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 1.12 1995/05/19 03:48:34 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 #ifdef __svr4__ /* SunOS 5.x */
61 #define ALLOCATE(n) kmem_alloc((n), KM_NOSLEEP)
63 #include <sys/kmem_alloc.h>
64 #define ALLOCATE(n) kmem_alloc((n), KMEM_NOSLEEP)
66 #define FREE(p, n) kmem_free((p), (n))
70 #include <kern/kalloc.h>
71 #define ALLOCATE(n) kalloc((n))
72 #define FREE(p, n) kfree((p), (n))
76 #define ALLOCATE(n) xmalloc((n), 0, pinned_heap)
77 #define FREE(p, n) xmfree((p), pinned_heap)
80 #define PACKETPTR mblk_t *
81 #include <net/ppp-comp.h>
86 * PPP "BSD compress" compression
87 * The differences between this compression and the classic BSD LZW
88 * source are obvious from the requirement that the classic code worked
89 * with files while this handles arbitrarily long streams that
90 * are broken into packets. They are:
92 * When the code size expands, a block of junk is not emitted by
93 * the compressor and not expected by the decompressor.
95 * New codes are not necessarily assigned every time an old
96 * code is output by the compressor. This is because a packet
97 * end forces a code to be emitted, but does not imply that a
98 * new sequence has been seen.
100 * The compression ratio is checked at the first end of a packet
101 * after the appropriate gap. Besides simplifying and speeding
102 * things up, this makes it more likely that the transmitter
103 * and receiver will agree when the dictionary is cleared when
104 * compression is not going well.
108 * A dictionary for doing BSD compress.
111 int totlen; /* length of this structure */
112 u_int hsize; /* size of the hash table */
113 u_char hshift; /* used in hash function */
114 u_char n_bits; /* current bits/code */
118 u_short seqno; /* sequence number of next packet */
119 u_int hdrlen; /* header length to preallocate */
121 u_int maxmaxcode; /* largest valid code */
122 u_int max_ent; /* largest code in use */
123 u_int in_count; /* uncompressed bytes, aged */
124 u_int bytes_out; /* compressed bytes, aged */
125 u_int ratio; /* recent compression ratio */
126 u_int checkpoint; /* when to next check the ratio */
127 u_int clear_count; /* times dictionary cleared */
128 u_int incomp_count; /* incompressible packets */
129 u_int incomp_bytes; /* incompressible bytes */
130 u_int uncomp_count; /* uncompressed packets */
131 u_int uncomp_bytes; /* uncompressed bytes */
132 u_int comp_count; /* compressed packets */
133 u_int comp_bytes; /* compressed bytes */
134 u_short *lens; /* array of lengths of codes */
136 union { /* hash value */
139 #ifdef BSD_LITTLE_ENDIAN
140 u_short prefix; /* preceding code */
141 u_char suffix; /* last character of new code */
145 u_char suffix; /* last character of new code */
146 u_short prefix; /* preceding code */
150 u_short codem1; /* output of hash table -1 */
151 u_short cptr; /* map code to hash table entry */
155 #define BSD_OVHD 2 /* BSD compress overhead/packet */
156 #define BSD_INIT_BITS BSD_MIN_BITS
158 static void *bsd_comp_alloc __P((u_char *options, int opt_len));
159 static void *bsd_decomp_alloc __P((u_char *options, int opt_len));
160 static void bsd_free __P((void *state));
161 static int bsd_comp_init __P((void *state, u_char *options, int opt_len,
162 int unit, int hdrlen, int debug));
163 static int bsd_decomp_init __P((void *state, u_char *options, int opt_len,
164 int unit, int hdrlen, int mru, int debug));
165 static int bsd_compress __P((void *state, mblk_t **mret,
166 mblk_t *mp, int slen, int maxolen));
167 static void bsd_incomp __P((void *state, mblk_t *dmsg));
168 static int bsd_decompress __P((void *state, mblk_t *cmp, mblk_t **dmpp));
169 static void bsd_reset __P((void *state));
170 static void bsd_comp_stats __P((void *state, struct compstat *stats));
173 * Procedures exported to ppp_comp.c.
