lib/decompress_unlzma.c

   1 /* Lzma decompressor for Linux kernel. Shamelessly snarfed
   2  *from busybox 1.1.1
   3  *
   4  *Linux kernel adaptation
   5  *Copyright (C) 2006  Alain < alain@knaff.lu >
   6  *
   7  *Based on small lzma deflate implementation/Small range coder
   8  *implementation for lzma.
   9  *Copyright (C) 2006  Aurelien Jacobs < aurel@gnuage.org >
  10  *
  11  *Based on LzmaDecode.c from the LZMA SDK 4.22 (http://www.7-zip.org/)
  12  *Copyright (C) 1999-2005  Igor Pavlov
  13  *
  14  *Copyrights of the parts, see headers below.
  15  *
  16  *
  17  *This program is free software; you can redistribute it and/or
  18  *modify it under the terms of the GNU Lesser General Public
  19  *License as published by the Free Software Foundation; either
  20  *version 2.1 of the License, or (at your option) any later version.
  21  *
  22  *This program is distributed in the hope that it will be useful,
  23  *but WITHOUT ANY WARRANTY; without even the implied warranty of
  24  *MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  25  *Lesser General Public License for more details.
  26  *
  27  *You should have received a copy of the GNU Lesser General Public
  28  *License along with this library; if not, write to the Free Software
  29  *Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  30  */
  31
  32 #ifndef STATIC
  33 #include <linux/decompress/unlzma.h>
  34 #endif /* STATIC */
  35
  36 #include <linux/decompress/mm.h>
  37 #include <linux/slab.h>
  38
  39 #define MIN(a, b) (((a) < (b)) ? (a) : (b))
  40
  41 static long long INIT read_int(unsigned char *ptr, int size)
  42 {
  43         int i;
  44         long long ret = 0;
  45
  46         for (i = 0; i < size; i++)
  47                 ret = (ret << 8) | ptr[size-i-1];
  48         return ret;
  49 }
  50
  51 #define ENDIAN_CONVERT(x) \
  52   x = (typeof(x))read_int((unsigned char *)&x, sizeof(x))
  53
  54
  55 /* Small range coder implementation for lzma.
  56  *Copyright (C) 2006  Aurelien Jacobs < aurel@gnuage.org >
  57  *
  58  *Based on LzmaDecode.c from the LZMA SDK 4.22 (http://www.7-zip.org/)
  59  *Copyright (c) 1999-2005  Igor Pavlov
  60  */
  61
  62 #include <linux/compiler.h>
  63
  64 #define LZMA_IOBUF_SIZE 0x10000
  65
  66 struct rc {
  67         int (*fill)(void*, unsigned int);
  68         uint8_t *ptr;
  69         uint8_t *buffer;
  70         uint8_t *buffer_end;
  71         int buffer_size;
  72         uint32_t code;
  73         uint32_t range;
  74         uint32_t bound;
  75 };
  76
  77
  78 #define RC_TOP_BITS 24
  79 #define RC_MOVE_BITS 5
  80 #define RC_MODEL_TOTAL_BITS 11
  81
  82
  83 /* Called twice: once at startup and once in rc_normalize() */
  84 static void INIT rc_read(struct rc *rc)
  85 {
  86         rc->buffer_size = rc->fill((char *)rc->buffer, LZMA_IOBUF_SIZE);
  87         if (rc->buffer_size <= 0)
  88                 error("unexpected EOF");
  89         rc->ptr = rc->buffer;
  90         rc->buffer_end = rc->buffer + rc->buffer_size;
  91 }
  92
  93 /* Called once */
  94 static inline void INIT rc_init(struct rc *rc,
  95                                        int (*fill)(void*, unsigned int),
  96                                        char *buffer, int buffer_size)
  97 {
  98         rc->fill = fill;
