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 1.9 1995/04/28 06:13:56 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 * A dictionary for doing BSD compress.
104 int totlen; /* length of this structure */
105 u_int hsize; /* size of the hash table */
106 u_char hshift; /* used in hash function */
107 u_char n_bits; /* current bits/code */
111 u_short seqno; /* sequence number of next packet */
112 u_int hdrlen; /* header length to preallocate */
114 u_int maxmaxcode; /* largest valid code */
115 u_int max_ent; /* largest code in use */
116 u_int in_count; /* uncompressed bytes, aged */
117 u_int bytes_out; /* compressed bytes, aged */
118 u_int ratio; /* recent compression ratio */
119 u_int checkpoint; /* when to next check the ratio */
120 u_int clear_count; /* times dictionary cleared */
121 u_int incomp_count; /* incompressible packets */
122 u_int incomp_bytes; /* incompressible bytes */
123 u_int uncomp_count; /* uncompressed packets */
124 u_int uncomp_bytes; /* uncompressed bytes */
125 u_int comp_count; /* compressed packets */
126 u_int comp_bytes; /* compressed bytes */
127 u_short *lens; /* array of lengths of codes */
129 union { /* hash value */
132 #ifdef BSD_LITTLE_ENDIAN
133 u_short prefix; /* preceding code */
134 u_char suffix; /* last character of new code */
138 u_char suffix; /* last character of new code */
139 u_short prefix; /* preceding code */
143 u_short codem1; /* output of hash table -1 */
144 u_short cptr; /* map code to hash table entry */
148 #define BSD_OVHD 2 /* BSD compress overhead/packet */
149 #define BSD_INIT_BITS MIN_BSD_BITS
151 static void *bsd_comp_alloc __P((u_char *options, int opt_len));
152 static void *bsd_decomp_alloc __P((u_char *options, int opt_len));
153 static void bsd_free __P((void *state));
154 static int bsd_comp_init __P((void *state, u_char *options, int opt_len,
155 int unit, int hdrlen, int debug));
156 static int bsd_decomp_init __P((void *state, u_char *options, int opt_len,
157 int unit, int hdrlen, int mru, int debug));
158 static int bsd_compress __P((void *state, mblk_t **mret,
159 mblk_t *mp, int slen, int maxolen));
160 static void bsd_incomp __P((void *state, mblk_t *dmsg));
161 static int bsd_decompress __P((void *state, mblk_t *cmp, mblk_t **dmpp));
162 static void bsd_reset __P((void *state));
163 static void bsd_comp_stats __P((void *state, struct compstat *stats));
166 * Procedures exported to ppp_comp.c.
168 struct compressor ppp_bsd_compress = {
169 CI_BSD_COMPRESS, /* compress_proto */
170 bsd_comp_alloc, /* comp_alloc */
171 bsd_free, /* comp_free */
172 bsd_comp_init, /* comp_init */
173 bsd_reset, /* comp_reset */
174 bsd_compress, /* compress */
175 bsd_comp_stats, /* comp_stat */
176 bsd_decomp_alloc, /* decomp_alloc */
177 bsd_free, /* decomp_free */
178 bsd_decomp_init, /* decomp_init */
179 bsd_reset, /* decomp_reset */
180 bsd_decompress, /* decompress */
181 bsd_incomp, /* incomp */
182 bsd_comp_stats, /* decomp_stat */
186 * the next two codes should not be changed lightly, as they must not
187 * lie within the contiguous general code space.
189 #define CLEAR 256 /* table clear output code */
190 #define FIRST 257 /* first free entry */
193 #define MAXCODE(b) ((1 << (b)) - 1)
194 #define BADCODEM1 MAXCODE(BSD_MAX_BITS)
196 #define BSD_HASH(prefix,suffix,hshift) ((((u_int32_t)(suffix)) << (hshift)) \
197 ^ (u_int32_t)(prefix))
198 #define BSD_KEY(prefix,suffix) ((((u_int32_t)(suffix)) << 16) \
199 + (u_int32_t)(prefix))
201 #define CHECK_GAP 10000 /* Ratio check interval */
203 #define RATIO_SCALE_LOG 8
204 #define RATIO_SCALE (1<<RATIO_SCALE_LOG)
205 #define RATIO_MAX (0x7fffffff>>RATIO_SCALE_LOG)
207 #define DECOMP_CHUNK 256
210 * clear the dictionary
217 db->max_ent = FIRST-1;
218 db->n_bits = BSD_INIT_BITS;
222 db->incomp_count = 0;
223 db->checkpoint = CHECK_GAP;
227 * If the dictionary is full, then see if it is time to reset it.
