDIAN) /* Little endian order */ |
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unsigned short prefix; /* preceding code */ |
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unsigned char suffix; /* last character of new code */ |
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unsigned char pad; |
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#elif defined(__BIG_ENDIAN) /* Big endian order */ |
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unsigned char pad; |
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unsigned char suffix; /* last character of new code */ |
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unsigned short prefix; /* preceding code */ |
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#else |
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#error Endianness not defined... |
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#endif |
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} hs; |
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} f; |
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unsigned short codem1; /* output of hash table -1 */ |
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unsigned short cptr; /* map code to hash table entry */ |
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}; |
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|
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struct bsd_db { |
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int totlen; /* length of this structure */ |
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unsigned int hsize; /* size of the hash table */ |
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unsigned char hshift; /* used in hash function */ |
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unsigned char n_bits; /* current bits/code */ |
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unsigned char maxbits; /* maximum bits/code */ |
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unsigned char debug; /* non-zero if debug desired */ |
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unsigned char unit; /* ppp unit number */ |
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unsigned short seqno; /* sequence # of next packet */ |
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unsigned int mru; /* size of receive (decompress) bufr */ |
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unsigned int maxmaxcode; /* largest valid code */ |
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unsigned int max_ent; /* largest code in use */ |
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unsigned int in_count; /* uncompressed bytes, aged */ |
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unsigned int bytes_out; /* compressed bytes, aged */ |
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unsigned int ratio; /* recent compression ratio */ |
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unsigned int checkpoint; /* when to next check the ratio */ |
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unsigned int clear_count; /* times dictionary cleared */ |
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unsigned int incomp_count; /* incompressible packets */ |
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unsigned int incomp_bytes; /* incompressible bytes */ |
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unsigned int uncomp_count; /* uncompressed packets */ |
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unsigned int uncomp_bytes; /* uncompressed bytes */ |
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unsigned int comp_count; /* compressed packets */ |
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unsigned int comp_bytes; /* compressed bytes */ |
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unsigned short *lens; /* array of lengths of codes */ |
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struct bsd_dict *dict; /* dictionary */ |
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}; |
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|
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#define BSD_OVHD 2 /* BSD compress overhead/packet */ |
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#define MIN_BSD_BITS 9 |
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#define BSD_INIT_BITS MIN_BSD_BITS |
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#define MAX_BSD_BITS 15 |
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|
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static void bsd_free (void *state); |
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static void *bsd_alloc(unsigned char *options, int opt_len, int decomp); |
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static void *bsd_comp_alloc (unsigned char *options, int opt_len); |
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static void *bsd_decomp_alloc (unsigned char *options, int opt_len); |
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|
