2 * Update: The Berkeley copyright was changed, and the change
3 * is retroactive to all "true" BSD software (ie everything
4 * from UCB as opposed to other peoples code that just carried
5 * the same license). The new copyright doesn't clash with the
6 * GPL, so the module-only restriction has been removed..
9 /* Because this code is derived from the 4.3BSD compress source:
11 * Copyright (c) 1985, 1986 The Regents of the University of California.
12 * All rights reserved.
14 * This code is derived from software contributed to Berkeley by
15 * James A. Woods, derived from original work by Spencer Thomas
18 * Redistribution and use in source and binary forms, with or without
19 * modification, are permitted provided that the following conditions
21 * 1. Redistributions of source code must retain the above copyright
22 * notice, this list of conditions and the following disclaimer.
23 * 2. Redistributions in binary form must reproduce the above copyright
24 * notice, this list of conditions and the following disclaimer in the
25 * documentation and/or other materials provided with the distribution.
26 * 3. All advertising materials mentioning features or use of this software
27 * must display the following acknowledgement:
28 * This product includes software developed by the University of
29 * California, Berkeley and its contributors.
30 * 4. Neither the name of the University nor the names of its contributors
31 * may be used to endorse or promote products derived from this software
32 * without specific prior written permission.
34 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
35 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
36 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
37 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
38 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
39 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
40 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
41 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
42 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
43 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
48 * This version is for use with contiguous buffers on Linux-derived systems.
50 * ==FILEVERSION 20000226==
52 * NOTE TO MAINTAINERS:
53 * If you modify this file at all, please set the number above to the
54 * date of the modification as YYMMDD (year month day).
55 * bsd_comp.c is shipped with a PPP distribution as well as with
56 * the kernel; if everyone increases the FILEVERSION number above,
57 * then scripts can do the right thing when deciding whether to
58 * install a new bsd_comp.c file. Don't change the format of that
59 * line otherwise, so the installation script can recognize it.
61 * From: bsd_comp.c,v 1.3 1994/12/08 01:59:58 paulus Exp
64 #include <linux/module.h>
65 #include <linux/init.h>
66 #include <linux/slab.h>
67 #include <linux/vmalloc.h>
68 #include <linux/string.h>
70 #include <linux/ppp_defs.h>
74 #include <linux/ppp-comp.h>
77 #include <asm/byteorder.h>
80 * PPP "BSD compress" compression
81 * The differences between this compression and the classic BSD LZW
82 * source are obvious from the requirement that the classic code worked
83 * with files while this handles arbitrarily long streams that
84 * are broken into packets. They are:
86 * When the code size expands, a block of junk is not emitted by
87 * the compressor and not expected by the decompressor.
89 * New codes are not necessarily assigned every time an old
90 * code is output by the compressor. This is because a packet
91 * end forces a code to be emitted, but does not imply that a
92 * new sequence has been seen.
94 * The compression ratio is checked at the first end of a packet
95 * after the appropriate gap. Besides simplifying and speeding
96 * things up, this makes it more likely that the transmitter
97 * and receiver will agree when the dictionary is cleared when
98 * compression is not going well.
102 * Macros to extract protocol version and number of bits
103 * from the third byte of the BSD Compress CCP configuration option.
106 #define BSD_VERSION(x) ((x) >> 5)
107 #define BSD_NBITS(x) ((x) & 0x1F)
109 #define BSD_CURRENT_VERSION 1
112 * A dictionary for doing BSD compress.
116 union { /* hash value */
119 #if defined(__LITTLE_ENDIAN) /* Little endian order */
120 unsigned short prefix
; /* preceding code */
121 unsigned char suffix
; /* last character of new code */
123 #elif defined(__BIG_ENDIAN) /* Big endian order */
125 unsigned char suffix
; /* last character of new code */
126 unsigned short prefix
; /* preceding code */
128 #error Endianness not defined...
