1 /* Because this code is derived from the 4.3BSD compress source:
4 * Copyright (c) 1985, 1986 The Regents of the University of California.
7 * This code is derived from software contributed to Berkeley by
8 * James A. Woods, derived from original work by Spencer Thomas
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 * 3. All advertising materials mentioning features or use of this software
20 * must display the following acknowledgement:
21 * This product includes software developed by the University of
22 * California, Berkeley and its contributors.
23 * 4. Neither the name of the University nor the names of its contributors
24 * may be used to endorse or promote products derived from this software
25 * without specific prior written permission.
27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
30 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
41 * This version is for use with STREAMS under SunOS 4.x,
42 * DEC Alpha OSF/1, and AIX 4.x.
44 * $Id: bsd-comp.c,v 1.8 1994/12/08 00:35:33 paulus Exp $
48 #include <net/net_globals.h>
50 #include <sys/param.h>
51 #include <sys/types.h>
52 #include <sys/stream.h>
53 #include <sys/socket.h>
55 #include <net/ppp_defs.h>
56 #include <net/ppp_str.h>
59 #include <sys/kmem_alloc.h>
60 #define ALLOCATE(n) kmem_alloc((n), KMEM_NOSLEEP)
61 #define FREE(p, n) kmem_free((p), (n))
65 #include <kern/kalloc.h>
66 #define ALLOCATE(n) kalloc((n))
67 #define FREE(p, n) kfree((p), (n))
71 #define ALLOCATE(n) xmalloc((n), 0, pinned_heap)
72 #define FREE(p, n) xmfree((p), pinned_heap)
75 #define PACKETPTR mblk_t *
76 #include <net/ppp-comp.h>
79 * PPP "BSD compress" compression
80 * The differences between this compression and the classic BSD LZW
81 * source are obvious from the requirement that the classic code worked
82 * with files while this handles arbitrarily long streams that
83 * are broken into packets. They are:
85 * When the code size expands, a block of junk is not emitted by
86 * the compressor and not expected by the decompressor.
88 * New codes are not necessarily assigned every time an old
89 * code is output by the compressor. This is because a packet
90 * end forces a code to be emitted, but does not imply that a
91 * new sequence has been seen.
93 * The compression ratio is checked at the first end of a packet
94 * after the appropriate gap. Besides simplifying and speeding
95 * things up, this makes it more likely that the transmitter
96 * and receiver will agree when the dictionary is cleared when
97 * compression is not going well.
101 * Macros to extract protocol version and number of bits
102 * from the third byte of the BSD Compress CCP configuration option.
104 #define BSD_VERSION(x) ((x) >> 5)
105 #define BSD_NBITS(x) ((x) & 0x1F)
107 #define BSD_CURRENT_VERSION 1
110 * A dictionary for doing BSD compress.