229 * Compute the compression ratio using fixed-point arithmetic
230 * with 8 fractional bits.
232 * Since we have an infinite stream instead of a single file,
233 * watch only the local compression ratio.
235 * Since both peers must reset the dictionary at the same time even in
236 * the absence of CLEAR codes (while packets are incompressible), they
237 * must compute the same ratio.
239 static int /* 1=output CLEAR */
245 if (db->in_count >= db->checkpoint) {
246 /* age the ratio by limiting the size of the counts */
247 if (db->in_count >= RATIO_MAX
248 || db->bytes_out >= RATIO_MAX) {
249 db->in_count -= db->in_count/4;
250 db->bytes_out -= db->bytes_out/4;
253 db->checkpoint = db->in_count + CHECK_GAP;
255 if (db->max_ent >= db->maxmaxcode) {
256 /* Reset the dictionary only if the ratio is worse,
257 * or if it looks as if it has been poisoned
258 * by incompressible data.
260 * This does not overflow, because
261 * db->in_count <= RATIO_MAX.
263 new_ratio = db->in_count << RATIO_SCALE_LOG;
264 if (db->bytes_out != 0)
265 new_ratio /= db->bytes_out;
267 if (new_ratio < db->ratio || new_ratio < 1 * RATIO_SCALE) {
271 db->ratio = new_ratio;
281 bsd_comp_stats(state, stats)
283 struct compstat *stats;
285 struct bsd_db *db = (struct bsd_db *) state;
288 stats->unc_bytes = db->uncomp_bytes;
289 stats->unc_packets = db->uncomp_count;
290 stats->comp_bytes = db->comp_bytes;
291 stats->comp_packets = db->comp_count;
292 stats->inc_bytes = db->incomp_bytes;
293 stats->inc_packets = db->incomp_count;
294 stats->ratio = db->in_count;
296 if (stats->ratio <= 0x7fffff)
305 * Reset state, as on a CCP ResetReq.
311 struct bsd_db *db = (struct bsd_db *) state;
319 * Allocate space for a (de) compressor.
322 bsd_alloc(options, opt_len, decomp)
327 u_int newlen, hsize, hshift, maxmaxcode;
330 if (opt_len != 3 || options[0] != CI_BSD_COMPRESS || options[1] != 3
331 || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION)
333 bits = BSD_NBITS(options[2]);
335 case 9: /* needs 82152 for both directions */
336 case 10: /* needs 84144 */
337 case 11: /* needs 88240 */
338 case 12: /* needs 96432 */
342 case 13: /* needs 176784 */
346 case 14: /* needs 353744 */
350 case 15: /* needs 691440 */
354 case 16: /* needs 1366160--far too much, */
355 /* hsize = 69001; */ /* and 69001 is too big for cptr */
356 /* hshift = 8; */ /* in struct bsd_db */
362 maxmaxcode = MAXCODE(bits);
363 newlen = sizeof(*db) + (hsize-1) * (sizeof(db->dict[0]));
364 db = (struct bsd_db *) ALLOCATE(newlen);
367 bzero(db, sizeof(*db) - sizeof(db->dict));
372 db->lens = (u_short *) ALLOCATE((maxmaxcode+1) * sizeof(db->lens[0]));
382 db->maxmaxcode = maxmaxcode;
392 struct bsd_db *db = (struct bsd_db *) state;
395 FREE(db->lens, (db->maxmaxcode+1) * sizeof(db->lens[0]));
396 FREE(db, db->totlen);
400 bsd_comp_alloc(options, opt_len)
404 return bsd_alloc(options, opt_len, 0);
408 bsd_decomp_alloc(options, opt_len)
412 return bsd_alloc(options, opt_len, 1);
416 * Initialize the database.