  99         rc->buffer = (uint8_t *)buffer;
 100         rc->buffer_size = buffer_size;
 101         rc->buffer_end = rc->buffer + rc->buffer_size;
 102         rc->ptr = rc->buffer;
 103
 104         rc->code = 0;
 105         rc->range = 0xFFFFFFFF;
 106 }
 107
 108 static inline void INIT rc_init_code(struct rc *rc)
 109 {
 110         int i;
 111
 112         for (i = 0; i < 5; i++) {
 113                 if (rc->ptr >= rc->buffer_end)
 114                         rc_read(rc);
 115                 rc->code = (rc->code << 8) | *rc->ptr++;
 116         }
 117 }
 118
 119
 120 /* Called once. TODO: bb_maybe_free() */
 121 static inline void INIT rc_free(struct rc *rc)
 122 {
 123         free(rc->buffer);
 124 }
 125
 126 /* Called twice, but one callsite is in inline'd rc_is_bit_0_helper() */
 127 static void INIT rc_do_normalize(struct rc *rc)
 128 {
 129         if (rc->ptr >= rc->buffer_end)
 130                 rc_read(rc);
 131         rc->range <<= 8;
 132         rc->code = (rc->code << 8) | *rc->ptr++;
 133 }
 134 static inline void INIT rc_normalize(struct rc *rc)
 135 {
 136         if (rc->range < (1 << RC_TOP_BITS))
 137                 rc_do_normalize(rc);
 138 }
 139
 140 /* Called 9 times */
 141 /* Why rc_is_bit_0_helper exists?
 142  *Because we want to always expose (rc->code < rc->bound) to optimizer
 143  */
 144 static inline uint32_t INIT rc_is_bit_0_helper(struct rc *rc, uint16_t *p)
 145 {
 146         rc_normalize(rc);
 147         rc->bound = *p * (rc->range >> RC_MODEL_TOTAL_BITS);
 148         return rc->bound;
 149 }
 150 static inline int INIT rc_is_bit_0(struct rc *rc, uint16_t *p)
 151 {
 152         uint32_t t = rc_is_bit_0_helper(rc, p);
 153         return rc->code < t;
 154 }
 155
 156 /* Called ~10 times, but very small, thus inlined */
 157 static inline void INIT rc_update_bit_0(struct rc *rc, uint16_t *p)
 158 {
 159         rc->range = rc->bound;
 160         *p += ((1 << RC_MODEL_TOTAL_BITS) - *p) >> RC_MOVE_BITS;
 161 }
 162 static inline void rc_update_bit_1(struct rc *rc, uint16_t *p)
 163 {
 164         rc->range -= rc->bound;
 165         rc->code -= rc->bound;
 166         *p -= *p >> RC_MOVE_BITS;
 167 }
 168
 169 /* Called 4 times in unlzma loop */
 170 static int INIT rc_get_bit(struct rc *rc, uint16_t *p, int *symbol)
 171 {
 172         if (rc_is_bit_0(rc, p)) {
 173                 rc_update_bit_0(rc, p);
 174                 *symbol *= 2;
 175                 return 0;
 176         } else {
 177                 rc_update_bit_1(rc, p);
 178                 *symbol = *symbol * 2 + 1;
 179                 return 1;
 180         }
 181 }
 182
 183 /* Called once */
 184 static inline int INIT rc_direct_bit(struct rc *rc)
 185 {
 186         rc_normalize(rc);
 187         rc->range >>= 1;
 188         if (rc->code >= rc->range) {
 189                 rc->code -= rc->range;
 190                 return 1;
 191         }
 192         return 0;
 193 }
 194
 195 /* Called twice */
 196 static inline void INIT
 197 rc_bit_tree_decode(struct rc *rc, uint16_t *p, int num_levels, int *symbol)
 198 {
 199         int i = num_levels;
 200
 201         *symbol = 1;
 202         while (i--)
 203                 rc_get_bit(rc, p + *symbol, symbol);
 204         *symbol -= 1 << num_levels;
 205 }
 206
 207
 208 /*
 209  * Small lzma deflate implementation.
