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 mbufs on Ultrix systems.
43 * $Id: bsd-comp.c,v 1.1 1994/11/21 05:02:49 paulus Exp $
46 #include "../h/param.h"
47 #include "../h/types.h"
48 #include "../h/mbuf.h"
49 #include "../h/socket.h"
50 #include "../net/net/if.h"
54 #define PACKET struct mbuf
58 * PPP "BSD compress" compression
59 * The differences between this compression and the classic BSD LZW
60 * source are obvious from the requirement that the classic code worked
61 * with files while this handles arbitrarily long streams that
62 * are broken into packets. They are:
64 * When the code size expands, a block of junk is not emitted by
65 * the compressor and not expected by the decompressor.
67 * New codes are not necessarily assigned every time an old
68 * code is output by the compressor. This is because a packet
69 * end forces a code to be emitted, but does not imply that a
70 * new sequence has been seen.
72 * The compression ratio is checked at the first end of a packet
73 * after the appropriate gap. Besides simplifying and speeding
74 * things up, this makes it more likely that the transmitter
75 * and receiver will agree when the dictionary is cleared when
76 * compression is not going well.
80 * Macros to extract protocol version and number of bits
81 * from the third byte of the BSD Compress CCP configuration option.
83 #define BSD_VERSION(x) ((x) >> 5)
84 #define BSD_NBITS(x) ((x) & 0x1F)
86 #define BSD_CURRENT_VERSION 1
89 * A dictionary for doing BSD compress.
92 int totlen; /* length of this structure */
93 u_int hsize; /* size of the hash table */
94 u_char hshift; /* used in hash function */
95 u_char n_bits; /* current bits/code */
99 u_short seqno; /* sequence # of next packet */
101 u_int maxmaxcode; /* largest valid code */
102 u_int max_ent; /* largest code in use */
103 u_int in_count; /* uncompressed bytes, aged */
104 u_int bytes_out; /* compressed bytes, aged */
105 u_int ratio; /* recent compression ratio */
106 u_int checkpoint; /* when to next check the ratio */
107 u_int clear_count; /* times dictionary cleared */
108 u_int incomp_count; /* incompressible packets */
109 u_int incomp_bytes; /* incompressible bytes */
110 u_int uncomp_count; /* uncompressed packets */
111 u_int uncomp_bytes; /* uncompressed bytes */
112 u_int comp_count; /* compressed packets */
113 u_int comp_bytes; /* compressed bytes */
114 u_short *lens; /* array of lengths of codes */
116 union { /* hash value */
119 #if BYTE_ORDER == LITTLE_ENDIAN
120 u_short prefix; /* preceding code */
121 u_char suffix; /* last character of new code */
125 u_char suffix; /* last character of new code */
126 u_short prefix; /* preceding code */
130 u_short codem1; /* output of hash table -1 */
131 u_short cptr; /* map code to hash table entry */
135 #define BSD_OVHD 2 /* BSD compress overhead/packet */
136 #define MIN_BSD_BITS 9
137 #define BSD_INIT_BITS MIN_BSD_BITS
138 #define MAX_BSD_BITS 15
140 static void *bsd_comp_alloc __P((u_char *options, int opt_len));
141 static void *bsd_decomp_alloc __P((u_char *options, int opt_len));
142 static void bsd_free __P((void *state));
143 static int bsd_comp_init __P((void *state, u_char *options, int opt_len,
144 int unit, int debug));
145 static int bsd_decomp_init __P((void *state, u_char *options, int opt_len,
146 int unit, int mru, int debug));
147 static int bsd_compress __P((void *state, struct mbuf **mret,
148 struct mbuf *mp, int slen, int maxolen));
149 static void bsd_incomp __P((void *state, struct mbuf *dmsg));
150 static int bsd_decompress __P((void *state, struct mbuf *cmp,
151 struct mbuf **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 if_ppp.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 * Some useful mbuf macros not in mbuf.h.
178 #define M_IS_CLUSTER(m) ((m)->m_off > MMAXOFF)
180 #define M_TRAILINGSPACE(m) \
181 ((M_IS_CLUSTER(m) ? (u_int)(m)->m_clptr + M_CLUSTERSZ : MSIZE) \
182 - ((m)->m_off + (m)->m_len))
185 * the next two codes should not be changed lightly, as they must not
186 * lie within the contiguous general code space.