113 int totlen; /* length of this structure */
114 u_int hsize; /* size of the hash table */
115 u_char hshift; /* used in hash function */
116 u_char n_bits; /* current bits/code */
120 u_short seqno; /* sequence number of next packet */
121 u_int hdrlen; /* header length to preallocate */
123 u_int maxmaxcode; /* largest valid code */
124 u_int max_ent; /* largest code in use */
125 u_int in_count; /* uncompressed bytes, aged */
126 u_int bytes_out; /* compressed bytes, aged */
127 u_int ratio; /* recent compression ratio */
128 u_int checkpoint; /* when to next check the ratio */
129 u_int clear_count; /* times dictionary cleared */
130 u_int incomp_count; /* incompressible packets */
131 u_int incomp_bytes; /* incompressible bytes */
132 u_int uncomp_count; /* uncompressed packets */
133 u_int uncomp_bytes; /* uncompressed bytes */
134 u_int comp_count; /* compressed packets */
135 u_int comp_bytes; /* compressed bytes */
136 u_short *lens; /* array of lengths of codes */
138 union { /* hash value */
141 #ifdef BSD_LITTLE_ENDIAN
142 u_short prefix; /* preceding code */
143 u_char suffix; /* last character of new code */
147 u_char suffix; /* last character of new code */
148 u_short prefix; /* preceding code */
152 u_short codem1; /* output of hash table -1 */
153 u_short cptr; /* map code to hash table entry */
157 #define BSD_OVHD 2 /* BSD compress overhead/packet */
158 #define MIN_BSD_BITS 9
159 #define BSD_INIT_BITS MIN_BSD_BITS
160 #define MAX_BSD_BITS 15
162 static void *bsd_comp_alloc __P((u_char *options, int opt_len));
163 static void *bsd_decomp_alloc __P((u_char *options, int opt_len));
164 static void bsd_free __P((void *state));
165 static int bsd_comp_init __P((void *state, u_char *options, int opt_len,
166 int unit, int debug));
167 static int bsd_decomp_init __P((void *state, u_char *options, int opt_len,
168 int unit, int hdrlen, int mru, int debug));
169 static int bsd_compress __P((void *state, mblk_t **mret,
170 mblk_t *mp, int slen, int maxolen));
171 static void bsd_incomp __P((void *state, mblk_t *dmsg));
172 static int bsd_decompress __P((void *state, mblk_t *cmp, mblk_t **dmpp));
173 static void bsd_reset __P((void *state));
174 static void bsd_comp_stats __P((void *state, struct compstat *stats));
177 * Procedures exported to ppp_comp.c.
179 struct compressor ppp_bsd_compress = {
180 0x21, /* compress_proto */
181 bsd_comp_alloc, /* comp_alloc */
182 bsd_free, /* comp_free */
183 bsd_comp_init, /* comp_init */
184 bsd_reset, /* comp_reset */
185 bsd_compress, /* compress */
186 bsd_comp_stats, /* comp_stat */
187 bsd_decomp_alloc, /* decomp_alloc */
188 bsd_free, /* decomp_free */
189 bsd_decomp_init, /* decomp_init */
190 bsd_reset, /* decomp_reset */
191 bsd_decompress, /* decompress */
192 bsd_incomp, /* incomp */
193 bsd_comp_stats, /* decomp_stat */
197 * the next two codes should not be changed lightly, as they must not
198 * lie within the contiguous general code space.
200 #define CLEAR 256 /* table clear output code */
201 #define FIRST 257 /* first free entry */
204 #define MAXCODE(b) ((1 << (b)) - 1)
205 #define BADCODEM1 MAXCODE(MAX_BSD_BITS);
207 #define BSD_HASH(prefix,suffix,hshift) ((((u_int32_t)(suffix)) << (hshift)) \
208 ^ (u_int32_t)(prefix))
209 #define BSD_KEY(prefix,suffix) ((((u_int32_t)(suffix)) << 16) \
210 + (u_int32_t)(prefix))
212 #define CHECK_GAP 10000 /* Ratio check interval */
214 #define RATIO_SCALE_LOG 8
215 #define RATIO_SCALE (1<<RATIO_SCALE_LOG)
216 #define RATIO_MAX (0x7fffffff>>RATIO_SCALE_LOG)
218 #define DECOMP_CHUNK 256
221 * clear the dictionary
228 db->max_ent = FIRST-1;
229 db->n_bits = BSD_INIT_BITS;
233 db->incomp_count = 0;
234 db->checkpoint = CHECK_GAP;
238 * If the dictionary is full, then see if it is time to reset it.
240 * Compute the compression ratio using fixed-point arithmetic
241 * with 8 fractional bits.
243 * Since we have an infinite stream instead of a single file,
244 * watch only the local compression ratio.
246 * Since both peers must reset the dictionary at the same time even in
247 * the absence of CLEAR codes (while packets are incompressible), they
248 * must compute the same ratio.