 210  * Copyright (C) 2006  Aurelien Jacobs < aurel@gnuage.org >
 211  *
 212  * Based on LzmaDecode.c from the LZMA SDK 4.22 (http://www.7-zip.org/)
 213  * Copyright (C) 1999-2005  Igor Pavlov
 214  */
 215
 216
 217 struct lzma_header {
 218         uint8_t pos;
 219         uint32_t dict_size;
 220         uint64_t dst_size;
 221 } __attribute__ ((packed)) ;
 222
 223
 224 #define LZMA_BASE_SIZE 1846
 225 #define LZMA_LIT_SIZE 768
 226
 227 #define LZMA_NUM_POS_BITS_MAX 4
 228
 229 #define LZMA_LEN_NUM_LOW_BITS 3
 230 #define LZMA_LEN_NUM_MID_BITS 3
 231 #define LZMA_LEN_NUM_HIGH_BITS 8
 232
 233 #define LZMA_LEN_CHOICE 0
 234 #define LZMA_LEN_CHOICE_2 (LZMA_LEN_CHOICE + 1)
 235 #define LZMA_LEN_LOW (LZMA_LEN_CHOICE_2 + 1)
 236 #define LZMA_LEN_MID (LZMA_LEN_LOW \
 237                       + (1 << (LZMA_NUM_POS_BITS_MAX + LZMA_LEN_NUM_LOW_BITS)))
 238 #define LZMA_LEN_HIGH (LZMA_LEN_MID \
 239                        +(1 << (LZMA_NUM_POS_BITS_MAX + LZMA_LEN_NUM_MID_BITS)))
 240 #define LZMA_NUM_LEN_PROBS (LZMA_LEN_HIGH + (1 << LZMA_LEN_NUM_HIGH_BITS))
 241
 242 #define LZMA_NUM_STATES 12
 243 #define LZMA_NUM_LIT_STATES 7
 244
 245 #define LZMA_START_POS_MODEL_INDEX 4
 246 #define LZMA_END_POS_MODEL_INDEX 14
 247 #define LZMA_NUM_FULL_DISTANCES (1 << (LZMA_END_POS_MODEL_INDEX >> 1))
 248
 249 #define LZMA_NUM_POS_SLOT_BITS 6
 250 #define LZMA_NUM_LEN_TO_POS_STATES 4
 251
 252 #define LZMA_NUM_ALIGN_BITS 4
 253
 254 #define LZMA_MATCH_MIN_LEN 2
 255
 256 #define LZMA_IS_MATCH 0
 257 #define LZMA_IS_REP (LZMA_IS_MATCH + (LZMA_NUM_STATES << LZMA_NUM_POS_BITS_MAX))
 258 #define LZMA_IS_REP_G0 (LZMA_IS_REP + LZMA_NUM_STATES)
 259 #define LZMA_IS_REP_G1 (LZMA_IS_REP_G0 + LZMA_NUM_STATES)
 260 #define LZMA_IS_REP_G2 (LZMA_IS_REP_G1 + LZMA_NUM_STATES)
 261 #define LZMA_IS_REP_0_LONG (LZMA_IS_REP_G2 + LZMA_NUM_STATES)
 262 #define LZMA_POS_SLOT (LZMA_IS_REP_0_LONG \
 263                        + (LZMA_NUM_STATES << LZMA_NUM_POS_BITS_MAX))
 264 #define LZMA_SPEC_POS (LZMA_POS_SLOT \
 265                        +(LZMA_NUM_LEN_TO_POS_STATES << LZMA_NUM_POS_SLOT_BITS))
 266 #define LZMA_ALIGN (LZMA_SPEC_POS \
 267                     + LZMA_NUM_FULL_DISTANCES - LZMA_END_POS_MODEL_INDEX)
 268 #define LZMA_LEN_CODER (LZMA_ALIGN + (1 << LZMA_NUM_ALIGN_BITS))
 269 #define LZMA_REP_LEN_CODER (LZMA_LEN_CODER + LZMA_NUM_LEN_PROBS)
 270 #define LZMA_LITERAL (LZMA_REP_LEN_CODER + LZMA_NUM_LEN_PROBS)
 271
 272
 273 struct writer {
 274         uint8_t *buffer;
 275         uint8_t previous_byte;
 276         size_t buffer_pos;
 277         int bufsize;
 278         size_t global_pos;
 279         int(*flush)(void*, unsigned int);
 280         struct lzma_header *header;
 281 };
 282
 283 struct cstate {
 284         int state;
 285         uint32_t rep0, rep1, rep2, rep3;
 286 };
 287
 288 static inline size_t INIT get_pos(struct writer *wr)
 289 {
 290         return
 291                 wr->global_pos + wr->buffer_pos;
 292 }
 293
 294 static inline uint8_t INIT peek_old_byte(struct writer *wr,
 295                                                 uint32_t offs)
 296 {
 297         if (!wr->flush) {
 298                 int32_t pos;
 299                 while (offs > wr->header->dict_size)
 300                         offs -= wr->header->dict_size;
 301                 pos = wr->buffer_pos - offs;
 302                 return wr->buffer[pos];
 303         } else {
 304                 uint32_t pos = wr->buffer_pos - offs;
 305                 while (pos >= wr->header->dict_size)