132 unsigned short codem1
; /* output of hash table -1 */
133 unsigned short cptr
; /* map code to hash table entry */
137 int totlen
; /* length of this structure */
138 unsigned int hsize
; /* size of the hash table */
139 unsigned char hshift
; /* used in hash function */
140 unsigned char n_bits
; /* current bits/code */
141 unsigned char maxbits
; /* maximum bits/code */
142 unsigned char debug
; /* non-zero if debug desired */
143 unsigned char unit
; /* ppp unit number */
144 unsigned short seqno
; /* sequence # of next packet */
145 unsigned int mru
; /* size of receive (decompress) bufr */
146 unsigned int maxmaxcode
; /* largest valid code */
147 unsigned int max_ent
; /* largest code in use */
148 unsigned int in_count
; /* uncompressed bytes, aged */
149 unsigned int bytes_out
; /* compressed bytes, aged */
150 unsigned int ratio
; /* recent compression ratio */
151 unsigned int checkpoint
; /* when to next check the ratio */
152 unsigned int clear_count
; /* times dictionary cleared */
153 unsigned int incomp_count
; /* incompressible packets */
154 unsigned int incomp_bytes
; /* incompressible bytes */
155 unsigned int uncomp_count
; /* uncompressed packets */
156 unsigned int uncomp_bytes
; /* uncompressed bytes */
157 unsigned int comp_count
; /* compressed packets */
158 unsigned int comp_bytes
; /* compressed bytes */
159 unsigned short *lens
; /* array of lengths of codes */
160 struct bsd_dict
*dict
; /* dictionary */
163 #define BSD_OVHD 2 /* BSD compress overhead/packet */
164 #define MIN_BSD_BITS 9
165 #define BSD_INIT_BITS MIN_BSD_BITS
166 #define MAX_BSD_BITS 15
168 static void bsd_free (void *state
);
169 static void *bsd_alloc(unsigned char *options
, int opt_len
, int decomp
);
170 static void *bsd_comp_alloc (unsigned char *options
, int opt_len
);
171 static void *bsd_decomp_alloc (unsigned char *options
, int opt_len
);
173 static int bsd_init (void *db
, unsigned char *options
,
174 int opt_len
, int unit
, int debug
, int decomp
);
175 static int bsd_comp_init (void *state
, unsigned char *options
,
176 int opt_len
, int unit
, int opthdr
, int debug
);
177 static int bsd_decomp_init (void *state
, unsigned char *options
,
178 int opt_len
, int unit
, int opthdr
, int mru
,
181 static void bsd_reset (void *state
);
182 static void bsd_comp_stats (void *state
, struct compstat
*stats
);
184 static int bsd_compress (void *state
, unsigned char *rptr
,
185 unsigned char *obuf
, int isize
, int osize
);
186 static void bsd_incomp (void *state
, unsigned char *ibuf
, int icnt
);
188 static int bsd_decompress (void *state
, unsigned char *ibuf
, int isize
,
189 unsigned char *obuf
, int osize
);
191 /* These are in ppp_generic.c */
192 extern int ppp_register_compressor (struct compressor
*cp
);
193 extern void ppp_unregister_compressor (struct compressor
*cp
);
196 * the next two codes should not be changed lightly, as they must not
197 * lie within the contiguous general code space.
199 #define CLEAR 256 /* table clear output code */
200 #define FIRST 257 /* first free entry */
203 #define MAXCODE(b) ((1 << (b)) - 1)
204 #define BADCODEM1 MAXCODE(MAX_BSD_BITS);
206 #define BSD_HASH(prefix,suffix,hshift) ((((unsigned long)(suffix))<<(hshift)) \
207 ^ (unsigned long)(prefix))
208 #define BSD_KEY(prefix,suffix) ((((unsigned long)(suffix)) << 16) \
209 + (unsigned long)(prefix))
211 #define CHECK_GAP 10000 /* Ratio check interval */
213 #define RATIO_SCALE_LOG 8
214 #define RATIO_SCALE (1<<RATIO_SCALE_LOG)
215 #define RATIO_MAX (0x7fffffff>>RATIO_SCALE_LOG)
218 * clear the dictionary
222 bsd_clear(struct bsd_db
*db
)
225 db
->max_ent
= FIRST
-1;
226 db
->n_bits
= BSD_INIT_BITS
;
230 db
->checkpoint
= CHECK_GAP
;
234 * If the dictionary is full, then see if it is time to reset it.