188 #define CLEAR 256 /* table clear output code */
189 #define FIRST 257 /* first free entry */
192 #define MAXCODE(b) ((1 << (b)) - 1)
193 #define BADCODEM1 MAXCODE(MAX_BSD_BITS);
195 #define BSD_HASH(prefix,suffix,hshift) ((((u_int32_t)(suffix)) << (hshift)) \
196 ^ (u_int32_t)(prefix))
197 #define BSD_KEY(prefix,suffix) ((((u_int32_t)(suffix)) << 16) \
198 + (u_int32_t)(prefix))
200 #define CHECK_GAP 10000 /* Ratio check interval */
202 #define RATIO_SCALE_LOG 8
203 #define RATIO_SCALE (1<<RATIO_SCALE_LOG)
204 #define RATIO_MAX (0x7fffffff>>RATIO_SCALE_LOG)
207 * clear the dictionary
210 bsd_clear(struct bsd_db *db)
213 db->max_ent = FIRST-1;
214 db->n_bits = BSD_INIT_BITS;
218 db->incomp_count = 0;
219 db->checkpoint = CHECK_GAP;
223 * If the dictionary is full, then see if it is time to reset it.
225 * Compute the compression ratio using fixed-point arithmetic
226 * with 8 fractional bits.
228 * Since we have an infinite stream instead of a single file,
229 * watch only the local compression ratio.
231 * Since both peers must reset the dictionary at the same time even in
232 * the absence of CLEAR codes (while packets are incompressible), they
233 * must compute the same ratio.
235 static int /* 1=output CLEAR */
236 bsd_check(struct bsd_db *db)
240 if (db->in_count >= db->checkpoint) {
241 /* age the ratio by limiting the size of the counts */
242 if (db->in_count >= RATIO_MAX
243 || db->bytes_out >= RATIO_MAX) {
244 db->in_count -= db->in_count/4;
245 db->bytes_out -= db->bytes_out/4;
248 db->checkpoint = db->in_count + CHECK_GAP;
250 if (db->max_ent >= db->maxmaxcode) {
251 /* Reset the dictionary only if the ratio is worse,
252 * or if it looks as if it has been poisoned
253 * by incompressible data.
255 * This does not overflow, because
256 * db->in_count <= RATIO_MAX.
258 new_ratio = db->in_count << RATIO_SCALE_LOG;
259 if (db->bytes_out != 0)
260 new_ratio /= db->bytes_out;
262 if (new_ratio < db->ratio || new_ratio < 1 * RATIO_SCALE) {
266 db->ratio = new_ratio;
276 bsd_comp_stats(state, stats)
278 struct compstat *stats;
280 struct bsd_db *db = (struct bsd_db *) state;
282 stats->unc_bytes = db->uncomp_bytes;
283 stats->unc_packets = db->uncomp_count;
284 stats->comp_bytes = db->comp_bytes;
285 stats->comp_packets = db->comp_count;
286 stats->inc_bytes = db->incomp_bytes;
287 stats->inc_packets = db->incomp_count;
288 stats->ratio = (double) db->in_count;
289 if (db->bytes_out != 0)
290 stats->ratio /= db->bytes_out;
294 * Reset state, as on a CCP ResetReq.
300 struct bsd_db *db = (struct bsd_db *) state;
308 * Allocate space for a (de) compressor.