 306                         pos += wr->header->dict_size;
 307                 return wr->buffer[pos];
 308         }
 309
 310 }
 311
 312 static inline void INIT write_byte(struct writer *wr, uint8_t byte)
 313 {
 314         wr->buffer[wr->buffer_pos++] = wr->previous_byte = byte;
 315         if (wr->flush && wr->buffer_pos == wr->header->dict_size) {
 316                 wr->buffer_pos = 0;
 317                 wr->global_pos += wr->header->dict_size;
 318                 wr->flush((char *)wr->buffer, wr->header->dict_size);
 319         }
 320 }
 321
 322
 323 static inline void INIT copy_byte(struct writer *wr, uint32_t offs)
 324 {
 325         write_byte(wr, peek_old_byte(wr, offs));
 326 }
 327
 328 static inline void INIT copy_bytes(struct writer *wr,
 329                                          uint32_t rep0, int len)
 330 {
 331         do {
 332                 copy_byte(wr, rep0);
 333                 len--;
 334         } while (len != 0 && wr->buffer_pos < wr->header->dst_size);
 335 }
 336
 337 static inline void INIT process_bit0(struct writer *wr, struct rc *rc,
 338                                      struct cstate *cst, uint16_t *p,
 339                                      int pos_state, uint16_t *prob,
 340                                      int lc, uint32_t literal_pos_mask) {
 341         int mi = 1;
 342         rc_update_bit_0(rc, prob);
 343         prob = (p + LZMA_LITERAL +
 344                 (LZMA_LIT_SIZE
 345                  * (((get_pos(wr) & literal_pos_mask) << lc)
 346                     + (wr->previous_byte >> (8 - lc))))
 347                 );
 348
 349         if (cst->state >= LZMA_NUM_LIT_STATES) {
 350                 int match_byte = peek_old_byte(wr, cst->rep0);
 351                 do {
 352                         int bit;
 353                         uint16_t *prob_lit;
 354
 355                         match_byte <<= 1;
 356                         bit = match_byte & 0x100;
 357                         prob_lit = prob + 0x100 + bit + mi;
 358                         if (rc_get_bit(rc, prob_lit, &mi)) {
 359                                 if (!bit)
 360                                         break;
 361                         } else {
 362                                 if (bit)
 363                                         break;
 364                         }
 365                 } while (mi < 0x100);
 366         }
 367         while (mi < 0x100) {
 368                 uint16_t *prob_lit = prob + mi;
 369                 rc_get_bit(rc, prob_lit, &mi);
 370         }
 371         write_byte(wr, mi);
 372         if (cst->state < 4)
 373                 cst->state = 0;
 374         else if (cst->state < 10)
 375                 cst->state -= 3;
 376         else
 377                 cst->state -= 6;
 378 }
 379
 380 static inline void INIT process_bit1(struct writer *wr, struct rc *rc,
 381                                             struct cstate *cst, uint16_t *p,
 382                                             int pos_state, uint16_t *prob) {
 383   int offset;
 384         uint16_t *prob_len;
 385         int num_bits;
 386         int len;
 387
 388         rc_update_bit_1(rc, prob);
 389         prob = p + LZMA_IS_REP + cst->state;
 390         if (rc_is_bit_0(rc, prob)) {
 391                 rc_update_bit_0(rc, prob);
 392                 cst->rep3 = cst->rep2;
 393                 cst->rep2 = cst->rep1;
 394                 cst->rep1 = cst->rep0;