419 bsd_init(db, options, opt_len, unit, hdrlen, mru, debug, decomp)
422 int opt_len, unit, hdrlen, mru, debug, decomp;
426 if (opt_len != 3 || options[0] != CI_BSD_COMPRESS || options[1] != 3
427 || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION
428 || BSD_NBITS(options[2]) != db->maxbits
429 || decomp && db->lens == NULL)
439 db->dict[--i].codem1 = BADCODEM1;
440 db->dict[i].cptr = 0;
455 bsd_comp_init(state, options, opt_len, unit, hdrlen, debug)
458 int opt_len, unit, hdrlen, debug;
460 return bsd_init((struct bsd_db *) state, options, opt_len,
461 unit, hdrlen, 0, debug, 0);
465 bsd_decomp_init(state, options, opt_len, unit, hdrlen, mru, debug)
468 int opt_len, unit, hdrlen, mru, debug;
470 return bsd_init((struct bsd_db *) state, options, opt_len,
471 unit, hdrlen, mru, debug, 1);
477 * One change from the BSD compress command is that when the
478 * code size expands, we do not output a bunch of padding.
480 * N.B. at present, we ignore the hdrlen specified in the comp_init call.
482 static int /* new slen */
483 bsd_compress(state, mretp, mp, slen, maxolen)
485 mblk_t **mretp; /* return compressed mbuf chain here */
486 mblk_t *mp; /* from here */
487 int slen; /* uncompressed length */
488 int maxolen; /* max compressed length */
490 struct bsd_db *db = (struct bsd_db *) state;
491 int hshift = db->hshift;
492 u_int max_ent = db->max_ent;
493 u_int n_bits = db->n_bits;
495 u_int32_t accm = 0, fcode;
496 struct bsd_dict *dictp;
498 int hval, disp, ent, ilen;
505 #define PUTBYTE(v) { \
508 if (wptr >= cp_end) { \
513 cp_end = m->b_datap->db_lim; \
521 #define OUTPUT(ent) { \
523 accm |= ((ent) << bitno); \
525 PUTBYTE(accm >> 24); \
528 } while (bitno <= 24); \
532 * First get the protocol and check that we're
533 * interested in this packet.
537 if (rptr + PPP_HDRLEN > mp->b_wptr) {
538 if (!pullupmsg(mp, PPP_HDRLEN))
542 ent = PPP_PROTOCOL(rptr); /* get the protocol */
543 if (ent < 0x21 || ent > 0xf9)
546 /* Don't generate compressed packets which are larger than
547 the uncompressed packet. */
551 /* Allocate enough message blocks to give maxolen total space. */
553 for (olen = maxolen; olen > 0; ) {
554 m = allocb((olen < 4096? olen: 4096), BPRI_MED);
564 olen -= m->b_datap->db_lim - m->b_wptr;
568 if ((m = mret) != NULL) {
570 cp_end = m->b_datap->db_lim;
572 wptr = cp_end = NULL;
576 * Copy the PPP header over, changing the protocol,
577 * and install the 2-byte sequence number.
580 wptr[0] = PPP_ADDRESS(rptr);
581 wptr[1] = PPP_CONTROL(rptr);
582 wptr[2] = 0; /* change the protocol */
584 wptr[4] = db->seqno >> 8;
586 wptr += PPP_HDRLEN + BSD_OVHD;
591 slen = mp->b_wptr - rptr;
599 slen = np->b_wptr - rptr;
602 continue; /* handle 0-length buffers */
608 fcode = BSD_KEY(ent, c);
609 hval = BSD_HASH(ent, c, hshift);
610 dictp = &db->dict[hval];
612 /* Validate and then check the entry. */
613 if (dictp->codem1 >= max_ent)
615 if (dictp->f.fcode == fcode) {
616 ent = dictp->codem1+1;
617 continue; /* found (prefix,suffix) */
620 /* continue probing until a match or invalid entry */
621 disp = (hval == 0) ? 1 : hval;
624 if (hval >= db->hsize)
626 dictp = &db->dict[hval];
627 if (dictp->codem1 >= max_ent)
629 } while (dictp->f.fcode != fcode);
630 ent = dictp->codem1 + 1; /* finally found (prefix,suffix) */
634 OUTPUT(ent); /* output the prefix */
636 /* code -> hashtable */
637 if (max_ent < db->maxmaxcode) {
638 struct bsd_dict *dictp2;
639 /* expand code size if needed */
640 if (max_ent >= MAXCODE(n_bits))
641 db->n_bits = ++n_bits;
643 /* Invalidate old hash table entry using
644 * this code, and then take it over.
