4 * LZX decompression routines, originally based on code taken from cabextract
5 * v0.5, which was, itself, a modified version of the lzx decompression code
10 * Copyright (C) 2012, 2013, 2014 Eric Biggers
12 * This file is part of wimlib, a library for working with WIM files.
14 * wimlib is free software; you can redistribute it and/or modify it under the
15 * terms of the GNU General Public License as published by the Free
16 * Software Foundation; either version 3 of the License, or (at your option)
19 * wimlib is distributed in the hope that it will be useful, but WITHOUT ANY
20 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
21 * A PARTICULAR PURPOSE. See the GNU General Public License for more
24 * You should have received a copy of the GNU General Public License
25 * along with wimlib; if not, see http://www.gnu.org/licenses/.
29 * LZX is an LZ77 and Huffman-code based compression format that has many
30 * similarities to the DEFLATE format used in zlib. The compression ratio is as
31 * good or better than DEFLATE.
33 * Some notes on the LZX compression format as used in Windows Imaging (WIM)
36 * A compressed WIM resource consists of a table of chunk offsets followed by
37 * the compressed chunks themselves. All compressed chunks except possibly the
38 * last decompress to a fixed number of bytes, by default 32768. This is quite
39 * similar to the cabinet (.cab) file format, but they are not the same.
40 * According to the cabinet format documentation, the LZX block size is
41 * independent from the CFDATA blocks, and an LZX block may span several CFDATA
42 * blocks. However, in WIMs, LZX blocks do not appear to ever span multiple WIM
43 * chunks. Note that this means any WIM chunk may be decompressed or compressed
44 * independently from any other chunk, which allows random access.
46 * An LZX compressed WIM chunk contains one or more LZX blocks of the aligned,
47 * verbatim, or uncompressed block types. For aligned and verbatim blocks, the
48 * size of the block in uncompressed bytes is specified by a bit following the 3
49 * bits that specify the block type, possibly followed by an additional 16 bits.
50 * '1' means to use the default block size (equal to 32768, the default size of
51 * a WIM chunk), while '0' means that the block size is provided by the next 16
54 * The cabinet format, as documented, allows for the possibility that a
55 * compressed CFDATA chunk is up to 6144 bytes larger than the data it
56 * uncompresses to. However, in the WIM format it appears that every chunk that
57 * would be 32768 bytes or more when compressed is actually stored fully
60 * The 'e8' preprocessing step that changes x86 call instructions to use
61 * absolute offsets instead of relative offsets relies on a filesize parameter.
62 * There is no such parameter for this in the WIM files (even though the size of
63 * the file resource could be used for this purpose), and instead a magic file
64 * size of 12000000 is used. The 'e8' preprocessing is always done, and there
65 * is no bit to indicate whether it is done or not.
69 * Some more notes about errors in Microsoft's LZX documentation:
71 * Microsoft's LZX document and their implementation of the com.ms.util.cab Java
72 * package do not concur.
74 * In the LZX document, there is a table showing the correlation between window
75 * size and the number of position slots. It states that the 1MB window = 40
76 * slots and the 2MB window = 42 slots. In the implementation, 1MB = 42 slots,
77 * 2MB = 50 slots. The actual calculation is 'find the first slot whose position
78 * base is equal to or more than the required window size'. This would explain
79 * why other tables in the document refer to 50 slots rather than 42.
81 * The constant NUM_PRIMARY_LENS used in the decompression pseudocode is not
82 * defined in the specification.
84 * The LZX document states that aligned offset blocks have their aligned offset
85 * Huffman tree AFTER the main and length trees. The implementation suggests
86 * that the aligned offset tree is BEFORE the main and length trees.
88 * The LZX document decoding algorithm states that, in an aligned offset block,
89 * if an extra_bits value is 1, 2 or 3, then that number of bits should be read
90 * and the result added to the match offset. This is correct for 1 and 2, but
91 * not 3, where just a Huffman symbol (using the aligned tree) should be read.
