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, AIX 4.x, and SVR4 systems including Solaris 2.
44 * $Id: bsd-comp.c,v 1.17 1995/12/11 02:57:48 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>
60 #include <sys/byteorder.h>
62 #define BSD_LITTLE_ENDIAN
69 #define BSD_LITTLE_ENDIAN
72 #define PACKETPTR mblk_t *
73 #include <net/ppp-comp.h>
78 * PPP "BSD compress" compression
79 * The differences between this compression and the classic BSD LZW
80 * source are obvious from the requirement that the classic code worked
81 * with files while this handles arbitrarily long streams that
82 * are broken into packets. They are:
84 * When the code size expands, a block of junk is not emitted by
85 * the compressor and not expected by the decompressor.
87 * New codes are not necessarily assigned every time an old
88 * code is output by the compressor. This is because a packet
89 * end forces a code to be emitted, but does not imply that a
90 * new sequence has been seen.
92 * The compression ratio is checked at the first end of a packet
93 * after the appropriate gap. Besides simplifying and speeding
94 * things up, this makes it more likely that the transmitter
95 * and receiver will agree when the dictionary is cleared when
96 * compression is not going well.
100 * A dictionary for doing BSD compress.
103 int totlen; /* length of this structure */
104 u_int hsize; /* size of the hash table */
105 u_char hshift; /* used in hash function */
106 u_char n_bits; /* current bits/code */
110 u_short seqno; /* sequence number of next packet */
111 u_int hdrlen; /* header length to preallocate */
113 u_int maxmaxcode; /* largest valid code */
114 u_int max_ent; /* largest code in use */
115 u_int in_count; /* uncompressed bytes, aged */
116 u_int bytes_out; /* compressed bytes, aged */
117 u_int ratio; /* recent compression ratio */
118 u_int checkpoint; /* when to next check the ratio */
119 u_int clear_count; /* times dictionary cleared */
120 u_int incomp_count; /* incompressible packets */
121 u_int incomp_bytes; /* incompressible bytes */
122 u_int uncomp_count; /* uncompressed packets */
123 u_int uncomp_bytes; /* uncompressed bytes */
124 u_int comp_count; /* compressed packets */
125 u_int comp_bytes; /* compressed bytes */
126 u_short *lens; /* array of lengths of codes */
128 union { /* hash value */
131 #ifdef BSD_LITTLE_ENDIAN
132 u_short prefix; /* preceding code */
133 u_char suffix; /* last character of new code */
137 u_char suffix; /* last character of new code */
138 u_short prefix; /* preceding code */
142 u_short codem1; /* output of hash table -1 */
143 u_short cptr; /* map code to hash table entry */
147 #define BSD_OVHD 2 /* BSD compress overhead/packet */
148 #define BSD_INIT_BITS BSD_MIN_BITS
150 static void *bsd_comp_alloc __P((u_char *options, int opt_len));
151 static void *bsd_decomp_alloc __P((u_char *options, int opt_len));
152 static void bsd_free __P((void *state));
153 static int bsd_comp_init __P((void *state, u_char *options, int opt_len,
154 int unit, int hdrlen, int debug));
155 static int bsd_decomp_init __P((void *state, u_char *options, int opt_len,
156 int unit, int hdrlen, int mru, int debug));
157 static int bsd_compress __P((void *state, mblk_t **mret,
158 mblk_t *mp, int slen, int maxolen));
159 static void bsd_incomp __P((void *state, mblk_t *dmsg));
160 static int bsd_decompress __P((void *state, mblk_t *cmp, mblk_t **dmpp));
161 static void bsd_reset __P((void *state));
162 static void bsd_comp_stats __P((void *state, struct compstat *stats));
165 * Procedures exported to ppp_comp.c.