311 bsd_alloc(options, opt_len, decomp)
316 u_int newlen, hsize, hshift, maxmaxcode;
319 if (opt_len != 3 || options[0] != 0x21 || options[1] != 3
320 || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION)
322 bits = BSD_NBITS(options[2]);
324 case 9: /* needs 82152 for both directions */
325 case 10: /* needs 84144 */
326 case 11: /* needs 88240 */
327 case 12: /* needs 96432 */
331 case 13: /* needs 176784 */
335 case 14: /* needs 353744 */
339 case 15: /* needs 691440 */
343 case 16: /* needs 1366160--far too much, */
344 /* hsize = 69001; */ /* and 69001 is too big for cptr */
345 /* hshift = 8; */ /* in struct bsd_db */
351 maxmaxcode = MAXCODE(bits);
352 newlen = sizeof(*db) + (hsize-1)*(sizeof(db->dict[0]));
353 MALLOC(db, struct bsd_db *, newlen, M_DEVBUF, M_NOWAIT);
356 bzero(db, sizeof(*db) - sizeof(db->dict));
361 MALLOC(db->lens, u_short *, (maxmaxcode+1) * sizeof(db->lens[0]),
372 db->maxmaxcode = maxmaxcode;
382 struct bsd_db *db = (struct bsd_db *) state;
385 FREE(db->lens, M_DEVBUF);
390 bsd_comp_alloc(options, opt_len)
394 return bsd_alloc(options, opt_len, 0);
398 bsd_decomp_alloc(options, opt_len)
402 return bsd_alloc(options, opt_len, 1);
406 * Initialize the database.
409 bsd_init(db, options, opt_len, unit, mru, debug, decomp)
412 int opt_len, unit, mru, debug, decomp;
416 if (opt_len != 3 || options[0] != 0x21 || options[1] != 3
417 || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION
418 || BSD_NBITS(options[2]) != db->maxbits
419 || decomp && db->lens == NULL)
429 db->dict[--i].codem1 = BADCODEM1;
430 db->dict[i].cptr = 0;
446 bsd_comp_init(state, options, opt_len, unit, debug)
449 int opt_len, unit, debug;
451 return bsd_init((struct bsd_db *) state, options, opt_len,
456 bsd_decomp_init(state, options, opt_len, unit, mru, debug)
459 int opt_len, unit, mru, debug;
461 return bsd_init((struct bsd_db *) state, options, opt_len,
462 unit, mru, debug, 1);
468 * One change from the BSD compress command is that when the
469 * code size expands, we do not output a bunch of padding.
472 bsd_compress(state, mret, mp, slen, maxolen)
474 struct mbuf **mret; /* return compressed mbuf chain here */
475 struct mbuf *mp; /* from here */
476 int slen; /* uncompressed length */
477 int maxolen; /* max compressed length */
479 struct bsd_db *db = (struct bsd_db *) state;
480 int hshift = db->hshift;
481 u_int max_ent = db->max_ent;
482 u_int n_bits = db->n_bits;
484 u_int32_t accm = 0, fcode;
485 struct bsd_dict *dictp;
487 int hval, disp, ent, ilen;
492 struct mbuf *m, **mnp, *clp;
494 #define PUTBYTE(v) { \
498 if (wptr >= cp_end) { \
499 m->m_len = wptr - mtod(m, u_char *); \
500 MGET(m->m_next, M_DONTWAIT, MT_DATA); \
504 if (maxolen - olen > MLEN) \
506 wptr = mtod(m, u_char *); \
507 cp_end = wptr + M_TRAILINGSPACE(m); \
514 #define OUTPUT(ent) { \
516 accm |= ((ent) << bitno); \
518 PUTBYTE(accm >> 24); \
521 } while (bitno <= 24); \
525 * If the protocol is not in the range we're interested in,
526 * just return without compressing the packet. If it is,
527 * the protocol becomes the first byte to compress.
529 rptr = mtod(mp, u_char *);
530 ent = PPP_PROTOCOL(rptr);
531 if (ent < 0x21 || ent > 0xf9) {
536 /* Don't generate compressed packets which are larger than
537 the uncompressed packet. */
541 /* Allocate one mbuf to start with. */
542 MGET(m, M_DONTWAIT, MT_DATA);
548 wptr = mtod(m, u_char *);
549 cp_end = wptr + M_TRAILINGSPACE(m);
551 wptr = cp_end = NULL;
554 * Copy the PPP header over, changing the protocol,
555 * and install the 2-byte packet sequence number.