93 * Regarding the E8 preprocessing, the LZX document states 'No translation may
94 * be performed on the last 6 bytes of the input block'. This is correct.
95 * However, the pseudocode provided checks for the *E8 leader* up to the last 6
96 * bytes. If the leader appears between -10 and -7 bytes from the end, this
97 * would cause the next four bytes to be modified, at least one of which would
98 * be in the last 6 bytes, which is not allowed according to the spec.
100 * The specification states that the Huffman trees must always contain at least
101 * one element. However, many CAB files contain blocks where the length tree is
102 * completely empty (because there are no matches), and this is expected to
111 #include "wimlib/decompressor_ops.h"
112 #include "wimlib/decompress_common.h"
113 #include "wimlib/lzx.h"
114 #include "wimlib/util.h"
118 /* Huffman decoding tables and maps from symbols to code lengths. */
121 u16 maintree_decode_table[(1 << LZX_MAINCODE_TABLEBITS) +
122 (LZX_MAINCODE_MAX_NUM_SYMBOLS * 2)]
123 _aligned_attribute(DECODE_TABLE_ALIGNMENT);
124 u8 maintree_lens[LZX_MAINCODE_MAX_NUM_SYMBOLS];
127 u16 lentree_decode_table[(1 << LZX_LENCODE_TABLEBITS) +
128 (LZX_LENCODE_NUM_SYMBOLS * 2)]
129 _aligned_attribute(DECODE_TABLE_ALIGNMENT);
130 u8 lentree_lens[LZX_LENCODE_NUM_SYMBOLS];
133 u16 alignedtree_decode_table[(1 << LZX_ALIGNEDCODE_TABLEBITS) +
134 (LZX_ALIGNEDCODE_NUM_SYMBOLS * 2)]
135 _aligned_attribute(DECODE_TABLE_ALIGNMENT);
136 u8 alignedtree_lens[LZX_ALIGNEDCODE_NUM_SYMBOLS];
137 } _aligned_attribute(DECODE_TABLE_ALIGNMENT);
139 struct lzx_decompressor {
141 unsigned num_main_syms;
142 struct lzx_tables tables;
146 * Reads a Huffman-encoded symbol using the pre-tree.
149 read_huffsym_using_pretree(struct input_bitstream *istream,
150 const u16 pretree_decode_table[])
152 return read_huffsym(istream, pretree_decode_table,
153 LZX_PRECODE_TABLEBITS, LZX_MAX_PRE_CODEWORD_LEN);
156 /* Reads a Huffman-encoded symbol using the main tree. */
158 read_huffsym_using_maintree(struct input_bitstream *istream,
159 const struct lzx_tables *tables)
161 return read_huffsym(istream, tables->maintree_decode_table,
162 LZX_MAINCODE_TABLEBITS, LZX_MAX_MAIN_CODEWORD_LEN);
165 /* Reads a Huffman-encoded symbol using the length tree. */
167 read_huffsym_using_lentree(struct input_bitstream *istream,
168 const struct lzx_tables *tables)
170 return read_huffsym(istream, tables->lentree_decode_table,
171 LZX_LENCODE_TABLEBITS, LZX_MAX_LEN_CODEWORD_LEN);
174 /* Reads a Huffman-encoded symbol using the aligned offset tree. */
176 read_huffsym_using_alignedtree(struct input_bitstream *istream,
177 const struct lzx_tables *tables)
179 return read_huffsym(istream, tables->alignedtree_decode_table,
180 LZX_ALIGNEDCODE_TABLEBITS, LZX_MAX_ALIGNED_CODEWORD_LEN);
184 * Reads the pretree from the input, then uses the pretree to decode @num_lens
185 * code length values from the input.
187 * @istream: The bit stream for the input. It is positioned on the beginning
188 * of the pretree for the code length values.
189 * @lens: An array that contains the length values from the previous time
190 * the code lengths for this Huffman tree were read, or all
191 * 0's if this is the first time.
192 * @num_lens: Number of length values to decode and return.