 395                 cst->state = cst->state < LZMA_NUM_LIT_STATES ? 0 : 3;
 396                 prob = p + LZMA_LEN_CODER;
 397         } else {
 398                 rc_update_bit_1(rc, prob);
 399                 prob = p + LZMA_IS_REP_G0 + cst->state;
 400                 if (rc_is_bit_0(rc, prob)) {
 401                         rc_update_bit_0(rc, prob);
 402                         prob = (p + LZMA_IS_REP_0_LONG
 403                                 + (cst->state <<
 404                                    LZMA_NUM_POS_BITS_MAX) +
 405                                 pos_state);
 406                         if (rc_is_bit_0(rc, prob)) {
 407                                 rc_update_bit_0(rc, prob);
 408
 409                                 cst->state = cst->state < LZMA_NUM_LIT_STATES ?
 410                                         9 : 11;
 411                                 copy_byte(wr, cst->rep0);
 412                                 return;
 413                         } else {
 414                                 rc_update_bit_1(rc, prob);
 415                         }
 416                 } else {
 417                         uint32_t distance;
 418
 419                         rc_update_bit_1(rc, prob);
 420                         prob = p + LZMA_IS_REP_G1 + cst->state;
 421                         if (rc_is_bit_0(rc, prob)) {
 422                                 rc_update_bit_0(rc, prob);
 423                                 distance = cst->rep1;
 424                         } else {
 425                                 rc_update_bit_1(rc, prob);
 426                                 prob = p + LZMA_IS_REP_G2 + cst->state;
 427                                 if (rc_is_bit_0(rc, prob)) {
 428                                         rc_update_bit_0(rc, prob);
 429                                         distance = cst->rep2;
 430                                 } else {
 431                                         rc_update_bit_1(rc, prob);
 432                                         distance = cst->rep3;
 433                                         cst->rep3 = cst->rep2;
 434                                 }
 435                                 cst->rep2 = cst->rep1;
 436                         }
 437                         cst->rep1 = cst->rep0;
 438                         cst->rep0 = distance;
 439                 }
 440                 cst->state = cst->state < LZMA_NUM_LIT_STATES ? 8 : 11;
 441                 prob = p + LZMA_REP_LEN_CODER;
 442         }
 443
 444         prob_len = prob + LZMA_LEN_CHOICE;
 445         if (rc_is_bit_0(rc, prob_len)) {
 446                 rc_update_bit_0(rc, prob_len);
 447                 prob_len = (prob + LZMA_LEN_LOW
 448                             + (pos_state <<
 449                                LZMA_LEN_NUM_LOW_BITS));
 450                 offset = 0;
 451                 num_bits = LZMA_LEN_NUM_LOW_BITS;
 452         } else {
 453                 rc_update_bit_1(rc, prob_len);
 454                 prob_len = prob + LZMA_LEN_CHOICE_2;
 455                 if (rc_is_bit_0(rc, prob_len)) {
 456                         rc_update_bit_0(rc, prob_len);
 457                         prob_len = (prob + LZMA_LEN_MID
 458                                     + (pos_state <<
 459                                        LZMA_LEN_NUM_MID_BITS));
 460                         offset = 1 << LZMA_LEN_NUM_LOW_BITS;
 461                         num_bits = LZMA_LEN_NUM_MID_BITS;
 462                 } else {