175 struct compressor ppp_bsd_compress = {
176 CI_BSD_COMPRESS, /* compress_proto */
177 bsd_comp_alloc, /* comp_alloc */
178 bsd_free, /* comp_free */
179 bsd_comp_init, /* comp_init */
180 bsd_reset, /* comp_reset */
181 bsd_compress, /* compress */
182 bsd_comp_stats, /* comp_stat */
183 bsd_decomp_alloc, /* decomp_alloc */
184 bsd_free, /* decomp_free */
185 bsd_decomp_init, /* decomp_init */
186 bsd_reset, /* decomp_reset */
187 bsd_decompress, /* decompress */
188 bsd_incomp, /* incomp */
189 bsd_comp_stats, /* decomp_stat */
193 * the next two codes should not be changed lightly, as they must not
194 * lie within the contiguous general code space.
196 #define CLEAR 256 /* table clear output code */
197 #define FIRST 257 /* first free entry */
200 #define MAXCODE(b) ((1 << (b)) - 1)
201 #define BADCODEM1 MAXCODE(BSD_MAX_BITS)
203 #define BSD_HASH(prefix,suffix,hshift) ((((u_int32_t)(suffix)) << (hshift)) \
204 ^ (u_int32_t)(prefix))
205 #define BSD_KEY(prefix,suffix) ((((u_int32_t)(suffix)) << 16) \
206 + (u_int32_t)(prefix))
208 #define CHECK_GAP 10000 /* Ratio check interval */
210 #define RATIO_SCALE_LOG 8
211 #define RATIO_SCALE (1<<RATIO_SCALE_LOG)
212 #define RATIO_MAX (0x7fffffff>>RATIO_SCALE_LOG)
214 #define DECOMP_CHUNK 256
217 * clear the dictionary
224 db->max_ent = FIRST-1;
225 db->n_bits = BSD_INIT_BITS;
229 db->incomp_count = 0;
230 db->checkpoint = CHECK_GAP;
234 * If the dictionary is full, then see if it is time to reset it.
236 * Compute the compression ratio using fixed-point arithmetic
237 * with 8 fractional bits.
239 * Since we have an infinite stream instead of a single file,
240 * watch only the local compression ratio.
242 * Since both peers must reset the dictionary at the same time even in
243 * the absence of CLEAR codes (while packets are incompressible), they
244 * must compute the same ratio.
246 static int /* 1=output CLEAR */
252 if (db->in_count >= db->checkpoint) {
253 /* age the ratio by limiting the size of the counts */
254 if (db->in_count >= RATIO_MAX
255 || db->bytes_out >= RATIO_MAX) {
256 db->in_count -= db->in_count/4;
257 db->bytes_out -= db->bytes_out/4;
260 db->checkpoint = db->in_count + CHECK_GAP;
262 if (db->max_ent >= db->maxmaxcode) {
263 /* Reset the dictionary only if the ratio is worse,
264 * or if it looks as if it has been poisoned
265 * by incompressible data.
267 * This does not overflow, because
268 * db->in_count <= RATIO_MAX.
270 new_ratio = db->in_count << RATIO_SCALE_LOG;
271 if (db->bytes_out != 0)
272 new_ratio /= db->bytes_out;
274 if (new_ratio < db->ratio || new_ratio < 1 * RATIO_SCALE) {
278 db->ratio = new_ratio;
288 bsd_comp_stats(state, stats)
290 struct compstat *stats;
292 struct bsd_db *db = (struct bsd_db *) state;
295 stats->unc_bytes = db->uncomp_bytes;
296 stats->unc_packets = db->uncomp_count;
297 stats->comp_bytes = db->comp_bytes;
298 stats->comp_packets = db->comp_count;
299 stats->inc_bytes = db->incomp_bytes;
300 stats->inc_packets = db->incomp_count;
301 stats->ratio = db->in_count;
303 if (stats->ratio <= 0x7fffff)
312 * Reset state, as on a CCP ResetReq.
318 struct bsd_db *db = (struct bsd_db *) state;
326 * Allocate space for a (de) compressor.
