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"
119 # include <emmintrin.h>
122 /* Huffman decoding tables and maps from symbols to code lengths. */
125 u16 maintree_decode_table[(1 << LZX_MAINCODE_TABLEBITS) +
126 (LZX_MAINCODE_MAX_NUM_SYMBOLS * 2)]
127 _aligned_attribute(DECODE_TABLE_ALIGNMENT);
128 u8 maintree_lens[LZX_MAINCODE_MAX_NUM_SYMBOLS];
131 u16 lentree_decode_table[(1 << LZX_LENCODE_TABLEBITS) +
132 (LZX_LENCODE_NUM_SYMBOLS * 2)]
133 _aligned_attribute(DECODE_TABLE_ALIGNMENT);
134 u8 lentree_lens[LZX_LENCODE_NUM_SYMBOLS];
137 u16 alignedtree_decode_table[(1 << LZX_ALIGNEDCODE_TABLEBITS) +
138 (LZX_ALIGNEDCODE_NUM_SYMBOLS * 2)]
139 _aligned_attribute(DECODE_TABLE_ALIGNMENT);
140 u8 alignedtree_lens[LZX_ALIGNEDCODE_NUM_SYMBOLS];
141 } _aligned_attribute(DECODE_TABLE_ALIGNMENT);
143 struct lzx_decompressor {
145 unsigned num_main_syms;
146 struct lzx_tables tables;
150 * Reads a Huffman-encoded symbol using the pre-tree.
153 read_huffsym_using_pretree(struct input_bitstream *istream,
154 const u16 pretree_decode_table[])
156 return read_huffsym(istream, pretree_decode_table,
157 LZX_PRECODE_NUM_SYMBOLS, LZX_PRECODE_TABLEBITS,
158 LZX_MAX_PRE_CODEWORD_LEN);
161 /* Reads a Huffman-encoded symbol using the main tree. */
163 read_huffsym_using_maintree(struct input_bitstream *istream,
164 const struct lzx_tables *tables,
165 unsigned num_main_syms)
167 return read_huffsym(istream, tables->maintree_decode_table,
169 LZX_MAINCODE_TABLEBITS, LZX_MAX_MAIN_CODEWORD_LEN);
172 /* Reads a Huffman-encoded symbol using the length tree. */
174 read_huffsym_using_lentree(struct input_bitstream *istream,
175 const struct lzx_tables *tables)
177 return read_huffsym(istream, tables->lentree_decode_table,
178 LZX_LENCODE_NUM_SYMBOLS,
179 LZX_LENCODE_TABLEBITS, LZX_MAX_LEN_CODEWORD_LEN);
182 /* Reads a Huffman-encoded symbol using the aligned offset tree. */
184 read_huffsym_using_alignedtree(struct input_bitstream *istream,
185 const struct lzx_tables *tables)
187 return read_huffsym(istream, tables->alignedtree_decode_table,
188 LZX_ALIGNEDCODE_NUM_SYMBOLS,
189 LZX_ALIGNEDCODE_TABLEBITS,
190 LZX_MAX_ALIGNED_CODEWORD_LEN);
194 * Reads the pretree from the input, then uses the pretree to decode @num_lens
195 * code length values from the input.
197 * @istream: The bit stream for the input. It is positioned on the beginning
198 * of the pretree for the code length values.
199 * @lens: An array that contains the length values from the previous time
200 * the code lengths for this Huffman tree were read, or all
201 * 0's if this is the first time.
202 * @num_lens: Number of length values to decode and return.