 463                         rc_update_bit_1(rc, prob_len);
 464                         prob_len = prob + LZMA_LEN_HIGH;
 465                         offset = ((1 << LZMA_LEN_NUM_LOW_BITS)
 466                                   + (1 << LZMA_LEN_NUM_MID_BITS));
 467                         num_bits = LZMA_LEN_NUM_HIGH_BITS;
 468                 }
 469         }
 470
 471         rc_bit_tree_decode(rc, prob_len, num_bits, &len);
 472         len += offset;
 473
 474         if (cst->state < 4) {
 475                 int pos_slot;
 476
 477                 cst->state += LZMA_NUM_LIT_STATES;
 478                 prob =
 479                         p + LZMA_POS_SLOT +
 480                         ((len <
 481                           LZMA_NUM_LEN_TO_POS_STATES ? len :
 482                           LZMA_NUM_LEN_TO_POS_STATES - 1)
 483                          << LZMA_NUM_POS_SLOT_BITS);
 484                 rc_bit_tree_decode(rc, prob,
 485                                    LZMA_NUM_POS_SLOT_BITS,
 486                                    &pos_slot);
 487                 if (pos_slot >= LZMA_START_POS_MODEL_INDEX) {
 488                         int i, mi;
 489                         num_bits = (pos_slot >> 1) - 1;
 490                         cst->rep0 = 2 | (pos_slot & 1);
 491                         if (pos_slot < LZMA_END_POS_MODEL_INDEX) {
 492                                 cst->rep0 <<= num_bits;
 493                                 prob = p + LZMA_SPEC_POS +
 494                                         cst->rep0 - pos_slot - 1;
 495                         } else {
 496                                 num_bits -= LZMA_NUM_ALIGN_BITS;
 497                                 while (num_bits--)
 498                                         cst->rep0 = (cst->rep0 << 1) |
 499                                                 rc_direct_bit(rc);
 500                                 prob = p + LZMA_ALIGN;
 501                                 cst->rep0 <<= LZMA_NUM_ALIGN_BITS;
 502                                 num_bits = LZMA_NUM_ALIGN_BITS;
 503                         }
 504                         i = 1;
 505                         mi = 1;
 506                         while (num_bits--) {
 507                                 if (rc_get_bit(rc, prob + mi, &mi))
 508                                         cst->rep0 |= i;
 509                                 i <<= 1;
 510                         }
 511                 } else
 512                         cst->rep0 = pos_slot;
 513                 if (++(cst->rep0) == 0)
 514                         return;
 515         }
 516
 517         len += LZMA_MATCH_MIN_LEN;
 518
 519         copy_bytes(wr, cst->rep0, len);
 520 }
 521
 522
 523
 524 STATIC inline int INIT unlzma(unsigned char *buf, int in_len,
 525                               int(*fill)(void*, unsigned int),
 526                               int(*flush)(void*, unsigned int),
 527                               unsigned char *output,
 528                               int *posp,
 529                               void(*error_fn)(char *x)
 530         )
 531 {
 532         struct lzma_header header;
 533         int lc, pb, lp;
 534         uint32_t pos_state_mask;
 535         uint32_t literal_pos_mask;
 536         uint16_t *p;
 537         int num_probs;
 538         struct rc rc;
 539         int i, mi;
 540         struct writer wr;
 541         struct cstate cst;
 542         unsigned char *inbuf;
 543         int ret = -1;
 544
 545         set_error_fn(error_fn);
