1/* Because this code is derived from the 4.3BSD compress source: 2 * 3 * 4 * Copyright (c) 1985, 1986 The Regents of the University of California. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * James A. Woods, derived from original work by Spencer Thomas 9 * and Joseph Orost. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 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. 26 * 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 37 * SUCH DAMAGE. 38 */ 39 40/* 41 * $Id: bsd-comp.c,v 1.4 2004/01/17 05:47:55 carlsonj Exp $ 42 */ 43 44#include <sys/types.h> 45#include <stdio.h> 46#include <stddef.h> 47#include <stdlib.h> 48#include <string.h> 49#include "ppp_defs.h" 50#include "ppp-comp.h" 51 52#if DO_BSD_COMPRESS 53 54/* 55 * PPP "BSD compress" compression 56 * The differences between this compression and the classic BSD LZW 57 * source are obvious from the requirement that the classic code worked 58 * with files while this handles arbitrarily long streams that 59 * are broken into packets. They are: 60 * 61 * When the code size expands, a block of junk is not emitted by 62 * the compressor and not expected by the decompressor. 63 * 64 * New codes are not necessarily assigned every time an old 65 * code is output by the compressor. This is because a packet 66 * end forces a code to be emitted, but does not imply that a 67 * new sequence has been seen. 68 * 69 * The compression ratio is checked at the first end of a packet 70 * after the appropriate gap. Besides simplifying and speeding 71 * things up, this makes it more likely that the transmitter 72 * and receiver will agree when the dictionary is cleared when 73 * compression is not going well. 74 */ 75 76/* 77 * A dictionary for doing BSD compress. 78 */ 79struct bsd_db { 80 int totlen; /* length of this structure */ 81 u_int hsize; /* size of the hash table */ 82 u_char hshift; /* used in hash function */ 83 u_char n_bits; /* current bits/code */ 84 u_char maxbits; 85 u_char debug; 86 u_char unit; 87 u_short seqno; /* sequence number of next packet */ 88 u_int hdrlen; /* header length to preallocate */ 89 u_int mru; 90 u_int maxmaxcode; /* largest valid code */ 91 u_int max_ent; /* largest code in use */ 92 u_int in_count; /* uncompressed bytes, aged */ 93 u_int bytes_out; /* compressed bytes, aged */ 94 u_int ratio; /* recent compression ratio */ 95 u_int checkpoint; /* when to next check the ratio */ 96 u_int clear_count; /* times dictionary cleared */ 97 u_int incomp_count; /* incompressible packets */ 98 u_int incomp_bytes; /* incompressible bytes */ 99 u_int uncomp_count; /* uncompressed packets */ 100 u_int uncomp_bytes; /* uncompressed bytes */ 101 u_int comp_count; /* compressed packets */ 102 u_int comp_bytes; /* compressed bytes */ 103 u_short *lens; /* array of lengths of codes */ 104 struct bsd_dict { 105 union { /* hash value */ 106 u_int32_t fcode; 107 struct { 108#ifdef BSD_LITTLE_ENDIAN 109 u_short prefix; /* preceding code */ 110 u_char suffix; /* last character of new code */ 111 u_char pad; 112#else 113 u_char pad; 114 u_char suffix; /* last character of new code */ 115 u_short prefix; /* preceding code */ 116#endif 117 } hs; 118 } f; 119 u_short codem1; /* output of hash table -1 */ 120 u_short cptr; /* map code to hash table entry */ 121 } dict[1]; 