196 lzx_read_code_lens(struct input_bitstream *istream, u8 lens[],
199 /* Declare the decoding table and length table for the pretree. */
200 u16 pretree_decode_table[(1 << LZX_PRECODE_TABLEBITS) +
201 (LZX_PRECODE_NUM_SYMBOLS * 2)]
202 _aligned_attribute(DECODE_TABLE_ALIGNMENT);
203 u8 pretree_lens[LZX_PRECODE_NUM_SYMBOLS];
207 /* Read the code lengths of the pretree codes. There are 20 lengths of
209 for (i = 0; i < LZX_PRECODE_NUM_SYMBOLS; i++) {
210 pretree_lens[i] = bitstream_read_bits(istream,
211 LZX_PRECODE_ELEMENT_SIZE);
214 /* Make the decoding table for the pretree. */
215 ret = make_huffman_decode_table(pretree_decode_table,
216 LZX_PRECODE_NUM_SYMBOLS,
217 LZX_PRECODE_TABLEBITS,
219 LZX_MAX_PRE_CODEWORD_LEN);
223 /* Pointer past the last length value that needs to be filled in. */
224 u8 *lens_end = lens + num_lens;
228 /* Decode a symbol from the input. If the symbol is between 0
229 * and 16, it is the difference from the old length. If it is
230 * between 17 and 19, it is a special code that indicates that
231 * some number of the next lengths are all 0, or some number of
232 * the next lengths are all equal to the next symbol in the
240 tree_code = read_huffsym_using_pretree(istream,
241 pretree_decode_table);
243 case 17: /* Run of 0's */
244 num_zeroes = bitstream_read_bits(istream, 4);
246 while (num_zeroes--) {
248 if (++lens == lens_end)
252 case 18: /* Longer run of 0's */
253 num_zeroes = bitstream_read_bits(istream, 5);
255 while (num_zeroes--) {
257 if (++lens == lens_end)
261 case 19: /* Run of identical lengths */
262 num_same = bitstream_read_bits(istream, 1);
264 code = read_huffsym_using_pretree(istream,
265 pretree_decode_table);
266 value = (signed char)*lens - (signed char)code;
271 if (++lens == lens_end)
275 default: /* Difference from old length. */
276 value = (signed char)*lens - (signed char)tree_code;
280 if (++lens == lens_end)
288 * Reads the header for an LZX-compressed block.
290 * @istream: The input bitstream.
291 * @block_size_ret: A pointer to an int into which the size of the block,
292 * in bytes, will be returned.
293 * @block_type_ret: A pointer to an int into which the type of the block
294 * (LZX_BLOCKTYPE_*) will be returned.
295 * @tables: A pointer to an lzx_tables structure in which the
296 * main tree, the length tree, and possibly the
297 * aligned offset tree will be constructed.