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static int bsd_init (void *db, unsigned char *options, |
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int opt_len, int unit, int debug, int decomp); |
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static int bsd_comp_init (void *state, unsigned char *options, |
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int opt_len, int unit, int opthdr, int debug); |
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static int bsd_decomp_init (void *state, unsigned char *options, |
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int opt_len, int unit, int opthdr, int mru, |
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int debug); |
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|
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static void bsd_reset (void *state); |
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static void bsd_comp_stats (void *state, struct compstat *stats); |
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|
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static int bsd_compress (void *state, unsigned char *rptr, |
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unsigned char *obuf, int isize, int osize); |
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static void bsd_incomp (void *state, unsigned char *ibuf, int icnt); |
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|
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static int bsd_decompress (void *state, unsigned char *ibuf, int isize, |
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unsigned char *obuf, int osize); |
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|
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/* These are in ppp_generic.c */ |
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extern int ppp_register_compressor (struct compressor *cp); |
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extern void ppp_unregister_compressor (struct compressor *cp); |
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|
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/* |
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* the next two codes should not be changed lightly, as they must not |
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* lie within the contiguous general code space. |
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*/ |
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#define CLEAR 256 /* table clear output code */ |
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#define FIRST 257 /* first free entry */ |
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#define LAST 255 |
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|
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#define MAXCODE(b) ((1 << (b)) - 1) |
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#define BADCODEM1 MAXCODE(MAX_BSD_BITS) |
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|
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#define BSD_HASH(prefix,suffix,hshift) ((((unsigned long)(suffix))<<(hshift)) \ |
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^ (unsigned long)(prefix)) |
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#define BSD_KEY(prefix,suffix) ((((unsigned long)(suffix)) << 16) \ |
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+ (unsigned long)(prefix)) |
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|
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#define CHECK_GAP 10000 /* Ratio check interval */ |
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|
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#define RATIO_SCALE_LOG 8 |
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#define RATIO_SCALE (1<<RATIO_SCALE_LOG) |
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#define RATIO_MAX (0x7fffffff>>RATIO_SCALE_LOG) |
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|
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/* |
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* clear the dictionary |
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*/ |
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|
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static void |
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bsd_clear(struct bsd_db *db) |
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{ |
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db->clear_count++; |
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db->max_ent = FIRST-1; |
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db->n_bits = BSD_INIT_BITS; |
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db->bytes_out = 0; |
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db->in_count = 0; |
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db->ratio = 0; |
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db->checkpoint = CHECK_GAP; |
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} |
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|