122}; 123 124#define BSD_OVHD 2 /* BSD compress overhead/packet */ 125#define BSD_INIT_BITS BSD_MIN_BITS 126 127static void *bsd_decomp_alloc __P((u_char *options, int opt_len)); 128static void bsd_free __P((void *state)); 129static int bsd_decomp_init __P((void *state, u_char *options, int opt_len, 130 int unit, int hdrlen, int mru, int debug)); 131static void bsd_incomp __P((void *state, u_char *dmsg, int len)); 132static int bsd_decompress __P((void *state, u_char *cmp, int inlen, 133 u_char *dmp, int *outlen)); 134static void bsd_reset __P((void *state)); 135static void bsd_comp_stats __P((void *state, struct compstat *stats)); 136 137/* 138 * Exported procedures. 139 */ 140struct compressor ppp_bsd_compress = { 141 CI_BSD_COMPRESS, /* compress_proto */ 142 bsd_decomp_alloc, /* decomp_alloc */ 143 bsd_free, /* decomp_free */ 144 bsd_decomp_init, /* decomp_init */ 145 bsd_reset, /* decomp_reset */ 146 bsd_decompress, /* decompress */ 147 bsd_incomp, /* incomp */ 148 bsd_comp_stats, /* decomp_stat */ 149}; 150 151/* 152 * the next two codes should not be changed lightly, as they must not 153 * lie within the contiguous general code space. 154 */ 155#define CLEAR 256 /* table clear output code */ 156#define FIRST 257 /* first free entry */ 157#define LAST 255 158 159#define MAXCODE(b) ((1 << (b)) - 1) 160#define BADCODEM1 MAXCODE(BSD_MAX_BITS) 161 162#define BSD_HASH(prefix,suffix,hshift) ((((u_int32_t)(suffix)) << (hshift)) \ 163 ^ (u_int32_t)(prefix)) 164#define BSD_KEY(prefix,suffix) ((((u_int32_t)(suffix)) << 16) \ 165 + (u_int32_t)(prefix)) 166 167#define CHECK_GAP 10000 /* Ratio check interval */ 168 169#define RATIO_SCALE_LOG 8 170#define RATIO_SCALE (1<<RATIO_SCALE_LOG) 171#define RATIO_MAX (0x7fffffff>>RATIO_SCALE_LOG) 172 173/* 174 * clear the dictionary 175 */ 176static void 177bsd_clear(db) 178 struct bsd_db *db; 179{ 180 db->clear_count++; 181 db->max_ent = FIRST-1; 182 db->n_bits = BSD_INIT_BITS; 183 db->ratio = 0; 184 db->bytes_out = 0; 185 db->in_count = 0; 186 db->checkpoint = CHECK_GAP; 187} 188 189/* 190 * If the dictionary is full, then see if it is time to reset it. 191 * 192 * Compute the compression ratio using fixed-point arithmetic 193 * with 8 fractional bits. 194 * 195 * Since we have an infinite stream instead of a single file, 196 * watch only the local compression ratio. 197 * 198 * Since both peers must reset the dictionary at the same time even in 199 * the absence of CLEAR codes (while packets are incompressible), they 200 * must compute the same ratio. 201 */ 202static int /* 1=output CLEAR */ 203bsd_check(db) 204 struct bsd_db *db; 205{ 206 u_int new_ratio; 207 208 if (db->in_count >= db->checkpoint) { 209 /* age the ratio by limiting the size of the counts */ 210 if (db->in_count >= RATIO_MAX 211 || db->bytes_out >= RATIO_MAX) { 212 db->in_count -= db->in_count/4; 213 db->bytes_out -= db->bytes_out/4; 214 } 215 216 db->checkpoint = db->in_count + CHECK_GAP; 217 218 if (db->max_ent >= db->maxmaxcode) { 219 /* Reset the dictionary only if the ratio is worse, 220 * or if it looks as if it has been poisoned 221 * by incompressible data. 222 * 223 * This does not overflow, because 224 * db->in_count <= RATIO_MAX. 225 */ 226 new_ratio = db->in_count << RATIO_SCALE_LOG; 227 if (db->bytes_out != 0) 228 new_ratio /= db->bytes_out; 229 230 if (new_ratio < db->ratio || new_ratio < 1 * RATIO_SCALE) { 231 bsd_clear(db); 232 return 1; 233 } 234 db->ratio = new_ratio; 235 } 236 } 237 return 0; 238} 239 240/* 241 * Return statistics. 