329 bsd_alloc(options, opt_len, decomp)
334 u_int newlen, hsize, hshift, maxmaxcode;
337 if (opt_len != 3 || options[0] != CI_BSD_COMPRESS || options[1] != 3
338 || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION)
340 bits = BSD_NBITS(options[2]);
342 case 9: /* needs 82152 for both directions */
343 case 10: /* needs 84144 */
344 case 11: /* needs 88240 */
345 case 12: /* needs 96432 */
349 case 13: /* needs 176784 */
353 case 14: /* needs 353744 */
357 case 15: /* needs 691440 */
361 case 16: /* needs 1366160--far too much, */
362 /* hsize = 69001; */ /* and 69001 is too big for cptr */
363 /* hshift = 8; */ /* in struct bsd_db */
369 maxmaxcode = MAXCODE(bits);
370 newlen = sizeof(*db) + (hsize-1) * (sizeof(db->dict[0]));
371 db = (struct bsd_db *) ALLOCATE(newlen);
374 bzero(db, sizeof(*db) - sizeof(db->dict));
379 db->lens = (u_short *) ALLOCATE((maxmaxcode+1) * sizeof(db->lens[0]));
389 db->maxmaxcode = maxmaxcode;
399 struct bsd_db *db = (struct bsd_db *) state;
402 FREE(db->lens, (db->maxmaxcode+1) * sizeof(db->lens[0]));
403 FREE(db, db->totlen);
407 bsd_comp_alloc(options, opt_len)
411 return bsd_alloc(options, opt_len, 0);
415 bsd_decomp_alloc(options, opt_len)
419 return bsd_alloc(options, opt_len, 1);
423 * Initialize the database.
426 bsd_init(db, options, opt_len, unit, hdrlen, mru, debug, decomp)
429 int opt_len, unit, hdrlen, mru, debug, decomp;
433 if (opt_len != 3 || options[0] != CI_BSD_COMPRESS || options[1] != 3
434 || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION
435 || BSD_NBITS(options[2]) != db->maxbits
436 || decomp && db->lens == NULL)
446 db->dict[--i].codem1 = BADCODEM1;
447 db->dict[i].cptr = 0;
462 bsd_comp_init(state, options, opt_len, unit, hdrlen, debug)
465 int opt_len, unit, hdrlen, debug;
467 return bsd_init((struct bsd_db *) state, options, opt_len,
468 unit, hdrlen, 0, debug, 0);
472 bsd_decomp_init(state, options, opt_len, unit, hdrlen, mru, debug)
475 int opt_len, unit, hdrlen, mru, debug;
477 return bsd_init((struct bsd_db *) state, options, opt_len,
478 unit, hdrlen, mru, debug, 1);
484 * One change from the BSD compress command is that when the
485 * code size expands, we do not output a bunch of padding.
487 * N.B. at present, we ignore the hdrlen specified in the comp_init call.
489 static int /* new slen */
490 bsd_compress(state, mretp, mp, slen, maxolen)
492 mblk_t **mretp; /* return compressed mbuf chain here */
493 mblk_t *mp; /* from here */
494 int slen; /* uncompressed length */
495 int maxolen; /* max compressed length */
497 struct bsd_db *db = (struct bsd_db *) state;
498 int hshift = db->hshift;
499 u_int max_ent = db->max_ent;
500 u_int n_bits = db->n_bits;
502 u_int32_t accm = 0, fcode;
503 struct bsd_dict *dictp;
505 int hval, disp, ent, ilen;
512 #define PUTBYTE(v) { \
515 if (wptr >= cp_end) { \
520 cp_end = m->b_datap->db_lim; \
528 #define OUTPUT(ent) { \
530 accm |= ((ent) << bitno); \
532 PUTBYTE(accm >> 24); \
535 } while (bitno <= 24); \
539 * First get the protocol and check that we're
540 * interested in this packet.
544 if (rptr + PPP_HDRLEN > mp->b_wptr) {
545 if (!pullupmsg(mp, PPP_HDRLEN))
549 ent = PPP_PROTOCOL(rptr); /* get the protocol */
550 if (ent < 0x21 || ent > 0xf9)
553 /* Don't generate compressed packets which are larger than
554 the uncompressed packet. */
558 /* Allocate enough message blocks to give maxolen total space. */
560 for (olen = maxolen; olen > 0; ) {
561 m = allocb((olen < 4096? olen: 4096), BPRI_MED);
571 olen -= m->b_datap->db_lim - m->b_wptr;
575 if ((m = mret) != NULL) {
577 cp_end = m->b_datap->db_lim;
579 wptr = cp_end = NULL;
583 * Copy the PPP header over, changing the protocol,
584 * and install the 2-byte sequence number.