298 * @queue: A pointer to the least-recently-used queue into which
299 * R0, R1, and R2 will be written (only for uncompressed
300 * blocks, which contain this information in the header)
303 lzx_read_block_header(struct input_bitstream *istream,
304 unsigned num_main_syms,
305 unsigned max_window_size,
306 unsigned *block_size_ret,
307 unsigned *block_type_ret,
308 struct lzx_tables *tables,
309 struct lzx_lru_queue *queue)
315 bitstream_ensure_bits(istream, 4);
317 /* The first three bits tell us what kind of block it is, and are one
318 * of the LZX_BLOCKTYPE_* values. */
319 block_type = bitstream_pop_bits(istream, 3);
321 /* Read the block size. This mirrors the behavior
322 * lzx_write_compressed_block() in lzx-compress.c; see that for more
324 if (bitstream_pop_bits(istream, 1)) {
325 block_size = LZX_DEFAULT_BLOCK_SIZE;
330 tmp = bitstream_read_bits(istream, 8);
332 tmp = bitstream_read_bits(istream, 8);
336 if (max_window_size >= 65536) {
337 tmp = bitstream_read_bits(istream, 8);
343 switch (block_type) {
344 case LZX_BLOCKTYPE_ALIGNED:
345 /* Read the path lengths for the elements of the aligned tree,
348 for (unsigned i = 0; i < LZX_ALIGNEDCODE_NUM_SYMBOLS; i++) {
349 tables->alignedtree_lens[i] =
350 bitstream_read_bits(istream,
351 LZX_ALIGNEDCODE_ELEMENT_SIZE);
354 LZX_DEBUG("Building the aligned tree.");
355 ret = make_huffman_decode_table(tables->alignedtree_decode_table,
356 LZX_ALIGNEDCODE_NUM_SYMBOLS,
357 LZX_ALIGNEDCODE_TABLEBITS,
358 tables->alignedtree_lens,
359 LZX_MAX_ALIGNED_CODEWORD_LEN);
361 LZX_DEBUG("Failed to make the decode table for the "
362 "aligned offset tree");
366 /* Fall though, since the rest of the header for aligned offset
367 * blocks is the same as that for verbatim blocks */
369 case LZX_BLOCKTYPE_VERBATIM:
370 if (block_type == LZX_BLOCKTYPE_VERBATIM)
371 LZX_DEBUG("Found verbatim block.");
373 LZX_DEBUG("Reading path lengths for main tree.");
374 /* Read the path lengths for the first 256 elements of the main
376 ret = lzx_read_code_lens(istream, tables->maintree_lens,
379 LZX_DEBUG("Failed to read the code lengths for the "
380 "first 256 elements of the main tree");
384 /* Read the path lengths for the remaining elements of the main
386 LZX_DEBUG("Reading path lengths for remaining elements of "
387 "main tree (%d elements).",
388 num_main_syms - LZX_NUM_CHARS);
389 ret = lzx_read_code_lens(istream,
390 tables->maintree_lens + LZX_NUM_CHARS,
391 num_main_syms - LZX_NUM_CHARS);
393 LZX_DEBUG("Failed to read the path lengths for the "
394 "remaining elements of the main tree");
398 LZX_DEBUG("Building the Huffman decoding "
399 "table for the main tree.");
401 ret = make_huffman_decode_table(tables->maintree_decode_table,
403 LZX_MAINCODE_TABLEBITS,
404 tables->maintree_lens,
405 LZX_MAX_MAIN_CODEWORD_LEN);
407 LZX_DEBUG("Failed to make the decode "
408 "table for the main tree");
412 LZX_DEBUG("Reading path lengths for the length tree.");
413 ret = lzx_read_code_lens(istream, tables->lentree_lens,
414 LZX_LENCODE_NUM_SYMBOLS);
416 LZX_DEBUG("Failed to read the path "
417 "lengths for the length tree");
421 LZX_DEBUG("Building the length tree.");
422 ret = make_huffman_decode_table(tables->lentree_decode_table,
423 LZX_LENCODE_NUM_SYMBOLS,
424 LZX_LENCODE_TABLEBITS,
425 tables->lentree_lens,
426 LZX_MAX_LEN_CODEWORD_LEN);
428 LZX_DEBUG("Failed to build the length Huffman tree");
431 /* The bitstream of compressed literals and matches for this
432 * block directly follows and will be read in
433 * lzx_decompress_block(). */
435 case LZX_BLOCKTYPE_UNCOMPRESSED:
436 LZX_DEBUG("Found uncompressed block.");
437 /* Before reading the three LRU match offsets from the
438 * uncompressed block header, the stream needs to be aligned on
439 * a 16-bit boundary. But, unexpectedly, if the stream is
440 * *already* aligned, the correct thing to do is to throw away
441 * the next 16 bits. */
442 if (istream->bitsleft == 0) {
443 if (istream->data_bytes_left < 14) {
444 LZX_DEBUG("Insufficient length in "
445 "uncompressed block");
449 istream->data_bytes_left -= 2;
451 if (istream->data_bytes_left < 12) {
452 LZX_DEBUG("Insufficient length in "
453 "uncompressed block");
456 istream->bitsleft = 0;
459 queue->R[0] = le32_to_cpu(*(le32*)(istream->data + 0));
460 queue->R[1] = le32_to_cpu(*(le32*)(istream->data + 4));
461 queue->R[2] = le32_to_cpu(*(le32*)(istream->data + 8));
463 istream->data_bytes_left -= 12;
464 /* The uncompressed data of this block directly follows and will
465 * be read in lzx_decompress(). */
468 LZX_DEBUG("Found invalid block");
471 *block_type_ret = block_type;
472 *block_size_ret = block_size;
477 * Decodes a compressed match from a block of LZX-compressed data. A match
478 * refers to some match_offset to a point earlier in the window as well as some
479 * match_len, for which the data is to be copied to the current position in the
482 * @main_element: The start of the match data, as decoded using the main
485 * @block_type: The type of the block (LZX_BLOCKTYPE_ALIGNED or
486 * LZX_BLOCKTYPE_VERBATIM)
488 * @bytes_remaining: The amount of uncompressed data remaining to be
489 * uncompressed in this block. It is an error if the match
490 * is longer than this number.