206 lzx_read_code_lens(struct input_bitstream *istream, u8 lens[],
209 /* Declare the decoding table and length table for the pretree. */
210 u16 pretree_decode_table[(1 << LZX_PRECODE_TABLEBITS) +
211 (LZX_PRECODE_NUM_SYMBOLS * 2)]
212 _aligned_attribute(DECODE_TABLE_ALIGNMENT);
213 u8 pretree_lens[LZX_PRECODE_NUM_SYMBOLS];
217 /* Read the code lengths of the pretree codes. There are 20 lengths of
219 for (i = 0; i < LZX_PRECODE_NUM_SYMBOLS; i++) {
220 pretree_lens[i] = bitstream_read_bits(istream,
221 LZX_PRECODE_ELEMENT_SIZE);
224 /* Make the decoding table for the pretree. */
225 ret = make_huffman_decode_table(pretree_decode_table,
226 LZX_PRECODE_NUM_SYMBOLS,
227 LZX_PRECODE_TABLEBITS,
229 LZX_MAX_PRE_CODEWORD_LEN);
233 /* Pointer past the last length value that needs to be filled in. */
234 u8 *lens_end = lens + num_lens;
238 /* Decode a symbol from the input. If the symbol is between 0
239 * and 16, it is the difference from the old length. If it is
240 * between 17 and 19, it is a special code that indicates that
241 * some number of the next lengths are all 0, or some number of
242 * the next lengths are all equal to the next symbol in the
250 tree_code = read_huffsym_using_pretree(istream,
251 pretree_decode_table);
253 case 17: /* Run of 0's */
254 num_zeroes = bitstream_read_bits(istream, 4);
256 while (num_zeroes--) {
258 if (++lens == lens_end)
262 case 18: /* Longer run of 0's */
263 num_zeroes = bitstream_read_bits(istream, 5);
265 while (num_zeroes--) {
267 if (++lens == lens_end)
271 case 19: /* Run of identical lengths */
272 num_same = bitstream_read_bits(istream, 1);
274 code = read_huffsym_using_pretree(istream,
275 pretree_decode_table);
276 value = (signed char)*lens - (signed char)code;
281 if (++lens == lens_end)
285 default: /* Difference from old length. */
286 value = (signed char)*lens - (signed char)tree_code;
290 if (++lens == lens_end)
298 * Reads the header for an LZX-compressed block.
300 * @istream: The input bitstream.
301 * @block_size_ret: A pointer to an int into which the size of the block,
302 * in bytes, will be returned.
303 * @block_type_ret: A pointer to an int into which the type of the block
304 * (LZX_BLOCKTYPE_*) will be returned.
305 * @tables: A pointer to an lzx_tables structure in which the
306 * main tree, the length tree, and possibly the
307 * aligned offset tree will be constructed.
308 * @queue: A pointer to the least-recently-used queue into which
309 * R0, R1, and R2 will be written (only for uncompressed
310 * blocks, which contain this information in the header)
313 lzx_read_block_header(struct input_bitstream *istream,
314 unsigned num_main_syms,
315 unsigned max_window_size,
316 unsigned *block_size_ret,
317 unsigned *block_type_ret,
318 struct lzx_tables *tables,
319 struct lzx_lru_queue *queue)
325 bitstream_ensure_bits(istream, 4);
327 /* The first three bits tell us what kind of block it is, and are one
328 * of the LZX_BLOCKTYPE_* values. */
329 block_type = bitstream_pop_bits(istream, 3);
331 /* Read the block size. This mirrors the behavior
332 * lzx_write_compressed_block() in lzx-compress.c; see that for more
334 if (bitstream_pop_bits(istream, 1)) {
335 block_size = LZX_DEFAULT_BLOCK_SIZE;
340 tmp = bitstream_read_bits(istream, 8);
342 tmp = bitstream_read_bits(istream, 8);
346 if (max_window_size >= 65536) {
347 tmp = bitstream_read_bits(istream, 8);
353 switch (block_type) {
354 case LZX_BLOCKTYPE_ALIGNED:
355 /* Read the path lengths for the elements of the aligned tree,
358 for (unsigned i = 0; i < LZX_ALIGNEDCODE_NUM_SYMBOLS; i++) {
359 tables->alignedtree_lens[i] =
360 bitstream_read_bits(istream,
361 LZX_ALIGNEDCODE_ELEMENT_SIZE);
364 LZX_DEBUG("Building the aligned tree.");
365 ret = make_huffman_decode_table(tables->alignedtree_decode_table,
