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 * Digital UNIX, AIX 4.x, and SVR4 systems including Solaris 2.
44 * $Id: bsd-comp.c,v 1.21 2004/01/17 05:47:55 carlsonj Exp $
48 #include <net/net_globals.h>
50 #include <sys/param.h>
51 #include <sys/types.h>
52 #include <sys/stream.h>
53 #include <net/ppp_defs.h>
57 #include <sys/byteorder.h>
59 #define BSD_LITTLE_ENDIAN
66 #define BSD_LITTLE_ENDIAN
70 #include <sys/sunddi.h>
73 #define PACKETPTR mblk_t *
74 #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 BSD_MIN_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->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)
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]));
365 db = (struct bsd_db *) ALLOC_SLEEP(newlen);
367 db = (struct bsd_db *) ALLOC_NOSLEEP(newlen);
371 bzero(db, sizeof(*db) - sizeof(db->dict));
377 db->lens = (u_short *) ALLOC_SLEEP((maxmaxcode+1) * sizeof(db->lens[0]));
379 db->lens = (u_short *) ALLOC_NOSLEEP((maxmaxcode+1) * sizeof(db->lens[0]));
390 db->maxmaxcode = maxmaxcode;
400 struct bsd_db *db = (struct bsd_db *) state;
403 FREE(db->lens, (db->maxmaxcode+1) * sizeof(db->lens[0]));
404 FREE(db, db->totlen);
408 bsd_comp_alloc(options, opt_len)
412 return bsd_alloc(options, opt_len, 0);
416 bsd_decomp_alloc(options, opt_len)
420 return bsd_alloc(options, opt_len, 1);
424 * Initialize the database.
427 bsd_init(db, options, opt_len, unit, hdrlen, mru, debug, decomp)
430 int opt_len, unit, hdrlen, mru, debug, decomp;
434 if (opt_len < CILEN_BSD_COMPRESS
435 || options[0] != CI_BSD_COMPRESS || options[1] != CILEN_BSD_COMPRESS
436 || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION
437 || BSD_NBITS(options[2]) != db->maxbits
438 || decomp && db->lens == NULL)
448 db->dict[--i].codem1 = BADCODEM1;
449 db->dict[i].cptr = 0;
464 bsd_comp_init(state, options, opt_len, unit, hdrlen, debug)
467 int opt_len, unit, hdrlen, debug;
469 return bsd_init((struct bsd_db *) state, options, opt_len,
470 unit, hdrlen, 0, debug, 0);
474 bsd_decomp_init(state, options, opt_len, unit, hdrlen, mru, debug)
477 int opt_len, unit, hdrlen, mru, debug;
479 return bsd_init((struct bsd_db *) state, options, opt_len,
480 unit, hdrlen, mru, debug, 1);
486 * One change from the BSD compress command is that when the
487 * code size expands, we do not output a bunch of padding.
489 * N.B. at present, we ignore the hdrlen specified in the comp_init call.
491 static int /* new slen */
492 bsd_compress(state, mretp, mp, slen, maxolen)
494 mblk_t **mretp; /* return compressed mbuf chain here */
495 mblk_t *mp; /* from here */
496 int slen; /* uncompressed length */
497 int maxolen; /* max compressed length */
499 struct bsd_db *db = (struct bsd_db *) state;
500 int hshift = db->hshift;
501 u_int max_ent = db->max_ent;
502 u_int n_bits = db->n_bits;
504 u_int32_t accm = 0, fcode;
505 struct bsd_dict *dictp;
507 int hval, disp, ent, ilen;
514 #define PUTBYTE(v) { \
517 if (wptr >= cp_end) { \
522 cp_end = m->b_datap->db_lim; \
530 #define OUTPUT(ent) { \
532 accm |= ((ent) << bitno); \
534 PUTBYTE(accm >> 24); \
537 } while (bitno <= 24); \
541 * First get the protocol and check that we're
542 * interested in this packet.
546 if (rptr + PPP_HDRLEN > mp->b_wptr) {
547 if (!pullupmsg(mp, PPP_HDRLEN))
551 ent = PPP_PROTOCOL(rptr); /* get the protocol */
552 if (ent < 0x21 || ent > 0xf9)
555 /* Don't generate compressed packets which are larger than
556 the uncompressed packet. */
560 /* Allocate enough message blocks to give maxolen total space. */
562 for (olen = maxolen; olen > 0; ) {
563 m = allocb((olen < 4096? olen: 4096), BPRI_MED);
573 olen -= m->b_datap->db_lim - m->b_wptr;
577 if ((m = mret) != NULL) {
579 cp_end = m->b_datap->db_lim;
581 wptr = cp_end = NULL;
585 * Copy the PPP header over, changing the protocol,
586 * and install the 2-byte sequence number.