236 * Compute the compression ratio using fixed-point arithmetic
237 * with 8 fractional bits.
239 * Since we have an infinite stream instead of a single file,
240 * watch only the local compression ratio.
242 * Since both peers must reset the dictionary at the same time even in
243 * the absence of CLEAR codes (while packets are incompressible), they
244 * must compute the same ratio.
247 static int bsd_check (struct bsd_db
*db
) /* 1=output CLEAR */
249 unsigned int new_ratio
;
251 if (db
->in_count
>= db
->checkpoint
)
253 /* age the ratio by limiting the size of the counts */
254 if (db
->in_count
>= RATIO_MAX
|| db
->bytes_out
>= RATIO_MAX
)
256 db
->in_count
-= (db
->in_count
>> 2);
257 db
->bytes_out
-= (db
->bytes_out
>> 2);
260 db
->checkpoint
= db
->in_count
+ CHECK_GAP
;
262 if (db
->max_ent
>= db
->maxmaxcode
)
264 /* Reset the dictionary only if the ratio is worse,
265 * or if it looks as if it has been poisoned
266 * by incompressible data.
268 * This does not overflow, because
269 * db->in_count <= RATIO_MAX.
272 new_ratio
= db
->in_count
<< RATIO_SCALE_LOG
;
273 if (db
->bytes_out
!= 0)
275 new_ratio
/= db
->bytes_out
;
278 if (new_ratio
< db
->ratio
|| new_ratio
< 1 * RATIO_SCALE
)
283 db
->ratio
= new_ratio
;
293 static void bsd_comp_stats (void *state
, struct compstat
*stats
)
295 struct bsd_db
*db
= (struct bsd_db
*) state
;
297 stats
->unc_bytes
= db
->uncomp_bytes
;
298 stats
->unc_packets
= db
->uncomp_count
;
299 stats
->comp_bytes
= db
->comp_bytes
;
300 stats
->comp_packets
= db
->comp_count
;
301 stats
->inc_bytes
= db
->incomp_bytes
;
302 stats
->inc_packets
= db
->incomp_count
;
303 stats
->in_count
= db
->in_count
;
304 stats
->bytes_out
= db
->bytes_out
;
308 * Reset state, as on a CCP ResetReq.
311 static void bsd_reset (void *state
)
313 struct bsd_db
*db
= (struct bsd_db
*) state
;
322 * Release the compression structure
325 static void bsd_free (void *state
)
327 struct bsd_db
*db
= state
;
333 * Release the dictionary
338 * Release the string buffer
343 * Finally release the structure itself.
349 * Allocate space for a (de) compressor.
352 static void *bsd_alloc (unsigned char *options
, int opt_len
, int decomp
)
355 unsigned int hsize
, hshift
, maxmaxcode
;
358 if (opt_len
!= 3 || options
[0] != CI_BSD_COMPRESS
|| options
[1] != 3
359 || BSD_VERSION(options
[2]) != BSD_CURRENT_VERSION
)
364 bits
= BSD_NBITS(options
[2]);
368 case 9: /* needs 82152 for both directions */
369 case 10: /* needs 84144 */
370 case 11: /* needs 88240 */
371 case 12: /* needs 96432 */
375 case 13: /* needs 176784 */
379 case 14: /* needs 353744 */
383 case 15: /* needs 691440 */
387 case 16: /* needs 1366160--far too much, */
388 /* hsize = 69001; */ /* and 69001 is too big for cptr */
389 /* hshift = 8; */ /* in struct bsd_db */
395 * Allocate the main control structure for this instance.
397 maxmaxcode
= MAXCODE(bits
);
398 db
= kzalloc(sizeof (struct bsd_db
),
406 * Allocate space for the dictionary. This may be more than one page in
409 db
->dict
= (struct bsd_dict
*) vmalloc (hsize
*
410 sizeof (struct bsd_dict
));
418 * If this is the compression buffer then there is no length data.
425 * For decompression, the length information is needed as well.
