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.
43 * $Id: bsd-comp.c,v 1.6 1994/10/24 04:28:14 paulus Exp $
46 #include <sys/param.h>
47 #include <sys/types.h>
48 #include <sys/stream.h>
49 #include <sys/kmem_alloc.h>
50 #include <sys/socket.h>
52 #include <net/ppp_defs.h>
53 #include <net/ppp_str.h>
55 #define PACKETPTR mblk_t *
56 #include <net/ppp-comp.h>
59 * PPP "BSD compress" compression
60 * The differences between this compression and the classic BSD LZW
61 * source are obvious from the requirement that the classic code worked
62 * with files while this handles arbitrarily long streams that
63 * are broken into packets. They are:
65 * When the code size expands, a block of junk is not emitted by
66 * the compressor and not expected by the decompressor.
68 * New codes are not necessarily assigned every time an old
69 * code is output by the compressor. This is because a packet
70 * end forces a code to be emitted, but does not imply that a
71 * new sequence has been seen.
73 * The compression ratio is checked at the first end of a packet
74 * after the appropriate gap. Besides simplifying and speeding
75 * things up, this makes it more likely that the transmitter
76 * and receiver will agree when the dictionary is cleared when
77 * compression is not going well.
81 * Macros to extract protocol version and number of bits
82 * from the third byte of the BSD Compress CCP configuration option.
84 #define BSD_VERSION(x) ((x) >> 5)
85 #define BSD_NBITS(x) ((x) & 0x1F)
87 #define BSD_CURRENT_VERSION 1
90 * A dictionary for doing BSD compress.
93 int totlen; /* length of this structure */
94 u_int hsize; /* size of the hash table */
95 u_char hshift; /* used in hash function */
96 u_char n_bits; /* current bits/code */
100 u_short seqno; /* sequence number of next packet */
102 u_int maxmaxcode; /* largest valid code */
103 u_int max_ent; /* largest code in use */
104 u_int in_count; /* uncompressed bytes, aged */
105 u_int bytes_out; /* compressed bytes, aged */
106 u_int ratio; /* recent compression ratio */
107 u_int checkpoint; /* when to next check the ratio */
108 u_int clear_count; /* times dictionary cleared */
109 u_int incomp_count; /* incompressible packets */
110 u_int incomp_bytes; /* incompressible bytes */
111 u_int uncomp_count; /* uncompressed packets */
112 u_int uncomp_bytes; /* uncompressed bytes */
113 u_int comp_count; /* compressed packets */
114 u_int comp_bytes; /* compressed bytes */
115 u_short *lens; /* array of lengths of codes */
117 union { /* hash value */
120 #ifdef BSD_LITTLE_ENDIAN
121 u_short prefix; /* preceding code */
122 u_char suffix; /* last character of new code */
126 u_char suffix; /* last character of new code */
127 u_short prefix; /* preceding code */
131 u_short codem1; /* output of hash table -1 */
132 u_short cptr; /* map code to hash table entry */
136 #define BSD_OVHD 2 /* BSD compress overhead/packet */
137 #define MIN_BSD_BITS 9
138 #define BSD_INIT_BITS MIN_BSD_BITS
139 #define MAX_BSD_BITS 15
141 static void *bsd_comp_alloc __P((u_char *options, int opt_len));
142 static void *bsd_decomp_alloc __P((u_char *options, int opt_len));
143 static void bsd_free __P((void *state));
144 static int bsd_comp_init __P((void *state, u_char *options, int opt_len,
145 int unit, int debug));
146 static int bsd_decomp_init __P((void *state, u_char *options, int opt_len,
147 int unit, int mru, int debug));
148 static int bsd_compress __P((void *state, mblk_t **mret,
149 mblk_t *mp, int slen, int maxolen));
150 static void bsd_incomp __P((void *state, mblk_t *dmsg));
151 static int bsd_decompress __P((void *state, mblk_t *cmp, mblk_t **dmpp));
152 static void bsd_reset __P((void *state));
153 static void bsd_comp_stats __P((void *state, struct compstat *stats));
156 * Procedures exported to ppp_comp.c.