366 LZX_ALIGNEDCODE_NUM_SYMBOLS,
367 LZX_ALIGNEDCODE_TABLEBITS,
368 tables->alignedtree_lens,
369 LZX_MAX_ALIGNED_CODEWORD_LEN);
371 LZX_DEBUG("Failed to make the decode table for the "
372 "aligned offset tree");
376 /* Fall though, since the rest of the header for aligned offset
377 * blocks is the same as that for verbatim blocks */
379 case LZX_BLOCKTYPE_VERBATIM:
380 if (block_type == LZX_BLOCKTYPE_VERBATIM)
381 LZX_DEBUG("Found verbatim block.");
383 LZX_DEBUG("Reading path lengths for main tree.");
384 /* Read the path lengths for the first 256 elements of the main
386 ret = lzx_read_code_lens(istream, tables->maintree_lens,
389 LZX_DEBUG("Failed to read the code lengths for the "
390 "first 256 elements of the main tree");
394 /* Read the path lengths for the remaining elements of the main
396 LZX_DEBUG("Reading path lengths for remaining elements of "
397 "main tree (%d elements).",
398 num_main_syms - LZX_NUM_CHARS);
399 ret = lzx_read_code_lens(istream,
400 tables->maintree_lens + LZX_NUM_CHARS,
401 num_main_syms - LZX_NUM_CHARS);
403 LZX_DEBUG("Failed to read the path lengths for the "
404 "remaining elements of the main tree");
408 LZX_DEBUG("Building the Huffman decoding "
409 "table for the main tree.");
411 ret = make_huffman_decode_table(tables->maintree_decode_table,
413 LZX_MAINCODE_TABLEBITS,
414 tables->maintree_lens,
415 LZX_MAX_MAIN_CODEWORD_LEN);
417 LZX_DEBUG("Failed to make the decode "
418 "table for the main tree");
422 LZX_DEBUG("Reading path lengths for the length tree.");
423 ret = lzx_read_code_lens(istream, tables->lentree_lens,
424 LZX_LENCODE_NUM_SYMBOLS);
426 LZX_DEBUG("Failed to read the path "
427 "lengths for the length tree");
431 LZX_DEBUG("Building the length tree.");
432 ret = make_huffman_decode_table(tables->lentree_decode_table,
433 LZX_LENCODE_NUM_SYMBOLS,
434 LZX_LENCODE_TABLEBITS,
435 tables->lentree_lens,
436 LZX_MAX_LEN_CODEWORD_LEN);
438 LZX_DEBUG("Failed to build the length Huffman tree");
441 /* The bitstream of compressed literals and matches for this
442 * block directly follows and will be read in
443 * lzx_decompress_block(). */
445 case LZX_BLOCKTYPE_UNCOMPRESSED:
446 LZX_DEBUG("Found uncompressed block.");
447 /* Before reading the three LRU match offsets from the
448 * uncompressed block header, the stream needs to be aligned on
449 * a 16-bit boundary. But, unexpectedly, if the stream is
450 * *already* aligned, the correct thing to do is to throw away
451 * the next 16 bits. */
452 if (istream->bitsleft == 0) {
453 if (istream->data_bytes_left < 14) {
454 LZX_DEBUG("Insufficient length in "
455 "uncompressed block");
459 istream->data_bytes_left -= 2;
461 if (istream->data_bytes_left < 12) {
462 LZX_DEBUG("Insufficient length in "
463 "uncompressed block");
466 istream->bitsleft = 0;
469 queue->R[0] = le32_to_cpu(*(le32*)(istream->data + 0));
470 queue->R[1] = le32_to_cpu(*(le32*)(istream->data + 4));
471 queue->R[2] = le32_to_cpu(*(le32*)(istream->data + 8));
473 istream->data_bytes_left -= 12;
474 /* The uncompressed data of this block directly follows and will
475 * be read in lzx_decompress(). */
478 LZX_DEBUG("Found invalid block");
481 *block_type_ret = block_type;
482 *block_size_ret = block_size;
487 * Decodes a compressed match from a block of LZX-compressed data. A match
488 * refers to some match_offset to a point earlier in the window as well as some
489 * match_len, for which the data is to be copied to the current position in the
492 * @main_element: The start of the match data, as decoded using the main
495 * @block_type: The type of the block (LZX_BLOCKTYPE_ALIGNED or
496 * LZX_BLOCKTYPE_VERBATIM)
498 * @bytes_remaining: The amount of uncompressed data remaining to be
499 * uncompressed in this block. It is an error if the match
500 * is longer than this number.