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/* |
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* If the dictionary is full, then see if it is time to reset it. |
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* |
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* Compute the compression ratio using fixed-point arithmetic |
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* with 8 fractional bits. |
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* |
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* Since we have an infinite stream instead of a single file, |
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* watch only the local compression ratio. |
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* |
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* Since both peers must reset the dictionary at the same time even in |
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* the absence of CLEAR codes (while packets are incompressible), they |
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* must compute the same ratio. |
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*/ |
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|
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static int bsd_check (struct bsd_db *db) /* 1=output CLEAR */ |
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{ |
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unsigned int new_ratio; |
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|
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if (db->in_count >= db->checkpoint) |
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{ |
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/* age the ratio by limiting the size of the counts */ |
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if (db->in_count >= RATIO_MAX || db->bytes_out >= RATIO_MAX) |
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{ |
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db->in_count -= (db->in_count >> 2); |
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db->bytes_out -= (db->bytes_out >> 2); |
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} |
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|
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db->checkpoint = db->in_count + CHECK_GAP; |
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|
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if (db->max_ent >= db->maxmaxcode) |
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{ |
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/* Reset the dictionary only if the ratio is worse, |
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* or if it looks as if it has been poisoned |
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* by incompressible data. |
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* |
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* This does not overflow, because |
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* db->in_count <= RATIO_MAX. |
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*/ |
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|
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new_ratio = db->in_count << RATIO_SCALE_LOG; |
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if (db->bytes_out != 0) |
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{ |
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new_ratio /= db->bytes_out; |
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} |
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|
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if (new_ratio < db->ratio || new_ratio < 1 * RATIO_SCALE) |
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{ |
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bsd_clear (db); |
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return 1; |
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} |
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db->ratio = new_ratio; |
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} |
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} |
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return 0; |
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} |
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|
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/* |
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* Return statistics. |
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*/ |
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|
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static void bsd_comp_stats (void *state, struct compstat *stats) |
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{ |
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struct bsd_db *db = (struct bsd_db *) state; |
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|
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stats->unc_bytes = db->uncomp_bytes; |
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stats->unc_packets = db->uncomp_count; |