429 db
->lens
= (unsigned short *) vmalloc ((maxmaxcode
+ 1) *
430 sizeof (db
->lens
[0]));
438 * Initialize the data information for the compression code
440 db
->totlen
= sizeof (struct bsd_db
) +
441 (sizeof (struct bsd_dict
) * hsize
);
445 db
->maxmaxcode
= maxmaxcode
;
451 static void *bsd_comp_alloc (unsigned char *options
, int opt_len
)
453 return bsd_alloc (options
, opt_len
, 0);
456 static void *bsd_decomp_alloc (unsigned char *options
, int opt_len
)
458 return bsd_alloc (options
, opt_len
, 1);
462 * Initialize the database.
465 static int bsd_init (void *state
, unsigned char *options
,
466 int opt_len
, int unit
, int debug
, int decomp
)
468 struct bsd_db
*db
= state
;
471 if ((opt_len
!= 3) || (options
[0] != CI_BSD_COMPRESS
) || (options
[1] != 3)
472 || (BSD_VERSION(options
[2]) != BSD_CURRENT_VERSION
)
473 || (BSD_NBITS(options
[2]) != db
->maxbits
)
474 || (decomp
&& db
->lens
== NULL
))
492 db
->dict
[indx
].codem1
= BADCODEM1
;
493 db
->dict
[indx
].cptr
= 0;
508 static int bsd_comp_init (void *state
, unsigned char *options
,
509 int opt_len
, int unit
, int opthdr
, int debug
)
511 return bsd_init (state
, options
, opt_len
, unit
, debug
, 0);
514 static int bsd_decomp_init (void *state
, unsigned char *options
,
515 int opt_len
, int unit
, int opthdr
, int mru
,
518 return bsd_init (state
, options
, opt_len
, unit
, debug
, 1);
522 * Obtain pointers to the various structures in the compression tables
525 #define dict_ptrx(p,idx) &(p->dict[idx])
526 #define lens_ptrx(p,idx) &(p->lens[idx])
529 static unsigned short *lens_ptr(struct bsd_db
*db
, int idx
)
531 if ((unsigned int) idx
> (unsigned int) db
->maxmaxcode
)
533 printk ("<9>ppp: lens_ptr(%d) > max\n", idx
);
536 return lens_ptrx (db
, idx
);
539 static struct bsd_dict
*dict_ptr(struct bsd_db
*db
, int idx
)
541 if ((unsigned int) idx
>= (unsigned int) db
->hsize
)
543 printk ("<9>ppp: dict_ptr(%d) > max\n", idx
);
546 return dict_ptrx (db
, idx
);
550 #define lens_ptr(db,idx) lens_ptrx(db,idx)
551 #define dict_ptr(db,idx) dict_ptrx(db,idx)
557 * The result of this function is the size of the compressed
558 * packet. A zero is returned if the packet was not compressed
559 * for some reason, such as the size being larger than uncompressed.
561 * One change from the BSD compress command is that when the
562 * code size expands, we do not output a bunch of padding.
565 static int bsd_compress (void *state
, unsigned char *rptr
, unsigned char *obuf
,
566 int isize
, int osize
)
570 unsigned int max_ent
;
576 struct bsd_dict
*dictp
;
590 *wptr++ = (unsigned char) (v); \
598 #define OUTPUT(ent) \
601 accm |= ((ent) << bitno); \
604 PUTBYTE(accm >> 24); \
608 while (bitno <= 24); \
612 * If the protocol is not in the range we're interested in,
613 * just return without compressing the packet. If it is,
614 * the protocol becomes the first byte to compress.