250 static int /* 1=output CLEAR */
256 if (db->in_count >= db->checkpoint) {
257 /* age the ratio by limiting the size of the counts */
258 if (db->in_count >= RATIO_MAX
259 || db->bytes_out >= RATIO_MAX) {
260 db->in_count -= db->in_count/4;
261 db->bytes_out -= db->bytes_out/4;
264 db->checkpoint = db->in_count + CHECK_GAP;
266 if (db->max_ent >= db->maxmaxcode) {
267 /* Reset the dictionary only if the ratio is worse,
268 * or if it looks as if it has been poisoned
269 * by incompressible data.
271 * This does not overflow, because
272 * db->in_count <= RATIO_MAX.
274 new_ratio = db->in_count << RATIO_SCALE_LOG;
275 if (db->bytes_out != 0)
276 new_ratio /= db->bytes_out;
278 if (new_ratio < db->ratio || new_ratio < 1 * RATIO_SCALE) {
282 db->ratio = new_ratio;
292 bsd_comp_stats(state, stats)
294 struct compstat *stats;
296 struct bsd_db *db = (struct bsd_db *) state;
299 stats->unc_bytes = db->uncomp_bytes;
300 stats->unc_packets = db->uncomp_count;
301 stats->comp_bytes = db->comp_bytes;
302 stats->comp_packets = db->comp_count;
303 stats->inc_bytes = db->incomp_bytes;
304 stats->inc_packets = db->incomp_count;
305 stats->ratio = db->in_count;
307 if (stats->ratio <= 0x7fffff)
316 * Reset state, as on a CCP ResetReq.
322 struct bsd_db *db = (struct bsd_db *) state;
330 * Allocate space for a (de) compressor.
333 bsd_alloc(options, opt_len, decomp)
338 u_int newlen, hsize, hshift, maxmaxcode;
341 if (opt_len != 3 || options[0] != 0x21 || options[1] != 3
342 || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION)
344 bits = BSD_NBITS(options[2]);
346 case 9: /* needs 82152 for both directions */
347 case 10: /* needs 84144 */
348 case 11: /* needs 88240 */
349 case 12: /* needs 96432 */
353 case 13: /* needs 176784 */
357 case 14: /* needs 353744 */
361 case 15: /* needs 691440 */
365 case 16: /* needs 1366160--far too much, */
366 /* hsize = 69001; */ /* and 69001 is too big for cptr */
367 /* hshift = 8; */ /* in struct bsd_db */
373 maxmaxcode = MAXCODE(bits);
374 newlen = sizeof(*db) + (hsize-1) * (sizeof(db->dict[0]));
375 db = (struct bsd_db *) ALLOCATE(newlen);
378 bzero(db, sizeof(*db) - sizeof(db->dict));
383 db->lens = (u_short *) ALLOCATE((maxmaxcode+1) * sizeof(db->lens[0]));
393 db->maxmaxcode = maxmaxcode;
403 struct bsd_db *db = (struct bsd_db *) state;
406 FREE(db->lens, (db->maxmaxcode+1) * sizeof(db->lens[0]));
407 FREE(db, db->totlen);
411 bsd_comp_alloc(options, opt_len)
415 return bsd_alloc(options, opt_len, 0);
419 bsd_decomp_alloc(options, opt_len)
423 return bsd_alloc(options, opt_len, 1);
427 * Initialize the database.
430 bsd_init(db, options, opt_len, unit, hdrlen, mru, debug, decomp)
433 int opt_len, unit, hdrlen, mru, debug, decomp;
437 if (opt_len != 3 || options[0] != 0x21 || options[1] != 3
438 || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION
439 || BSD_NBITS(options[2]) != db->maxbits
440 || decomp && db->lens == NULL)
450 db->dict[--i].codem1 = BADCODEM1;
451 db->dict[i].cptr = 0;
466 bsd_comp_init(state, options, opt_len, unit, debug)
469 int opt_len, unit, debug;
471 return bsd_init((struct bsd_db *) state, options, opt_len,
472 unit, 0, 0, debug, 0);
476 bsd_decomp_init(state, options, opt_len, unit, hdrlen, mru, debug)
479 int opt_len, unit, hdrlen, mru, debug;
481 return bsd_init((struct bsd_db *) state, options, opt_len,
482 unit, hdrlen, mru, debug, 1);
488 * One change from the BSD compress command is that when the
489 * code size expands, we do not output a bunch of padding.