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stats->comp_bytes = db->comp_bytes; |
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stats->comp_packets = db->comp_count; |
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stats->inc_bytes = db->incomp_bytes; |
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stats->inc_packets = db->incomp_count; |
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stats->in_count = db->in_count; |
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stats->bytes_out = db->bytes_out; |
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} |
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|
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/* |
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* Reset state, as on a CCP ResetReq. |
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*/ |
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|
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static void bsd_reset (void *state) |
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{ |
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struct bsd_db *db = (struct bsd_db *) state; |
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|
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bsd_clear(db); |
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|
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db->seqno = 0; |
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db->clear_count = 0; |
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} |
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|
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/* |
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* Release the compression structure |
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*/ |
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|
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static void bsd_free (void *state) |
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{ |
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struct bsd_db *db = state; |
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|
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if (!db) |
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return; |
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|
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/* |
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* Release the dictionary |
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*/ |
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vfree(db->dict); |
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db->dict = NULL; |
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/* |
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* Release the string buffer |
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*/ |
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vfree(db->lens); |
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db->lens = NULL; |
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/* |
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* Finally release the structure itself. |
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*/ |
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kfree(db); |
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} |
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|
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/* |
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* Allocate space for a (de) compressor. |
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*/ |
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|
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static void *bsd_alloc (unsigned char *options, int opt_len, int decomp) |
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{ |
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int bits; |
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unsigned int hsize, hshift, maxmaxcode; |
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struct bsd_db *db; |
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|
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if (opt_len != 3 || options[0] != CI_BSD_COMPRESS || options[1] != 3 |
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|| BSD_VERSION(options[2]) != BSD_CURRENT_VERSION) |
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{ |
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return NULL; |
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} |
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|
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bits = BSD_NBITS(options[2]); |
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|
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switch (bits) |
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{ |
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case 9: /* needs 82152 for both directions */ |