158 struct compressor ppp_bsd_compress = {
159 0x21, /* compress_proto */
160 bsd_comp_alloc, /* comp_alloc */
161 bsd_free, /* comp_free */
162 bsd_comp_init, /* comp_init */
163 bsd_reset, /* comp_reset */
164 bsd_compress, /* compress */
165 bsd_comp_stats, /* comp_stat */
166 bsd_decomp_alloc, /* decomp_alloc */
167 bsd_free, /* decomp_free */
168 bsd_decomp_init, /* decomp_init */
169 bsd_reset, /* decomp_reset */
170 bsd_decompress, /* decompress */
171 bsd_incomp, /* incomp */
172 bsd_comp_stats, /* decomp_stat */
176 * the next two codes should not be changed lightly, as they must not
177 * lie within the contiguous general code space.
179 #define CLEAR 256 /* table clear output code */
180 #define FIRST 257 /* first free entry */
183 #define MAXCODE(b) ((1 << (b)) - 1)
184 #define BADCODEM1 MAXCODE(MAX_BSD_BITS);
186 #define BSD_HASH(prefix,suffix,hshift) ((((u_int32_t)(suffix)) << (hshift)) \
187 ^ (u_int32_t)(prefix))
188 #define BSD_KEY(prefix,suffix) ((((u_int32_t)(suffix)) << 16) \
189 + (u_int32_t)(prefix))
191 #define CHECK_GAP 10000 /* Ratio check interval */
193 #define RATIO_SCALE_LOG 8
194 #define RATIO_SCALE (1<<RATIO_SCALE_LOG)
195 #define RATIO_MAX (0x7fffffff>>RATIO_SCALE_LOG)
197 #define DECOMP_CHUNK 256
200 * clear the dictionary
207 db->max_ent = FIRST-1;
208 db->n_bits = BSD_INIT_BITS;
212 db->incomp_count = 0;
213 db->checkpoint = CHECK_GAP;
217 * If the dictionary is full, then see if it is time to reset it.
219 * Compute the compression ratio using fixed-point arithmetic
220 * with 8 fractional bits.
222 * Since we have an infinite stream instead of a single file,
223 * watch only the local compression ratio.
225 * Since both peers must reset the dictionary at the same time even in
226 * the absence of CLEAR codes (while packets are incompressible), they
227 * must compute the same ratio.
229 static int /* 1=output CLEAR */
235 if (db->in_count >= db->checkpoint) {
236 /* age the ratio by limiting the size of the counts */
237 if (db->in_count >= RATIO_MAX
238 || db->bytes_out >= RATIO_MAX) {
239 db->in_count -= db->in_count/4;
240 db->bytes_out -= db->bytes_out/4;
243 db->checkpoint = db->in_count + CHECK_GAP;
245 if (db->max_ent >= db->maxmaxcode) {
246 /* Reset the dictionary only if the ratio is worse,
247 * or if it looks as if it has been poisoned
248 * by incompressible data.
250 * This does not overflow, because
251 * db->in_count <= RATIO_MAX.
253 new_ratio = db->in_count << RATIO_SCALE_LOG;
254 if (db->bytes_out != 0)
255 new_ratio /= db->bytes_out;
257 if (new_ratio < db->ratio || new_ratio < 1 * RATIO_SCALE) {
261 db->ratio = new_ratio;
271 bsd_comp_stats(state, stats)
273 struct compstat *stats;
275 struct bsd_db *db = (struct bsd_db *) state;
278 stats->unc_bytes = db->uncomp_bytes;
279 stats->unc_packets = db->uncomp_count;
280 stats->comp_bytes = db->comp_bytes;
281 stats->comp_packets = db->comp_count;
282 stats->inc_bytes = db->incomp_bytes;
283 stats->inc_packets = db->incomp_count;
284 stats->ratio = db->in_count;
286 if (stats->ratio <= 0x7fffff)
295 * Reset state, as on a CCP ResetReq.
301 struct bsd_db *db = (struct bsd_db *) state;
309 * Allocate space for a (de) compressor.
