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 1.13 1995/05/29 06:34:33 paulus Exp $
48 #include <net/net_globals.h>
50 #include <sys/param.h>
51 #include <sys/types.h>
52 #include <sys/stream.h>
53 #include <sys/socket.h>
55 #include <net/ppp_defs.h>
56 #include <net/ppp_str.h>
58 #ifdef __svr4__ /* SVR4, including SunOS 5.x */
59 # include <sys/kmem.h>
60 # define ALLOCATE(n) kmem_alloc((n), KM_NOSLEEP)
61 # define FREE(p, n) kmem_free((p), (n))
64 # include <sys/kmem_alloc.h>
65 # define ALLOCATE(n) kmem_alloc((n), KMEM_NOSLEEP)
66 # define FREE(p, n) kmem_free((p), (n))
78 #include <kern/kalloc.h>
79 #define ALLOCATE(n) kalloc((n))
80 #define FREE(p, n) kfree((p), (n))
84 #define ALLOCATE(n) xmalloc((n), 0, pinned_heap)
85 #define FREE(p, n) xmfree((p), pinned_heap)
88 #define PACKETPTR mblk_t *
89 #include <net/ppp-comp.h>
94 * PPP "BSD compress" compression
95 * The differences between this compression and the classic BSD LZW
96 * source are obvious from the requirement that the classic code worked
97 * with files while this handles arbitrarily long streams that
98 * are broken into packets. They are:
100 * When the code size expands, a block of junk is not emitted by
101 * the compressor and not expected by the decompressor.
103 * New codes are not necessarily assigned every time an old
104 * code is output by the compressor. This is because a packet
105 * end forces a code to be emitted, but does not imply that a
106 * new sequence has been seen.
108 * The compression ratio is checked at the first end of a packet
109 * after the appropriate gap. Besides simplifying and speeding
110 * things up, this makes it more likely that the transmitter
111 * and receiver will agree when the dictionary is cleared when
112 * compression is not going well.
116 * A dictionary for doing BSD compress.
119 int totlen; /* length of this structure */
120 u_int hsize; /* size of the hash table */
121 u_char hshift; /* used in hash function */
122 u_char n_bits; /* current bits/code */
126 u_short seqno; /* sequence number of next packet */
127 u_int hdrlen; /* header length to preallocate */
129 u_int maxmaxcode; /* largest valid code */
130 u_int max_ent; /* largest code in use */
131 u_int in_count; /* uncompressed bytes, aged */
132 u_int bytes_out; /* compressed bytes, aged */
133 u_int ratio; /* recent compression ratio */
134 u_int checkpoint; /* when to next check the ratio */
135 u_int clear_count; /* times dictionary cleared */
136 u_int incomp_count; /* incompressible packets */
137 u_int incomp_bytes; /* incompressible bytes */
138 u_int uncomp_count; /* uncompressed packets */
139 u_int uncomp_bytes; /* uncompressed bytes */
140 u_int comp_count; /* compressed packets */
141 u_int comp_bytes; /* compressed bytes */
142 u_short *lens; /* array of lengths of codes */
144 union { /* hash value */
147 #ifdef BSD_LITTLE_ENDIAN
148 u_short prefix; /* preceding code */
149 u_char suffix; /* last character of new code */
153 u_char suffix; /* last character of new code */
154 u_short prefix; /* preceding code */
158 u_short codem1; /* output of hash table -1 */
159 u_short cptr; /* map code to hash table entry */
163 #define BSD_OVHD 2 /* BSD compress overhead/packet */
164 #define BSD_INIT_BITS BSD_MIN_BITS
166 static void *bsd_comp_alloc __P((u_char *options, int opt_len));
167 static void *bsd_decomp_alloc __P((u_char *options, int opt_len));
168 static void bsd_free __P((void *state));
169 static int bsd_comp_init __P((void *state, u_char *options, int opt_len,
170 int unit, int hdrlen, int debug));
171 static int bsd_decomp_init __P((void *state, u_char *options, int opt_len,
172 int unit, int hdrlen, int mru, int debug));
173 static int bsd_compress __P((void *state, mblk_t **mret,
174 mblk_t *mp, int slen, int maxolen));
175 static void bsd_incomp __P((void *state, mblk_t *dmsg));
176 static int bsd_decompress __P((void *state, mblk_t *cmp, mblk_t **dmpp));
177 static void bsd_reset __P((void *state));
178 static void bsd_comp_stats __P((void *state, struct compstat *stats));
181 * Procedures exported to ppp_comp.c.