589 wptr[0] = PPP_ADDRESS(rptr);
590 wptr[1] = PPP_CONTROL(rptr);
591 wptr[2] = 0; /* change the protocol */
593 wptr[4] = db->seqno >> 8;
595 wptr += PPP_HDRLEN + BSD_OVHD;
600 slen = mp->b_wptr - rptr;
608 slen = np->b_wptr - rptr;
611 continue; /* handle 0-length buffers */
617 fcode = BSD_KEY(ent, c);
618 hval = BSD_HASH(ent, c, hshift);
619 dictp = &db->dict[hval];
621 /* Validate and then check the entry. */
622 if (dictp->codem1 >= max_ent)
624 if (dictp->f.fcode == fcode) {
625 ent = dictp->codem1+1;
626 continue; /* found (prefix,suffix) */
629 /* continue probing until a match or invalid entry */
630 disp = (hval == 0) ? 1 : hval;
633 if (hval >= db->hsize)
635 dictp = &db->dict[hval];
636 if (dictp->codem1 >= max_ent)
638 } while (dictp->f.fcode != fcode);
639 ent = dictp->codem1 + 1; /* finally found (prefix,suffix) */
643 OUTPUT(ent); /* output the prefix */
645 /* code -> hashtable */
646 if (max_ent < db->maxmaxcode) {
647 struct bsd_dict *dictp2;
648 /* expand code size if needed */
649 if (max_ent >= MAXCODE(n_bits))
650 db->n_bits = ++n_bits;
652 /* Invalidate old hash table entry using
653 * this code, and then take it over.
655 dictp2 = &db->dict[max_ent+1];
656 if (db->dict[dictp2->cptr].codem1 == max_ent)
657 db->dict[dictp2->cptr].codem1 = BADCODEM1;
659 dictp->codem1 = max_ent;
660 dictp->f.fcode = fcode;
662 db->max_ent = ++max_ent;
667 OUTPUT(ent); /* output the last code */
668 db->bytes_out += olen;
669 db->in_count += ilen;
671 ++db->bytes_out; /* count complete bytes */
674 OUTPUT(CLEAR); /* do not count the CLEAR */
677 * Pad dribble bits of last code with ones.
678 * Do not emit a completely useless byte of ones.
681 PUTBYTE((accm | (0xff << (bitno-8))) >> 24);
684 * Increase code size if we would have without the packet
685 * boundary and as the decompressor will.
687 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode)
690 db->uncomp_bytes += ilen;
692 if (olen + PPP_HDRLEN + BSD_OVHD > maxolen && mret != NULL) {
693 /* throw away the compressed stuff if it is longer than uncompressed */
697 db->incomp_bytes += ilen;
698 } else if (wptr != NULL) {
705 db->comp_bytes += olen + BSD_OVHD;
709 return olen + PPP_HDRLEN + BSD_OVHD;
716 * Update the "BSD Compress" dictionary on the receiver for
717 * incompressible data by pretending to compress the incoming data.
720 bsd_incomp(state, dmsg)
724 struct bsd_db *db = (struct bsd_db *) state;
725 u_int hshift = db->hshift;
726 u_int max_ent = db->max_ent;
727 u_int n_bits = db->n_bits;
728 struct bsd_dict *dictp;
738 if (rptr + PPP_HDRLEN > dmsg->b_wptr) {
739 if (!pullupmsg(dmsg, PPP_HDRLEN))
743 ent = PPP_PROTOCOL(rptr); /* get the protocol */
744 if (ent < 0x21 || ent > 0xf9)
748 ilen = 1; /* count the protocol as 1 byte */
751 slen = dmsg->b_wptr - rptr;
757 continue; /* skip zero-length buffers */
763 fcode = BSD_KEY(ent, c);
764 hval = BSD_HASH(ent, c, hshift);
765 dictp = &db->dict[hval];
767 /* validate and then check the entry */
768 if (dictp->codem1 >= max_ent)
770 if (dictp->f.fcode == fcode) {
771 ent = dictp->codem1+1;
772 continue; /* found (prefix,suffix) */
775 /* continue probing until a match or invalid entry */
776 disp = (hval == 0) ? 1 : hval;
779 if (hval >= db->hsize)
781 dictp = &db->dict[hval];
782 if (dictp->codem1 >= max_ent)
784 } while (dictp->f.fcode != fcode);
785 ent = dictp->codem1+1;
786 continue; /* finally found (prefix,suffix) */
788 nomatch: /* output (count) the prefix */
791 /* code -> hashtable */
792 if (max_ent < db->maxmaxcode) {
793 struct bsd_dict *dictp2;
794 /* expand code size if needed */
795 if (max_ent >= MAXCODE(n_bits))
796 db->n_bits = ++n_bits;
798 /* Invalidate previous hash table entry
799 * assigned this code, and then take it over.