167 struct compressor ppp_bsd_compress = {
168 CI_BSD_COMPRESS, /* compress_proto */
169 bsd_comp_alloc, /* comp_alloc */
170 bsd_free, /* comp_free */
171 bsd_comp_init, /* comp_init */
172 bsd_reset, /* comp_reset */
173 bsd_compress, /* compress */
174 bsd_comp_stats, /* comp_stat */
175 bsd_decomp_alloc, /* decomp_alloc */
176 bsd_free, /* decomp_free */
177 bsd_decomp_init, /* decomp_init */
178 bsd_reset, /* decomp_reset */
179 bsd_decompress, /* decompress */
180 bsd_incomp, /* incomp */
181 bsd_comp_stats, /* decomp_stat */
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(BSD_MAX_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)
206 #define DECOMP_CHUNK 256
209 * clear the dictionary
216 db->max_ent = FIRST-1;
217 db->n_bits = BSD_INIT_BITS;
221 db->incomp_count = 0;
222 db->checkpoint = CHECK_GAP;
226 * If the dictionary is full, then see if it is time to reset it.
228 * Compute the compression ratio using fixed-point arithmetic
229 * with 8 fractional bits.
231 * Since we have an infinite stream instead of a single file,
232 * watch only the local compression ratio.
234 * Since both peers must reset the dictionary at the same time even in
235 * the absence of CLEAR codes (while packets are incompressible), they
236 * must compute the same ratio.
238 static int /* 1=output CLEAR */
244 if (db->in_count >= db->checkpoint) {
245 /* age the ratio by limiting the size of the counts */
246 if (db->in_count >= RATIO_MAX
247 || db->bytes_out >= RATIO_MAX) {
248 db->in_count -= db->in_count/4;
249 db->bytes_out -= db->bytes_out/4;
252 db->checkpoint = db->in_count + CHECK_GAP;
254 if (db->max_ent >= db->maxmaxcode) {
255 /* Reset the dictionary only if the ratio is worse,
256 * or if it looks as if it has been poisoned
257 * by incompressible data.
259 * This does not overflow, because
260 * db->in_count <= RATIO_MAX.
262 new_ratio = db->in_count << RATIO_SCALE_LOG;
263 if (db->bytes_out != 0)
264 new_ratio /= db->bytes_out;
266 if (new_ratio < db->ratio || new_ratio < 1 * RATIO_SCALE) {
270 db->ratio = new_ratio;
280 bsd_comp_stats(state, stats)
282 struct compstat *stats;
284 struct bsd_db *db = (struct bsd_db *) state;
287 stats->unc_bytes = db->uncomp_bytes;
288 stats->unc_packets = db->uncomp_count;
289 stats->comp_bytes = db->comp_bytes;
290 stats->comp_packets = db->comp_count;
291 stats->inc_bytes = db->incomp_bytes;
292 stats->inc_packets = db->incomp_count;
293 stats->ratio = db->in_count;
295 if (stats->ratio <= 0x7fffff)
304 * Reset state, as on a CCP ResetReq.
310 struct bsd_db *db = (struct bsd_db *) state;
318 * Allocate space for a (de) compressor.
321 bsd_alloc(options, opt_len, decomp)
326 u_int newlen, hsize, hshift, maxmaxcode;
329 if (opt_len != 3 || options[0] != CI_BSD_COMPRESS || options[1] != 3
330 || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION)
332 bits = BSD_NBITS(options[2]);
334 case 9: /* needs 82152 for both directions */
335 case 10: /* needs 84144 */
336 case 11: /* needs 88240 */
337 case 12: /* needs 96432 */
341 case 13: /* needs 176784 */
345 case 14: /* needs 353744 */
349 case 15: /* needs 691440 */
353 case 16: /* needs 1366160--far too much, */
354 /* hsize = 69001; */ /* and 69001 is too big for cptr */
355 /* hshift = 8; */ /* in struct bsd_db */
361 maxmaxcode = MAXCODE(bits);
362 newlen = sizeof(*db) + (hsize-1) * (sizeof(db->dict[0]));
363 db = (struct bsd_db *) ALLOC_NOSLEEP(newlen);
366 bzero(db, sizeof(*db) - sizeof(db->dict));
371 db->lens = (u_short *) ALLOC_NOSLEEP((maxmaxcode+1) * sizeof(db->lens[0]));
381 db->maxmaxcode = maxmaxcode;
391 struct bsd_db *db = (struct bsd_db *) state;
394 FREE(db->lens, (db->maxmaxcode+1) * sizeof(db->lens[0]));
395 FREE(db, db->totlen);
399 bsd_comp_alloc(options, opt_len)
403 return bsd_alloc(options, opt_len, 0);
407 bsd_decomp_alloc(options, opt_len)
411 return bsd_alloc(options, opt_len, 1);
415 * Initialize the database.