491 static int /* new slen */
492 bsd_compress(state, mretp, mp, slen, maxolen)
494 mblk_t **mretp; /* return compressed mbuf chain here */
495 mblk_t *mp; /* from here */
496 int slen; /* uncompressed length */
497 int maxolen; /* max compressed length */
499 struct bsd_db *db = (struct bsd_db *) state;
500 int hshift = db->hshift;
501 u_int max_ent = db->max_ent;
502 u_int n_bits = db->n_bits;
504 u_int32_t accm = 0, fcode;
505 struct bsd_dict *dictp;
507 int hval, disp, ent, ilen;
514 #define PUTBYTE(v) { \
517 if (wptr >= cp_end) { \
522 cp_end = m->b_datap->db_lim; \
530 #define OUTPUT(ent) { \
532 accm |= ((ent) << bitno); \
534 PUTBYTE(accm >> 24); \
537 } while (bitno <= 24); \
541 * First get the protocol and check that we're
542 * interested in this packet.
546 if (rptr + PPP_HDRLEN > mp->b_wptr) {
547 if (!pullupmsg(mp, PPP_HDRLEN))
551 ent = PPP_PROTOCOL(rptr); /* get the protocol */
552 if (ent < 0x21 || ent > 0xf9)
555 /* Don't generate compressed packets which are larger than
556 the uncompressed packet. */
560 /* Allocate enough message blocks to give maxolen total space. */
562 for (olen = maxolen; olen > 0; ) {
563 m = allocb((olen < 4096? olen: 4096), BPRI_MED);
573 olen -= m->b_datap->db_lim - m->b_wptr;
577 if ((m = mret) != NULL) {
579 cp_end = m->b_datap->db_lim;
581 wptr = cp_end = NULL;
585 * Copy the PPP header over, changing the protocol,
586 * and install the 2-byte sequence number.
589 wptr[0] = PPP_ADDRESS(rptr);
590 wptr[1] = PPP_CONTROL(rptr);
591 wptr[2] = 0; /* change the protocol */
593 wptr[4] = db->seqno >> 8;
595 wptr += PPP_HDRLEN + BSD_OVHD;
600 slen = mp->b_wptr - rptr;
608 slen = np->b_wptr - rptr;
611 continue; /* handle 0-length buffers */
617 fcode = BSD_KEY(ent, c);
618 hval = BSD_HASH(ent, c, hshift);
619 dictp = &db->dict[hval];
621 /* Validate and then check the entry. */
622 if (dictp->codem1 >= max_ent)
624 if (dictp->f.fcode == fcode) {
625 ent = dictp->codem1+1;
626 continue; /* found (prefix,suffix) */
629 /* continue probing until a match or invalid entry */
630 disp = (hval == 0) ? 1 : hval;
633 if (hval >= db->hsize)
635 dictp = &db->dict[hval];
636 if (dictp->codem1 >= max_ent)
638 } while (dictp->f.fcode != fcode);
639 ent = dictp->codem1 + 1; /* finally found (prefix,suffix) */
643 OUTPUT(ent); /* output the prefix */
645 /* code -> hashtable */
646 if (max_ent < db->maxmaxcode) {
647 struct bsd_dict *dictp2;
648 /* expand code size if needed */
649 if (max_ent >= MAXCODE(n_bits))
650 db->n_bits = ++n_bits;
652 /* Invalidate old hash table entry using
653 * this code, and then take it over.