558 *wptr++ = PPP_ADDRESS(rptr); /* assumes the ppp header is */
559 *wptr++ = PPP_CONTROL(rptr); /* all in one mbuf */
560 *wptr++ = 0; /* change the protocol */
562 *wptr++ = db->seqno >> 8;
569 slen = mp->m_len - PPP_HDRLEN;
576 rptr = mtod(mp, u_char *);
579 continue; /* handle 0-length buffers */
585 fcode = BSD_KEY(ent, c);
586 hval = BSD_HASH(ent, c, hshift);
587 dictp = &db->dict[hval];
589 /* Validate and then check the entry. */
590 if (dictp->codem1 >= max_ent)
592 if (dictp->f.fcode == fcode) {
593 ent = dictp->codem1+1;
594 continue; /* found (prefix,suffix) */
597 /* continue probing until a match or invalid entry */
598 disp = (hval == 0) ? 1 : hval;
601 if (hval >= db->hsize)
603 dictp = &db->dict[hval];
604 if (dictp->codem1 >= max_ent)
606 } while (dictp->f.fcode != fcode);
607 ent = dictp->codem1 + 1; /* finally found (prefix,suffix) */
611 OUTPUT(ent); /* output the prefix */
613 /* code -> hashtable */
614 if (max_ent < db->maxmaxcode) {
615 struct bsd_dict *dictp2;
616 /* expand code size if needed */
617 if (max_ent >= MAXCODE(n_bits))
618 db->n_bits = ++n_bits;
620 /* Invalidate old hash table entry using
621 * this code, and then take it over.
623 dictp2 = &db->dict[max_ent+1];
624 if (db->dict[dictp2->cptr].codem1 == max_ent)
625 db->dict[dictp2->cptr].codem1 = BADCODEM1;
627 dictp->codem1 = max_ent;
628 dictp->f.fcode = fcode;
630 db->max_ent = ++max_ent;
635 OUTPUT(ent); /* output the last code */
636 db->bytes_out += olen;
637 db->in_count += ilen;
639 ++db->bytes_out; /* count complete bytes */
642 OUTPUT(CLEAR); /* do not count the CLEAR */
645 * Pad dribble bits of last code with ones.
646 * Do not emit a completely useless byte of ones.
649 PUTBYTE((accm | (0xff << (bitno-8))) >> 24);
652 m->m_len = wptr - mtod(m, u_char *);
657 * Increase code size if we would have without the packet
658 * boundary and as the decompressor will.
660 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode)
663 db->uncomp_bytes += ilen;
665 if (olen + PPP_HDRLEN + BSD_OVHD > maxolen && *mret != NULL) {
666 /* throw away the compressed stuff if it is longer than uncompressed */
670 db->incomp_bytes += ilen;
673 db->comp_bytes += olen + BSD_OVHD;
676 return olen + PPP_HDRLEN + BSD_OVHD;
683 * Update the "BSD Compress" dictionary on the receiver for
684 * incompressible data by pretending to compress the incoming data.
687 bsd_incomp(state, dmsg)
691 struct bsd_db *db = (struct bsd_db *) state;
692 u_int hshift = db->hshift;
693 u_int max_ent = db->max_ent;
694 u_int n_bits = db->n_bits;
695 struct bsd_dict *dictp;
705 * If the protocol is not in the range we're interested in,
706 * just return without looking at the packet. If it is,
707 * the protocol becomes the first byte to "compress".
709 rptr = mtod(dmsg, u_char *);
710 ent = PPP_PROTOCOL(rptr);
711 if (ent < 0x21 || ent > 0xf9)
716 ilen = 1; /* count the protocol as 1 byte */
718 slen = dmsg->m_len - PPP_HDRLEN;
724 rptr = mtod(dmsg, u_char *);
732 fcode = BSD_KEY(ent, c);
733 hval = BSD_HASH(ent, c, hshift);
734 dictp = &db->dict[hval];
736 /* validate and then check the entry */
737 if (dictp->codem1 >= max_ent)
739 if (dictp->f.fcode == fcode) {
740 ent = dictp->codem1+1;
741 continue; /* found (prefix,suffix) */
744 /* continue probing until a match or invalid entry */
745 disp = (hval == 0) ? 1 : hval;
748 if (hval >= db->hsize)
750 dictp = &db->dict[hval];
751 if (dictp->codem1 >= max_ent)
753 } while (dictp->f.fcode != fcode);
754 ent = dictp->codem1+1;
755 continue; /* finally found (prefix,suffix) */
757 nomatch: /* output (count) the prefix */
760 /* code -> hashtable */
761 if (max_ent < db->maxmaxcode) {
762 struct bsd_dict *dictp2;
763 /* expand code size if needed */
764 if (max_ent >= MAXCODE(n_bits))
765 db->n_bits = ++n_bits;
767 /* Invalidate previous hash table entry
768 * assigned this code, and then take it over.
