+++ /dev/null
-/*
- * lzx-comp.c
- *
- * LZX compression routines, originally based on code written by Matthew T.
- * Russotto (liblzxcomp), but heavily modified.
- */
-
-/*
- * Copyright (C) 2002 Matthew T. Russotto
- * Copyright (C) 2012 Eric Biggers
- *
- * This file is part of wimlib, a library for working with WIM files.
- *
- * wimlib is free software; you can redistribute it and/or modify it under the
- * terms of the GNU General Public License as published by the Free
- * Software Foundation; either version 3 of the License, or (at your option)
- * any later version.
- *
- * wimlib is distributed in the hope that it will be useful, but WITHOUT ANY
- * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
- * A PARTICULAR PURPOSE. See the GNU General Public License for more
- * details.
- *
- * You should have received a copy of the GNU General Public License
- * along with wimlib; if not, see http://www.gnu.org/licenses/.
- */
-
-
-/*
- * This file provides lzx_compress(), a function to compress an in-memory buffer
- * of data using LZX compression, as used in the WIM file format.
- *
- * Please see the comments in lzx-decomp.c for more information about this
- * compression format.
- *
- * One thing to keep in mind is that there is no sliding window, since the
- * window is always the entirety of a WIM chunk, which is at most WIM_CHUNK_SIZE
- * ( = 32768) bytes.
- *
- * The basic compression algorithm used here should be familiar if you are
- * familiar with Huffman trees and with other LZ77 and Huffman-based formats
- * such as DEFLATE. Otherwise it can be quite tricky to understand. Basically
- * it is the following:
- *
- * - Preprocess the input data (LZX-specific)
- * - Go through the input data and determine matches. This part is based on
- * code from zlib, and a hash table of 3-character strings is used to
- * accelerate the process of finding matches.
- * - Build the Huffman trees based on the frequencies of symbols determined
- * while recording matches.
- * - Output the block header, including the Huffman trees; then output the
- * compressed stream of matches and literal characters.
- *
- * It is possible for a WIM chunk to include multiple LZX blocks, since for some
- * input data this will produce a better compression ratio (especially since
- * each block can include new Huffman codes). However, producing multiple LZX
- * blocks from one input chunk is not yet implemented.
- */
-
-#include "lzx.h"
-#include "comp.h"
-#include <math.h>
-#include <stdlib.h>
-#include <string.h>
-
-
-/* Structure to contain the Huffman codes for the main, length, and aligned
- * offset trees. */
-struct lzx_codes {
- u16 main_codewords[LZX_MAINTREE_NUM_SYMBOLS];
- u8 main_lens[LZX_MAINTREE_NUM_SYMBOLS];
-
- u16 len_codewords[LZX_LENTREE_NUM_SYMBOLS];
- u8 len_lens[LZX_LENTREE_NUM_SYMBOLS];
-
- u16 aligned_codewords[LZX_ALIGNEDTREE_NUM_SYMBOLS];
- u8 aligned_lens[LZX_ALIGNEDTREE_NUM_SYMBOLS];
-};
-
-struct lzx_freq_tables {
- u32 main_freq_table[LZX_MAINTREE_NUM_SYMBOLS];
- u32 len_freq_table[LZX_LENTREE_NUM_SYMBOLS];
- u32 aligned_freq_table[LZX_ALIGNEDTREE_NUM_SYMBOLS];
-};
-
-/* Returns the LZX position slot that corresponds to a given formatted offset.
- *
- * Logically, this returns the smallest i such that
- * formatted_offset >= lzx_position_base[i].
- *
- * The actual implementation below takes advantage of the regularity of the
- * numbers in the lzx_position_base array to calculate the slot directly from
- * the formatted offset without actually looking at the array.
- */
-static inline unsigned lzx_get_position_slot(unsigned formatted_offset)
-{
-#if 0
- /*
- * Slots 36-49 (formatted_offset >= 262144) can be found by
- * (formatted_offset/131072) + 34 == (formatted_offset >> 17) + 34;
- * however, this check for formatted_offset >= 262144 is commented out
- * because WIM chunks cannot be that large.