655 dictp2 = &db->dict[max_ent+1];
656 if (db->dict[dictp2->cptr].codem1 == max_ent)
657 db->dict[dictp2->cptr].codem1 = BADCODEM1;
659 dictp->codem1 = max_ent;
660 dictp->f.fcode = fcode;
662 db->max_ent = ++max_ent;
667 OUTPUT(ent); /* output the last code */
668 db->bytes_out += olen;
669 db->in_count += ilen;
671 ++db->bytes_out; /* count complete bytes */
674 OUTPUT(CLEAR); /* do not count the CLEAR */
677 * Pad dribble bits of last code with ones.
678 * Do not emit a completely useless byte of ones.
681 PUTBYTE((accm | (0xff << (bitno-8))) >> 24);
684 * Increase code size if we would have without the packet
685 * boundary and as the decompressor will.
687 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode)
690 db->uncomp_bytes += ilen;
692 if (olen + PPP_HDRLEN + BSD_OVHD > maxolen && mret != NULL) {
693 /* throw away the compressed stuff if it is longer than uncompressed */
697 db->incomp_bytes += ilen;
698 } else if (wptr != NULL) {
705 db->comp_bytes += olen + BSD_OVHD;
709 return olen + PPP_HDRLEN + BSD_OVHD;
716 * Update the "BSD Compress" dictionary on the receiver for
717 * incompressible data by pretending to compress the incoming data.
720 bsd_incomp(state, dmsg)
724 struct bsd_db *db = (struct bsd_db *) state;
725 u_int hshift = db->hshift;
726 u_int max_ent = db->max_ent;
727 u_int n_bits = db->n_bits;
728 struct bsd_dict *dictp;
738 if (rptr + PPP_HDRLEN > dmsg->b_wptr) {
739 if (!pullupmsg(dmsg, PPP_HDRLEN))
743 ent = PPP_PROTOCOL(rptr); /* get the protocol */
744 if (ent < 0x21 || ent > 0xf9)
749 ilen = 1; /* count the protocol as 1 byte */
752 slen = dmsg->b_wptr - rptr;
758 continue; /* skip zero-length buffers */
764 fcode = BSD_KEY(ent, c);
765 hval = BSD_HASH(ent, c, hshift);
766 dictp = &db->dict[hval];
768 /* validate and then check the entry */
769 if (dictp->codem1 >= max_ent)
771 if (dictp->f.fcode == fcode) {
772 ent = dictp->codem1+1;
773 continue; /* found (prefix,suffix) */
776 /* continue probing until a match or invalid entry */
777 disp = (hval == 0) ? 1 : hval;
780 if (hval >= db->hsize)
782 dictp = &db->dict[hval];
783 if (dictp->codem1 >= max_ent)
785 } while (dictp->f.fcode != fcode);
786 ent = dictp->codem1+1;
787 continue; /* finally found (prefix,suffix) */
789 nomatch: /* output (count) the prefix */
792 /* code -> hashtable */
793 if (max_ent < db->maxmaxcode) {
794 struct bsd_dict *dictp2;
795 /* expand code size if needed */
796 if (max_ent >= MAXCODE(n_bits))
797 db->n_bits = ++n_bits;
799 /* Invalidate previous hash table entry
800 * assigned this code, and then take it over.
802 dictp2 = &db->dict[max_ent+1];
803 if (db->dict[dictp2->cptr].codem1 == max_ent)
804 db->dict[dictp2->cptr].codem1 = BADCODEM1;
806 dictp->codem1 = max_ent;
807 dictp->f.fcode = fcode;
809 db->max_ent = ++max_ent;
810 db->lens[max_ent] = db->lens[ent]+1;
813 } while (--slen != 0);
815 bitno += n_bits; /* output (count) the last code */
816 db->bytes_out += bitno/8;
817 db->in_count += ilen;
821 db->incomp_bytes += ilen;
823 db->uncomp_bytes += ilen;
825 /* Increase code size if we would have without the packet
826 * boundary and as the decompressor will.