418 bsd_init(db, options, opt_len, unit, hdrlen, mru, debug, decomp)
421 int opt_len, unit, hdrlen, mru, debug, decomp;
425 if (opt_len != 3 || options[0] != CI_BSD_COMPRESS || options[1] != 3
426 || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION
427 || BSD_NBITS(options[2]) != db->maxbits
428 || decomp && db->lens == NULL)
438 db->dict[--i].codem1 = BADCODEM1;
439 db->dict[i].cptr = 0;
454 bsd_comp_init(state, options, opt_len, unit, hdrlen, debug)
457 int opt_len, unit, hdrlen, debug;
459 return bsd_init((struct bsd_db *) state, options, opt_len,
460 unit, hdrlen, 0, debug, 0);
464 bsd_decomp_init(state, options, opt_len, unit, hdrlen, mru, debug)
467 int opt_len, unit, hdrlen, mru, debug;
469 return bsd_init((struct bsd_db *) state, options, opt_len,
470 unit, hdrlen, mru, debug, 1);
476 * One change from the BSD compress command is that when the
477 * code size expands, we do not output a bunch of padding.
479 * N.B. at present, we ignore the hdrlen specified in the comp_init call.
481 static int /* new slen */
482 bsd_compress(state, mretp, mp, slen, maxolen)
484 mblk_t **mretp; /* return compressed mbuf chain here */
485 mblk_t *mp; /* from here */
486 int slen; /* uncompressed length */
487 int maxolen; /* max compressed length */
489 struct bsd_db *db = (struct bsd_db *) state;
490 int hshift = db->hshift;
491 u_int max_ent = db->max_ent;
492 u_int n_bits = db->n_bits;
494 u_int32_t accm = 0, fcode;
495 struct bsd_dict *dictp;
497 int hval, disp, ent, ilen;
504 #define PUTBYTE(v) { \
507 if (wptr >= cp_end) { \
512 cp_end = m->b_datap->db_lim; \
520 #define OUTPUT(ent) { \
522 accm |= ((ent) << bitno); \
524 PUTBYTE(accm >> 24); \
527 } while (bitno <= 24); \
531 * First get the protocol and check that we're
532 * interested in this packet.
536 if (rptr + PPP_HDRLEN > mp->b_wptr) {
537 if (!pullupmsg(mp, PPP_HDRLEN))
541 ent = PPP_PROTOCOL(rptr); /* get the protocol */
542 if (ent < 0x21 || ent > 0xf9)
545 /* Don't generate compressed packets which are larger than
546 the uncompressed packet. */
550 /* Allocate enough message blocks to give maxolen total space. */
552 for (olen = maxolen; olen > 0; ) {
553 m = allocb((olen < 4096? olen: 4096), BPRI_MED);
563 olen -= m->b_datap->db_lim - m->b_wptr;
567 if ((m = mret) != NULL) {
569 cp_end = m->b_datap->db_lim;
571 wptr = cp_end = NULL;
575 * Copy the PPP header over, changing the protocol,
576 * and install the 2-byte sequence number.
579 wptr[0] = PPP_ADDRESS(rptr);
580 wptr[1] = PPP_CONTROL(rptr);
581 wptr[2] = 0; /* change the protocol */
583 wptr[4] = db->seqno >> 8;
585 wptr += PPP_HDRLEN + BSD_OVHD;
590 slen = mp->b_wptr - rptr;
598 slen = np->b_wptr - rptr;
601 continue; /* handle 0-length buffers */
607 fcode = BSD_KEY(ent, c);
608 hval = BSD_HASH(ent, c, hshift);
609 dictp = &db->dict[hval];
611 /* Validate and then check the entry. */
612 if (dictp->codem1 >= max_ent)
614 if (dictp->f.fcode == fcode) {
615 ent = dictp->codem1+1;
616 continue; /* found (prefix,suffix) */
619 /* continue probing until a match or invalid entry */
620 disp = (hval == 0) ? 1 : hval;
623 if (hval >= db->hsize)
625 dictp = &db->dict[hval];
626 if (dictp->codem1 >= max_ent)
628 } while (dictp->f.fcode != fcode);
629 ent = dictp->codem1 + 1; /* finally found (prefix,suffix) */
633 OUTPUT(ent); /* output the prefix */
635 /* code -> hashtable */
636 if (max_ent < db->maxmaxcode) {
637 struct bsd_dict *dictp2;
638 /* expand code size if needed */
639 if (max_ent >= MAXCODE(n_bits))
640 db->n_bits = ++n_bits;
642 /* Invalidate old hash table entry using
643 * this code, and then take it over.