- */
- if (formatted_offset >= 262144) {
- return (formatted_offset >> 17) + 34;
- } else
-#endif
- {
- /* Note: this part here only works if:
- *
- * 2 <= formatted_offset < 655360
- *
- * It is < 655360 because the frequency of the position bases
- * increases starting at the 655360 entry, and it is >= 2
- * because the below calculation fails if the most significant
- * bit is lower than the 2's place. */
- wimlib_assert(formatted_offset >= 2 && formatted_offset < 655360);
- unsigned mssb_idx = bsr32(formatted_offset);
- return (mssb_idx << 1) |
- ((formatted_offset >> (mssb_idx - 1)) & 1);
- }
-}
-
-static u32 lzx_record_literal(u8 literal, void *__main_freq_tab)
-{
- u32 *main_freq_tab = __main_freq_tab;
- main_freq_tab[literal]++;
- return literal;
-}
-
-/* Equivalent to lzx_extra_bits[position_slot] except position_slot must be
- * between 2 and 37 */
-static inline unsigned lzx_get_num_extra_bits(unsigned position_slot)
-{
-#if 0
- return lzx_extra_bits[position_slot];
-#endif
- wimlib_assert(position_slot >= 2 && position_slot <= 37);
- return (position_slot >> 1) - 1;
-}
-
-/* Constructs a match from an offset and a length, and updates the LRU queue and
- * the frequency of symbols in the main, length, and aligned offset alphabets.
- * The return value is a 32-bit number that provides the match in an
- * intermediate representation documented below. */
-static u32 lzx_record_match(unsigned match_offset, unsigned match_len,
- void *__freq_tabs, void *__queue)
-{
- struct lzx_freq_tables *freq_tabs = __freq_tabs;
- struct lru_queue *queue = __queue;
- unsigned formatted_offset;
- unsigned position_slot;
- unsigned position_footer = 0;
- u32 match;
- u32 len_header;
- u32 len_pos_header;
- unsigned len_footer;
- unsigned adjusted_match_len;
-
- wimlib_assert(match_len >= LZX_MIN_MATCH && match_len <= LZX_MAX_MATCH);
- wimlib_assert(match_offset != 0);
-
- /* If possible, encode this offset as a repeated offset. */
- if (match_offset == queue->R0) {
- formatted_offset = 0;
- position_slot = 0;
- } else if (match_offset == queue->R1) {
- swap(queue->R0, queue->R1);
- formatted_offset = 1;
- position_slot = 1;
- } else if (match_offset == queue->R2) {
- swap(queue->R0, queue->R2);
- formatted_offset = 2;
- position_slot = 2;
- } else {
- /* Not a repeated offset. */
-
- /* offsets of 0, 1, and 2 are reserved for the repeated offset
- * codes, so non-repeated offsets must be encoded as 3+. The
- * minimum offset is 1, so encode the offsets offset by 2. */
- formatted_offset = match_offset + LZX_MIN_MATCH;
-
- queue->R2 = queue->R1;
- queue->R1 = queue->R0;
- queue->R0 = match_offset;
-
- /* The (now-formatted) offset will actually be encoded as a
- * small position slot number that maps to a certain hard-coded
- * offset (position base), followed by a number of extra bits---
- * the position footer--- that are added to the position base to
- * get the original formatted offset. */
-
- position_slot = lzx_get_position_slot(formatted_offset);
- position_footer = formatted_offset &
- ((1 << lzx_get_num_extra_bits(position_slot)) - 1);
- }
-
- adjusted_match_len = match_len - LZX_MIN_MATCH;
-
- /* Pack the position slot, position footer, and match length into an
- * intermediate representation.
- *
- * bits description
- * ---- -----------------------------------------------------------
- *
- * 31 1 if a match, 0 if a literal.
- *
- * 30-25 position slot. This can be at most 50, so it will fit in 6
- * bits.
- *
- * 8-24 position footer. This is the offset of the real formatted
- * offset from the position base. This can be at most 17 bits
- * (since lzx_extra_bits[LZX_NUM_POSITION_SLOTS - 1] is 17).