492 * @window: A pointer to the window into which the uncompressed
493 * data is being written.
495 * @window_pos: The current byte offset in the window.
497 * @tables: The Huffman decoding tables for this LZX block (main
498 * code, length code, and for LZX_BLOCKTYPE_ALIGNED blocks,
499 * also the aligned offset code).
501 * @queue: The least-recently used queue for match offsets.
503 * @istream: The input bitstream.
505 * Returns the length of the match, or a negative number on error. The possible
507 * - Match would exceed the amount of data remaining to be uncompressed.
508 * - Match refers to data before the window.
509 * - The input bitstream ended unexpectedly.
512 lzx_decode_match(unsigned main_element, int block_type,
513 unsigned bytes_remaining, u8 *window,
515 const struct lzx_tables *tables,
516 struct lzx_lru_queue *queue,
517 struct input_bitstream *istream)
519 unsigned length_header;
520 unsigned position_slot;
522 unsigned match_offset;
523 unsigned num_extra_bits;
527 /* The main element is offset by 256 because values under 256 indicate a
529 main_element -= LZX_NUM_CHARS;
531 /* The length header consists of the lower 3 bits of the main element.
532 * The position slot is the rest of it. */
533 length_header = main_element & LZX_NUM_PRIMARY_LENS;
534 position_slot = main_element >> 3;
536 /* If the length_header is less than LZX_NUM_PRIMARY_LENS (= 7), it
537 * gives the match length as the offset from LZX_MIN_MATCH_LEN.
538 * Otherwise, the length is given by an additional symbol encoded using
539 * the length tree, offset by 9 (LZX_MIN_MATCH_LEN +
540 * LZX_NUM_PRIMARY_LENS) */
541 match_len = LZX_MIN_MATCH_LEN + length_header;
542 if (length_header == LZX_NUM_PRIMARY_LENS)
543 match_len += read_huffsym_using_lentree(istream, tables);
545 /* If the position_slot is 0, 1, or 2, the match offset is retrieved
546 * from the LRU queue. Otherwise, the match offset is not in the LRU
548 if (position_slot <= 2) {
549 /* Note: This isn't a real LRU queue, since using the R2 offset
550 * doesn't bump the R1 offset down to R2. This quirk allows all
551 * 3 recent offsets to be handled by the same code. (For R0,
552 * the swap is a no-op.) */
553 match_offset = queue->R[position_slot];
554 queue->R[position_slot] = queue->R[0];
555 queue->R[0] = match_offset;
557 /* Otherwise, the offset was not encoded as one the offsets in
558 * the queue. Depending on the position slot, there is a
559 * certain number of extra bits that need to be read to fully
560 * decode the match offset. */
562 /* Look up the number of extra bits that need to be read. */
563 num_extra_bits = lzx_get_num_extra_bits(position_slot);
565 /* For aligned blocks, if there are at least 3 extra bits, the
566 * actual number of extra bits is 3 less, and they encode a
567 * number of 8-byte words that are added to the offset; there
568 * is then an additional symbol read using the aligned tree that
569 * specifies the actual byte alignment. */
570 if (block_type == LZX_BLOCKTYPE_ALIGNED && num_extra_bits >= 3) {
572 /* There is an error in the LZX "specification" at this
573 * point; it indicates that a Huffman symbol is to be