828 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode)
834 * Decompress "BSD Compress"
836 * Because of patent problems, we return DECOMP_ERROR for errors
837 * found by inspecting the input data and for system problems, but
838 * DECOMP_FATALERROR for any errors which could possibly be said to
839 * be being detected "after" decompression. For DECOMP_ERROR,
840 * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be
841 * infringing a patent of Motorola's if we do, so we take CCP down
844 * Given that the frame has the correct sequence number and a good FCS,
845 * errors such as invalid codes in the input most likely indicate a
846 * bug, so we return DECOMP_FATALERROR for them in order to turn off
847 * compression, even though they are detected by inspecting the input.
850 bsd_decompress(state, cmsg, dmpp)
852 mblk_t *cmsg, **dmpp;
854 struct bsd_db *db = (struct bsd_db *) state;
855 u_int max_ent = db->max_ent;
857 u_int bitno = 32; /* 1st valid bit in accm */
858 u_int n_bits = db->n_bits;
859 u_int tgtbitno = 32-n_bits; /* bitno when we have a code */
860 struct bsd_dict *dictp;
861 int explen, i, seq, len;
862 u_int incode, oldcode, finchar;
863 u_char *p, *rptr, *wptr;
865 int adrs, ctrl, ilen;
866 int dlen, space, codelen, extra;
869 * Get at least the BSD Compress header in the first buffer
872 if (rptr + PPP_HDRLEN + BSD_OVHD >= cmsg->b_wptr) {
873 if (!pullupmsg(cmsg, PPP_HDRLEN + BSD_OVHD + 1)) {
875 printf("bsd_decomp%d: failed to pullup\n", db->unit);
882 * Save the address/control from the PPP header
883 * and then get the sequence number.
885 adrs = PPP_ADDRESS(rptr);
886 ctrl = PPP_CONTROL(rptr);
888 seq = (rptr[0] << 8) + rptr[1];
890 ilen = len = cmsg->b_wptr - rptr;
893 * Check the sequence number and give up if it is not what we expect.
895 if (seq != db->seqno++) {
897 printf("bsd_decomp%d: bad sequence # %d, expected %d\n",
898 db->unit, seq, db->seqno - 1);
903 * Allocate one message block to start with.
905 if ((dmsg = allocb(DECOMP_CHUNK + db->hdrlen, BPRI_MED)) == NULL)
908 dmsg->b_wptr += db->hdrlen;
909 dmsg->b_rptr = wptr = dmsg->b_wptr;
911 /* Fill in the ppp header, but not the last byte of the protocol
912 (that comes from the decompressed data). */
916 wptr += PPP_HDRLEN - 1;
917 space = dmsg->b_datap->db_lim - wptr;
924 if (!cmsg) /* quit at end of message */
927 len = cmsg->b_wptr - rptr;
929 continue; /* handle 0-length buffers */
933 * Accumulate bytes until we have a complete code.
934 * Then get the next code, relying on the 32-bit,
935 * unsigned accm to mask the result.
938 accm |= *rptr++ << bitno;
940 if (tgtbitno < bitno)
942 incode = accm >> tgtbitno;
946 if (incode == CLEAR) {
948 * The dictionary must only be cleared at
949 * the end of a packet. But there could be an
950 * empty message block at the end.
952 if (len > 0 || cmsg->b_cont != 0) {
954 len += msgdsize(cmsg->b_cont);
958 printf("bsd_decomp%d: bad CLEAR\n", db->unit);
959 return DECOMP_FATALERROR;
967 if (incode > max_ent + 2 || incode > db->maxmaxcode
968 || incode > max_ent && oldcode == CLEAR) {
971 printf("bsd_decomp%d: bad code 0x%x oldcode=0x%x ",
972 db->unit, incode, oldcode);
973 printf("max_ent=0x%x dlen=%d seqno=%d\n",
974 max_ent, dlen, db->seqno);
976 return DECOMP_FATALERROR; /* probably a bug */
979 /* Special case for KwKwK string. */
980 if (incode > max_ent) {
988 codelen = db->lens[finchar];
989 explen += codelen + extra;
990 if (explen > db->mru + 1) {
993 printf("bsd_decomp%d: ran out of mru\n", db->unit);
994 return DECOMP_FATALERROR;
998 * Decode this code and install it in the decompressed buffer.