645 dictp2 = &db->dict[max_ent+1];
646 if (db->dict[dictp2->cptr].codem1 == max_ent)
647 db->dict[dictp2->cptr].codem1 = BADCODEM1;
649 dictp->codem1 = max_ent;
650 dictp->f.fcode = fcode;
652 db->max_ent = ++max_ent;
657 OUTPUT(ent); /* output the last code */
658 db->bytes_out += olen;
659 db->in_count += ilen;
661 ++db->bytes_out; /* count complete bytes */
664 OUTPUT(CLEAR); /* do not count the CLEAR */
667 * Pad dribble bits of last code with ones.
668 * Do not emit a completely useless byte of ones.
671 PUTBYTE((accm | (0xff << (bitno-8))) >> 24);
674 * Increase code size if we would have without the packet
675 * boundary and as the decompressor will.
677 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode)
680 db->uncomp_bytes += ilen;
682 if (olen + PPP_HDRLEN + BSD_OVHD > maxolen && mret != NULL) {
683 /* throw away the compressed stuff if it is longer than uncompressed */
687 db->incomp_bytes += ilen;
688 } else if (wptr != NULL) {
695 db->comp_bytes += olen + BSD_OVHD;
699 return olen + PPP_HDRLEN + BSD_OVHD;
706 * Update the "BSD Compress" dictionary on the receiver for
707 * incompressible data by pretending to compress the incoming data.
710 bsd_incomp(state, dmsg)
714 struct bsd_db *db = (struct bsd_db *) state;
715 u_int hshift = db->hshift;
716 u_int max_ent = db->max_ent;
717 u_int n_bits = db->n_bits;
718 struct bsd_dict *dictp;
728 if (rptr + PPP_HDRLEN > dmsg->b_wptr) {
729 if (!pullupmsg(dmsg, PPP_HDRLEN))
733 ent = PPP_PROTOCOL(rptr); /* get the protocol */
734 if (ent < 0x21 || ent > 0xf9)
739 ilen = 1; /* count the protocol as 1 byte */
742 slen = dmsg->b_wptr - rptr;
748 continue; /* skip zero-length buffers */
754 fcode = BSD_KEY(ent, c);
755 hval = BSD_HASH(ent, c, hshift);
756 dictp = &db->dict[hval];
758 /* validate and then check the entry */
759 if (dictp->codem1 >= max_ent)
761 if (dictp->f.fcode == fcode) {
762 ent = dictp->codem1+1;
763 continue; /* found (prefix,suffix) */
766 /* continue probing until a match or invalid entry */
767 disp = (hval == 0) ? 1 : hval;
770 if (hval >= db->hsize)
772 dictp = &db->dict[hval];
773 if (dictp->codem1 >= max_ent)
775 } while (dictp->f.fcode != fcode);
776 ent = dictp->codem1+1;
777 continue; /* finally found (prefix,suffix) */
779 nomatch: /* output (count) the prefix */
782 /* code -> hashtable */
783 if (max_ent < db->maxmaxcode) {
784 struct bsd_dict *dictp2;
785 /* expand code size if needed */
786 if (max_ent >= MAXCODE(n_bits))
787 db->n_bits = ++n_bits;
789 /* Invalidate previous hash table entry
790 * assigned this code, and then take it over.