574 * read only if num_extra_bits is greater than 3, but
575 * actually it is if num_extra_bits is greater than or
576 * equal to 3. (Note that in the case with
577 * num_extra_bits == 3, the assignment to verbatim_bits
578 * will just set it to 0. ) */
579 verbatim_bits = bitstream_read_bits(istream,
582 aligned_bits = read_huffsym_using_alignedtree(istream,
585 /* For non-aligned blocks, or for aligned blocks with
586 * less than 3 extra bits, the extra bits are added
587 * directly to the match offset, and the correction for
588 * the alignment is taken to be 0. */
589 verbatim_bits = bitstream_read_bits(istream, num_extra_bits);
593 /* Calculate the match offset. */
594 match_offset = lzx_position_base[position_slot] +
595 verbatim_bits + aligned_bits - LZX_OFFSET_OFFSET;
597 /* Update the LRU queue. */
598 queue->R[2] = queue->R[1];
599 queue->R[1] = queue->R[0];
600 queue->R[0] = match_offset;
603 /* Verify that the match is in the bounds of the part of the window
604 * currently in use, then copy the source of the match to the current
607 if (unlikely(match_len > bytes_remaining)) {
608 LZX_DEBUG("Match of length %u bytes overflows "
609 "uncompressed block size", match_len);
613 if (unlikely(match_offset > window_pos)) {
614 LZX_DEBUG("Match of length %u bytes references "
615 "data before window (match_offset = %u, "
617 match_len, match_offset, window_pos);
621 lz_copy(&window[window_pos], match_len, match_offset,
622 &window[window_pos + bytes_remaining]);
628 * Decompresses an LZX-compressed block of data from which the header has already
631 * @block_type: The type of the block (LZX_BLOCKTYPE_VERBATIM or
632 * LZX_BLOCKTYPE_ALIGNED)
633 * @block_size: The size of the block, in bytes.
634 * @window: Pointer to the decompression window.
635 * @window_pos: The current position in the window. Will be 0 for the first
637 * @tables: The Huffman decoding tables for the block (main, length, and
638 * aligned offset, the latter only for LZX_BLOCKTYPE_ALIGNED)
639 * @queue: The least-recently-used queue for match offsets.
640 * @istream: The input bitstream for the compressed literals.
643 lzx_decompress_block(int block_type, unsigned block_size,
646 const struct lzx_tables *tables,
647 struct lzx_lru_queue *queue,
648 struct input_bitstream *istream)
650 unsigned main_element;
654 end = window_pos + block_size;
655 while (window_pos < end) {
656 main_element = read_huffsym_using_maintree(istream, tables);
657 if (main_element < LZX_NUM_CHARS) {
658 /* literal: 0 to LZX_NUM_CHARS - 1 */
659 window[window_pos++] = main_element;
661 /* match: LZX_NUM_CHARS to num_main_syms - 1 */
662 match_len = lzx_decode_match(main_element,
670 if (unlikely(match_len < 0))
672 window_pos += match_len;
679 lzx_decompress(const void *compressed_data, size_t compressed_size,
680 void *uncompressed_data, size_t uncompressed_size,
683 struct lzx_decompressor *ctx = _ctx;
684 struct input_bitstream istream;
685 struct lzx_lru_queue queue;
690 bool e8_preprocessing_done;
692 LZX_DEBUG("compressed_data = %p, compressed_size = %zu, "
693 "uncompressed_data = %p, uncompressed_size = %zu, "
694 "max_window_size=%u).",