242 */ 243static void 244bsd_comp_stats(state, stats) 245 void *state; 246 struct compstat *stats; 247{ 248 struct bsd_db *db = (struct bsd_db *) state; 249 u_int out; 250 251 stats->unc_bytes = db->uncomp_bytes; 252 stats->unc_packets = db->uncomp_count; 253 stats->comp_bytes = db->comp_bytes; 254 stats->comp_packets = db->comp_count; 255 stats->inc_bytes = db->incomp_bytes; 256 stats->inc_packets = db->incomp_count; 257 stats->ratio = db->in_count; 258 out = db->bytes_out; 259 if (stats->ratio <= 0x7fffff) 260 stats->ratio <<= 8; 261 else 262 out >>= 8; 263 if (out != 0) 264 stats->ratio /= out; 265} 266 267/* 268 * Reset state, as on a CCP ResetReq. 269 */ 270static void 271bsd_reset(state) 272 void *state; 273{ 274 struct bsd_db *db = (struct bsd_db *) state; 275 276 db->seqno = 0; 277 bsd_clear(db); 278 db->clear_count = 0; 279} 280 281/* 282 * Allocate space for a (de) compressor. 283 */ 284static void * 285bsd_alloc(options, opt_len, decomp) 286 u_char *options; 287 int opt_len, decomp; 288{ 289 int bits; 290 u_int newlen, hsize, hshift, maxmaxcode; 291 struct bsd_db *db; 292 293 if (opt_len != 3 || options[0] != CI_BSD_COMPRESS || options[1] != 3 294 || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION) 295 return NULL; 296 297 bits = BSD_NBITS(options[2]); 298 switch (bits) { 299 case 9: /* needs 82152 for both directions */ 300 case 10: /* needs 84144 */ 301 case 11: /* needs 88240 */ 302 case 12: /* needs 96432 */ 303 hsize = 5003; 304 hshift = 4; 305 break; 306 case 13: /* needs 176784 */ 307 hsize = 9001; 308 hshift = 5; 309 break; 310 case 14: /* needs 353744 */ 311 hsize = 18013; 312 hshift = 6; 313 break; 314 case 15: /* needs 691440 */ 315 hsize = 35023; 316 hshift = 7; 317 break; 318 case 16: /* needs 1366160--far too much, */ 319 /* hsize = 69001; */ /* and 69001 is too big for cptr */ 320 /* hshift = 8; */ /* in struct bsd_db */ 321 /* break; */ 322 default: 323 return NULL; 324 } 325 326 maxmaxcode = MAXCODE(bits); 327 newlen = sizeof(*db) + (hsize-1) * (sizeof(db->dict[0])); 328 db = (struct bsd_db *) malloc(newlen); 329 if (!db) 330 return NULL; 331 memset(db, 0, sizeof(*db) - sizeof(db->dict)); 332 333 if (!decomp) { 334 db->lens = NULL; 335 } else { 336 db->lens = (u_short *) malloc((maxmaxcode+1) * sizeof(db->lens[0])); 337 if (!db->lens) { 338 free(db); 339 return NULL; 340 } 341 } 342 343 db->totlen = newlen; 344 db->hsize = hsize; 345 db->hshift = hshift; 346 db->maxmaxcode = maxmaxcode; 347 db->maxbits = bits; 348 349 return (void *) db; 350} 351 352static void 353bsd_free(state) 354 void *state; 355{ 356 struct bsd_db *db = (struct bsd_db *) state; 357 358 if (db->lens) 359 free(db->lens); 360 free(db); 361} 362 363static void * 364bsd_decomp_alloc(options, opt_len) 365 u_char *options; 366 int opt_len; 367{ 368 return bsd_alloc(options, opt_len, 1); 369} 370 371/* 372 * Initialize the database. 