183 struct compressor ppp_bsd_compress = {
184 CI_BSD_COMPRESS, /* compress_proto */
185 bsd_comp_alloc, /* comp_alloc */
186 bsd_free, /* comp_free */
187 bsd_comp_init, /* comp_init */
188 bsd_reset, /* comp_reset */
189 bsd_compress, /* compress */
190 bsd_comp_stats, /* comp_stat */
191 bsd_decomp_alloc, /* decomp_alloc */
192 bsd_free, /* decomp_free */
193 bsd_decomp_init, /* decomp_init */
194 bsd_reset, /* decomp_reset */
195 bsd_decompress, /* decompress */
196 bsd_incomp, /* incomp */
197 bsd_comp_stats, /* decomp_stat */
201 * the next two codes should not be changed lightly, as they must not
202 * lie within the contiguous general code space.
204 #define CLEAR 256 /* table clear output code */
205 #define FIRST 257 /* first free entry */
208 #define MAXCODE(b) ((1 << (b)) - 1)
209 #define BADCODEM1 MAXCODE(BSD_MAX_BITS)
211 #define BSD_HASH(prefix,suffix,hshift) ((((u_int32_t)(suffix)) << (hshift)) \
212 ^ (u_int32_t)(prefix))
213 #define BSD_KEY(prefix,suffix) ((((u_int32_t)(suffix)) << 16) \
214 + (u_int32_t)(prefix))
216 #define CHECK_GAP 10000 /* Ratio check interval */
218 #define RATIO_SCALE_LOG 8
219 #define RATIO_SCALE (1<<RATIO_SCALE_LOG)
220 #define RATIO_MAX (0x7fffffff>>RATIO_SCALE_LOG)
222 #define DECOMP_CHUNK 256
225 * clear the dictionary
232 db->max_ent = FIRST-1;
233 db->n_bits = BSD_INIT_BITS;
237 db->incomp_count = 0;
238 db->checkpoint = CHECK_GAP;
242 * If the dictionary is full, then see if it is time to reset it.
244 * Compute the compression ratio using fixed-point arithmetic
245 * with 8 fractional bits.
247 * Since we have an infinite stream instead of a single file,
248 * watch only the local compression ratio.
250 * Since both peers must reset the dictionary at the same time even in
251 * the absence of CLEAR codes (while packets are incompressible), they
252 * must compute the same ratio.
254 static int /* 1=output CLEAR */
260 if (db->in_count >= db->checkpoint) {
261 /* age the ratio by limiting the size of the counts */
262 if (db->in_count >= RATIO_MAX
263 || db->bytes_out >= RATIO_MAX) {
264 db->in_count -= db->in_count/4;
265 db->bytes_out -= db->bytes_out/4;
268 db->checkpoint = db->in_count + CHECK_GAP;
270 if (db->max_ent >= db->maxmaxcode) {
271 /* Reset the dictionary only if the ratio is worse,
272 * or if it looks as if it has been poisoned
273 * by incompressible data.
275 * This does not overflow, because
276 * db->in_count <= RATIO_MAX.
278 new_ratio = db->in_count << RATIO_SCALE_LOG;
279 if (db->bytes_out != 0)
280 new_ratio /= db->bytes_out;
282 if (new_ratio < db->ratio || new_ratio < 1 * RATIO_SCALE) {
286 db->ratio = new_ratio;
296 bsd_comp_stats(state, stats)
298 struct compstat *stats;
300 struct bsd_db *db = (struct bsd_db *) state;
303 stats->unc_bytes = db->uncomp_bytes;
304 stats->unc_packets = db->uncomp_count;
305 stats->comp_bytes = db->comp_bytes;
306 stats->comp_packets = db->comp_count;
307 stats->inc_bytes = db->incomp_bytes;
308 stats->inc_packets = db->incomp_count;
309 stats->ratio = db->in_count;
311 if (stats->ratio <= 0x7fffff)
320 * Reset state, as on a CCP ResetReq.
326 struct bsd_db *db = (struct bsd_db *) state;
334 * Allocate space for a (de) compressor.