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case 10: /* needs 84144 */ |
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case 11: /* needs 88240 */ |
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case 12: /* needs 96432 */ |
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hsize = 5003; |
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hshift = 4; |
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break; |
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case 13: /* needs 176784 */ |
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hsize = 9001; |
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hshift = 5; |
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break; |
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case 14: /* needs 353744 */ |
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hsize = 18013; |
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hshift = 6; |
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break; |
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case 15: /* needs 691440 */ |
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hsize = 35023; |
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hshift = 7; |
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break; |
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case 16: /* needs 1366160--far too much, */ |
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/* hsize = 69001; */ /* and 69001 is too big for cptr */ |
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/* hshift = 8; */ /* in struct bsd_db */ |
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/* break; */ |
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default: |
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return NULL; |
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} |
|
/* |
|
* Allocate the main control structure for this instance. |
|
*/ |
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maxmaxcode = MAXCODE(bits); |
|
db = kzalloc(sizeof (struct bsd_db), |
|
GFP_KERNEL); |
|
if (!db) |
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{ |
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return NULL; |
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} |
|
|
|
/* |
|
* Allocate space for the dictionary. This may be more than one page in |
|
* length. |
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*/ |
|
db->dict = vmalloc(array_size(hsize, sizeof(struct bsd_dict))); |
|
if (!db->dict) |
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{ |
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bsd_free (db); |
|
return NULL; |
|
} |
|
|
|
/* |
|
* If this is the compression buffer then there is no length data. |
|
*/ |
|
if (!decomp) |
|
{ |
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db->lens = NULL; |
|
} |
|
/* |
|
* For decompression, the length information is needed as well. |
|
*/ |
|
else |
|
{ |
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db->lens = vmalloc(array_size(sizeof(db->lens[0]), (maxmaxcode + 1))); |
|
if (!db->lens) |
|
{ |
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bsd_free (db); |
|
return NULL; |
|
} |
|
} |
|
/* |
|
* Initialize the data information for the compression code |
|
*/ |
|
db->totlen = sizeof (struct bsd_db) + |
|
(sizeof (struct bsd_dict) * hsize); |
|
|
|
db->hsize = hsize; |
|
db->hshift = hshift; |
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db->maxmaxcode = maxmaxcode; |
|
db->maxbits = bits; |
|
|
|
return (void *) db; |
|
} |
|
|
|
static void *bsd_comp_alloc (unsigned char *options, int opt_len) |
|
{ |
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return bsd_alloc (options, opt_len, 0); |
|
} |
|
|
|
static void *bsd_decomp_alloc (unsigned char *options, int opt_len) |
|
{ |
|
return bsd_alloc (options, opt_len, 1); |
|
} |
|
|
|
/* |
|
* Initialize the database. |
|
*/ |
|
|
|
static int bsd_init (void *state, unsigned char *options, |
|
int opt_len, int unit, int debug, int decomp) |
|
{ |
|
struct bsd_db *db = state; |
|
int indx; |
|
|
|
if ((opt_len != 3) || (options[0] != CI_BSD_COMPRESS) || (options[1] != 3) |
|
|| (BSD_VERSION(options[2]) != BSD_CURRENT_VERSION) |
|
|| (BSD_NBITS(options[2]) != db->maxbits) |
|
|| (decomp && db->lens == NULL)) |
|
{ |
|
return 0; |
|
} |
|
|
|
if (decomp) |
|
{ |
|
indx = LAST; |
|
do |
|
{ |
|
db->lens[indx] = 1; |
|
} |
|
while (indx-- > 0); |
|
} |
|
|
|
indx = db->hsize; |
|
while (indx-- != 0) |
|
{ |
|
db->dict[indx].codem1 = BADCODEM1; |
|
db->dict[indx].cptr = 0; |
|
} |
|
|
|
db->unit = unit; |
|
db->mru = 0; |
|
#ifndef DEBUG |
|
if (debug) |
|
#endif |
|
db->debug = 1; |
|
|
|
bsd_reset(db); |
|
|
|
return 1; |
|
} |
|
|
|
static int bsd_comp_init (void *state, unsigned char *options, |
|
int opt_len, int unit, int opthdr, int debug) |
|
{ |
|
return bsd_init (state, options, opt_len, unit, debug, 0); |
|
} |
|
|
|
static int bsd_decomp_init (void *state, unsigned char *options, |
|
int opt_len, int unit, int opthdr, int mru, |
|
int debug) |
|
{ |
|