312 bsd_alloc(options, opt_len, decomp)
317 u_int newlen, hsize, hshift, maxmaxcode;
320 if (opt_len != 3 || options[0] != 0x21 || options[1] != 3
321 || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION)
323 bits = BSD_NBITS(options[2]);
325 case 9: /* needs 82152 for both directions */
326 case 10: /* needs 84144 */
327 case 11: /* needs 88240 */
328 case 12: /* needs 96432 */
332 case 13: /* needs 176784 */
336 case 14: /* needs 353744 */
340 case 15: /* needs 691440 */
344 case 16: /* needs 1366160--far too much, */
345 /* hsize = 69001; */ /* and 69001 is too big for cptr */
346 /* hshift = 8; */ /* in struct bsd_db */
352 maxmaxcode = MAXCODE(bits);
353 newlen = sizeof(*db) + (hsize-1) * (sizeof(db->dict[0]));
354 db = (struct bsd_db *) kmem_alloc(newlen, KMEM_NOSLEEP);
357 bzero(db, sizeof(*db) - sizeof(db->dict));
362 db->lens = (u_short *) kmem_alloc((maxmaxcode+1) * sizeof(db->lens[0]),
365 kmem_free(db, newlen);
373 db->maxmaxcode = maxmaxcode;
383 struct bsd_db *db = (struct bsd_db *) state;
386 kmem_free(db->lens, (db->maxmaxcode+1) * sizeof(db->lens[0]));
387 kmem_free(db, db->totlen);
391 bsd_comp_alloc(options, opt_len)
395 return bsd_alloc(options, opt_len, 0);
399 bsd_decomp_alloc(options, opt_len)
403 return bsd_alloc(options, opt_len, 1);
407 * Initialize the database.
410 bsd_init(db, options, opt_len, unit, mru, debug, decomp)
413 int opt_len, unit, mru, debug, decomp;
417 if (opt_len != 3 || options[0] != 0x21 || options[1] != 3
418 || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION
419 || BSD_NBITS(options[2]) != db->maxbits
420 || decomp && db->lens == NULL)
430 db->dict[--i].codem1 = BADCODEM1;
431 db->dict[i].cptr = 0;
445 bsd_comp_init(state, options, opt_len, unit, debug)
448 int opt_len, unit, debug;
450 return bsd_init((struct bsd_db *) state, options, opt_len,
455 bsd_decomp_init(state, options, opt_len, unit, mru, debug)
458 int opt_len, unit, mru, debug;
460 return bsd_init((struct bsd_db *) state, options, opt_len,
461 unit, mru, debug, 1);
467 * One change from the BSD compress command is that when the
468 * code size expands, we do not output a bunch of padding.
470 static int /* new slen */
471 bsd_compress(state, mretp, mp, slen, maxolen)
473 mblk_t **mretp; /* return compressed mbuf chain here */
474 mblk_t *mp; /* from here */
475 int slen; /* uncompressed length */
476 int maxolen; /* max compressed length */
478 struct bsd_db *db = (struct bsd_db *) state;
479 int hshift = db->hshift;
480 u_int max_ent = db->max_ent;
481 u_int n_bits = db->n_bits;
483 u_int32_t accm = 0, fcode;
484 struct bsd_dict *dictp;
486 int hval, disp, ent, ilen;
493 #define PUTBYTE(v) { \
496 if (wptr >= cp_end) { \
501 cp_end = m->b_datap->db_lim; \
509 #define OUTPUT(ent) { \
511 accm |= ((ent) << bitno); \
513 PUTBYTE(accm >> 24); \
516 } while (bitno <= 24); \
520 * First get the protocol and check that we're
521 * interested in this packet.
525 if (rptr + PPP_HDRLEN > mp->b_wptr) {
526 if (!pullupmsg(mp, PPP_HDRLEN))
530 ent = PPP_PROTOCOL(rptr); /* get the protocol */
531 if (ent < 0x21 || ent > 0xf9)
534 /* Don't generate compressed packets which are larger than
535 the uncompressed packet. */
539 /* Allocate enough message blocks to give maxolen total space. */
541 for (olen = maxolen; olen > 0; ) {
542 m = allocb((olen < 4096? olen: 4096), BPRI_MED);
552 olen -= m->b_datap->db_lim - m->b_wptr;
556 if ((m = mret) != NULL) {
558 cp_end = m->b_datap->db_lim;
560 wptr = cp_end = NULL;
564 * Copy the PPP header over, changing the protocol,
565 * and install the 2-byte sequence number.