770 dictp2 = &db->dict[max_ent+1];
771 if (db->dict[dictp2->cptr].codem1 == max_ent)
772 db->dict[dictp2->cptr].codem1 = BADCODEM1;
774 dictp->codem1 = max_ent;
775 dictp->f.fcode = fcode;
777 db->max_ent = ++max_ent;
778 db->lens[max_ent] = db->lens[ent]+1;
781 } while (--slen != 0);
783 bitno += n_bits; /* output (count) the last code */
784 db->bytes_out += bitno/8;
785 db->in_count += ilen;
789 db->comp_bytes += bitno / 8;
791 db->incomp_bytes += ilen;
793 /* Increase code size if we would have without the packet
794 * boundary and as the decompressor will.
796 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode)
802 * Decompress "BSD Compress"
805 bsd_decompress(state, cmp, dmpp)
807 struct mbuf *cmp, **dmpp;
809 struct bsd_db *db = (struct bsd_db *) state;
810 u_int max_ent = db->max_ent;
812 u_int bitno = 32; /* 1st valid bit in accm */
813 u_int n_bits = db->n_bits;
814 u_int tgtbitno = 32-n_bits; /* bitno when we have a code */
815 struct bsd_dict *dictp;
816 int explen, i, seq, len;
817 u_int incode, oldcode, finchar;
818 u_char *p, *rptr, *wptr;
819 struct mbuf *m, *dmp, *mret;
820 int adrs, ctrl, ilen;
821 int space, codelen, extra;
822 struct mbuf *last, *clp;
825 * Save the address/control from the PPP header
826 * and then get the sequence number.
829 rptr = mtod(cmp, u_char *);
830 adrs = PPP_ADDRESS(rptr);
831 ctrl = PPP_CONTROL(rptr);
833 len = cmp->m_len - PPP_HDRLEN;
835 for (i = 0; i < 2; ++i) {
840 rptr = mtod(cmp, u_char *);
843 seq = (seq << 8) + *rptr++;
848 * Check the sequence number and give up if it differs from
849 * the value we're expecting.
851 if (seq != db->seqno++) {
853 printf("bsd_decomp%d: bad sequence # %d, expected %d\n",
854 db->unit, seq, db->seqno - 1);
859 * Allocate one mbuf to start with.
861 MGET(dmp, M_DONTWAIT, MT_DATA);
868 wptr = mtod(dmp, u_char *);
869 space = M_TRAILINGSPACE(dmp) - PPP_HDRLEN + 1;
872 * Fill in the ppp header, but not the last byte of the protocol
873 * (that comes from the decompressed data).
878 wptr += PPP_HDRLEN - 1;
886 if (!cmp) /* quit at end of message */
888 rptr = mtod(cmp, u_char *);
891 continue; /* handle 0-length buffers */
895 * Accumulate bytes until we have a complete code.
896 * Then get the next code, relying on the 32-bit,
897 * unsigned accm to mask the result.
900 accm |= *rptr++ << bitno;
902 if (tgtbitno < bitno)
904 incode = accm >> tgtbitno;
908 if (incode == CLEAR) {
910 * The dictionary must only be cleared at
911 * the end of a packet. But there could be an
912 * empty mbuf at the end.