- *
- * 0-7 length of match, offset by 2. This can be at most
- * (LZX_MAX_MATCH - 2) == 255, so it will fit in 8 bits. */
- match = 0x80000000 |
- (position_slot << 25) |
- (position_footer << 8) |
- (adjusted_match_len);
-
- /* The match length must be at least 2, so let the adjusted match length
- * be the match length minus 2.
- *
- * If it is less than 7, the adjusted match length is encoded as a 3-bit
- * number offset by 2. Otherwise, the 3-bit length header is all 1's
- * and the actual adjusted length is given as a symbol encoded with the
- * length tree, offset by 7.
- */
- if (adjusted_match_len < LZX_NUM_PRIMARY_LENS) {
- len_header = adjusted_match_len;
- } else {
- len_header = LZX_NUM_PRIMARY_LENS;
- len_footer = adjusted_match_len - LZX_NUM_PRIMARY_LENS;
- freq_tabs->len_freq_table[len_footer]++;
- }
- len_pos_header = (position_slot << 3) | len_header;
-
- wimlib_assert(len_pos_header < LZX_MAINTREE_NUM_SYMBOLS - LZX_NUM_CHARS);
-
- freq_tabs->main_freq_table[len_pos_header + LZX_NUM_CHARS]++;
-
- /* Equivalent to:
- * if (lzx_extra_bits[position_slot] >= 3) */
- if (position_slot >= 8)
- freq_tabs->aligned_freq_table[position_footer & 7]++;
-
- return match;
-}
-
-/*
- * Writes a compressed literal match to the output.
- *
- * @out: The output bitstream.
- * @block_type: The type of the block (LZX_BLOCKTYPE_ALIGNED or LZX_BLOCKTYPE_VERBATIM)
- * @match: The match, encoded as a 32-bit number.
- * @codes: Pointer to a structure that contains the codewords for the
- * main, length, and aligned offset Huffman codes.
- */
-static int lzx_write_match(struct output_bitstream *out, int block_type,
- u32 match, const struct lzx_codes *codes)
-{
- /* low 8 bits are the match length minus 2 */
- unsigned match_len_minus_2 = match & 0xff;
- /* Next 17 bits are the position footer */
- unsigned position_footer = (match >> 8) & 0x1ffff; /* 17 bits */
- /* Next 6 bits are the position slot. */
- unsigned position_slot = (match >> 25) & 0x3f; /* 6 bits */
- unsigned len_header;
- unsigned len_footer;
- unsigned len_pos_header;
- unsigned main_symbol;
- unsigned num_extra_bits;
- unsigned verbatim_bits;
- unsigned aligned_bits;
- int ret;
-
- /* If the match length is less than MIN_MATCH (= 2) +
- * NUM_PRIMARY_LENS (= 7), the length header contains
- * the match length minus MIN_MATCH, and there is no
- * length footer.
- *
- * Otherwise, the length header contains
- * NUM_PRIMARY_LENS, and the length footer contains
- * the match length minus NUM_PRIMARY_LENS minus
- * MIN_MATCH. */
- if (match_len_minus_2 < LZX_NUM_PRIMARY_LENS) {
- len_header = match_len_minus_2;
- /* No length footer-- mark it with a special
- * value. */
- len_footer = (unsigned)(-1);
- } else {
- len_header = LZX_NUM_PRIMARY_LENS;
- len_footer = match_len_minus_2 - LZX_NUM_PRIMARY_LENS;
- }
-
- /* Combine the position slot with the length header into
- * a single symbol that will be encoded with the main
- * tree. */
- len_pos_header = (position_slot << 3) | len_header;
-
- /* The actual main symbol is offset by LZX_NUM_CHARS because
- * values under LZX_NUM_CHARS are used to indicate a literal
- * byte rather than a match. */
- main_symbol = len_pos_header + LZX_NUM_CHARS;
-
- /* Output main symbol. */
- ret = bitstream_put_bits(out, codes->main_codewords[main_symbol],
- codes->main_lens[main_symbol]);
- if (ret != 0)
- return ret;
-
- /* If there is a length footer, output it using the
- * length Huffman code. */
- if (len_footer != (unsigned)(-1)) {
- ret = bitstream_put_bits(out, codes->len_codewords[len_footer],
- codes->len_lens[len_footer]);
- if (ret != 0)
- return ret;
- }
-
- wimlib_assert(position_slot < LZX_NUM_POSITION_SLOTS);
-
- num_extra_bits = lzx_extra_bits[position_slot];
-
- /* For aligned offset blocks with at least 3 extra bits, output the