337 bsd_alloc(options, opt_len, decomp)
342 u_int newlen, hsize, hshift, maxmaxcode;
345 if (opt_len != 3 || options[0] != CI_BSD_COMPRESS || options[1] != 3
346 || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION)
348 bits = BSD_NBITS(options[2]);
350 case 9: /* needs 82152 for both directions */
351 case 10: /* needs 84144 */
352 case 11: /* needs 88240 */
353 case 12: /* needs 96432 */
357 case 13: /* needs 176784 */
361 case 14: /* needs 353744 */
365 case 15: /* needs 691440 */
369 case 16: /* needs 1366160--far too much, */
370 /* hsize = 69001; */ /* and 69001 is too big for cptr */
371 /* hshift = 8; */ /* in struct bsd_db */
377 maxmaxcode = MAXCODE(bits);
378 newlen = sizeof(*db) + (hsize-1) * (sizeof(db->dict[0]));
379 db = (struct bsd_db *) ALLOCATE(newlen);
382 bzero(db, sizeof(*db) - sizeof(db->dict));
387 db->lens = (u_short *) ALLOCATE((maxmaxcode+1) * sizeof(db->lens[0]));
397 db->maxmaxcode = maxmaxcode;
407 struct bsd_db *db = (struct bsd_db *) state;
410 FREE(db->lens, (db->maxmaxcode+1) * sizeof(db->lens[0]));
411 FREE(db, db->totlen);
415 bsd_comp_alloc(options, opt_len)
419 return bsd_alloc(options, opt_len, 0);
423 bsd_decomp_alloc(options, opt_len)
427 return bsd_alloc(options, opt_len, 1);
431 * Initialize the database.
434 bsd_init(db, options, opt_len, unit, hdrlen, mru, debug, decomp)
437 int opt_len, unit, hdrlen, mru, debug, decomp;
441 if (opt_len != 3 || options[0] != CI_BSD_COMPRESS || options[1] != 3
442 || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION
443 || BSD_NBITS(options[2]) != db->maxbits
444 || decomp && db->lens == NULL)
454 db->dict[--i].codem1 = BADCODEM1;
455 db->dict[i].cptr = 0;
470 bsd_comp_init(state, options, opt_len, unit, hdrlen, debug)
473 int opt_len, unit, hdrlen, debug;
475 return bsd_init((struct bsd_db *) state, options, opt_len,
476 unit, hdrlen, 0, debug, 0);
480 bsd_decomp_init(state, options, opt_len, unit, hdrlen, mru, debug)
483 int opt_len, unit, hdrlen, mru, debug;
485 return bsd_init((struct bsd_db *) state, options, opt_len,
486 unit, hdrlen, mru, debug, 1);
492 * One change from the BSD compress command is that when the
493 * code size expands, we do not output a bunch of padding.
495 * N.B. at present, we ignore the hdrlen specified in the comp_init call.
497 static int /* new slen */
498 bsd_compress(state, mretp, mp, slen, maxolen)
500 mblk_t **mretp; /* return compressed mbuf chain here */
501 mblk_t *mp; /* from here */
502 int slen; /* uncompressed length */
503 int maxolen; /* max compressed length */
505 struct bsd_db *db = (struct bsd_db *) state;
506 int hshift = db->hshift;
507 u_int max_ent = db->max_ent;
508 u_int n_bits = db->n_bits;
510 u_int32_t accm = 0, fcode;
511 struct bsd_dict *dictp;
513 int hval, disp, ent, ilen;
520 #define PUTBYTE(v) { \
523 if (wptr >= cp_end) { \
528 cp_end = m->b_datap->db_lim; \
536 #define OUTPUT(ent) { \
538 accm |= ((ent) << bitno); \
540 PUTBYTE(accm >> 24); \
543 } while (bitno <= 24); \
547 * First get the protocol and check that we're
548 * interested in this packet.
552 if (rptr + PPP_HDRLEN > mp->b_wptr) {
553 if (!pullupmsg(mp, PPP_HDRLEN))
557 ent = PPP_PROTOCOL(rptr); /* get the protocol */
558 if (ent < 0x21 || ent > 0xf9)
561 /* Don't generate compressed packets which are larger than
562 the uncompressed packet. */
566 /* Allocate enough message blocks to give maxolen total space. */
568 for (olen = maxolen; olen > 0; ) {
569 m = allocb((olen < 4096? olen: 4096), BPRI_MED);
579 olen -= m->b_datap->db_lim - m->b_wptr;
583 if ((m = mret) != NULL) {
585 cp_end = m->b_datap->db_lim;
587 wptr = cp_end = NULL;
591 * Copy the PPP header over, changing the protocol,
592 * and install the 2-byte sequence number.