646 dictp2 = &db->dict[max_ent+1];
647 if (db->dict[dictp2->cptr].codem1 == max_ent)
648 db->dict[dictp2->cptr].codem1 = BADCODEM1;
650 dictp->codem1 = max_ent;
651 dictp->f.fcode = fcode;
653 db->max_ent = ++max_ent;
658 OUTPUT(ent); /* output the last code */
659 db->bytes_out += olen;
660 db->in_count += ilen;
662 ++db->bytes_out; /* count complete bytes */
665 OUTPUT(CLEAR); /* do not count the CLEAR */
668 * Pad dribble bits of last code with ones.
669 * Do not emit a completely useless byte of ones.
672 PUTBYTE((accm | (0xff << (bitno-8))) >> 24);
675 * Increase code size if we would have without the packet
676 * boundary and as the decompressor will.
678 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode)
681 db->uncomp_bytes += ilen;
683 if (olen + PPP_HDRLEN + BSD_OVHD > maxolen && mret != NULL) {
684 /* throw away the compressed stuff if it is longer than uncompressed */
688 db->incomp_bytes += ilen;
689 } else if (wptr != NULL) {
696 db->comp_bytes += olen + BSD_OVHD;
700 return olen + PPP_HDRLEN + BSD_OVHD;
707 * Update the "BSD Compress" dictionary on the receiver for
708 * incompressible data by pretending to compress the incoming data.
711 bsd_incomp(state, dmsg)
715 struct bsd_db *db = (struct bsd_db *) state;
716 u_int hshift = db->hshift;
717 u_int max_ent = db->max_ent;
718 u_int n_bits = db->n_bits;
719 struct bsd_dict *dictp;
729 if (rptr + PPP_HDRLEN > dmsg->b_wptr) {
730 if (!pullupmsg(dmsg, PPP_HDRLEN))
734 ent = PPP_PROTOCOL(rptr); /* get the protocol */
735 if (ent < 0x21 || ent > 0xf9)
740 ilen = 1; /* count the protocol as 1 byte */
743 slen = dmsg->b_wptr - rptr;
749 continue; /* skip zero-length buffers */
755 fcode = BSD_KEY(ent, c);
756 hval = BSD_HASH(ent, c, hshift);
757 dictp = &db->dict[hval];
759 /* validate and then check the entry */
760 if (dictp->codem1 >= max_ent)
762 if (dictp->f.fcode == fcode) {
763 ent = dictp->codem1+1;
764 continue; /* found (prefix,suffix) */
767 /* continue probing until a match or invalid entry */
768 disp = (hval == 0) ? 1 : hval;
771 if (hval >= db->hsize)
773 dictp = &db->dict[hval];
774 if (dictp->codem1 >= max_ent)
776 } while (dictp->f.fcode != fcode);
777 ent = dictp->codem1+1;
778 continue; /* finally found (prefix,suffix) */
780 nomatch: /* output (count) the prefix */
783 /* code -> hashtable */
784 if (max_ent < db->maxmaxcode) {
785 struct bsd_dict *dictp2;
786 /* expand code size if needed */
787 if (max_ent >= MAXCODE(n_bits))
788 db->n_bits = ++n_bits;
790 /* Invalidate previous hash table entry
791 * assigned this code, and then take it over.