- * verbatim bits literally, then the aligned bits encoded using the
- * aligned offset tree. Otherwise, only the verbatim bits need to be
- * output. */
- if ((block_type == LZX_BLOCKTYPE_ALIGNED) && (num_extra_bits >= 3)) {
-
- verbatim_bits = position_footer >> 3;
- ret = bitstream_put_bits(out, verbatim_bits,
- num_extra_bits - 3);
- if (ret != 0)
- return ret;
-
- aligned_bits = (position_footer & 7);
- ret = bitstream_put_bits(out,
- codes->aligned_codewords[aligned_bits],
- codes->aligned_lens[aligned_bits]);
- if (ret != 0)
- return ret;
- } else {
- /* verbatim bits is the same as the position
- * footer, in this case. */
- ret = bitstream_put_bits(out, position_footer, num_extra_bits);
- if (ret != 0)
- return ret;
- }
- return 0;
-}
-
-/*
- * Writes all compressed literals in a block, both matches and literal bytes, to
- * the output bitstream.
- *
- * @out: The output bitstream.
- * @block_type: The type of the block (LZX_BLOCKTYPE_ALIGNED or LZX_BLOCKTYPE_VERBATIM)
- * @match_tab[]: The array of matches that will be output. It has length
- * of @num_compressed_literals.
- * @num_compressed_literals: Number of compressed literals to be output.
- * @codes: Pointer to a structure that contains the codewords for the
- * main, length, and aligned offset Huffman codes.
- */
-static int lzx_write_compressed_literals(struct output_bitstream *ostream,
- int block_type,
- const u32 match_tab[],
- unsigned num_compressed_literals,
- const struct lzx_codes *codes)
-{
- unsigned i;
- u32 match;
- int ret;
-
- for (i = 0; i < num_compressed_literals; i++) {
- match = match_tab[i];
-
- /* High bit of the match indicates whether the match is an
- * actual match (1) or a literal uncompressed byte (0) */
- if (match & 0x80000000) {
- /* match */
- ret = lzx_write_match(ostream, block_type, match,
- codes);
- if (ret != 0)
- return ret;
- } else {
- /* literal byte */
- wimlib_assert(match < LZX_NUM_CHARS);
- ret = bitstream_put_bits(ostream,
- codes->main_codewords[match],
- codes->main_lens[match]);
- if (ret != 0)
- return ret;
- }
- }
- return 0;
-}
-
-/*
- * Writes a compressed Huffman tree to the output, preceded by the pretree for
- * it.
- *
- * The Huffman tree is represented in the output as a series of path lengths
- * from which the canonical Huffman code can be reconstructed. The path lengths
- * themselves are compressed using a separate Huffman code, the pretree, which
- * consists of LZX_PRETREE_NUM_SYMBOLS (= 20) symbols that cover all possible code
- * lengths, plus extra codes for repeated lengths. The path lengths of the
- * pretree precede the path lengths of the larger code and are uncompressed,
- * consisting of 20 entries of 4 bits each.
- *
- * @out: The bitstream for the compressed output.
- * @lens: The code lengths for the Huffman tree, indexed by symbol.
- * @num_symbols: The number of symbols in the code.
- */
-static int lzx_write_compressed_tree(struct output_bitstream *out,
- const u8 lens[], unsigned num_symbols)
-{
- /* Frequencies of the length symbols, including the RLE symbols (NOT the
- * actual lengths themselves). */
- unsigned pretree_freqs[LZX_PRETREE_NUM_SYMBOLS];
- u8 pretree_lens[LZX_PRETREE_NUM_SYMBOLS];
- u16 pretree_codewords[LZX_PRETREE_NUM_SYMBOLS];
- u8 output_syms[num_symbols * 2];
- unsigned output_syms_idx;
- unsigned cur_run_len;
- unsigned i;
- unsigned len_in_run;
- unsigned additional_bits;
- char delta;
- u8 pretree_sym;
-
- ZERO_ARRAY(pretree_freqs);
-
- /* Since the code word lengths use a form of RLE encoding, the goal here
- * is to find each run of identical lengths when going through them in
- * symbol order (including runs of length 1). For each run, as many
- * lengths are encoded using RLE as possible, and the rest are output
- * literally.