595 wptr[0] = PPP_ADDRESS(rptr);
596 wptr[1] = PPP_CONTROL(rptr);
597 wptr[2] = 0; /* change the protocol */
599 wptr[4] = db->seqno >> 8;
601 wptr += PPP_HDRLEN + BSD_OVHD;
606 slen = mp->b_wptr - rptr;
614 slen = np->b_wptr - rptr;
617 continue; /* handle 0-length buffers */
623 fcode = BSD_KEY(ent, c);
624 hval = BSD_HASH(ent, c, hshift);
625 dictp = &db->dict[hval];
627 /* Validate and then check the entry. */
628 if (dictp->codem1 >= max_ent)
630 if (dictp->f.fcode == fcode) {
631 ent = dictp->codem1+1;
632 continue; /* found (prefix,suffix) */
635 /* continue probing until a match or invalid entry */
636 disp = (hval == 0) ? 1 : hval;
639 if (hval >= db->hsize)
641 dictp = &db->dict[hval];
642 if (dictp->codem1 >= max_ent)
644 } while (dictp->f.fcode != fcode);
645 ent = dictp->codem1 + 1; /* finally found (prefix,suffix) */
649 OUTPUT(ent); /* output the prefix */
651 /* code -> hashtable */
652 if (max_ent < db->maxmaxcode) {
653 struct bsd_dict *dictp2;
654 /* expand code size if needed */
655 if (max_ent >= MAXCODE(n_bits))
656 db->n_bits = ++n_bits;
658 /* Invalidate old hash table entry using
659 * this code, and then take it over.
661 dictp2 = &db->dict[max_ent+1];
662 if (db->dict[dictp2->cptr].codem1 == max_ent)
663 db->dict[dictp2->cptr].codem1 = BADCODEM1;
665 dictp->codem1 = max_ent;
666 dictp->f.fcode = fcode;
668 db->max_ent = ++max_ent;
673 OUTPUT(ent); /* output the last code */
674 db->bytes_out += olen;
675 db->in_count += ilen;
677 ++db->bytes_out; /* count complete bytes */
680 OUTPUT(CLEAR); /* do not count the CLEAR */
683 * Pad dribble bits of last code with ones.
684 * Do not emit a completely useless byte of ones.
687 PUTBYTE((accm | (0xff << (bitno-8))) >> 24);
690 * Increase code size if we would have without the packet
691 * boundary and as the decompressor will.
693 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode)
696 db->uncomp_bytes += ilen;
698 if (olen + PPP_HDRLEN + BSD_OVHD > maxolen && mret != NULL) {
699 /* throw away the compressed stuff if it is longer than uncompressed */
703 db->incomp_bytes += ilen;
704 } else if (wptr != NULL) {
711 db->comp_bytes += olen + BSD_OVHD;
715 return olen + PPP_HDRLEN + BSD_OVHD;
722 * Update the "BSD Compress" dictionary on the receiver for
723 * incompressible data by pretending to compress the incoming data.
726 bsd_incomp(state, dmsg)
730 struct bsd_db *db = (struct bsd_db *) state;
731 u_int hshift = db->hshift;
732 u_int max_ent = db->max_ent;
733 u_int n_bits = db->n_bits;
734 struct bsd_dict *dictp;
744 if (rptr + PPP_HDRLEN > dmsg->b_wptr) {
745 if (!pullupmsg(dmsg, PPP_HDRLEN))
749 ent = PPP_PROTOCOL(rptr); /* get the protocol */
750 if (ent < 0x21 || ent > 0xf9)
755 ilen = 1; /* count the protocol as 1 byte */
758 slen = dmsg->b_wptr - rptr;
764 continue; /* skip zero-length buffers */
770 fcode = BSD_KEY(ent, c);
771 hval = BSD_HASH(ent, c, hshift);
772 dictp = &db->dict[hval];
774 /* validate and then check the entry */
775 if (dictp->codem1 >= max_ent)
777 if (dictp->f.fcode == fcode) {
778 ent = dictp->codem1+1;
779 continue; /* found (prefix,suffix) */
782 /* continue probing until a match or invalid entry */
783 disp = (hval == 0) ? 1 : hval;
786 if (hval >= db->hsize)
788 dictp = &db->dict[hval];
789 if (dictp->codem1 >= max_ent)
791 } while (dictp->f.fcode != fcode);
792 ent = dictp->codem1+1;
793 continue; /* finally found (prefix,suffix) */
795 nomatch: /* output (count) the prefix */
798 /* code -> hashtable */
799 if (max_ent < db->maxmaxcode) {
800 struct bsd_dict *dictp2;
801 /* expand code size if needed */
802 if (max_ent >= MAXCODE(n_bits))
803 db->n_bits = ++n_bits;
805 /* Invalidate previous hash table entry
806 * assigned this code, and then take it over.