1000 space -= codelen + extra;
1002 /* Allocate another message block. */
1003 dmsg->b_wptr = wptr;
1004 dlen = codelen + extra;
1005 if (dlen < DECOMP_CHUNK)
1006 dlen = DECOMP_CHUNK;
1007 if ((dmsg->b_cont = allocb(dlen, BPRI_MED)) == NULL) {
1009 return DECOMP_ERROR;
1011 dmsg = dmsg->b_cont;
1012 wptr = dmsg->b_wptr;
1013 space = dmsg->b_datap->db_lim - wptr - codelen - extra;
1015 p = (wptr += codelen);
1016 while (finchar > LAST) {
1017 dictp = &db->dict[db->dict[finchar].cptr];
1022 printf("bsd_decomp%d: fell off end of chain ", db->unit);
1023 printf("0x%x at 0x%x by 0x%x, max_ent=0x%x\n",
1024 incode, finchar, db->dict[finchar].cptr, max_ent);
1025 return DECOMP_FATALERROR;
1027 if (dictp->codem1 != finchar-1) {
1029 printf("bsd_decomp%d: bad code chain 0x%x finchar=0x%x ",
1030 db->unit, incode, finchar);
1031 printf("oldcode=0x%x cptr=0x%x codem1=0x%x\n", oldcode,
1032 db->dict[finchar].cptr, dictp->codem1);
1033 return DECOMP_FATALERROR;
1036 *--p = dictp->f.hs.suffix;
1037 finchar = dictp->f.hs.prefix;
1043 printf("bsd_decomp%d: short by %d after code 0x%x, max_ent=0x%x\n",
1044 db->unit, codelen, incode, max_ent);
1047 if (extra) /* the KwKwK case again */
1051 * If not first code in a packet, and
1052 * if not out of code space, then allocate a new code.
1054 * Keep the hash table correct so it can be used
1055 * with uncompressed packets.
1057 if (oldcode != CLEAR && max_ent < db->maxmaxcode) {
1058 struct bsd_dict *dictp2;
1062 fcode = BSD_KEY(oldcode,finchar);
1063 hval = BSD_HASH(oldcode,finchar,db->hshift);
1064 dictp = &db->dict[hval];
1066 /* look for a free hash table entry */
1067 if (dictp->codem1 < max_ent) {
1068 disp = (hval == 0) ? 1 : hval;
1071 if (hval >= db->hsize)
1073 dictp = &db->dict[hval];
1074 } while (dictp->codem1 < max_ent);
1078 * Invalidate previous hash table entry
1079 * assigned this code, and then take it over
1081 dictp2 = &db->dict[max_ent+1];
1082 if (db->dict[dictp2->cptr].codem1 == max_ent) {
1083 db->dict[dictp2->cptr].codem1 = BADCODEM1;
1085 dictp2->cptr = hval;
1086 dictp->codem1 = max_ent;
1087 dictp->f.fcode = fcode;
1089 db->max_ent = ++max_ent;
1090 db->lens[max_ent] = db->lens[oldcode]+1;
1092 /* Expand code size if needed. */
1093 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) {
1094 db->n_bits = ++n_bits;
1095 tgtbitno = 32-n_bits;
1100 dmsg->b_wptr = wptr;
1103 * Keep the checkpoint right so that incompressible packets
1104 * clear the dictionary at the right times.
1106 db->bytes_out += ilen;
1107 db->in_count += explen;
1108 if (bsd_check(db) && db->debug) {
1109 printf("bsd_decomp%d: peer should have cleared dictionary\n",
1114 db->comp_bytes += ilen + BSD_OVHD;
1116 db->uncomp_bytes += explen;