568 wptr[0] = PPP_ADDRESS(rptr);
569 wptr[1] = PPP_CONTROL(rptr);
570 wptr[2] = 0; /* change the protocol */
572 wptr[4] = db->seqno >> 8;
574 wptr += PPP_HDRLEN + BSD_OVHD;
579 slen = mp->b_wptr - rptr;
587 slen = np->b_wptr - rptr;
590 continue; /* handle 0-length buffers */
596 fcode = BSD_KEY(ent, c);
597 hval = BSD_HASH(ent, c, hshift);
598 dictp = &db->dict[hval];
600 /* Validate and then check the entry. */
601 if (dictp->codem1 >= max_ent)
603 if (dictp->f.fcode == fcode) {
604 ent = dictp->codem1+1;
605 continue; /* found (prefix,suffix) */
608 /* continue probing until a match or invalid entry */
609 disp = (hval == 0) ? 1 : hval;
612 if (hval >= db->hsize)
614 dictp = &db->dict[hval];
615 if (dictp->codem1 >= max_ent)
617 } while (dictp->f.fcode != fcode);
618 ent = dictp->codem1 + 1; /* finally found (prefix,suffix) */
622 OUTPUT(ent); /* output the prefix */
624 /* code -> hashtable */
625 if (max_ent < db->maxmaxcode) {
626 struct bsd_dict *dictp2;
627 /* expand code size if needed */
628 if (max_ent >= MAXCODE(n_bits))
629 db->n_bits = ++n_bits;
631 /* Invalidate old hash table entry using
632 * this code, and then take it over.
634 dictp2 = &db->dict[max_ent+1];
635 if (db->dict[dictp2->cptr].codem1 == max_ent)
636 db->dict[dictp2->cptr].codem1 = BADCODEM1;
638 dictp->codem1 = max_ent;
639 dictp->f.fcode = fcode;
641 db->max_ent = ++max_ent;
646 OUTPUT(ent); /* output the last code */
647 db->bytes_out += olen;
648 db->in_count += ilen;
650 ++db->bytes_out; /* count complete bytes */
653 OUTPUT(CLEAR); /* do not count the CLEAR */
656 * Pad dribble bits of last code with ones.
657 * Do not emit a completely useless byte of ones.
660 PUTBYTE((accm | (0xff << (bitno-8))) >> 24);
663 * Increase code size if we would have without the packet
664 * boundary and as the decompressor will.
666 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode)
669 db->uncomp_bytes += ilen;
671 if (olen + PPP_HDRLEN + BSD_OVHD > maxolen && mret != NULL) {
672 /* throw away the compressed stuff if it is longer than uncompressed */
676 db->incomp_bytes += ilen;
677 } else if (wptr != NULL) {
684 db->comp_bytes += olen + BSD_OVHD;
688 return olen + PPP_HDRLEN + BSD_OVHD;
695 * Update the "BSD Compress" dictionary on the receiver for
696 * incompressible data by pretending to compress the incoming data.
699 bsd_incomp(state, dmsg)
703 struct bsd_db *db = (struct bsd_db *) state;
704 u_int hshift = db->hshift;
705 u_int max_ent = db->max_ent;
706 u_int n_bits = db->n_bits;
707 struct bsd_dict *dictp;
717 if (rptr + PPP_HDRLEN > dmsg->b_wptr) {
718 if (!pullupmsg(dmsg, PPP_HDRLEN))
722 ent = PPP_PROTOCOL(rptr); /* get the protocol */
723 if (ent < 0x21 || ent > 0xf9)
728 ilen = 1; /* count the protocol as 1 byte */
731 slen = dmsg->b_wptr - rptr;
737 continue; /* skip zero-length buffers */
743 fcode = BSD_KEY(ent, c);
744 hval = BSD_HASH(ent, c, hshift);
745 dictp = &db->dict[hval];
747 /* validate and then check the entry */
748 if (dictp->codem1 >= max_ent)
750 if (dictp->f.fcode == fcode) {
751 ent = dictp->codem1+1;
752 continue; /* found (prefix,suffix) */
755 /* continue probing until a match or invalid entry */
756 disp = (hval == 0) ? 1 : hval;
759 if (hval >= db->hsize)
761 dictp = &db->dict[hval];
762 if (dictp->codem1 >= max_ent)
764 } while (dictp->f.fcode != fcode);
765 ent = dictp->codem1+1;
766 continue; /* finally found (prefix,suffix) */
768 nomatch: /* output (count) the prefix */
771 /* code -> hashtable */
772 if (max_ent < db->maxmaxcode) {
773 struct bsd_dict *dictp2;
774 /* expand code size if needed */
775 if (max_ent >= MAXCODE(n_bits))
776 db->n_bits = ++n_bits;
778 /* Invalidate previous hash table entry
779 * assigned this code, and then take it over.