- *
- * output_syms[] will be filled in with the length symbols that will be
- * output, including RLE codes, not yet encoded using the pre-tree.
- *
- * cur_run_len keeps track of how many code word lengths are in the
- * current run of identical lengths.
- */
- output_syms_idx = 0;
- cur_run_len = 1;
- for (i = 1; i <= num_symbols; i++) {
-
- if (i != num_symbols && lens[i] == lens[i - 1]) {
- /* Still in a run--- keep going. */
- cur_run_len++;
- continue;
- }
-
- /* Run ended! Check if it is a run of zeroes or a run of
- * nonzeroes. */
-
- /* The symbol that was repeated in the run--- not to be confused
- * with the length *of* the run (cur_run_len) */
- len_in_run = lens[i - 1];
-
- if (len_in_run == 0) {
- /* A run of 0's. Encode it in as few length
- * codes as we can. */
-
- /* The magic length 18 indicates a run of 20 + n zeroes,
- * where n is an uncompressed literal 5-bit integer that
- * follows the magic length. */
- while (cur_run_len >= 20) {
-
- additional_bits = min(cur_run_len - 20, 0x1f);
- pretree_freqs[18]++;
- output_syms[output_syms_idx++] = 18;
- output_syms[output_syms_idx++] = additional_bits;
- cur_run_len -= 20 + additional_bits;
- }
-
- /* The magic length 17 indicates a run of 4 + n zeroes,
- * where n is an uncompressed literal 4-bit integer that
- * follows the magic length. */
- while (cur_run_len >= 4) {
- additional_bits = min(cur_run_len - 4, 0xf);
- pretree_freqs[17]++;
- output_syms[output_syms_idx++] = 17;
- output_syms[output_syms_idx++] = additional_bits;
- cur_run_len -= 4 + additional_bits;
- }
-
- } else {
-
- /* A run of nonzero lengths. */
-
- /* The magic length 19 indicates a run of 4 + n
- * nonzeroes, where n is a literal bit that follows the
- * magic length, and where the value of the lengths in
- * the run is given by an extra length symbol, encoded
- * with the pretree, that follows the literal bit.
- *
- * The extra length symbol is encoded as a difference
- * from the length of the codeword for the first symbol
- * in the run in the previous tree.
- * */
- while (cur_run_len >= 4) {
- additional_bits = (cur_run_len > 4);
- delta = -(char)len_in_run;
- if (delta < 0)
- delta += 17;
- pretree_freqs[19]++;
- pretree_freqs[(unsigned char)delta]++;
- output_syms[output_syms_idx++] = 19;
- output_syms[output_syms_idx++] = additional_bits;
- output_syms[output_syms_idx++] = delta;
- cur_run_len -= 4 + additional_bits;
- }
- }
-
- /* Any remaining lengths in the run are outputted without RLE,
- * as a difference from the length of that codeword in the
- * previous tree. */
- while (cur_run_len--) {
- delta = -(char)len_in_run;
- if (delta < 0)
- delta += 17;
-
- pretree_freqs[(unsigned char)delta]++;
- output_syms[output_syms_idx++] = delta;
- }
-
- cur_run_len = 1;
- }
-
- wimlib_assert(output_syms_idx < ARRAY_LEN(output_syms));
-
- /* Build the pretree from the frequencies of the length symbols. */
-
- make_canonical_huffman_code(LZX_PRETREE_NUM_SYMBOLS,
- LZX_MAX_CODEWORD_LEN,
- pretree_freqs, pretree_lens,
- pretree_codewords);
-
- /* Write the lengths of the pretree codes to the output. */
- for (i = 0; i < LZX_PRETREE_NUM_SYMBOLS; i++)
- bitstream_put_bits(out, pretree_lens[i],
- LZX_PRETREE_ELEMENT_SIZE);
-
- /* Write the length symbols, encoded with the pretree, to the output. */
-
- i = 0;
- while (i < output_syms_idx) {
- pretree_sym = output_syms[i++];