808 dictp2 = &db->dict[max_ent+1];
809 if (db->dict[dictp2->cptr].codem1 == max_ent)
810 db->dict[dictp2->cptr].codem1 = BADCODEM1;
812 dictp->codem1 = max_ent;
813 dictp->f.fcode = fcode;
815 db->max_ent = ++max_ent;
816 db->lens[max_ent] = db->lens[ent]+1;
819 } while (--slen != 0);
821 bitno += n_bits; /* output (count) the last code */
822 db->bytes_out += bitno/8;
823 db->in_count += ilen;
827 db->incomp_bytes += ilen;
829 db->uncomp_bytes += ilen;
831 /* Increase code size if we would have without the packet
832 * boundary and as the decompressor will.
834 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode)
840 * Decompress "BSD Compress"
842 * Because of patent problems, we return DECOMP_ERROR for errors
843 * found by inspecting the input data and for system problems, but
844 * DECOMP_FATALERROR for any errors which could possibly be said to
845 * be being detected "after" decompression. For DECOMP_ERROR,
846 * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be
847 * infringing a patent of Motorola's if we do, so we take CCP down
850 * Given that the frame has the correct sequence number and a good FCS,
851 * errors such as invalid codes in the input most likely indicate a
852 * bug, so we return DECOMP_FATALERROR for them in order to turn off
853 * compression, even though they are detected by inspecting the input.
856 bsd_decompress(state, cmsg, dmpp)
858 mblk_t *cmsg, **dmpp;
860 struct bsd_db *db = (struct bsd_db *) state;
861 u_int max_ent = db->max_ent;
863 u_int bitno = 32; /* 1st valid bit in accm */
864 u_int n_bits = db->n_bits;
865 u_int tgtbitno = 32-n_bits; /* bitno when we have a code */
866 struct bsd_dict *dictp;
867 int explen, i, seq, len;
868 u_int incode, oldcode, finchar;
869 u_char *p, *rptr, *wptr;
871 int adrs, ctrl, ilen;
872 int dlen, space, codelen, extra;
875 * Get at least the BSD Compress header in the first buffer
878 if (rptr + PPP_HDRLEN + BSD_OVHD >= cmsg->b_wptr) {
879 if (!pullupmsg(cmsg, PPP_HDRLEN + BSD_OVHD + 1)) {
881 printf("bsd_decomp%d: failed to pullup\n", db->unit);
888 * Save the address/control from the PPP header
889 * and then get the sequence number.
891 adrs = PPP_ADDRESS(rptr);
892 ctrl = PPP_CONTROL(rptr);
894 seq = (rptr[0] << 8) + rptr[1];
896 ilen = len = cmsg->b_wptr - rptr;
899 * Check the sequence number and give up if it is not what we expect.
901 if (seq != db->seqno++) {
903 printf("bsd_decomp%d: bad sequence # %d, expected %d\n",
904 db->unit, seq, db->seqno - 1);
909 * Allocate one message block to start with.
911 if ((dmsg = allocb(DECOMP_CHUNK + db->hdrlen, BPRI_MED)) == NULL)
914 dmsg->b_wptr += db->hdrlen;
915 dmsg->b_rptr = wptr = dmsg->b_wptr;
917 /* Fill in the ppp header, but not the last byte of the protocol
918 (that comes from the decompressed data). */
922 wptr += PPP_HDRLEN - 1;
923 space = dmsg->b_datap->db_lim - wptr;
930 if (!cmsg) /* quit at end of message */
933 len = cmsg->b_wptr - rptr;
935 continue; /* handle 0-length buffers */
939 * Accumulate bytes until we have a complete code.
940 * Then get the next code, relying on the 32-bit,
941 * unsigned accm to mask the result.
944 accm |= *rptr++ << bitno;
946 if (tgtbitno < bitno)
948 incode = accm >> tgtbitno;
952 if (incode == CLEAR) {
954 * The dictionary must only be cleared at
955 * the end of a packet. But there could be an
956 * empty message block at the end.