781 dictp2 = &db->dict[max_ent+1];
782 if (db->dict[dictp2->cptr].codem1 == max_ent)
783 db->dict[dictp2->cptr].codem1 = BADCODEM1;
785 dictp->codem1 = max_ent;
786 dictp->f.fcode = fcode;
788 db->max_ent = ++max_ent;
789 db->lens[max_ent] = db->lens[ent]+1;
792 } while (--slen != 0);
794 bitno += n_bits; /* output (count) the last code */
795 db->bytes_out += bitno/8;
796 db->in_count += ilen;
800 db->incomp_bytes += ilen;
802 db->uncomp_bytes += ilen;
804 /* Increase code size if we would have without the packet
805 * boundary and as the decompressor will.
807 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode)
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 bsd_decompress(state, cmsg, dmpp)
831 mblk_t *cmsg, **dmpp;
833 struct bsd_db *db = (struct bsd_db *) state;
834 u_int max_ent = db->max_ent;
836 u_int bitno = 32; /* 1st valid bit in accm */
837 u_int n_bits = db->n_bits;
838 u_int tgtbitno = 32-n_bits; /* bitno when we have a code */
839 struct bsd_dict *dictp;
840 int explen, i, seq, len;
841 u_int incode, oldcode, finchar;
842 u_char *p, *rptr, *wptr;
844 int adrs, ctrl, ilen;
845 int dlen, space, codelen, extra;
848 * Get at least the BSD Compress header in the first buffer
851 if (rptr + PPP_HDRLEN + BSD_OVHD >= cmsg->b_wptr) {
852 if (!pullupmsg(cmsg, PPP_HDRLEN + BSD_OVHD + 1)) {
854 printf("bsd_decomp%d: failed to pullup\n", db->unit);
861 * Save the address/control from the PPP header
862 * and then get the sequence number.
864 adrs = PPP_ADDRESS(rptr);
865 ctrl = PPP_CONTROL(rptr);
867 seq = (rptr[0] << 8) + rptr[1];
869 ilen = len = cmsg->b_wptr - rptr;
872 * Check the sequence number and give up if it is not what we expect.
874 if (seq != db->seqno++) {
876 printf("bsd_decomp%d: bad sequence # %d, expected %d\n",
877 db->unit, seq, db->seqno - 1);
882 * Allocate one message block to start with.
884 if ((dmsg = allocb(DECOMP_CHUNK, BPRI_MED)) == NULL)
887 dmsg->b_rptr = wptr = dmsg->b_wptr;
889 /* Fill in the ppp header, but not the last byte of the protocol
890 (that comes from the decompressed data). */
894 wptr += PPP_HDRLEN - 1;
895 space = dmsg->b_datap->db_lim - wptr;
902 if (!cmsg) /* quit at end of message */
905 len = cmsg->b_wptr - rptr;
907 continue; /* handle 0-length buffers */
911 * Accumulate bytes until we have a complete code.
912 * Then get the next code, relying on the 32-bit,
913 * unsigned accm to mask the result.
916 accm |= *rptr++ << bitno;
918 if (tgtbitno < bitno)
920 incode = accm >> tgtbitno;
924 if (incode == CLEAR) {
926 * The dictionary must only be cleared at
927 * the end of a packet. But there could be an
928 * empty message block at the end.