914 if (len > 0 || cmp->m_next != NULL) {
915 while ((cmp = cmp->m_next) != NULL)
920 printf("bsd_decomp%d: bad CLEAR\n", db->unit);
921 return DECOMP_FATALERROR; /* probably a bug */
929 if (incode > max_ent + 2 || incode > db->maxmaxcode
930 || incode > max_ent && oldcode == CLEAR) {
933 printf("bsd_decomp%d: bad code 0x%x oldcode=0x%x ",
934 db->unit, incode, oldcode);
935 printf("max_ent=0x%x explen=%d seqno=%d\n",
936 max_ent, explen, db->seqno);
938 return DECOMP_FATALERROR; /* probably a bug */
941 /* Special case for KwKwK string. */
942 if (incode > max_ent) {
950 codelen = db->lens[finchar];
951 explen += codelen + extra;
952 if (explen > db->mru + 1) {
955 printf("bsd_decomp%d: ran out of mru\n", db->unit);
957 while ((cmp = cmp->m_next) != NULL)
959 printf(" len=%d, finchar=0x%x, codelen=%d, explen=%d\n",
960 len, finchar, codelen, explen);
963 return DECOMP_FATALERROR;
967 * For simplicity, the decoded characters go in a single mbuf,
968 * so we allocate a single extra cluster mbuf if necessary.
970 if ((space -= codelen + extra) < 0) {
971 dmp->m_len = wptr - mtod(dmp, u_char *);
972 MGET(m, M_DONTWAIT, MT_DATA);
981 space = M_TRAILINGSPACE(m) - (codelen + extra);
983 /* now that's what I call *compression*. */
988 wptr = mtod(dmp, u_char *);
992 * Decode this code and install it in the decompressed buffer.
994 p = (wptr += codelen);
995 while (finchar > LAST) {
996 dictp = &db->dict[db->dict[finchar].cptr];
998 if (--codelen <= 0 || dictp->codem1 != finchar-1)
1001 *--p = dictp->f.hs.suffix;
1002 finchar = dictp->f.hs.prefix;
1008 printf("bsd_decomp%d: short by %d after code 0x%x, max_ent=0x%x\n",
1009 db->unit, codelen, incode, max_ent);
1012 if (extra) /* the KwKwK case again */
1016 * If not first code in a packet, and
1017 * if not out of code space, then allocate a new code.
1019 * Keep the hash table correct so it can be used
1020 * with uncompressed packets.
1022 if (oldcode != CLEAR && max_ent < db->maxmaxcode) {
1023 struct bsd_dict *dictp2;
1027 fcode = BSD_KEY(oldcode,finchar);
1028 hval = BSD_HASH(oldcode,finchar,db->hshift);
1029 dictp = &db->dict[hval];
1031 /* look for a free hash table entry */
1032 if (dictp->codem1 < max_ent) {
1033 disp = (hval == 0) ? 1 : hval;
1036 if (hval >= db->hsize)
1038 dictp = &db->dict[hval];
1039 } while (dictp->codem1 < max_ent);
1043 * Invalidate previous hash table entry
1044 * assigned this code, and then take it over
1046 dictp2 = &db->dict[max_ent+1];
1047 if (db->dict[dictp2->cptr].codem1 == max_ent) {
1048 db->dict[dictp2->cptr].codem1 = BADCODEM1;
1050 dictp2->cptr = hval;
1051 dictp->codem1 = max_ent;
1052 dictp->f.fcode = fcode;
1054 db->max_ent = ++max_ent;
1055 db->lens[max_ent] = db->lens[oldcode]+1;
1057 /* Expand code size if needed. */
1058 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) {
1059 db->n_bits = ++n_bits;
1060 tgtbitno = 32-n_bits;
1065 dmp->m_len = wptr - mtod(dmp, u_char *);
1068 * Keep the checkpoint right so that incompressible packets
1069 * clear the dictionary at the right times.
1071 db->bytes_out += ilen;
1072 db->in_count += explen;
1073 if (bsd_check(db) && db->debug) {
1074 printf("bsd_decomp%d: peer should have cleared dictionary\n",
1079 db->comp_bytes += ilen + BSD_OVHD;
1081 db->uncomp_bytes += explen;
1089 printf("bsd_decomp%d: fell off end of chain ", db->unit);
1090 printf("0x%x at 0x%x by 0x%x, max_ent=0x%x\n",
1091 incode, finchar, db->dict[finchar].cptr, max_ent);
1092 } else if (dictp->codem1 != finchar-1) {
1093 printf("bsd_decomp%d: bad code chain 0x%x finchar=0x%x ",
1094 db->unit, incode, finchar);
1095 printf("oldcode=0x%x cptr=0x%x codem1=0x%x\n", oldcode,
1096 db->dict[finchar].cptr, dictp->codem1);
1099 return DECOMP_FATALERROR;