793 dictp2 = &db->dict[max_ent+1];
794 if (db->dict[dictp2->cptr].codem1 == max_ent)
795 db->dict[dictp2->cptr].codem1 = BADCODEM1;
797 dictp->codem1 = max_ent;
798 dictp->f.fcode = fcode;
800 db->max_ent = ++max_ent;
801 db->lens[max_ent] = db->lens[ent]+1;
804 } while (--slen != 0);
806 bitno += n_bits; /* output (count) the last code */
807 db->bytes_out += bitno/8;
808 db->in_count += ilen;
812 db->incomp_bytes += ilen;
814 db->uncomp_bytes += ilen;
816 /* Increase code size if we would have without the packet
817 * boundary and as the decompressor will.
819 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode)
825 * Decompress "BSD Compress"
827 * Because of patent problems, we return DECOMP_ERROR for errors
828 * found by inspecting the input data and for system problems, but
829 * DECOMP_FATALERROR for any errors which could possibly be said to
830 * be being detected "after" decompression. For DECOMP_ERROR,
831 * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be
832 * infringing a patent of Motorola's if we do, so we take CCP down
835 * Given that the frame has the correct sequence number and a good FCS,
836 * errors such as invalid codes in the input most likely indicate a
837 * bug, so we return DECOMP_FATALERROR for them in order to turn off
838 * compression, even though they are detected by inspecting the input.
841 bsd_decompress(state, cmsg, dmpp)
843 mblk_t *cmsg, **dmpp;
845 struct bsd_db *db = (struct bsd_db *) state;
846 u_int max_ent = db->max_ent;
848 u_int bitno = 32; /* 1st valid bit in accm */
849 u_int n_bits = db->n_bits;
850 u_int tgtbitno = 32-n_bits; /* bitno when we have a code */
851 struct bsd_dict *dictp;
852 int explen, i, seq, len;
853 u_int incode, oldcode, finchar;
854 u_char *p, *rptr, *wptr;
856 int adrs, ctrl, ilen;
857 int dlen, space, codelen, extra;
860 * Get at least the BSD Compress header in the first buffer
863 if (rptr + PPP_HDRLEN + BSD_OVHD >= cmsg->b_wptr) {
864 if (!pullupmsg(cmsg, PPP_HDRLEN + BSD_OVHD + 1)) {
866 printf("bsd_decomp%d: failed to pullup\n", db->unit);
873 * Save the address/control from the PPP header
874 * and then get the sequence number.
876 adrs = PPP_ADDRESS(rptr);
877 ctrl = PPP_CONTROL(rptr);
879 seq = (rptr[0] << 8) + rptr[1];
881 ilen = len = cmsg->b_wptr - rptr;
884 * Check the sequence number and give up if it is not what we expect.
886 if (seq != db->seqno++) {
888 printf("bsd_decomp%d: bad sequence # %d, expected %d\n",
889 db->unit, seq, db->seqno - 1);
894 * Allocate one message block to start with.
896 if ((dmsg = allocb(DECOMP_CHUNK + db->hdrlen, BPRI_MED)) == NULL)
899 dmsg->b_wptr += db->hdrlen;
900 dmsg->b_rptr = wptr = dmsg->b_wptr;
902 /* Fill in the ppp header, but not the last byte of the protocol
903 (that comes from the decompressed data). */
907 wptr += PPP_HDRLEN - 1;
908 space = dmsg->b_datap->db_lim - wptr;
915 if (!cmsg) /* quit at end of message */
918 len = cmsg->b_wptr - rptr;
920 continue; /* handle 0-length buffers */
924 * Accumulate bytes until we have a complete code.
925 * Then get the next code, relying on the 32-bit,
926 * unsigned accm to mask the result.
929 accm |= *rptr++ << bitno;
931 if (tgtbitno < bitno)
933 incode = accm >> tgtbitno;
937 if (incode == CLEAR) {
939 * The dictionary must only be cleared at
940 * the end of a packet. But there could be an
941 * empty message block at the end.
