/* * Update: The Berkeley copyright was changed, and the change * is retroactive to all "true" BSD software (ie everything * from UCB as opposed to other peoples code that just carried * the same license). The new copyright doesn't clash with the * GPL, so the module-only restriction has been removed.. */ /* Because this code is derived from the 4.3BSD compress source: * * Copyright (c) 1985, 1986 The Regents of the University of California. * All rights reserved. * * This code is derived from software contributed to Berkeley by * James A. Woods, derived from original work by Spencer Thomas * and Joseph Orost. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ /* * This version is for use with contiguous buffers on Linux-derived systems. * * ==FILEVERSION 20000226== * * NOTE TO MAINTAINERS: * If you modify this file at all, please set the number above to the * date of the modification as YYMMDD (year month day). * bsd_comp.c is shipped with a PPP distribution as well as with * the kernel; if everyone increases the FILEVERSION number above, * then scripts can do the right thing when deciding whether to * install a new bsd_comp.c file. Don't change the format of that * line otherwise, so the installation script can recognize it. * * From: bsd_comp.c,v 1.3 1994/12/08 01:59:58 paulus Exp */ #include <linux/module.h> #include <linux/init.h> #include <linux/slab.h> #include <linux/vmalloc.h> #include <linux/string.h> #include <linux/ppp_defs.h> #undef PACKETPTR #define PACKETPTR … #include <linux/ppp-comp.h> #undef PACKETPTR #include <asm/byteorder.h> /* * PPP "BSD compress" compression * The differences between this compression and the classic BSD LZW * source are obvious from the requirement that the classic code worked * with files while this handles arbitrarily long streams that * are broken into packets. They are: * * When the code size expands, a block of junk is not emitted by * the compressor and not expected by the decompressor. * * New codes are not necessarily assigned every time an old * code is output by the compressor. This is because a packet * end forces a code to be emitted, but does not imply that a * new sequence has been seen. * * The compression ratio is checked at the first end of a packet * after the appropriate gap. Besides simplifying and speeding * things up, this makes it more likely that the transmitter * and receiver will agree when the dictionary is cleared when * compression is not going well. */ /* * Macros to extract protocol version and number of bits * from the third byte of the BSD Compress CCP configuration option. */ #define BSD_VERSION(x) … #define BSD_NBITS(x) … #define BSD_CURRENT_VERSION … /* * A dictionary for doing BSD compress. */ struct bsd_dict { … }; struct bsd_db { … }; #define BSD_OVHD … #define MIN_BSD_BITS … #define BSD_INIT_BITS … #define MAX_BSD_BITS … static void bsd_free (void *state); static void *bsd_alloc(unsigned char *options, int opt_len, int decomp); static void *bsd_comp_alloc (unsigned char *options, int opt_len); static void *bsd_decomp_alloc (unsigned char *options, int opt_len); static int bsd_init (void *db, unsigned char *options, int opt_len, int unit, int debug, int decomp); static int bsd_comp_init (void *state, unsigned char *options, int opt_len, int unit, int opthdr, int debug); static int bsd_decomp_init (void *state, unsigned char *options, int opt_len, int unit, int opthdr, int mru, int debug); static void bsd_reset (void *state); static void bsd_comp_stats (void *state, struct compstat *stats); static int bsd_compress (void *state, unsigned char *rptr, unsigned char *obuf, int isize, int osize); static void bsd_incomp (void *state, unsigned char *ibuf, int icnt); static int bsd_decompress (void *state, unsigned char *ibuf, int isize, unsigned char *obuf, int osize); /* These are in ppp_generic.c */ extern int ppp_register_compressor (struct compressor *cp); extern void ppp_unregister_compressor (struct compressor *cp); /* * the next two codes should not be changed lightly, as they must not * lie within the contiguous general code space. */ #define CLEAR … #define FIRST … #define LAST … #define MAXCODE(b) … #define BADCODEM1 … #define BSD_HASH(prefix,suffix,hshift) … #define BSD_KEY(prefix,suffix) … #define CHECK_GAP … #define RATIO_SCALE_LOG … #define RATIO_SCALE … #define RATIO_MAX … /* * clear the dictionary */ static void bsd_clear(struct bsd_db *db) { … } /* * If the dictionary is full, then see if it is time to reset it. * * Compute the compression ratio using fixed-point arithmetic * with 8 fractional bits. * * Since we have an infinite stream instead of a single file, * watch only the local compression ratio. * * Since both peers must reset the dictionary at the same time even in * the absence of CLEAR codes (while packets are incompressible), they * must compute the same ratio. */ static int bsd_check (struct bsd_db *db) /* 1=output CLEAR */ { … } /* * Return statistics. */ static void bsd_comp_stats (void *state, struct compstat *stats) { … } /* * Reset state, as on a CCP ResetReq. */ static void bsd_reset (void *state) { … } /* * Release the compression structure */ static void bsd_free (void *state) { … } /* * Allocate space for a (de) compressor. */ static void *bsd_alloc (unsigned char *options, int opt_len, int decomp) { … } static void *bsd_comp_alloc (unsigned char *options, int opt_len) { … } static void *bsd_decomp_alloc (unsigned char *options, int opt_len) { … } /* * Initialize the database. */ static int bsd_init (void *state, unsigned char *options, int opt_len, int unit, int debug, int decomp) { … } static int bsd_comp_init (void *state, unsigned char *options, int opt_len, int unit, int opthdr, int debug) { … } static int bsd_decomp_init (void *state, unsigned char *options, int opt_len, int unit, int opthdr, int mru, int debug) { … } /* * Obtain pointers to the various structures in the compression tables */ #define dict_ptrx(p,idx) … #define lens_ptrx(p,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) … #define dict_ptr(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) { … } /* * 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) { … } /* * 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) { … } /************************************************************* * Table of addresses for the BSD compression module *************************************************************/ static struct compressor ppp_bsd_compress = …; /************************************************************* * Module support routines *************************************************************/ static int __init bsdcomp_init(void) { … } static void __exit bsdcomp_cleanup(void) { … } module_init(…) …; module_exit(bsdcomp_cleanup); MODULE_DESCRIPTION(…) …; MODULE_LICENSE(…) …; MODULE_ALIAS(…) …;
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