587 wptr[0] = PPP_ADDRESS(rptr);
588 wptr[1] = PPP_CONTROL(rptr);
589 wptr[2] = 0; /* change the protocol */
591 wptr[4] = db->seqno >> 8;
593 wptr += PPP_HDRLEN + BSD_OVHD;
598 slen = mp->b_wptr - rptr;
606 slen = np->b_wptr - rptr;
609 continue; /* handle 0-length buffers */
615 fcode = BSD_KEY(ent, c);
616 hval = BSD_HASH(ent, c, hshift);
617 dictp = &db->dict[hval];
619 /* Validate and then check the entry. */
620 if (dictp->codem1 >= max_ent)
622 if (dictp->f.fcode == fcode) {
623 ent = dictp->codem1+1;
624 continue; /* found (prefix,suffix) */
627 /* continue probing until a match or invalid entry */
628 disp = (hval == 0) ? 1 : hval;
631 if (hval >= db->hsize)
633 dictp = &db->dict[hval];
634 if (dictp->codem1 >= max_ent)
636 } while (dictp->f.fcode != fcode);
637 ent = dictp->codem1 + 1; /* finally found (prefix,suffix) */
641 OUTPUT(ent); /* output the prefix */
643 /* code -> hashtable */
644 if (max_ent < db->maxmaxcode) {
645 struct bsd_dict *dictp2;
646 /* expand code size if needed */
647 if (max_ent >= MAXCODE(n_bits))
648 db->n_bits = ++n_bits;
650 /* Invalidate old hash table entry using
651 * this code, and then take it over.
653 dictp2 = &db->dict[max_ent+1];
654 if (db->dict[dictp2->cptr].codem1 == max_ent)
655 db->dict[dictp2->cptr].codem1 = BADCODEM1;
657 dictp->codem1 = max_ent;
658 dictp->f.fcode = fcode;
660 db->max_ent = ++max_ent;
665 OUTPUT(ent); /* output the last code */
666 db->bytes_out += olen;
667 db->in_count += ilen;
669 ++db->bytes_out; /* count complete bytes */
672 OUTPUT(CLEAR); /* do not count the CLEAR */
675 * Pad dribble bits of last code with ones.
676 * Do not emit a completely useless byte of ones.
679 PUTBYTE((accm | (0xff << (bitno-8))) >> 24);
682 * Increase code size if we would have without the packet
683 * boundary and as the decompressor will.
685 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode)
688 db->uncomp_bytes += ilen;
690 if (olen + PPP_HDRLEN + BSD_OVHD > maxolen && mret != NULL) {
691 /* throw away the compressed stuff if it is longer than uncompressed */
695 db->incomp_bytes += ilen;
696 } else if (wptr != NULL) {
703 db->comp_bytes += olen + BSD_OVHD;
707 return olen + PPP_HDRLEN + BSD_OVHD;
714 * Update the "BSD Compress" dictionary on the receiver for
715 * incompressible data by pretending to compress the incoming data.
718 bsd_incomp(state, dmsg)
722 struct bsd_db *db = (struct bsd_db *) state;
723 u_int hshift = db->hshift;
724 u_int max_ent = db->max_ent;
725 u_int n_bits = db->n_bits;
726 struct bsd_dict *dictp;
736 if (rptr + PPP_HDRLEN > dmsg->b_wptr) {
737 if (!pullupmsg(dmsg, PPP_HDRLEN))
741 ent = PPP_PROTOCOL(rptr); /* get the protocol */
742 if (ent < 0x21 || ent > 0xf9)
747 ilen = 1; /* count the protocol as 1 byte */
750 slen = dmsg->b_wptr - rptr;
756 continue; /* skip zero-length buffers */
762 fcode = BSD_KEY(ent, c);
763 hval = BSD_HASH(ent, c, hshift);
764 dictp = &db->dict[hval];
766 /* validate and then check the entry */
767 if (dictp->codem1 >= max_ent)
769 if (dictp->f.fcode == fcode) {
770 ent = dictp->codem1+1;
771 continue; /* found (prefix,suffix) */
774 /* continue probing until a match or invalid entry */
775 disp = (hval == 0) ? 1 : hval;
778 if (hval >= db->hsize)
780 dictp = &db->dict[hval];
781 if (dictp->codem1 >= max_ent)
783 } while (dictp->f.fcode != fcode);
784 ent = dictp->codem1+1;
785 continue; /* finally found (prefix,suffix) */
787 nomatch: /* output (count) the prefix */
790 /* code -> hashtable */
791 if (max_ent < db->maxmaxcode) {
792 struct bsd_dict *dictp2;
793 /* expand code size if needed */
794 if (max_ent >= MAXCODE(n_bits))
795 db->n_bits = ++n_bits;
797 /* Invalidate previous hash table entry
798 * assigned this code, and then take it over.