373 */ 374static int 375bsd_init(db, options, opt_len, unit, hdrlen, mru, debug, decomp) 376 struct bsd_db *db; 377 u_char *options; 378 int opt_len, unit, hdrlen, mru, debug, decomp; 379{ 380 int i; 381 382 if (opt_len < CILEN_BSD_COMPRESS 383 || options[0] != CI_BSD_COMPRESS || options[1] != CILEN_BSD_COMPRESS 384 || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION 385 || BSD_NBITS(options[2]) != db->maxbits 386 || decomp && db->lens == NULL) 387 return 0; 388 389 if (decomp) { 390 i = LAST+1; 391 while (i != 0) 392 db->lens[--i] = 1; 393 } 394 i = db->hsize; 395 while (i != 0) { 396 db->dict[--i].codem1 = BADCODEM1; 397 db->dict[i].cptr = 0; 398 } 399 400 db->unit = unit; 401 db->hdrlen = hdrlen; 402 db->mru = mru; 403 if (debug) 404 db->debug = 1; 405 406 bsd_reset(db); 407 408 return 1; 409} 410 411static int 412bsd_decomp_init(state, options, opt_len, unit, hdrlen, mru, debug) 413 void *state; 414 u_char *options; 415 int opt_len, unit, hdrlen, mru, debug; 416{ 417 return bsd_init((struct bsd_db *) state, options, opt_len, 418 unit, hdrlen, mru, debug, 1); 419} 420 421 422/* 423 * Update the "BSD Compress" dictionary on the receiver for 424 * incompressible data by pretending to compress the incoming data. 425 */ 426static void 427bsd_incomp(state, dmsg, mlen) 428 void *state; 429 u_char *dmsg; 430 int mlen; 431{ 432 struct bsd_db *db = (struct bsd_db *) state; 433 u_int hshift = db->hshift; 434 u_int max_ent = db->max_ent; 435 u_int n_bits = db->n_bits; 436 struct bsd_dict *dictp; 437 u_int32_t fcode; 438 u_char c; 439 long hval, disp; 440 int slen, ilen; 441 u_int bitno = 7; 442 u_char *rptr; 443 u_int ent; 444 445 rptr = dmsg; 446 ent = rptr[0]; /* get the protocol */ 447 if (ent == 0) { 448 ++rptr; 449 --mlen; 450 ent = rptr[0]; 451 } 452 if ((ent & 1) == 0 || ent < 0x21 || ent > 0xf9) 453 return; 454 455 db->seqno++; 456 ilen = 1; /* count the protocol as 1 byte */ 457 ++rptr; 458 slen = dmsg + mlen - rptr; 459 ilen += slen; 460 for (; slen > 0; --slen) { 461 c = *rptr++; 462 fcode = BSD_KEY(ent, c); 463 hval = BSD_HASH(ent, c, hshift); 464 dictp = &db->dict[hval]; 465 466 /* validate and then check the entry */ 467 if (dictp->codem1 >= max_ent) 468 goto nomatch; 469 if (dictp->f.fcode == fcode) { 470 ent = dictp->codem1+1; 471 continue; /* found (prefix,suffix) */ 472 } 473 474 /* continue probing until a match or invalid entry */ 475 disp = (hval == 0) ? 1 : hval; 476 do { 477 hval += disp; 478 if (hval >= db->hsize) 479 hval -= db->hsize; 480 dictp = &db->dict[hval]; 481 if (dictp->codem1 >= max_ent) 482 goto nomatch; 483 } while (dictp->f.fcode != fcode); 484 ent = dictp->codem1+1; 485 continue; /* finally found (prefix,suffix) */ 486 487 nomatch: /* output (count) the prefix */ 488 bitno += n_bits; 489 490 /* code -> hashtable */ 491 if (max_ent < db->maxmaxcode) { 492 struct bsd_dict *dictp2; 493 /* expand code size if needed */ 494 if (max_ent >= MAXCODE(n_bits)) 495 db->n_bits = ++n_bits; 496 497 /* Invalidate previous hash table entry 498 * assigned this code, and then take it over. 499 */ 500 dictp2 = &db->dict[max_ent+1]; 501 if (db->dict[dictp2->cptr].codem1 == max_ent) 502 db->dict[dictp2->cptr].codem1 = BADCODEM1; 503 dictp2->cptr = hval; 504 dictp->codem1 = max_ent; 505 dictp->f.fcode = fcode; 506 507 db->max_ent = ++max_ent; 508 db->lens[max_ent] = db->lens[ent]+1; 509 } 510 ent = c; 511 } 512 bitno += n_bits; /* output (count) the last code */ 513 db->bytes_out += bitno/8; 514 db->in_count += ilen; 515 (void)bsd_check(db); 516 517 ++db->incomp_count; 518 db->incomp_bytes += ilen; 519 ++db->uncomp_count; 520 db->uncomp_bytes += ilen; 521 522 /* Increase code size if we would have without the packet 523 * boundary and as the decompressor will. 524 */ 525 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) 526 db->n_bits++; 527} 528 529 530/* 531 * Decompress "BSD Compress" 532 * 533 * Because of patent problems, we return DECOMP_ERROR for errors 534 * found by inspecting the input data and for system problems, but 535 * DECOMP_FATALERROR for any errors which could possibly be said to 536 * be being detected "after" decompression. For DECOMP_ERROR, 537 * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be 538 * infringing a patent of Motorola's if we do, so we take CCP down 539 * instead. 540 * 541 * Given that the frame has the correct sequence number and a good FCS, 542 * errors such as invalid codes in the input most likely indicate a 543 * bug, so we return DECOMP_FATALERROR for them in order to turn off 544 * compression, even though they are detected by inspecting the input. 545 */ 546static int 547bsd_decompress(state, cmsg, inlen, dmp, outlenp) 548 void *state; 549 u_char *cmsg, *dmp; 550 int inlen, *outlenp; 551{ 552 struct bsd_db *db = (struct bsd_db *) state; 553 u_int max_ent = db->max_ent; 554 u_int32_t accm = 0; 555 u_int bitno = 32; /* 1st valid bit in accm */ 556 u_int n_bits = db->n_bits; 557 u_int tgtbitno = 32-n_bits; /* bitno when we have a code */ 558 struct bsd_dict *dictp; 559 int explen, i, seq, len; 560 u_int incode, oldcode, finchar; 561 u_char *p, *rptr, *wptr; 562 int ilen; 563 int dlen, space, codelen, extra; 564 565 rptr = cmsg; 566 if (*rptr == 0) 567 ++rptr; 568 ++rptr; /* skip protocol (assumed 0xfd) */ 569 seq = (rptr[0] << 8) + rptr[1]; 570 rptr += BSD_OVHD; 571 ilen = len = cmsg + inlen - rptr; 572 573 /* 574 * Check the sequence number and give up if it is not what we expect. 575 */ 576 if (seq != db->seqno++) { 577 if (db->debug) 578 printf("bsd_decomp%d: bad sequence # %d, expected %d\n", 579 db->unit, seq, db->seqno - 1); 580 return DECOMP_ERROR; 581 } 582 583 wptr = dmp + db->hdrlen; 584 585 oldcode = CLEAR; 586 explen = 0; 587 while (len > 0) { 588 /* 589 * Accumulate bytes until we have a complete code. 590 * Then get the next code, relying on the 32-bit, 591 * unsigned accm to mask the result. 592 */ 593 bitno -= 8; 594 accm |= *rptr++ << bitno; 595 --len; 596 if (tgtbitno < bitno) 597 continue; 598 incode = accm >> tgtbitno; 599 accm <<= n_bits; 600 bitno += n_bits; 601 602 if (incode == CLEAR) { 603 /* 604 * The dictionary must only be cleared at 605 * the end of a packet. But there could be an 606 * empty message block at the end. 607 */ 608 if (len > 0) { 609 if (db->debug) 610 printf("bsd_decomp%d: bad CLEAR\n", db->unit); 611 return DECOMP_FATALERROR; 612 } 613 bsd_clear(db); 614 explen = ilen = 0; 615 break; 616 } 617 618 if (incode > max_ent + 2 || incode > db->maxmaxcode 619 || incode > max_ent && oldcode == CLEAR) { 620 if (db->debug) { 621 printf("bsd_decomp%d: bad code 0x%x oldcode=0x%x ", 622 db->unit, incode, oldcode); 623 printf("max_ent=0x%x dlen=%d seqno=%d\n", 624 max_ent, dlen, db->seqno); 625 } 626 return DECOMP_FATALERROR; /* probably a bug */ 627 } 628 629 /* Special case for KwKwK string. */ 630 if (incode > max_ent) { 631 finchar = oldcode; 632 extra = 1; 633 } else { 634 finchar = incode; 635 extra = 0; 636 } 637 638 codelen = db->lens[finchar]; 639 explen += codelen + extra; 640 if (explen > db->mru + 1) { 641 if (db->debug) 642 printf("bsd_decomp%d: ran out of mru\n", db->unit); 643 return DECOMP_FATALERROR; 644 } 645 646 /* 647 * Decode this code and install it in the decompressed buffer. 