617 ent
= PPP_PROTOCOL(rptr
);
618 if (ent
< 0x21 || ent
> 0xf9)
623 db
= (struct bsd_db
*) state
;
625 max_ent
= db
->max_ent
;
629 mxcode
= MAXCODE (n_bits
);
631 /* Initialize the output pointers */
633 olen
= PPP_HDRLEN
+ BSD_OVHD
;
640 /* This is the PPP header information */
643 *wptr
++ = PPP_ADDRESS(rptr
);
644 *wptr
++ = PPP_CONTROL(rptr
);
647 *wptr
++ = db
->seqno
>> 8;
651 /* Skip the input header */
654 ilen
= ++isize
; /* Low byte of protocol is counted as input */
659 fcode
= BSD_KEY (ent
, c
);
660 hval
= BSD_HASH (ent
, c
, hshift
);
661 dictp
= dict_ptr (db
, hval
);
663 /* Validate and then check the entry. */
664 if (dictp
->codem1
>= max_ent
)
669 if (dictp
->f
.fcode
== fcode
)
671 ent
= dictp
->codem1
+ 1;
672 continue; /* found (prefix,suffix) */
675 /* continue probing until a match or invalid entry */
676 disp
= (hval
== 0) ? 1 : hval
;
681 if (hval
>= db
->hsize
)
685 dictp
= dict_ptr (db
, hval
);
686 if (dictp
->codem1
>= max_ent
)
691 while (dictp
->f
.fcode
!= fcode
);
693 ent
= dictp
->codem1
+ 1; /* finally found (prefix,suffix) */
697 OUTPUT(ent
); /* output the prefix */
699 /* code -> hashtable */
700 if (max_ent
< db
->maxmaxcode
)
702 struct bsd_dict
*dictp2
;
703 struct bsd_dict
*dictp3
;
706 /* expand code size if needed */
707 if (max_ent
>= mxcode
)
709 db
->n_bits
= ++n_bits
;
710 mxcode
= MAXCODE (n_bits
);
713 /* Invalidate old hash table entry using
714 * this code, and then take it over.
717 dictp2
= dict_ptr (db
, max_ent
+ 1);
719 dictp3
= dict_ptr (db
, indx
);
721 if (dictp3
->codem1
== max_ent
)
723 dictp3
->codem1
= BADCODEM1
;
727 dictp
->codem1
= max_ent
;
728 dictp
->f
.fcode
= fcode
;
729 db
->max_ent
= ++max_ent
;
733 unsigned short *len1
= lens_ptr (db
, max_ent
);
734 unsigned short *len2
= lens_ptr (db
, ent
);
741 OUTPUT(ent
); /* output the last code */
743 db
->bytes_out
+= olen
- PPP_HDRLEN
- BSD_OVHD
;
744 db
->uncomp_bytes
+= isize
;
745 db
->in_count
+= isize
;
751 ++db
->bytes_out
; /* must be set before calling bsd_check */
755 * Generate the clear command if needed
764 * Pad dribble bits of last code with ones.
765 * Do not emit a completely useless byte of ones.
770 PUTBYTE((accm
| (0xff << (bitno
-8))) >> 24);
774 * Increase code size if we would have without the packet
775 * boundary because the decompressor will do so.
778 if (max_ent
>= mxcode
&& max_ent
< db
->maxmaxcode
)
783 /* If output length is too large then this is an incomplete frame. */
787 db
->incomp_bytes
+= isize
;
790 else /* Count the number of compressed frames */
793 db
->comp_bytes
+= olen
;
796 /* Return the resulting output length */
803 * Update the "BSD Compress" dictionary on the receiver for
804 * incompressible data by pretending to compress the incoming data.
807 static void bsd_incomp (void *state
, unsigned char *ibuf
, int icnt
)
809 (void) bsd_compress (state
, ibuf
, (char *) 0, icnt
, 0);
813 * Decompress "BSD Compress".
815 * Because of patent problems, we return DECOMP_ERROR for errors
816 * found by inspecting the input data and for system problems, but
817 * DECOMP_FATALERROR for any errors which could possibly be said to
818 * be being detected "after" decompression. For DECOMP_ERROR,
819 * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be
820 * infringing a patent of Motorola's if we do, so we take CCP down
823 * Given that the frame has the correct sequence number and a good FCS,
824 * errors such as invalid codes in the input most likely indicate a
825 * bug, so we return DECOMP_FATALERROR for them in order to turn off
826 * compression, even though they are detected by inspecting the input.