800 dictp2 = &db->dict[max_ent+1];
801 if (db->dict[dictp2->cptr].codem1 == max_ent)
802 db->dict[dictp2->cptr].codem1 = BADCODEM1;
804 dictp->codem1 = max_ent;
805 dictp->f.fcode = fcode;
807 db->max_ent = ++max_ent;
808 db->lens[max_ent] = db->lens[ent]+1;
811 } while (--slen != 0);
813 bitno += n_bits; /* output (count) the last code */
814 db->bytes_out += bitno/8;
815 db->in_count += ilen;
819 db->incomp_bytes += ilen;
821 db->uncomp_bytes += ilen;
823 /* Increase code size if we would have without the packet
824 * boundary and as the decompressor will.
826 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode)
832 * Decompress "BSD Compress"
834 * Because of patent problems, we return DECOMP_ERROR for errors
835 * found by inspecting the input data and for system problems, but
836 * DECOMP_FATALERROR for any errors which could possibly be said to
837 * be being detected "after" decompression. For DECOMP_ERROR,
838 * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be
839 * infringing a patent of Motorola's if we do, so we take CCP down
842 * Given that the frame has the correct sequence number and a good FCS,
843 * errors such as invalid codes in the input most likely indicate a
844 * bug, so we return DECOMP_FATALERROR for them in order to turn off
845 * compression, even though they are detected by inspecting the input.
848 bsd_decompress(state, cmsg, dmpp)
850 mblk_t *cmsg, **dmpp;
852 struct bsd_db *db = (struct bsd_db *) state;
853 u_int max_ent = db->max_ent;
855 u_int bitno = 32; /* 1st valid bit in accm */
856 u_int n_bits = db->n_bits;
857 u_int tgtbitno = 32-n_bits; /* bitno when we have a code */
858 struct bsd_dict *dictp;
859 int explen, i, seq, len;
860 u_int incode, oldcode, finchar;
861 u_char *p, *rptr, *wptr;
863 int adrs, ctrl, ilen;
864 int dlen, space, codelen, extra;
867 * Get at least the BSD Compress header in the first buffer
870 if (rptr + PPP_HDRLEN + BSD_OVHD >= cmsg->b_wptr) {
871 if (!pullupmsg(cmsg, PPP_HDRLEN + BSD_OVHD + 1)) {
873 printf("bsd_decomp%d: failed to pullup\n", db->unit);
880 * Save the address/control from the PPP header
881 * and then get the sequence number.
883 adrs = PPP_ADDRESS(rptr);
884 ctrl = PPP_CONTROL(rptr);
886 seq = (rptr[0] << 8) + rptr[1];
888 ilen = len = cmsg->b_wptr - rptr;
891 * Check the sequence number and give up if it is not what we expect.
893 if (seq != db->seqno++) {
895 printf("bsd_decomp%d: bad sequence # %d, expected %d\n",
896 db->unit, seq, db->seqno - 1);
901 * Allocate one message block to start with.
903 if ((dmsg = allocb(DECOMP_CHUNK + db->hdrlen, BPRI_MED)) == NULL)
906 dmsg->b_wptr += db->hdrlen;
907 dmsg->b_rptr = wptr = dmsg->b_wptr;
909 /* Fill in the ppp header, but not the last byte of the protocol
910 (that comes from the decompressed data). */
914 wptr += PPP_HDRLEN - 1;
915 space = dmsg->b_datap->db_lim - wptr;
922 if (!cmsg) /* quit at end of message */
925 len = cmsg->b_wptr - rptr;
927 continue; /* handle 0-length buffers */
931 * Accumulate bytes until we have a complete code.
932 * Then get the next code, relying on the 32-bit,
933 * unsigned accm to mask the result.
936 accm |= *rptr++ << bitno;
938 if (tgtbitno < bitno)
940 incode = accm >> tgtbitno;
944 if (incode == CLEAR) {
946 * The dictionary must only be cleared at
947 * the end of a packet. But there could be an
948 * empty message block at the end.