502 * @window: A pointer to the window into which the uncompressed
503 * data is being written.
505 * @window_pos: The current byte offset in the window.
507 * @tables: The Huffman decoding tables for this LZX block (main
508 * code, length code, and for LZX_BLOCKTYPE_ALIGNED blocks,
509 * also the aligned offset code).
511 * @queue: The least-recently used queue for match offsets.
513 * @istream: The input bitstream.
515 * Returns the length of the match, or a negative number on error. The possible
517 * - Match would exceed the amount of data remaining to be uncompressed.
518 * - Match refers to data before the window.
519 * - The input bitstream ended unexpectedly.
522 lzx_decode_match(unsigned main_element, int block_type,
523 unsigned bytes_remaining, u8 *window,
525 const struct lzx_tables *tables,
526 struct lzx_lru_queue *queue,
527 struct input_bitstream *istream)
529 unsigned length_header;
530 unsigned position_slot;
532 unsigned match_offset;
533 unsigned num_extra_bits;
540 /* The main element is offset by 256 because values under 256 indicate a
542 main_element -= LZX_NUM_CHARS;
544 /* The length header consists of the lower 3 bits of the main element.
545 * The position slot is the rest of it. */
546 length_header = main_element & LZX_NUM_PRIMARY_LENS;
547 position_slot = main_element >> 3;
549 /* If the length_header is less than LZX_NUM_PRIMARY_LENS (= 7), it
550 * gives the match length as the offset from LZX_MIN_MATCH_LEN.
551 * Otherwise, the length is given by an additional symbol encoded using
552 * the length tree, offset by 9 (LZX_MIN_MATCH_LEN +
553 * LZX_NUM_PRIMARY_LENS) */
554 match_len = LZX_MIN_MATCH_LEN + length_header;
555 if (length_header == LZX_NUM_PRIMARY_LENS)
556 match_len += read_huffsym_using_lentree(istream, tables);
558 /* If the position_slot is 0, 1, or 2, the match offset is retrieved
559 * from the LRU queue. Otherwise, the match offset is not in the LRU
561 switch (position_slot) {
563 match_offset = queue->R[0];
566 match_offset = queue->R[1];
567 swap(queue->R[0], queue->R[1]);
570 /* The queue doesn't work quite the same as a real LRU queue,
571 * since using the R2 offset doesn't bump the R1 offset down to
573 match_offset = queue->R[2];
574 swap(queue->R[0], queue->R[2]);
577 /* Otherwise, the offset was not encoded as one the offsets in
578 * the queue. Depending on the position slot, there is a
579 * certain number of extra bits that need to be read to fully
580 * decode the match offset. */
582 /* Look up the number of extra bits that need to be read. */
583 num_extra_bits = lzx_get_num_extra_bits(position_slot);
585 /* For aligned blocks, if there are at least 3 extra bits, the
586 * actual number of extra bits is 3 less, and they encode a
587 * number of 8-byte words that are added to the offset; there
588 * is then an additional symbol read using the aligned tree that
589 * specifies the actual byte alignment. */
590 if (block_type == LZX_BLOCKTYPE_ALIGNED && num_extra_bits >= 3) {
592 /* There is an error in the LZX "specification" at this
593 * point; it indicates that a Huffman symbol is to be
594 * read only if num_extra_bits is greater than 3, but
595 * actually it is if num_extra_bits is greater than or
596 * equal to 3. (Note that in the case with
597 * num_extra_bits == 3, the assignment to verbatim_bits
598 * will just set it to 0. ) */
599 verbatim_bits = bitstream_read_bits(istream,
602 aligned_bits = read_huffsym_using_alignedtree(istream,
605 /* For non-aligned blocks, or for aligned blocks with
606 * less than 3 extra bits, the extra bits are added
607 * directly to the match offset, and the correction for
608 * the alignment is taken to be 0. */
609 verbatim_bits = bitstream_read_bits(istream, num_extra_bits);
613 /* Calculate the match offset. */
614 match_offset = lzx_position_base[position_slot] +
615 verbatim_bits + aligned_bits - LZX_OFFSET_OFFSET;
617 /* Update the LRU queue. */
618 queue->R[2] = queue->R[1];
619 queue->R[1] = queue->R[0];
620 queue->R[0] = match_offset;