829 static int bsd_decompress (void *state
, unsigned char *ibuf
, int isize
,
830 unsigned char *obuf
, int osize
)
833 unsigned int max_ent
;
835 unsigned int bitno
; /* 1st valid bit in accm */
837 unsigned int tgtbitno
; /* bitno when we have a code */
838 struct bsd_dict
*dictp
;
842 unsigned int oldcode
;
843 unsigned int finchar
;
852 db
= (struct bsd_db
*) state
;
853 max_ent
= db
->max_ent
;
855 bitno
= 32; /* 1st valid bit in accm */
857 tgtbitno
= 32 - n_bits
; /* bitno when we have a code */
860 * Save the address/control from the PPP header
861 * and then get the sequence number.
864 adrs
= PPP_ADDRESS (ibuf
);
865 ctrl
= PPP_CONTROL (ibuf
);
867 seq
= (ibuf
[4] << 8) + ibuf
[5];
869 ibuf
+= (PPP_HDRLEN
+ 2);
870 ilen
= isize
- (PPP_HDRLEN
+ 2);
873 * Check the sequence number and give up if it differs from
874 * the value we're expecting.
877 if (seq
!= db
->seqno
)
881 printk("bsd_decomp%d: bad sequence # %d, expected %d\n",
882 db
->unit
, seq
, db
->seqno
- 1);
888 db
->bytes_out
+= ilen
;
891 * Fill in the ppp header, but not the last byte of the protocol
892 * (that comes from the decompressed data).
904 * Keep the checkpoint correctly so that incompressible packets
905 * clear the dictionary at the proper times.
912 db
->in_count
+= (explen
- 3); /* don't count the header */
917 * Accumulate bytes until we have a complete code.
918 * Then get the next code, relying on the 32-bit,
919 * unsigned accm to mask the result.
923 accm
|= *ibuf
++ << bitno
;
924 if (tgtbitno
< bitno
)
929 incode
= accm
>> tgtbitno
;
934 * The dictionary must only be cleared at the end of a packet.
943 printk("bsd_decomp%d: bad CLEAR\n", db
->unit
);
945 return DECOMP_FATALERROR
; /* probably a bug */
952 if ((incode
> max_ent
+ 2) || (incode
> db
->maxmaxcode
)
953 || (incode
> max_ent
&& oldcode
== CLEAR
))
957 printk("bsd_decomp%d: bad code 0x%x oldcode=0x%x ",
958 db
->unit
, incode
, oldcode
);
959 printk("max_ent=0x%x explen=%d seqno=%d\n",
960 max_ent
, explen
, db
->seqno
);
962 return DECOMP_FATALERROR
; /* probably a bug */
965 /* Special case for KwKwK string. */
966 if (incode
> max_ent
)
977 codelen
= *(lens_ptr (db
, finchar
));
978 explen
+= codelen
+ extra
;
983 printk("bsd_decomp%d: ran out of mru\n", db
->unit
);
985 printk(" len=%d, finchar=0x%x, codelen=%d, explen=%d\n",
986 ilen
, finchar
, codelen
, explen
);
989 return DECOMP_FATALERROR
;
993 * Decode this code and install it in the decompressed buffer.
998 while (finchar
> LAST
)
1000 struct bsd_dict
*dictp2
= dict_ptr (db
, finchar
);
1002 dictp
= dict_ptr (db
, dictp2
->cptr
);
1004 if (--codelen
<= 0 || dictp
->codem1
!= finchar
-1)
1008 printk("bsd_decomp%d: fell off end of chain ", db
->unit
);
1009 printk("0x%x at 0x%x by 0x%x, max_ent=0x%x\n",
1010 incode
, finchar
, dictp2
->cptr
, max_ent
);
1014 if (dictp
->codem1
!= finchar
-1)
1016 printk("bsd_decomp%d: bad code chain 0x%x "
1018 db
->unit
, incode
, finchar
);
1020 printk("oldcode=0x%x cptr=0x%x codem1=0x%x\n",
1021 oldcode
, dictp2
->cptr
, dictp
->codem1
);
1024 return DECOMP_FATALERROR
;
1027 *--p
= dictp
->f
.hs
.suffix
;
1028 finchar
= dictp
->f
.hs
.prefix
;
1035 printk("bsd_decomp%d: short by %d after code 0x%x, max_ent=0x%x\n",
1036 db
->unit
, codelen
, incode
, max_ent
);
1040 if (extra
) /* the KwKwK case again */
1046 * If not first code in a packet, and
1047 * if not out of code space, then allocate a new code.