return bsd_init (state, options, opt_len, unit, debug, 1); |
|
} |
|
|
|
/* |
|
* Obtain pointers to the various structures in the compression tables |
|
*/ |
|
|
|
#define dict_ptrx(p,idx) &(p->dict[idx]) |
|
#define lens_ptrx(p,idx) &(p->lens[idx]) |
|
|
|
#ifdef DEBUG |
|
static unsigned short *lens_ptr(struct bsd_db *db, int idx) |
|
{ |
|
if ((unsigned int) idx > (unsigned int) db->maxmaxcode) |
|
{ |
|
printk ("<9>ppp: lens_ptr(%d) > max\n", idx); |
|
idx = 0; |
|
} |
|
return lens_ptrx (db, idx); |
|
} |
|
|
|
static struct bsd_dict *dict_ptr(struct bsd_db *db, int idx) |
|
{ |
|
if ((unsigned int) idx >= (unsigned int) db->hsize) |
|
{ |
|
printk ("<9>ppp: dict_ptr(%d) > max\n", idx); |
|
idx = 0; |
|
} |
|
return dict_ptrx (db, idx); |
|
} |
|
|
|
#else |
|
#define lens_ptr(db,idx) lens_ptrx(db,idx) |
|
#define dict_ptr(db,idx) dict_ptrx(db,idx) |
|
#endif |
|
|
|
/* |
|
* compress a packet |
|
* |
|
* The result of this function is the size of the compressed |
|
* packet. A zero is returned if the packet was not compressed |
|
* for some reason, such as the size being larger than uncompressed. |
|
* |
|
* One change from the BSD compress command is that when the |
|
* code size expands, we do not output a bunch of padding. |
|
*/ |
|
|
|
static int bsd_compress (void *state, unsigned char *rptr, unsigned char *obuf, |
|
int isize, int osize) |
|
{ |
|
struct bsd_db *db; |
|
int hshift; |
|
unsigned int max_ent; |
|
unsigned int n_bits; |
|
unsigned int bitno; |
|
unsigned long accm; |
|
int ent; |
|
unsigned long fcode; |
|
struct bsd_dict *dictp; |
|
unsigned char c; |
|
int hval; |
|
int disp; |
|
int ilen; |
|
int mxcode; |
|
unsigned char *wptr; |
|
int olen; |
|
|
|
#define PUTBYTE(v) \ |
|
{ \ |
|
++olen; \ |
|
if (wptr) \ |
|
{ \ |
|
*wptr++ = (unsigned char) (v); \ |
|
if (olen >= osize) \ |
|
{ \ |
|
wptr = NULL; \ |
|
} \ |
|
} \ |
|
} |
|
|
|
#define OUTPUT(ent) \ |
|
{ \ |
|
bitno -= n_bits; \ |
|
accm |= ((ent) << bitno); \ |
|
do \ |
|
{ \ |
|
PUTBYTE(accm >> 24); \ |
|
accm <<= 8; \ |
|
bitno += 8; \ |
|
} \ |
|
while (bitno <= 24); \ |
|
} |
|
|
|
/* |
|
* If the protocol is not in the range we're interested in, |
|
* just return without compressing the packet. If it is, |
|
* the protocol becomes the first byte to compress. |
|
*/ |
|
|
|
ent = PPP_PROTOCOL(rptr); |
|
if (ent < 0x21 || ent > 0xf9) |
|
{ |
|
return 0; |
|
} |
|
|
|
db = (struct bsd_db *) state; |
|
hshift = db->hshift; |
|
max_ent = db->max_ent; |
|
n_bits = db->n_bits; |
|
bitno = 32; |
|
accm = 0; |
|
mxcode = MAXCODE (n_bits); |
|
|
|
/* Initialize the output pointers */ |
|
wptr = obuf; |
|
olen = PPP_HDRLEN + BSD_OVHD; |
|
|
|
if (osize > isize) |
|
{ |
|
osize = isize; |
|
} |
|
|
|
/* This is the PPP header information */ |
|
if (wptr) |
|
{ |
|
*wptr++ = PPP_ADDRESS(rptr); |
|
*wptr++ = PPP_CONTROL(rptr); |
|
*wptr++ = 0; |
|
*wptr++ = PPP_COMP; |
|
*wptr++ = db->seqno >> 8; |
|
*wptr++ = db->seqno; |
|
} |
|
|
|
/* Skip the input header */ |
|
rptr += PPP_HDRLEN; |
|
isize -= PPP_HDRLEN; |
|
ilen = ++isize; /* Low byte of protocol is counted as input */ |
|
|
|
while (--ilen > 0) |
|
{ |
|
c = *rptr++; |
|
fcode = BSD_KEY (ent, c); |
|
hval = BSD_HASH (ent, c, hshift); |
|
dictp = dict_ptr (db, hval); |
|
|
|
/* Validate and then check the entry. */ |
|
if (dictp->codem1 >= max_ent) |
|
{ |
|
goto nomatch; |
|
} |
|
|
|
if (dictp->f.fcode == fcode) |
|
{ |
|
ent = dictp->codem1 + 1; |
|
continue; /* found (prefix,suffix) */ |
|
} |
|
|
|
/* continue probing until a match or invalid entry */ |
|
disp = (hval == 0) ? 1 : hval; |
|
|
|
do |
|
{ |
|
hval += disp; |
|
if (hval >= db->hsize) |
|
{ |
|
hval -= db->hsize; |
|
} |
|
dictp = dict_ptr (db, hval); |
|
if (dictp->codem1 >= max_ent) |
|
{ |
|
goto nomatch; |
|
} |
|
} |
|
while (dictp->f.fcode != fcode); |
|
|
|
ent = dictp->codem1 + 1; /* finally found (prefix,suffix) */ |
|
continue; |
|
|
|
nomatch: |
|
OUTPUT(ent); /* output the prefix */ |
|
|
|
/* code -> hashtable */ |
|
if (max_ent < db->maxmaxcode) |
|
{ |
|
struct bsd_dict *dictp2; |
|
struct bsd_dict *dictp3; |
|
int indx; |
|
|
|
/* expand code size if needed */ |
|
if (max_ent >= mxcode) |
|
{ |
|
db->n_bits = ++n_bits; |
|
mxcode = MAXCODE (n_bits); |
|
} |
|
|
|
/* Invalidate old hash table entry using |
|
* this code, and then take it over. |
|
*/ |
|
|
|
dictp2 = dict_ptr (db, max_ent + 1); |
|
indx = dictp2->cptr; |
|
dictp3 = dict_ptr (db, indx); |
|
|
|
if (dictp3->codem1 == max_ent) |
|
{ |
|
dictp3->codem1 = BADCODEM1; |
|
} |
|
|
|
dictp2->cptr = hval; |
|
dictp->codem1 = max_ent; |
|
dictp->f.fcode = fcode; |
|
db->max_ent = ++max_ent; |
|
|
|
if (db->lens) |
|
{ |
|
unsigned short *len1 = lens_ptr (db, max_ent); |
|
unsigned short *len2 = lens_ptr (db, ent); |
|
*len1 = *len2 + 1; |
|
} |
|
} |
|
ent = c; |
|
} |
|
|
|
OUTPUT(ent); /* output the last code */ |
|
|
|
db->bytes_out += olen - PPP_HDRLEN - BSD_OVHD; |
|
db->uncomp_bytes += isize; |
|
db->in_count += isize; |
|
++db->uncomp_count; |
|
++db->seqno; |
|
|
|
if (bitno < 32) |
|
{ |
|