624 /* Verify that the match is in the bounds of the part of the window
625 * currently in use, then copy the source of the match to the current
628 if (unlikely(match_len > bytes_remaining)) {
629 LZX_DEBUG("Match of length %u bytes overflows "
630 "uncompressed block size", match_len);
634 if (unlikely(match_offset > window_pos)) {
635 LZX_DEBUG("Match of length %u bytes references "
636 "data before window (match_offset = %u, "
638 match_len, match_offset, window_pos);
642 match_dest = window + window_pos;
643 match_src = match_dest - match_offset;
646 printf("Match: src %u, dst %u, len %u\n", match_src - window,
650 for (i = 0; i < match_len; i++) {
651 match_dest[i] = match_src[i];
652 putchar(match_src[i]);
657 for (i = 0; i < match_len; i++)
658 match_dest[i] = match_src[i];
665 undo_call_insn_translation(u32 *call_insn_target, s32 input_pos)
670 abs_offset = le32_to_cpu(*call_insn_target);
671 if (abs_offset >= 0) {
672 if (abs_offset < LZX_WIM_MAGIC_FILESIZE) {
673 /* "good translation" */
674 rel_offset = abs_offset - input_pos;
676 *call_insn_target = cpu_to_le32(rel_offset);
679 if (abs_offset >= -input_pos) {
680 /* "compensating translation" */
681 rel_offset = abs_offset + LZX_WIM_MAGIC_FILESIZE;
683 *call_insn_target = cpu_to_le32(rel_offset);
688 /* Undo the 'E8' preprocessing, where the targets of x86 CALL instructions were
689 * changed from relative offsets to absolute offsets.
691 * Note that this call instruction preprocessing can and will be used on any
692 * data even if it is not actually x86 machine code. In fact, this type of
693 * preprocessing appears to always be used in LZX-compressed resources in WIM
694 * files; there is no bit to indicate whether it is used or not, unlike in the
695 * LZX compressed format as used in cabinet files, where a bit is reserved for
698 * Call instruction preprocessing is disabled in the last 6 bytes of the
699 * uncompressed data, which really means the 5-byte call instruction cannot
700 * start in the last 10 bytes of the uncompressed data. This is one of the
701 * errors in the LZX documentation.
703 * Call instruction preprocessing does not appear to be disabled after the
704 * 32768th chunk of a WIM stream, which is apparently is yet another difference
705 * from the LZX compression used in cabinet files.
707 * Call instruction processing is supposed to take the file size as a parameter,
708 * as it is used in calculating the translated jump targets. But in WIM files,
709 * this file size is always the same (LZX_WIM_MAGIC_FILESIZE == 12000000).*/
711 undo_call_insn_preprocessing(u8 *uncompressed_data, size_t uncompressed_size)
715 /* SSE2 vectorized implementation for x86_64. This speeds up LZX
716 * decompression by about 5-8% overall. (Usually --- the performance
717 * actually regresses slightly in the degenerate case that the data
718 * consists entirely of 0xe8 bytes.) */
719 __m128i *p128 = (__m128i *)uncompressed_data;
720 u32 valid_mask = 0xFFFFFFFF;
722 if (uncompressed_size >= 32 &&
723 ((uintptr_t)uncompressed_data % 16 == 0))
725 __m128i * const end128 = p128 + uncompressed_size / 16 - 1;
727 /* Create a vector of all 0xe8 bytes */
728 const __m128i e8_bytes = _mm_set1_epi8(0xe8);
730 /* Iterate through the 16-byte vectors in the input. */
732 /* Compare the current 16-byte vector with the vector of
733 * all 0xe8 bytes. This produces 0xff where the byte is
734 * 0xe8 and 0x00 where it is not. */
735 __m128i cmpresult = _mm_cmpeq_epi8(*p128, e8_bytes);
737 /* Map the comparison results into a single 16-bit
738 * number. It will contain a 1 bit when the
739 * corresponding byte in the current 16-byte vector is
740 * an e8 byte. Note: the low-order bit corresponds to
741 * the first (lowest address) byte. */
742 u32 e8_mask = _mm_movemask_epi8(cmpresult);
745 /* If e8_mask is 0, then none of these 16 bytes
746 * have value 0xe8. No e8 translation is
747 * needed, and there is no restriction that
748 * carries over to the next 16 bytes. */
749 valid_mask = 0xFFFFFFFF;
751 /* At least one byte has value 0xe8.