648 */ 649 p = (wptr += codelen); 650 while (finchar > LAST) { 651 dictp = &db->dict[db->dict[finchar].cptr]; 652#ifdef DEBUG 653 --codelen; 654 if (codelen <= 0) { 655 printf("bsd_decomp%d: fell off end of chain ", db->unit); 656 printf("0x%x at 0x%x by 0x%x, max_ent=0x%x\n", 657 incode, finchar, db->dict[finchar].cptr, max_ent); 658 return DECOMP_FATALERROR; 659 } 660 if (dictp->codem1 != finchar-1) { 661 printf("bsd_decomp%d: bad code chain 0x%x finchar=0x%x ", 662 db->unit, incode, finchar); 663 printf("oldcode=0x%x cptr=0x%x codem1=0x%x\n", oldcode, 664 db->dict[finchar].cptr, dictp->codem1); 665 return DECOMP_FATALERROR; 666 } 667#endif 668 *--p = dictp->f.hs.suffix; 669 finchar = dictp->f.hs.prefix; 670 } 671 *--p = finchar; 672 673#ifdef DEBUG 674 if (--codelen != 0) 675 printf("bsd_decomp%d: short by %d after code 0x%x, max_ent=0x%x\n", 676 db->unit, codelen, incode, max_ent); 677#endif 678 679 if (extra) /* the KwKwK case again */ 680 *wptr++ = finchar; 681 682 /* 683 * If not first code in a packet, and 684 * if not out of code space, then allocate a new code. 685 * 686 * Keep the hash table correct so it can be used 687 * with uncompressed packets. 688 */ 689 if (oldcode != CLEAR && max_ent < db->maxmaxcode) { 690 struct bsd_dict *dictp2; 691 u_int32_t fcode; 692 int hval, disp; 693 694 fcode = BSD_KEY(oldcode,finchar); 695 hval = BSD_HASH(oldcode,finchar,db->hshift); 696 dictp = &db->dict[hval]; 697 698 /* look for a free hash table entry */ 699 if (dictp->codem1 < max_ent) { 700 disp = (hval == 0) ? 1 : hval; 701 do { 702 hval += disp; 703 if (hval >= db->hsize) 704 hval -= db->hsize; 705 dictp = &db->dict[hval]; 706 } while (dictp->codem1 < max_ent); 707 } 708 709 /* 710 * Invalidate previous hash table entry 711 * assigned this code, and then take it over 712 */ 713 dictp2 = &db->dict[max_ent+1]; 714 if (db->dict[dictp2->cptr].codem1 == max_ent) { 715 db->dict[dictp2->cptr].codem1 = BADCODEM1; 716 } 717 dictp2->cptr = hval; 718 dictp->codem1 = max_ent; 719 dictp->f.fcode = fcode; 720 721 db->max_ent = ++max_ent; 722 db->lens[max_ent] = db->lens[oldcode]+1; 723 724 /* Expand code size if needed. */ 725 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) { 726 db->n_bits = ++n_bits; 727 tgtbitno = 32-n_bits; 728 } 729 } 730 oldcode = incode; 731 } 732 *outlenp = wptr - (dmp + db->hdrlen); 733 734 /* 735 * Keep the checkpoint right so that incompressible packets 736 * clear the dictionary at the right times. 737 */ 738 db->bytes_out += ilen; 739 db->in_count += explen; 740 if (bsd_check(db) && db->debug) { 741 printf("bsd_decomp%d: peer should have cleared dictionary\n", 742 db->unit); 743 } 744 745 ++db->comp_count; 746 db->comp_bytes += ilen + BSD_OVHD; 747 ++db->uncomp_count; 748 db->uncomp_bytes += explen; 749 750 return DECOMP_OK; 751} 752#endif /* DO_BSD_COMPRESS */ 753