930 if (len > 0 || cmsg->b_cont != 0) {
932 len += msgdsize(cmsg->b_cont);
936 printf("bsd_decomp%d: bad CLEAR\n", db->unit);
937 return DECOMP_FATALERROR;
945 if (incode > max_ent + 2 || incode > db->maxmaxcode
946 || incode > max_ent && oldcode == CLEAR) {
949 printf("bsd_decomp%d: bad code 0x%x oldcode=0x%x ",
950 db->unit, incode, oldcode);
951 printf("max_ent=0x%x dlen=%d seqno=%d\n",
952 max_ent, dlen, db->seqno);
954 return DECOMP_FATALERROR; /* probably a bug */
957 /* Special case for KwKwK string. */
958 if (incode > max_ent) {
966 codelen = db->lens[finchar];
967 explen += codelen + extra;
968 if (explen > db->mru + 1) {
971 printf("bsd_decomp%d: ran out of mru\n", db->unit);
972 return DECOMP_FATALERROR;
976 * Decode this code and install it in the decompressed buffer.
978 space -= codelen + extra;
980 /* Allocate another message block. */
982 dlen = codelen + extra;
983 if (dlen < DECOMP_CHUNK)
985 if ((dmsg->b_cont = allocb(dlen, BPRI_MED)) == NULL) {
991 space = dmsg->b_datap->db_lim - wptr - codelen - extra;
993 p = (wptr += codelen);
994 while (finchar > LAST) {
995 dictp = &db->dict[db->dict[finchar].cptr];
1000 printf("bsd_decomp%d: fell off end of chain ", db->unit);
1001 printf("0x%x at 0x%x by 0x%x, max_ent=0x%x\n",
1002 incode, finchar, db->dict[finchar].cptr, max_ent);
1003 return DECOMP_FATALERROR;
1005 if (dictp->codem1 != finchar-1) {
1007 printf("bsd_decomp%d: bad code chain 0x%x finchar=0x%x ",
1008 db->unit, incode, finchar);
1009 printf("oldcode=0x%x cptr=0x%x codem1=0x%x\n", oldcode,
1010 db->dict[finchar].cptr, dictp->codem1);
1011 return DECOMP_FATALERROR;
1014 *--p = dictp->f.hs.suffix;
1015 finchar = dictp->f.hs.prefix;
1021 printf("bsd_decomp%d: short by %d after code 0x%x, max_ent=0x%x\n",
1022 db->unit, codelen, incode, max_ent);
1025 if (extra) /* the KwKwK case again */
1029 * If not first code in a packet, and
1030 * if not out of code space, then allocate a new code.
1032 * Keep the hash table correct so it can be used
1033 * with uncompressed packets.
1035 if (oldcode != CLEAR && max_ent < db->maxmaxcode) {
1036 struct bsd_dict *dictp2;
1040 fcode = BSD_KEY(oldcode,finchar);
1041 hval = BSD_HASH(oldcode,finchar,db->hshift);
1042 dictp = &db->dict[hval];
1044 /* look for a free hash table entry */
1045 if (dictp->codem1 < max_ent) {
1046 disp = (hval == 0) ? 1 : hval;
1049 if (hval >= db->hsize)
1051 dictp = &db->dict[hval];
1052 } while (dictp->codem1 < max_ent);
1056 * Invalidate previous hash table entry
1057 * assigned this code, and then take it over
1059 dictp2 = &db->dict[max_ent+1];
1060 if (db->dict[dictp2->cptr].codem1 == max_ent) {
1061 db->dict[dictp2->cptr].codem1 = BADCODEM1;
1063 dictp2->cptr = hval;
1064 dictp->codem1 = max_ent;
1065 dictp->f.fcode = fcode;
1067 db->max_ent = ++max_ent;
1068 db->lens[max_ent] = db->lens[oldcode]+1;
1070 /* Expand code size if needed. */
1071 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) {
1072 db->n_bits = ++n_bits;
1073 tgtbitno = 32-n_bits;
1078 dmsg->b_wptr = wptr;
1081 * Keep the checkpoint right so that incompressible packets
1082 * clear the dictionary at the right times.
1084 db->bytes_out += ilen;
1085 db->in_count += explen;
1086 if (bsd_check(db) && db->debug) {
1087 printf("bsd_decomp%d: peer should have cleared dictionary\n",
1092 db->comp_bytes += ilen + BSD_OVHD;
1094 db->uncomp_bytes += explen;