 546         if (!flush)
 547                 in_len -= 4; /* Uncompressed size hack active in pre-boot
 548                                 environment */
 549         if (buf)
 550                 inbuf = buf;
 551         else
 552                 inbuf = malloc(LZMA_IOBUF_SIZE);
 553         if (!inbuf) {
 554                 error("Could not allocate input bufer");
 555                 goto exit_0;
 556         }
 557
 558         cst.state = 0;
 559         cst.rep0 = cst.rep1 = cst.rep2 = cst.rep3 = 1;
 560
 561         wr.header = &header;
 562         wr.flush = flush;
 563         wr.global_pos = 0;
 564         wr.previous_byte = 0;
 565         wr.buffer_pos = 0;
 566
 567         rc_init(&rc, fill, inbuf, in_len);
 568
 569         for (i = 0; i < sizeof(header); i++) {
 570                 if (rc.ptr >= rc.buffer_end)
 571                         rc_read(&rc);
 572                 ((unsigned char *)&header)[i] = *rc.ptr++;
 573         }
 574
 575         if (header.pos >= (9 * 5 * 5))
 576                 error("bad header");
 577
 578         mi = 0;
 579         lc = header.pos;
 580         while (lc >= 9) {
 581                 mi++;
 582                 lc -= 9;
 583         }
 584         pb = 0;
 585         lp = mi;
 586         while (lp >= 5) {
 587                 pb++;
 588                 lp -= 5;
 589         }
 590         pos_state_mask = (1 << pb) - 1;
 591         literal_pos_mask = (1 << lp) - 1;
 592
 593         ENDIAN_CONVERT(header.dict_size);
 594         ENDIAN_CONVERT(header.dst_size);
 595
 596         if (header.dict_size == 0)
 597                 header.dict_size = 1;
 598
 599         if (output)
 600                 wr.buffer = output;
 601         else {
 602                 wr.bufsize = MIN(header.dst_size, header.dict_size);
 603                 wr.buffer = large_malloc(wr.bufsize);
 604         }
 605         if (wr.buffer == NULL)
 606                 goto exit_1;
 607
 608         num_probs = LZMA_BASE_SIZE + (LZMA_LIT_SIZE << (lc + lp));
 609         p = (uint16_t *) large_malloc(num_probs * sizeof(*p));
 610         if (p == 0)
 611                 goto exit_2;
 612         num_probs = LZMA_LITERAL + (LZMA_LIT_SIZE << (lc + lp));
 613         for (i = 0; i < num_probs; i++)
 614                 p[i] = (1 << RC_MODEL_TOTAL_BITS) >> 1;
 615
 616         rc_init_code(&rc);
 617
 618         while (get_pos(&wr) < header.dst_size) {
 619                 int pos_state = get_pos(&wr) & pos_state_mask;
 620                 uint16_t *prob = p + LZMA_IS_MATCH +
 621                         (cst.state << LZMA_NUM_POS_BITS_MAX) + pos_state;
 622                 if (rc_is_bit_0(&rc, prob))
 623                         process_bit0(&wr, &rc, &cst, p, pos_state, prob,
 624                                      lc, literal_pos_mask);
 625                 else {
 626                         process_bit1(&wr, &rc, &cst, p, pos_state, prob);
 627                         if (cst.rep0 == 0)
 628                                 break;
 629                 }
 630         }
 631
 632         if (posp)
 633                 *posp = rc.ptr-rc.buffer;
 634         if (wr.flush)
 635                 wr.flush(wr.buffer, wr.buffer_pos);
 636         ret = 0;
 637         large_free(p);
 638 exit_2:
 639         if (!output)
 640                 large_free(wr.buffer);
 641 exit_1:
 642         if (!buf)
 643                 free(inbuf);
 644 exit_0:
 645         return ret;
 646 }
 647
 648 #define decompress unlzma