950 if (len > 0 || cmsg->b_cont != 0) {
952 len += msgdsize(cmsg->b_cont);
956 printf("bsd_decomp%d: bad CLEAR\n", db->unit);
957 return DECOMP_FATALERROR;
965 if (incode > max_ent + 2 || incode > db->maxmaxcode
966 || incode > max_ent && oldcode == CLEAR) {
969 printf("bsd_decomp%d: bad code 0x%x oldcode=0x%x ",
970 db->unit, incode, oldcode);
971 printf("max_ent=0x%x dlen=%d seqno=%d\n",
972 max_ent, dlen, db->seqno);
974 return DECOMP_FATALERROR; /* probably a bug */
977 /* Special case for KwKwK string. */
978 if (incode > max_ent) {
986 codelen = db->lens[finchar];
987 explen += codelen + extra;
988 if (explen > db->mru + 1) {
991 printf("bsd_decomp%d: ran out of mru\n", db->unit);
992 return DECOMP_FATALERROR;
996 * Decode this code and install it in the decompressed buffer.
998 space -= codelen + extra;
1000 /* Allocate another message block. */
1001 dmsg->b_wptr = wptr;
1002 dlen = codelen + extra;
1003 if (dlen < DECOMP_CHUNK)
1004 dlen = DECOMP_CHUNK;
1005 if ((dmsg->b_cont = allocb(dlen, BPRI_MED)) == NULL) {
1007 return DECOMP_ERROR;
1009 dmsg = dmsg->b_cont;
1010 wptr = dmsg->b_wptr;
1011 space = dmsg->b_datap->db_lim - wptr - codelen - extra;
1013 p = (wptr += codelen);
1014 while (finchar > LAST) {
1015 dictp = &db->dict[db->dict[finchar].cptr];
1020 printf("bsd_decomp%d: fell off end of chain ", db->unit);
1021 printf("0x%x at 0x%x by 0x%x, max_ent=0x%x\n",
1022 incode, finchar, db->dict[finchar].cptr, max_ent);
1023 return DECOMP_FATALERROR;
1025 if (dictp->codem1 != finchar-1) {
1027 printf("bsd_decomp%d: bad code chain 0x%x finchar=0x%x ",
1028 db->unit, incode, finchar);
1029 printf("oldcode=0x%x cptr=0x%x codem1=0x%x\n", oldcode,
1030 db->dict[finchar].cptr, dictp->codem1);
1031 return DECOMP_FATALERROR;
1034 *--p = dictp->f.hs.suffix;
1035 finchar = dictp->f.hs.prefix;
1041 printf("bsd_decomp%d: short by %d after code 0x%x, max_ent=0x%x\n",
1042 db->unit, codelen, incode, max_ent);
1045 if (extra) /* the KwKwK case again */
1049 * If not first code in a packet, and
1050 * if not out of code space, then allocate a new code.
1052 * Keep the hash table correct so it can be used
1053 * with uncompressed packets.
1055 if (oldcode != CLEAR && max_ent < db->maxmaxcode) {
1056 struct bsd_dict *dictp2;
1060 fcode = BSD_KEY(oldcode,finchar);
1061 hval = BSD_HASH(oldcode,finchar,db->hshift);
1062 dictp = &db->dict[hval];
1064 /* look for a free hash table entry */
1065 if (dictp->codem1 < max_ent) {
1066 disp = (hval == 0) ? 1 : hval;
1069 if (hval >= db->hsize)
1071 dictp = &db->dict[hval];
1072 } while (dictp->codem1 < max_ent);
1076 * Invalidate previous hash table entry
1077 * assigned this code, and then take it over
1079 dictp2 = &db->dict[max_ent+1];
1080 if (db->dict[dictp2->cptr].codem1 == max_ent) {
1081 db->dict[dictp2->cptr].codem1 = BADCODEM1;
1083 dictp2->cptr = hval;
1084 dictp->codem1 = max_ent;
1085 dictp->f.fcode = fcode;
1087 db->max_ent = ++max_ent;
1088 db->lens[max_ent] = db->lens[oldcode]+1;
1090 /* Expand code size if needed. */
1091 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) {
1092 db->n_bits = ++n_bits;
1093 tgtbitno = 32-n_bits;
1098 dmsg->b_wptr = wptr;
1101 * Keep the checkpoint right so that incompressible packets
1102 * clear the dictionary at the right times.
1104 db->bytes_out += ilen;
1105 db->in_count += explen;
1106 if (bsd_check(db) && db->debug) {
1107 printf("bsd_decomp%d: peer should have cleared dictionary\n",
1112 db->comp_bytes += ilen + BSD_OVHD;
1114 db->uncomp_bytes += explen;
1119 #endif /* DO_BSD_COMPRESS */