801 dictp2 = &db->dict[max_ent+1];
802 if (db->dict[dictp2->cptr].codem1 == max_ent)
803 db->dict[dictp2->cptr].codem1 = BADCODEM1;
805 dictp->codem1 = max_ent;
806 dictp->f.fcode = fcode;
808 db->max_ent = ++max_ent;
809 db->lens[max_ent] = db->lens[ent]+1;
812 } while (--slen != 0);
814 bitno += n_bits; /* output (count) the last code */
815 db->bytes_out += bitno/8;
816 db->in_count += ilen;
820 db->incomp_bytes += ilen;
822 db->uncomp_bytes += ilen;
824 /* Increase code size if we would have without the packet
825 * boundary and as the decompressor will.
827 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode)
833 * Decompress "BSD Compress"
835 * Because of patent problems, we return DECOMP_ERROR for errors
836 * found by inspecting the input data and for system problems, but
837 * DECOMP_FATALERROR for any errors which could possibly be said to
838 * be being detected "after" decompression. For DECOMP_ERROR,
839 * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be
840 * infringing a patent of Motorola's if we do, so we take CCP down
843 * Given that the frame has the correct sequence number and a good FCS,
844 * errors such as invalid codes in the input most likely indicate a
845 * bug, so we return DECOMP_FATALERROR for them in order to turn off
846 * compression, even though they are detected by inspecting the input.
849 bsd_decompress(state, cmsg, dmpp)
851 mblk_t *cmsg, **dmpp;
853 struct bsd_db *db = (struct bsd_db *) state;
854 u_int max_ent = db->max_ent;
856 u_int bitno = 32; /* 1st valid bit in accm */
857 u_int n_bits = db->n_bits;
858 u_int tgtbitno = 32-n_bits; /* bitno when we have a code */
859 struct bsd_dict *dictp;
860 int explen, i, seq, len;
861 u_int incode, oldcode, finchar;
862 u_char *p, *rptr, *wptr;
864 int adrs, ctrl, ilen;
865 int dlen, space, codelen, extra;
868 * Get at least the BSD Compress header in the first buffer
871 if (rptr + PPP_HDRLEN + BSD_OVHD >= cmsg->b_wptr) {
872 if (!pullupmsg(cmsg, PPP_HDRLEN + BSD_OVHD + 1)) {
874 printf("bsd_decomp%d: failed to pullup\n", db->unit);
881 * Save the address/control from the PPP header
882 * and then get the sequence number.
884 adrs = PPP_ADDRESS(rptr);
885 ctrl = PPP_CONTROL(rptr);
887 seq = (rptr[0] << 8) + rptr[1];
889 ilen = len = cmsg->b_wptr - rptr;
892 * Check the sequence number and give up if it is not what we expect.
894 if (seq != db->seqno++) {
896 printf("bsd_decomp%d: bad sequence # %d, expected %d\n",
897 db->unit, seq, db->seqno - 1);
902 * Allocate one message block to start with.
904 if ((dmsg = allocb(DECOMP_CHUNK + db->hdrlen, BPRI_MED)) == NULL)
907 dmsg->b_wptr += db->hdrlen;
908 dmsg->b_rptr = wptr = dmsg->b_wptr;
910 /* Fill in the ppp header, but not the last byte of the protocol
911 (that comes from the decompressed data). */
915 wptr += PPP_HDRLEN - 1;
916 space = dmsg->b_datap->db_lim - wptr;
923 if (!cmsg) /* quit at end of message */
926 len = cmsg->b_wptr - rptr;
928 continue; /* handle 0-length buffers */
932 * Accumulate bytes until we have a complete code.
933 * Then get the next code, relying on the 32-bit,
934 * unsigned accm to mask the result.
937 accm |= *rptr++ << bitno;
939 if (tgtbitno < bitno)
941 incode = accm >> tgtbitno;
945 if (incode == CLEAR) {
947 * The dictionary must only be cleared at
948 * the end of a packet. But there could be an
949 * empty message block at the end.