792 dictp2 = &db->dict[max_ent+1];
793 if (db->dict[dictp2->cptr].codem1 == max_ent)
794 db->dict[dictp2->cptr].codem1 = BADCODEM1;
796 dictp->codem1 = max_ent;
797 dictp->f.fcode = fcode;
799 db->max_ent = ++max_ent;
800 db->lens[max_ent] = db->lens[ent]+1;
803 } while (--slen != 0);
805 bitno += n_bits; /* output (count) the last code */
806 db->bytes_out += bitno/8;
807 db->in_count += ilen;
811 db->incomp_bytes += ilen;
813 db->uncomp_bytes += ilen;
815 /* Increase code size if we would have without the packet
816 * boundary and as the decompressor will.
818 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode)
824 * Decompress "BSD Compress"
826 * Because of patent problems, we return DECOMP_ERROR for errors
827 * found by inspecting the input data and for system problems, but
828 * DECOMP_FATALERROR for any errors which could possibly be said to
829 * be being detected "after" decompression. For DECOMP_ERROR,
830 * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be
831 * infringing a patent of Motorola's if we do, so we take CCP down
834 * Given that the frame has the correct sequence number and a good FCS,
835 * errors such as invalid codes in the input most likely indicate a
836 * bug, so we return DECOMP_FATALERROR for them in order to turn off
837 * compression, even though they are detected by inspecting the input.
840 bsd_decompress(state, cmsg, dmpp)
842 mblk_t *cmsg, **dmpp;
844 struct bsd_db *db = (struct bsd_db *) state;
845 u_int max_ent = db->max_ent;
847 u_int bitno = 32; /* 1st valid bit in accm */
848 u_int n_bits = db->n_bits;
849 u_int tgtbitno = 32-n_bits; /* bitno when we have a code */
850 struct bsd_dict *dictp;
851 int explen, i, seq, len;
852 u_int incode, oldcode, finchar;
853 u_char *p, *rptr, *wptr;
855 int adrs, ctrl, ilen;
856 int dlen, space, codelen, extra;
859 * Get at least the BSD Compress header in the first buffer
862 if (rptr + PPP_HDRLEN + BSD_OVHD >= cmsg->b_wptr) {
863 if (!pullupmsg(cmsg, PPP_HDRLEN + BSD_OVHD + 1)) {
865 printf("bsd_decomp%d: failed to pullup\n", db->unit);
872 * Save the address/control from the PPP header
873 * and then get the sequence number.
875 adrs = PPP_ADDRESS(rptr);
876 ctrl = PPP_CONTROL(rptr);
878 seq = (rptr[0] << 8) + rptr[1];
880 ilen = len = cmsg->b_wptr - rptr;
883 * Check the sequence number and give up if it is not what we expect.
885 if (seq != db->seqno++) {
887 printf("bsd_decomp%d: bad sequence # %d, expected %d\n",
888 db->unit, seq, db->seqno - 1);
893 * Allocate one message block to start with.
895 if ((dmsg = allocb(DECOMP_CHUNK + db->hdrlen, BPRI_MED)) == NULL)
898 dmsg->b_wptr += db->hdrlen;
899 dmsg->b_rptr = wptr = dmsg->b_wptr;
901 /* Fill in the ppp header, but not the last byte of the protocol
902 (that comes from the decompressed data). */
906 wptr += PPP_HDRLEN - 1;
907 space = dmsg->b_datap->db_lim - wptr;
914 if (!cmsg) /* quit at end of message */
917 len = cmsg->b_wptr - rptr;
919 continue; /* handle 0-length buffers */
923 * Accumulate bytes until we have a complete code.
924 * Then get the next code, relying on the 32-bit,
925 * unsigned accm to mask the result.
928 accm |= *rptr++ << bitno;
930 if (tgtbitno < bitno)
932 incode = accm >> tgtbitno;
936 if (incode == CLEAR) {
938 * The dictionary must only be cleared at
939 * the end of a packet. But there could be an
940 * empty message block at the end.