753 * The AND with valid_mask accounts for the fact
754 * that we can't start an e8 translation that
755 * overlaps the previous one. */
756 while ((e8_mask &= valid_mask)) {
758 /* Count the number of trailing zeroes
759 * in e8_mask. This will produce the
760 * index of the byte, within the 16, at
761 * which the next e8 translation should
763 u32 bit = __builtin_ctz(e8_mask);
765 /* Do the e8 translation. */
766 u8 *p8 = (u8 *)p128 + bit;
767 undo_call_insn_translation((s32 *)(p8 + 1),
768 p8 - uncompressed_data);
770 /* Don't start an e8 translation in the
772 valid_mask &= ~((u32)0x1F << bit);
774 /* Moving on to the next vector. Shift and set
775 * valid_mask accordingly. */
777 valid_mask |= 0xFFFF0000;
779 } while (++p128 < end128);
783 while (!(valid_mask & 1)) {
788 u8 *p8 = uncompressed_data;
789 #endif /* !__SSE2__ */
791 if (uncompressed_size > 10) {
792 /* Finish any bytes that weren't processed by the vectorized
794 u8 *p8_end = uncompressed_data + uncompressed_size - 10;
797 undo_call_insn_translation((s32 *)(p8 + 1),
798 p8 - uncompressed_data);
803 } while (p8 < p8_end);
808 * Decompresses an LZX-compressed block of data from which the header has already
811 * @block_type: The type of the block (LZX_BLOCKTYPE_VERBATIM or
812 * LZX_BLOCKTYPE_ALIGNED)
813 * @block_size: The size of the block, in bytes.
814 * @num_main_syms: Number of symbols in the main alphabet.
815 * @window: Pointer to the decompression window.
816 * @window_pos: The current position in the window. Will be 0 for the first
818 * @tables: The Huffman decoding tables for the block (main, length, and
819 * aligned offset, the latter only for LZX_BLOCKTYPE_ALIGNED)
820 * @queue: The least-recently-used queue for match offsets.
821 * @istream: The input bitstream for the compressed literals.