951 if (len > 0 || cmsg->b_cont != 0) {
953 len += msgdsize(cmsg->b_cont);
957 printf("bsd_decomp%d: bad CLEAR\n", db->unit);
958 return DECOMP_FATALERROR;
966 if (incode > max_ent + 2 || incode > db->maxmaxcode
967 || incode > max_ent && oldcode == CLEAR) {
970 printf("bsd_decomp%d: bad code 0x%x oldcode=0x%x ",
971 db->unit, incode, oldcode);
972 printf("max_ent=0x%x dlen=%d seqno=%d\n",
973 max_ent, dlen, db->seqno);
975 return DECOMP_FATALERROR; /* probably a bug */
978 /* Special case for KwKwK string. */
979 if (incode > max_ent) {
987 codelen = db->lens[finchar];
988 explen += codelen + extra;
989 if (explen > db->mru + 1) {
992 printf("bsd_decomp%d: ran out of mru\n", db->unit);
993 return DECOMP_FATALERROR;
997 * Decode this code and install it in the decompressed buffer.
999 space -= codelen + extra;
1001 /* Allocate another message block. */
1002 dmsg->b_wptr = wptr;
1003 dlen = codelen + extra;
1004 if (dlen < DECOMP_CHUNK)
1005 dlen = DECOMP_CHUNK;
1006 if ((dmsg->b_cont = allocb(dlen, BPRI_MED)) == NULL) {
1008 return DECOMP_ERROR;
1010 dmsg = dmsg->b_cont;
1011 wptr = dmsg->b_wptr;
1012 space = dmsg->b_datap->db_lim - wptr - codelen - extra;
1014 p = (wptr += codelen);
1015 while (finchar > LAST) {
1016 dictp = &db->dict[db->dict[finchar].cptr];
1021 printf("bsd_decomp%d: fell off end of chain ", db->unit);
1022 printf("0x%x at 0x%x by 0x%x, max_ent=0x%x\n",
1023 incode, finchar, db->dict[finchar].cptr, max_ent);
1024 return DECOMP_FATALERROR;
1026 if (dictp->codem1 != finchar-1) {
1028 printf("bsd_decomp%d: bad code chain 0x%x finchar=0x%x ",
1029 db->unit, incode, finchar);
1030 printf("oldcode=0x%x cptr=0x%x codem1=0x%x\n", oldcode,
1031 db->dict[finchar].cptr, dictp->codem1);
1032 return DECOMP_FATALERROR;
1035 *--p = dictp->f.hs.suffix;
1036 finchar = dictp->f.hs.prefix;
1042 printf("bsd_decomp%d: short by %d after code 0x%x, max_ent=0x%x\n",
1043 db->unit, codelen, incode, max_ent);
1046 if (extra) /* the KwKwK case again */
1050 * If not first code in a packet, and
1051 * if not out of code space, then allocate a new code.
1053 * Keep the hash table correct so it can be used
1054 * with uncompressed packets.
1056 if (oldcode != CLEAR && max_ent < db->maxmaxcode) {
1057 struct bsd_dict *dictp2;
1061 fcode = BSD_KEY(oldcode,finchar);
1062 hval = BSD_HASH(oldcode,finchar,db->hshift);
1063 dictp = &db->dict[hval];
1065 /* look for a free hash table entry */
1066 if (dictp->codem1 < max_ent) {
1067 disp = (hval == 0) ? 1 : hval;
1070 if (hval >= db->hsize)
1072 dictp = &db->dict[hval];
1073 } while (dictp->codem1 < max_ent);
1077 * Invalidate previous hash table entry
1078 * assigned this code, and then take it over
1080 dictp2 = &db->dict[max_ent+1];
1081 if (db->dict[dictp2->cptr].codem1 == max_ent) {
1082 db->dict[dictp2->cptr].codem1 = BADCODEM1;
1084 dictp2->cptr = hval;
1085 dictp->codem1 = max_ent;
1086 dictp->f.fcode = fcode;
1088 db->max_ent = ++max_ent;
1089 db->lens[max_ent] = db->lens[oldcode]+1;
1091 /* Expand code size if needed. */
1092 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) {
1093 db->n_bits = ++n_bits;
1094 tgtbitno = 32-n_bits;
1099 dmsg->b_wptr = wptr;
1102 * Keep the checkpoint right so that incompressible packets
1103 * clear the dictionary at the right times.
1105 db->bytes_out += ilen;
1106 db->in_count += explen;
1107 if (bsd_check(db) && db->debug) {
1108 printf("bsd_decomp%d: peer should have cleared dictionary\n",
1113 db->comp_bytes += ilen + BSD_OVHD;
1115 db->uncomp_bytes += explen;
1120 #endif /* DO_BSD_COMPRESS */