942 if (len > 0 || cmsg->b_cont != 0) {
944 len += msgdsize(cmsg->b_cont);
948 printf("bsd_decomp%d: bad CLEAR\n", db->unit);
949 return DECOMP_FATALERROR;
957 if (incode > max_ent + 2 || incode > db->maxmaxcode
958 || incode > max_ent && oldcode == CLEAR) {
961 printf("bsd_decomp%d: bad code 0x%x oldcode=0x%x ",
962 db->unit, incode, oldcode);
963 printf("max_ent=0x%x dlen=%d seqno=%d\n",
964 max_ent, dlen, db->seqno);
966 return DECOMP_FATALERROR; /* probably a bug */
969 /* Special case for KwKwK string. */
970 if (incode > max_ent) {
978 codelen = db->lens[finchar];
979 explen += codelen + extra;
980 if (explen > db->mru + 1) {
983 printf("bsd_decomp%d: ran out of mru\n", db->unit);
984 return DECOMP_FATALERROR;
988 * Decode this code and install it in the decompressed buffer.
990 space -= codelen + extra;
992 /* Allocate another message block. */
994 dlen = codelen + extra;
995 if (dlen < DECOMP_CHUNK)
997 if ((dmsg->b_cont = allocb(dlen, BPRI_MED)) == NULL) {
1001 dmsg = dmsg->b_cont;
1002 wptr = dmsg->b_wptr;
1003 space = dmsg->b_datap->db_lim - wptr - codelen - extra;
1005 p = (wptr += codelen);
1006 while (finchar > LAST) {
1007 dictp = &db->dict[db->dict[finchar].cptr];
1012 printf("bsd_decomp%d: fell off end of chain ", db->unit);
1013 printf("0x%x at 0x%x by 0x%x, max_ent=0x%x\n",
1014 incode, finchar, db->dict[finchar].cptr, max_ent);
1015 return DECOMP_FATALERROR;
1017 if (dictp->codem1 != finchar-1) {
1019 printf("bsd_decomp%d: bad code chain 0x%x finchar=0x%x ",
1020 db->unit, incode, finchar);
1021 printf("oldcode=0x%x cptr=0x%x codem1=0x%x\n", oldcode,
1022 db->dict[finchar].cptr, dictp->codem1);
1023 return DECOMP_FATALERROR;
1026 *--p = dictp->f.hs.suffix;
1027 finchar = dictp->f.hs.prefix;
1033 printf("bsd_decomp%d: short by %d after code 0x%x, max_ent=0x%x\n",
1034 db->unit, codelen, incode, max_ent);
1037 if (extra) /* the KwKwK case again */
1041 * If not first code in a packet, and
1042 * if not out of code space, then allocate a new code.
1044 * Keep the hash table correct so it can be used
1045 * with uncompressed packets.
1047 if (oldcode != CLEAR && max_ent < db->maxmaxcode) {
1048 struct bsd_dict *dictp2;
1052 fcode = BSD_KEY(oldcode,finchar);
1053 hval = BSD_HASH(oldcode,finchar,db->hshift);
1054 dictp = &db->dict[hval];
1056 /* look for a free hash table entry */
1057 if (dictp->codem1 < max_ent) {
1058 disp = (hval == 0) ? 1 : hval;
1061 if (hval >= db->hsize)
1063 dictp = &db->dict[hval];
1064 } while (dictp->codem1 < max_ent);
1068 * Invalidate previous hash table entry
1069 * assigned this code, and then take it over
1071 dictp2 = &db->dict[max_ent+1];
1072 if (db->dict[dictp2->cptr].codem1 == max_ent) {
1073 db->dict[dictp2->cptr].codem1 = BADCODEM1;
1075 dictp2->cptr = hval;
1076 dictp->codem1 = max_ent;
1077 dictp->f.fcode = fcode;
1079 db->max_ent = ++max_ent;
1080 db->lens[max_ent] = db->lens[oldcode]+1;
1082 /* Expand code size if needed. */
1083 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) {
1084 db->n_bits = ++n_bits;
1085 tgtbitno = 32-n_bits;
1090 dmsg->b_wptr = wptr;
1093 * Keep the checkpoint right so that incompressible packets
1094 * clear the dictionary at the right times.
1096 db->bytes_out += ilen;
1097 db->in_count += explen;
1098 if (bsd_check(db) && db->debug) {
1099 printf("bsd_decomp%d: peer should have cleared dictionary\n",
1104 db->comp_bytes += ilen + BSD_OVHD;
1106 db->uncomp_bytes += explen;
1111 #endif /* DO_BSD_COMPRESS */