943 if (len > 0 || cmsg->b_cont != 0) {
945 len += msgdsize(cmsg->b_cont);
949 printf("bsd_decomp%d: bad CLEAR\n", db->unit);
950 return DECOMP_FATALERROR;
958 if (incode > max_ent + 2 || incode > db->maxmaxcode
959 || incode > max_ent && oldcode == CLEAR) {
962 printf("bsd_decomp%d: bad code 0x%x oldcode=0x%x ",
963 db->unit, incode, oldcode);
964 printf("max_ent=0x%x dlen=%d seqno=%d\n",
965 max_ent, dlen, db->seqno);
967 return DECOMP_FATALERROR; /* probably a bug */
970 /* Special case for KwKwK string. */
971 if (incode > max_ent) {
979 codelen = db->lens[finchar];
980 explen += codelen + extra;
981 if (explen > db->mru + 1) {
984 printf("bsd_decomp%d: ran out of mru\n", db->unit);
985 return DECOMP_FATALERROR;
989 * Decode this code and install it in the decompressed buffer.
991 space -= codelen + extra;
993 /* Allocate another message block. */
995 dlen = codelen + extra;
996 if (dlen < DECOMP_CHUNK)
998 if ((dmsg->b_cont = allocb(dlen, BPRI_MED)) == NULL) {
1000 return DECOMP_ERROR;
1002 dmsg = dmsg->b_cont;
1003 wptr = dmsg->b_wptr;
1004 space = dmsg->b_datap->db_lim - wptr - codelen - extra;
1006 p = (wptr += codelen);
1007 while (finchar > LAST) {
1008 dictp = &db->dict[db->dict[finchar].cptr];
1013 printf("bsd_decomp%d: fell off end of chain ", db->unit);
1014 printf("0x%x at 0x%x by 0x%x, max_ent=0x%x\n",
1015 incode, finchar, db->dict[finchar].cptr, max_ent);
1016 return DECOMP_FATALERROR;
1018 if (dictp->codem1 != finchar-1) {
1020 printf("bsd_decomp%d: bad code chain 0x%x finchar=0x%x ",
1021 db->unit, incode, finchar);
1022 printf("oldcode=0x%x cptr=0x%x codem1=0x%x\n", oldcode,
1023 db->dict[finchar].cptr, dictp->codem1);
1024 return DECOMP_FATALERROR;
1027 *--p = dictp->f.hs.suffix;
1028 finchar = dictp->f.hs.prefix;
1034 printf("bsd_decomp%d: short by %d after code 0x%x, max_ent=0x%x\n",
1035 db->unit, codelen, incode, max_ent);
1038 if (extra) /* the KwKwK case again */
1042 * If not first code in a packet, and
1043 * if not out of code space, then allocate a new code.
1045 * Keep the hash table correct so it can be used
1046 * with uncompressed packets.
1048 if (oldcode != CLEAR && max_ent < db->maxmaxcode) {
1049 struct bsd_dict *dictp2;
1053 fcode = BSD_KEY(oldcode,finchar);
1054 hval = BSD_HASH(oldcode,finchar,db->hshift);
1055 dictp = &db->dict[hval];
1057 /* look for a free hash table entry */
1058 if (dictp->codem1 < max_ent) {
1059 disp = (hval == 0) ? 1 : hval;
1062 if (hval >= db->hsize)
1064 dictp = &db->dict[hval];
1065 } while (dictp->codem1 < max_ent);
1069 * Invalidate previous hash table entry
1070 * assigned this code, and then take it over
1072 dictp2 = &db->dict[max_ent+1];
1073 if (db->dict[dictp2->cptr].codem1 == max_ent) {
1074 db->dict[dictp2->cptr].codem1 = BADCODEM1;
1076 dictp2->cptr = hval;
1077 dictp->codem1 = max_ent;
1078 dictp->f.fcode = fcode;
1080 db->max_ent = ++max_ent;
1081 db->lens[max_ent] = db->lens[oldcode]+1;
1083 /* Expand code size if needed. */
1084 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) {
1085 db->n_bits = ++n_bits;
1086 tgtbitno = 32-n_bits;
1091 dmsg->b_wptr = wptr;
1094 * Keep the checkpoint right so that incompressible packets
1095 * clear the dictionary at the right times.
1097 db->bytes_out += ilen;
1098 db->in_count += explen;
1099 if (bsd_check(db) && db->debug) {
1100 printf("bsd_decomp%d: peer should have cleared dictionary\n",
1105 db->comp_bytes += ilen + BSD_OVHD;
1107 db->uncomp_bytes += explen;