++db->bytes_out; /* must be set before calling bsd_check */ |
|
} |
|
|
|
/* |
|
* Generate the clear command if needed |
|
*/ |
|
|
|
if (bsd_check(db)) |
|
{ |
|
OUTPUT (CLEAR); |
|
} |
|
|
|
/* |
|
* Pad dribble bits of last code with ones. |
|
* Do not emit a completely useless byte of ones. |
|
*/ |
|
|
|
if (bitno != 32) |
|
{ |
|
PUTBYTE((accm | (0xff << (bitno-8))) >> 24); |
|
} |
|
|
|
/* |
|
* Increase code size if we would have without the packet |
|
* boundary because the decompressor will do so. |
|
*/ |
|
|
|
if (max_ent >= mxcode && max_ent < db->maxmaxcode) |
|
{ |
|
db->n_bits++; |
|
} |
|
|
|
/* If output length is too large then this is an incomplete frame. */ |
|
if (wptr == NULL) |
|
{ |
|
++db->incomp_count; |
|
db->incomp_bytes += isize; |
|
olen = 0; |
|
} |
|
else /* Count the number of compressed frames */ |
|
{ |
|
++db->comp_count; |
|
db->comp_bytes += olen; |
|
} |
|
|
|
/* Return the resulting output length */ |
|
return olen; |
|
#undef OUTPUT |
|
#undef PUTBYTE |
|
} |
|
|
|
/* |
|
* Update the "BSD Compress" dictionary on the receiver for |
|
* incompressible data by pretending to compress the incoming data. |
|
*/ |
|
|
|
static void bsd_incomp (void *state, unsigned char *ibuf, int icnt) |
|
{ |
|
(void) bsd_compress (state, ibuf, (char *) 0, icnt, 0); |
|
} |
|
|
|
/* |
|
* Decompress "BSD Compress". |
|
* |
|
* Because of patent problems, we return DECOMP_ERROR for errors |
|
* found by inspecting the input data and for system problems, but |
|
* DECOMP_FATALERROR for any errors which could possibly be said to |
|
* be being detected "after" decompression. For DECOMP_ERROR, |
|
* we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be |
|
* infringing a patent of Motorola's if we do, so we take CCP down |
|
* instead. |
|
* |
|
* Given that the frame has the correct sequence number and a good FCS, |
|
* errors such as invalid codes in the input most likely indicate a |
|
* bug, so we return DECOMP_FATALERROR for them in order to turn off |
|
* compression, even though they are detected by inspecting the input. |
|
*/ |
|
|
|
static int bsd_decompress (void *state, unsigned char *ibuf, int isize, |
|
unsigned char *obuf, int osize) |
|
{ |
|
struct bsd_db *db; |
|
unsigned int max_ent; |
|
unsigned long accm; |
|
unsigned int bitno; /* 1st valid bit in accm */ |
|
unsigned int n_bits; |
|
unsigned int tgtbitno; /* bitno when we have a code */ |
|
struct bsd_dict *dictp; |
|
int explen; |
|
int seq; |
|
unsigned int incode; |
|
unsigned int oldcode; |
|
unsigned int finchar; |
|
unsigned char *p; |
|
unsigned char *wptr; |
|
int adrs; |
|
int ctrl; |
|
int ilen; |
|
int codelen; |
|
int extra; |
|
|
|
db = (struct bsd_db *) state; |
|
max_ent = db->max_ent; |
|
accm = 0; |
|
bitno = 32; /* 1st valid bit in accm */ |
|
n_bits = db->n_bits; |
|
tgtbitno = 32 - n_bits; /* bitno when we have a code */ |
|
|
|
/* |
|
* Save the address/control from the PPP header |
|
* and then get the sequence number. |
|
*/ |
|
|
|
adrs = PPP_ADDRESS (ibuf); |
|
ctrl = PPP_CONTROL (ibuf); |
|
|
|
seq = (ibuf[4] << 8) + ibuf[5]; |
|
|
|
ibuf += (PPP_HDRLEN + 2); |
|
ilen = isize - (PPP_HDRLEN + 2); |
|
|
|
/* |
|
* Check the sequence number and give up if it differs from |
|
* the value we're expecting. |
|
*/ |
|
|
|
if (seq != db->seqno) |
|
{ |
|
if (db->debug) |
|
{ |
|
printk("bsd_decomp%d: bad sequence # %d, expected %d\n", |
|
db->unit, seq, db->seqno - 1); |
|
} |
|
return DECOMP_ERROR; |
|
} |
|
|
|
++db->seqno; |
|
db->bytes_out += ilen; |
|
|
|
/* |
|
* Fill in the ppp header, but not the last byte of the protocol |
|
* (that comes from the decompressed data). |
|
*/ |
|
|
|
wptr = obuf; |
|
*wptr++ = adrs; |
|
*wptr++ = ctrl; |
|
*wptr++ = 0; |
|
|
|
oldcode = CLEAR; |
|
explen = 3; |
|
|
|
/* |
|
* Keep the checkpoint correctly so that incompressible packets |
|
* clear the dictionary at the proper times. |
|
*/ |
|
|
|
for (;;) |
|
{ |
|
if (ilen-- <= 0) |
|
{ |
|
db->in_count += (explen - 3); /* don't count the header */ |
|
break; |
|
} |
|
|
|
/* |
|
* Accumulate bytes until we have a complete code. |
|
* Then get the next code, relying on the 32-bit, |
|
* unsigned accm to mask the result. |
|
*/ |
|
|
|
bitno -= 8; |
|
accm |= *ibuf++ << bitno; |
|
if (tgtbitno < bitno) |
|
{ |
|
continue; |
|
} |
|
|
|
incode = accm >> tgtbitno; |
|
accm <<= n_bits; |
|
bitno += n_bits; |
|
|
|
/* |
|
* The dictionary must only be cleared at the end of a packet. |
|
*/ |
|
|
|
if (incode == CLEAR) |
|
{ |
|
if (ilen > 0) |
|
{ |
|
if (db->debug) |
|
{ |
|
printk("bsd_decomp%d: bad CLEAR\n", db->unit); |
|
} |
|
return DECOMP_FATALERROR; /* probably a bug */ |
|
} |
|
|
|
bsd_clear(db); |
|
break; |
|
} |
|
|
|
if ((incode > max_ent + 2) || (incode > db->maxmaxcode) |
|
|| (incode > max_ent && oldcode == CLEAR)) |
|
{ |
|
if (db->debug) |
|
{ |
|
printk("bsd_decomp%d: bad code 0x%x oldcode=0x%x ", |
|
db->unit, incode, oldcode); |
|
printk("max_ent=0x%x explen=%d seqno=%d\n", |
|
max_ent, explen, db->seqno); |
|
} |
|
return DECOMP_FATALERROR; /* probably a bug */ |