824 lzx_decompress_block(int block_type, unsigned block_size,
825 unsigned num_main_syms,
828 const struct lzx_tables *tables,
829 struct lzx_lru_queue *queue,
830 struct input_bitstream *istream)
832 unsigned main_element;
836 end = window_pos + block_size;
837 while (window_pos < end) {
838 main_element = read_huffsym_using_maintree(istream, tables,
840 if (main_element < LZX_NUM_CHARS) {
841 /* literal: 0 to LZX_NUM_CHARS - 1 */
842 window[window_pos++] = main_element;
844 /* match: LZX_NUM_CHARS to num_main_syms - 1 */
845 match_len = lzx_decode_match(main_element,
853 if (unlikely(match_len < 0))
855 window_pos += match_len;
862 lzx_decompress(const void *compressed_data, size_t compressed_size,
863 void *uncompressed_data, size_t uncompressed_size,
866 struct lzx_decompressor *ctx = _ctx;
867 struct input_bitstream istream;
868 struct lzx_lru_queue queue;
873 bool e8_preprocessing_done;
875 LZX_DEBUG("compressed_data = %p, compressed_size = %zu, "
876 "uncompressed_data = %p, uncompressed_size = %zu, "
877 "max_window_size=%u).",
878 compressed_data, compressed_size,
879 uncompressed_data, uncompressed_size,
880 ctx->max_window_size);
882 if (uncompressed_size > ctx->max_window_size) {
883 LZX_DEBUG("Uncompressed size of %zu exceeds "
884 "window size of %u!",
885 uncompressed_size, ctx->max_window_size);
889 memset(ctx->tables.maintree_lens, 0, sizeof(ctx->tables.maintree_lens));
890 memset(ctx->tables.lentree_lens, 0, sizeof(ctx->tables.lentree_lens));
891 lzx_lru_queue_init(&queue);
892 init_input_bitstream(&istream, compressed_data, compressed_size);
894 e8_preprocessing_done = false; /* Set to true if there may be 0xe8 bytes
895 in the uncompressed data. */
897 /* The compressed data will consist of one or more blocks. The
898 * following loop decompresses one block, and it runs until there all
899 * the compressed data has been decompressed, so there are no more
903 window_pos < uncompressed_size;
904 window_pos += block_size)
906 LZX_DEBUG("Reading block header.");
907 ret = lzx_read_block_header(&istream, ctx->num_main_syms,
908 ctx->max_window_size, &block_size,
909 &block_type, &ctx->tables, &queue);
913 LZX_DEBUG("block_size = %u, window_pos = %u",
914 block_size, window_pos);
916 if (block_size > uncompressed_size - window_pos) {
917 LZX_DEBUG("Expected a block size of at "
918 "most %zu bytes (found %u bytes)",
919 uncompressed_size - window_pos, block_size);
923 switch (block_type) {
924 case LZX_BLOCKTYPE_VERBATIM:
925 case LZX_BLOCKTYPE_ALIGNED:
926 if (block_type == LZX_BLOCKTYPE_VERBATIM)
927 LZX_DEBUG("LZX_BLOCKTYPE_VERBATIM");
929 LZX_DEBUG("LZX_BLOCKTYPE_ALIGNED");
930 ret = lzx_decompress_block(block_type,
941 if (ctx->tables.maintree_lens[0xe8] != 0)
942 e8_preprocessing_done = true;
944 case LZX_BLOCKTYPE_UNCOMPRESSED:
945 LZX_DEBUG("LZX_BLOCKTYPE_UNCOMPRESSED");
946 if (istream.data_bytes_left < block_size) {
947 LZX_DEBUG("Unexpected end of input when "
948 "reading %u bytes from LZX bitstream "
949 "(only have %u bytes left)",
950 block_size, istream.data_bytes_left);
953 memcpy(&((u8*)uncompressed_data)[window_pos], istream.data,
955 istream.data += block_size;
956 istream.data_bytes_left -= block_size;
957 /* Re-align bitstream if an odd number of bytes were
959 if (istream.data_bytes_left && (block_size & 1)) {
960 istream.data_bytes_left--;
963 e8_preprocessing_done = true;
967 if (e8_preprocessing_done)
968 undo_call_insn_preprocessing(uncompressed_data, uncompressed_size);
973 lzx_free_decompressor(void *_ctx)
975 struct lzx_decompressor *ctx = _ctx;
981 lzx_create_decompressor(size_t max_window_size,
982 const struct wimlib_decompressor_params_header *params,
985 struct lzx_decompressor *ctx;
987 if (!lzx_window_size_valid(max_window_size))
988 return WIMLIB_ERR_INVALID_PARAM;
990 ctx = MALLOC(sizeof(struct lzx_decompressor));
992 return WIMLIB_ERR_NOMEM;
994 ctx->max_window_size = max_window_size;
995 ctx->num_main_syms = lzx_get_num_main_syms(max_window_size);
1001 const struct decompressor_ops lzx_decompressor_ops = {
1002 .create_decompressor = lzx_create_decompressor,
1003 .decompress = lzx_decompress,
1004 .free_decompressor = lzx_free_decompressor,