695 compressed_data, compressed_size,
696 uncompressed_data, uncompressed_size,
697 ctx->max_window_size);
699 if (uncompressed_size > ctx->max_window_size) {
700 LZX_DEBUG("Uncompressed size of %zu exceeds "
701 "window size of %u!",
702 uncompressed_size, ctx->max_window_size);
706 memset(ctx->tables.maintree_lens, 0, sizeof(ctx->tables.maintree_lens));
707 memset(ctx->tables.lentree_lens, 0, sizeof(ctx->tables.lentree_lens));
708 lzx_lru_queue_init(&queue);
709 init_input_bitstream(&istream, compressed_data, compressed_size);
711 e8_preprocessing_done = false; /* Set to true if there may be 0xe8 bytes
712 in the uncompressed data. */
714 /* The compressed data will consist of one or more blocks. The
715 * following loop decompresses one block, and it runs until there all
716 * the compressed data has been decompressed, so there are no more
720 window_pos < uncompressed_size;
721 window_pos += block_size)
723 LZX_DEBUG("Reading block header.");
724 ret = lzx_read_block_header(&istream, ctx->num_main_syms,
725 ctx->max_window_size, &block_size,
726 &block_type, &ctx->tables, &queue);
730 LZX_DEBUG("block_size = %u, window_pos = %u",
731 block_size, window_pos);
733 if (block_size > uncompressed_size - window_pos) {
734 LZX_DEBUG("Expected a block size of at "
735 "most %zu bytes (found %u bytes)",
736 uncompressed_size - window_pos, block_size);
740 switch (block_type) {
741 case LZX_BLOCKTYPE_VERBATIM:
742 case LZX_BLOCKTYPE_ALIGNED:
743 if (block_type == LZX_BLOCKTYPE_VERBATIM)
744 LZX_DEBUG("LZX_BLOCKTYPE_VERBATIM");
746 LZX_DEBUG("LZX_BLOCKTYPE_ALIGNED");
747 ret = lzx_decompress_block(block_type,
757 if (ctx->tables.maintree_lens[0xe8] != 0)
758 e8_preprocessing_done = true;
760 case LZX_BLOCKTYPE_UNCOMPRESSED:
761 LZX_DEBUG("LZX_BLOCKTYPE_UNCOMPRESSED");
762 if (istream.data_bytes_left < block_size) {
763 LZX_DEBUG("Unexpected end of input when "
764 "reading %u bytes from LZX bitstream "
765 "(only have %u bytes left)",
766 block_size, istream.data_bytes_left);
769 memcpy(&((u8*)uncompressed_data)[window_pos], istream.data,
771 istream.data += block_size;
772 istream.data_bytes_left -= block_size;
773 /* Re-align bitstream if an odd number of bytes were
775 if (istream.data_bytes_left && (block_size & 1)) {
776 istream.data_bytes_left--;
779 e8_preprocessing_done = true;
783 if (e8_preprocessing_done)
784 lzx_undo_e8_preprocessing(uncompressed_data, uncompressed_size);
789 lzx_free_decompressor(void *_ctx)
791 struct lzx_decompressor *ctx = _ctx;
797 lzx_create_decompressor(size_t max_window_size,
798 const struct wimlib_decompressor_params_header *params,
801 struct lzx_decompressor *ctx;
803 if (!lzx_window_size_valid(max_window_size))
804 return WIMLIB_ERR_INVALID_PARAM;
806 ctx = ALIGNED_MALLOC(sizeof(struct lzx_decompressor),
807 DECODE_TABLE_ALIGNMENT);
809 return WIMLIB_ERR_NOMEM;
811 ctx->max_window_size = max_window_size;
812 ctx->num_main_syms = lzx_get_num_main_syms(max_window_size);
818 const struct decompressor_ops lzx_decompressor_ops = {
819 .create_decompressor = lzx_create_decompressor,
820 .decompress = lzx_decompress,
821 .free_decompressor = lzx_free_decompressor,