|
} |
|
|
|
/* Special case for KwKwK string. */ |
|
if (incode > max_ent) |
|
{ |
|
finchar = oldcode; |
|
extra = 1; |
|
} |
|
else |
|
{ |
|
finchar = incode; |
|
extra = 0; |
|
} |
|
|
|
codelen = *(lens_ptr (db, finchar)); |
|
explen += codelen + extra; |
|
if (explen > osize) |
|
{ |
|
if (db->debug) |
|
{ |
|
printk("bsd_decomp%d: ran out of mru\n", db->unit); |
|
#ifdef DEBUG |
|
printk(" len=%d, finchar=0x%x, codelen=%d, explen=%d\n", |
|
ilen, finchar, codelen, explen); |
|
#endif |
|
} |
|
return DECOMP_FATALERROR; |
|
} |
|
|
|
/* |
|
* Decode this code and install it in the decompressed buffer. |
|
*/ |
|
|
|
wptr += codelen; |
|
p = wptr; |
|
while (finchar > LAST) |
|
{ |
|
struct bsd_dict *dictp2 = dict_ptr (db, finchar); |
|
|
|
dictp = dict_ptr (db, dictp2->cptr); |
|
#ifdef DEBUG |
|
if (--codelen <= 0 || dictp->codem1 != finchar-1) |
|
{ |
|
if (codelen <= 0) |
|
{ |
|
printk("bsd_decomp%d: fell off end of chain ", db->unit); |
|
printk("0x%x at 0x%x by 0x%x, max_ent=0x%x\n", |
|
incode, finchar, dictp2->cptr, max_ent); |
|
} |
|
else |
|
{ |
|
if (dictp->codem1 != finchar-1) |
|
{ |
|
printk("bsd_decomp%d: bad code chain 0x%x " |
|
"finchar=0x%x ", |
|
db->unit, incode, finchar); |
|
|
|
printk("oldcode=0x%x cptr=0x%x codem1=0x%x\n", |
|
oldcode, dictp2->cptr, dictp->codem1); |
|
} |
|
} |
|
return DECOMP_FATALERROR; |
|
} |
|
#endif |
|
*--p = dictp->f.hs.suffix; |
|
finchar = dictp->f.hs.prefix; |
|
} |
|
*--p = finchar; |
|
|
|
#ifdef DEBUG |
|
if (--codelen != 0) |
|
{ |
|
printk("bsd_decomp%d: short by %d after code 0x%x, max_ent=0x%x\n", |
|
db->unit, codelen, incode, max_ent); |
|
} |
|
#endif |
|
|
|
if (extra) /* the KwKwK case again */ |
|
{ |
|
*wptr++ = finchar; |
|
} |
|
|
|
/* |
|
* If not first code in a packet, and |
|
* if not out of code space, then allocate a new code. |
|
* |
|
* Keep the hash table correct so it can be used |
|
* with uncompressed packets. |
|
*/ |
|
|
|
if (oldcode != CLEAR && max_ent < db->maxmaxcode) |
|
{ |
|
struct bsd_dict *dictp2, *dictp3; |
|
unsigned short *lens1, *lens2; |
|
unsigned long fcode; |
|
int hval, disp, indx; |
|
|
|
fcode = BSD_KEY(oldcode,finchar); |
|
hval = BSD_HASH(oldcode,finchar,db->hshift); |
|
dictp = dict_ptr (db, hval); |
|
|
|
/* look for a free hash table entry */ |
|
if (dictp->codem1 < max_ent) |
|
{ |
|
disp = (hval == 0) ? 1 : hval; |
|
do |
|
{ |
|
hval += disp; |
|
if (hval >= db->hsize) |
|
{ |
|
hval -= db->hsize; |
|
} |
|
dictp = dict_ptr (db, hval); |
|
} |
|
while (dictp->codem1 < max_ent); |
|
} |
|
|
|
/* |
|
* Invalidate previous hash table entry |
|
* assigned this code, and then take it over |
|
*/ |
|
|
|
dictp2 = dict_ptr (db, max_ent + 1); |
|
indx = dictp2->cptr; |
|
dictp3 = dict_ptr (db, indx); |
|
|
|
if (dictp3->codem1 == max_ent) |
|
{ |
|
dictp3->codem1 = BADCODEM1; |
|
} |
|
|
|
dictp2->cptr = hval; |
|
dictp->codem1 = max_ent; |
|
dictp->f.fcode = fcode; |
|
db->max_ent = ++max_ent; |
|
|
|
/* Update the length of this string. */ |
|
lens1 = lens_ptr (db, max_ent); |
|
lens2 = lens_ptr (db, oldcode); |
|
*lens1 = *lens2 + 1; |
|
|
|
/* Expand code size if needed. */ |
|
if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) |
|
{ |
|
db->n_bits = ++n_bits; |
|
tgtbitno = 32-n_bits; |
|
} |
|
} |
|
oldcode = incode; |
|
} |
|
|
|
++db->comp_count; |
|
++db->uncomp_count; |
|
db->comp_bytes += isize - BSD_OVHD - PPP_HDRLEN; |
|
db->uncomp_bytes += explen; |
|
|
|
if (bsd_check(db)) |
|
{ |
|
if (db->debug) |
|
{ |
|
printk("bsd_decomp%d: peer should have cleared dictionary on %d\n", |
|
db->unit, db->seqno - 1); |
|
} |
|
} |
|
return explen; |
|
} |
|
|
|
/************************************************************* |
|
* Table of addresses for the BSD compression module |
|
*************************************************************/ |
|
|
|
static struct compressor ppp_bsd_compress = { |
|
.compress_proto = CI_BSD_COMPRESS, |
|
.comp_alloc = bsd_comp_alloc, |
|
.comp_free = bsd_free, |
|
.comp_init = bsd_comp_init, |
|
.comp_reset = bsd_reset, |
|
.compress = bsd_compress, |
|
.comp_stat = bsd_comp_stats, |
|
.decomp_alloc = bsd_decomp_alloc, |
|
.decomp_free = bsd_free, |
|
.decomp_init = bsd_decomp_init, |
|
.decomp_reset = bsd_reset, |
|
.decompress = bsd_decompress, |
|
.incomp = bsd_incomp, |
|
.decomp_stat = bsd_comp_stats, |
|
.owner = THIS_MODULE |
|
}; |
|
|
|
/************************************************************* |
|
* Module support routines |
|
*************************************************************/ |
|
|
|
static int __init bsdcomp_init(void) |
|
{ |
|
int answer = ppp_register_compressor(&ppp_bsd_compress); |
|
if (answer == 0) |
|
printk(KERN_INFO "PPP BSD Compression module registered\n"); |
|
return answer; |
|
} |
|
|
|
static void __exit bsdcomp_cleanup(void) |
|
{ |
|
ppp_unregister_compressor(&ppp_bsd_compress); |
|
} |
|
|
|
module_init(bsdcomp_init); |
|
module_exit(bsdcomp_cleanup); |
|
MODULE_LICENSE("Dual BSD/GPL"); |
|
MODULE_ALIAS("ppp-compress-" __stringify(CI_BSD_COMPRESS));
|
|
|