1049 * Keep the hash table correct so it can be used
1050 * with uncompressed packets.
1053 if (oldcode
!= CLEAR
&& max_ent
< db
->maxmaxcode
)
1055 struct bsd_dict
*dictp2
, *dictp3
;
1056 unsigned short *lens1
, *lens2
;
1057 unsigned long fcode
;
1058 int hval
, disp
, indx
;
1060 fcode
= BSD_KEY(oldcode
,finchar
);
1061 hval
= BSD_HASH(oldcode
,finchar
,db
->hshift
);
1062 dictp
= dict_ptr (db
, hval
);
1064 /* look for a free hash table entry */
1065 if (dictp
->codem1
< max_ent
)
1067 disp
= (hval
== 0) ? 1 : hval
;
1071 if (hval
>= db
->hsize
)
1075 dictp
= dict_ptr (db
, hval
);
1077 while (dictp
->codem1
< max_ent
);
1081 * Invalidate previous hash table entry
1082 * assigned this code, and then take it over
1085 dictp2
= dict_ptr (db
, max_ent
+ 1);
1086 indx
= dictp2
->cptr
;
1087 dictp3
= dict_ptr (db
, indx
);
1089 if (dictp3
->codem1
== max_ent
)
1091 dictp3
->codem1
= BADCODEM1
;
1094 dictp2
->cptr
= hval
;
1095 dictp
->codem1
= max_ent
;
1096 dictp
->f
.fcode
= fcode
;
1097 db
->max_ent
= ++max_ent
;
1099 /* Update the length of this string. */
1100 lens1
= lens_ptr (db
, max_ent
);
1101 lens2
= lens_ptr (db
, oldcode
);
1102 *lens1
= *lens2
+ 1;
1104 /* Expand code size if needed. */
1105 if (max_ent
>= MAXCODE(n_bits
) && max_ent
< db
->maxmaxcode
)
1107 db
->n_bits
= ++n_bits
;
1108 tgtbitno
= 32-n_bits
;
1116 db
->comp_bytes
+= isize
- BSD_OVHD
- PPP_HDRLEN
;
1117 db
->uncomp_bytes
+= explen
;
1123 printk("bsd_decomp%d: peer should have cleared dictionary on %d\n",
1124 db
->unit
, db
->seqno
- 1);
1130 /*************************************************************
1131 * Table of addresses for the BSD compression module
1132 *************************************************************/
1134 static struct compressor ppp_bsd_compress
= {
1135 .compress_proto
= CI_BSD_COMPRESS
,
1136 .comp_alloc
= bsd_comp_alloc
,
1137 .comp_free
= bsd_free
,
1138 .comp_init
= bsd_comp_init
,
1139 .comp_reset
= bsd_reset
,
1140 .compress
= bsd_compress
,
1141 .comp_stat
= bsd_comp_stats
,
1142 .decomp_alloc
= bsd_decomp_alloc
,
1143 .decomp_free
= bsd_free
,
1144 .decomp_init
= bsd_decomp_init
,
1145 .decomp_reset
= bsd_reset
,
1146 .decompress
= bsd_decompress
,
1147 .incomp
= bsd_incomp
,
1148 .decomp_stat
= bsd_comp_stats
,
1149 .owner
= THIS_MODULE
1152 /*************************************************************
1153 * Module support routines
1154 *************************************************************/
1156 static int __init
bsdcomp_init(void)
1158 int answer
= ppp_register_compressor(&ppp_bsd_compress
);
1160 printk(KERN_INFO
"PPP BSD Compression module registered\n");
1164 static void __exit
bsdcomp_cleanup(void)
1166 ppp_unregister_compressor(&ppp_bsd_compress
);
1169 module_init(bsdcomp_init
);
1170 module_exit(bsdcomp_cleanup
);
1171 MODULE_LICENSE("Dual BSD/GPL");
1172 MODULE_ALIAS("ppp-compress-" __stringify(CI_BSD_COMPRESS
));