958 if (len > 0 || cmsg->b_cont != 0) {
960 len += msgdsize(cmsg->b_cont);
964 printf("bsd_decomp%d: bad CLEAR\n", db->unit);
965 return DECOMP_FATALERROR;
973 if (incode > max_ent + 2 || incode > db->maxmaxcode
974 || incode > max_ent && oldcode == CLEAR) {
977 printf("bsd_decomp%d: bad code 0x%x oldcode=0x%x ",
978 db->unit, incode, oldcode);
979 printf("max_ent=0x%x dlen=%d seqno=%d\n",
980 max_ent, dlen, db->seqno);
982 return DECOMP_FATALERROR; /* probably a bug */
985 /* Special case for KwKwK string. */
986 if (incode > max_ent) {
994 codelen = db->lens[finchar];
995 explen += codelen + extra;
996 if (explen > db->mru + 1) {
999 printf("bsd_decomp%d: ran out of mru\n", db->unit);
1000 return DECOMP_FATALERROR;
1004 * Decode this code and install it in the decompressed buffer.
1006 space -= codelen + extra;
1008 /* Allocate another message block. */
1009 dmsg->b_wptr = wptr;
1010 dlen = codelen + extra;
1011 if (dlen < DECOMP_CHUNK)
1012 dlen = DECOMP_CHUNK;
1013 if ((dmsg->b_cont = allocb(dlen, BPRI_MED)) == NULL) {
1015 return DECOMP_ERROR;
1017 dmsg = dmsg->b_cont;
1018 wptr = dmsg->b_wptr;
1019 space = dmsg->b_datap->db_lim - wptr - codelen - extra;
1021 p = (wptr += codelen);
1022 while (finchar > LAST) {
1023 dictp = &db->dict[db->dict[finchar].cptr];
1028 printf("bsd_decomp%d: fell off end of chain ", db->unit);
1029 printf("0x%x at 0x%x by 0x%x, max_ent=0x%x\n",
1030 incode, finchar, db->dict[finchar].cptr, max_ent);
1031 return DECOMP_FATALERROR;
1033 if (dictp->codem1 != finchar-1) {
1035 printf("bsd_decomp%d: bad code chain 0x%x finchar=0x%x ",
1036 db->unit, incode, finchar);
1037 printf("oldcode=0x%x cptr=0x%x codem1=0x%x\n", oldcode,
1038 db->dict[finchar].cptr, dictp->codem1);
1039 return DECOMP_FATALERROR;
1042 *--p = dictp->f.hs.suffix;
1043 finchar = dictp->f.hs.prefix;
1049 printf("bsd_decomp%d: short by %d after code 0x%x, max_ent=0x%x\n",
1050 db->unit, codelen, incode, max_ent);
1053 if (extra) /* the KwKwK case again */
1057 * If not first code in a packet, and
1058 * if not out of code space, then allocate a new code.
1060 * Keep the hash table correct so it can be used
1061 * with uncompressed packets.
1063 if (oldcode != CLEAR && max_ent < db->maxmaxcode) {
1064 struct bsd_dict *dictp2;
1068 fcode = BSD_KEY(oldcode,finchar);
1069 hval = BSD_HASH(oldcode,finchar,db->hshift);
1070 dictp = &db->dict[hval];
1072 /* look for a free hash table entry */
1073 if (dictp->codem1 < max_ent) {
1074 disp = (hval == 0) ? 1 : hval;
1077 if (hval >= db->hsize)
1079 dictp = &db->dict[hval];
1080 } while (dictp->codem1 < max_ent);
1084 * Invalidate previous hash table entry
1085 * assigned this code, and then take it over
1087 dictp2 = &db->dict[max_ent+1];
1088 if (db->dict[dictp2->cptr].codem1 == max_ent) {
1089 db->dict[dictp2->cptr].codem1 = BADCODEM1;
1091 dictp2->cptr = hval;
1092 dictp->codem1 = max_ent;
1093 dictp->f.fcode = fcode;
1095 db->max_ent = ++max_ent;
1096 db->lens[max_ent] = db->lens[oldcode]+1;
1098 /* Expand code size if needed. */
1099 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) {
1100 db->n_bits = ++n_bits;
1101 tgtbitno = 32-n_bits;
1106 dmsg->b_wptr = wptr;
1109 * Keep the checkpoint right so that incompressible packets
1110 * clear the dictionary at the right times.
1112 db->bytes_out += ilen;
1113 db->in_count += explen;
1114 if (bsd_check(db) && db->debug) {
1115 printf("bsd_decomp%d: peer should have cleared dictionary\n",
1120 db->comp_bytes += ilen + BSD_OVHD;
1122 db->uncomp_bytes += explen;
1127 #endif /* DO_BSD_COMPRESS */