-
- bitstream_put_bits(out, pretree_codewords[pretree_sym],
- pretree_lens[pretree_sym]);
- switch (pretree_sym) {
- case 17:
- bitstream_put_bits(out, output_syms[i++], 4);
- break;
- case 18:
- bitstream_put_bits(out, output_syms[i++], 5);
- break;
- case 19:
- bitstream_put_bits(out, output_syms[i++], 1);
- bitstream_put_bits(out,
- pretree_codewords[output_syms[i]],
- pretree_lens[output_syms[i]]);
- i++;
- break;
- default:
- break;
- }
- }
- return 0;
-}
-
-/* Builds the canonical Huffman code for the main tree, the length tree, and the
- * aligned offset tree. */
-static void lzx_make_huffman_codes(const struct lzx_freq_tables *freq_tabs,
- struct lzx_codes *codes)
-{
- make_canonical_huffman_code(LZX_MAINTREE_NUM_SYMBOLS,
- LZX_MAX_CODEWORD_LEN,
- freq_tabs->main_freq_table,
- codes->main_lens,
- codes->main_codewords);
-
- make_canonical_huffman_code(LZX_LENTREE_NUM_SYMBOLS,
- LZX_MAX_CODEWORD_LEN,
- freq_tabs->len_freq_table,
- codes->len_lens,
- codes->len_codewords);
-
- make_canonical_huffman_code(LZX_ALIGNEDTREE_NUM_SYMBOLS, 8,
- freq_tabs->aligned_freq_table,
- codes->aligned_lens,
- codes->aligned_codewords);
-}
-
-/* Do the 'E8' preprocessing, where the targets of x86 CALL instructions were
- * changed from relative offsets to absolute offsets. This type of
- * preprocessing can be used on any binary data even if it is not actually
- * machine code. It seems to always be used in WIM files, even though there is
- * no bit to indicate that it actually is used, unlike in the LZX compressed
- * format as used in other file formats such as the cabinet format, where a bit
- * is reserved for that purpose. */
-static void do_call_insn_preprocessing(u8 uncompressed_data[],
- unsigned uncompressed_data_len)
-{
- int i = 0;
- int file_size = LZX_MAGIC_FILESIZE;
- int32_t rel_offset;
- int32_t abs_offset;
-
- /* Not enabled in the last 6 bytes, which means the 5-byte call
- * instruction cannot start in the last *10* bytes. */
- while (i < uncompressed_data_len - 10) {
- if (uncompressed_data[i] != 0xe8) {
- i++;
- continue;
- }
- rel_offset = le32_to_cpu(*(int32_t*)(uncompressed_data + i + 1));
-
- if (rel_offset >= -i && rel_offset < file_size) {
- if (rel_offset < file_size - i) {
- /* "good translation" */
- abs_offset = rel_offset + i;
- } else {
- /* "compensating translation" */
- abs_offset = rel_offset - file_size;
- }
- *(int32_t*)(uncompressed_data + i + 1) = cpu_to_le32(abs_offset);
- }
- i += 5;
- }
-}
-
-
-static const struct lz_params lzx_lz_params = {
-
- /* LZX_MIN_MATCH == 2, but 2-character matches are rarely useful; the
- * minimum match for compression is set to 3 instead. */
- .min_match = 3,
-
- .max_match = LZX_MAX_MATCH,
- .good_match = LZX_MAX_MATCH,
- .nice_match = LZX_MAX_MATCH,
- .max_chain_len = LZX_MAX_MATCH,
- .max_lazy_match = LZX_MAX_MATCH,
- .too_far = 4096,
-};
-
-/*
- * Performs LZX compression on a block of data.
- *
- * @__uncompressed_data: Pointer to the data to be compressed.
- * @uncompressed_len: Length, in bytes, of the data to be compressed.
- * @compressed_data: Pointer to a location at least (@uncompressed_len - 1)
- * bytes long into which the compressed data may be
- * written.
- * @compressed_len_ret: A pointer to an unsigned int into which the length of
- * the compressed data may be returned.
- *
- * Returns zero if compression was successfully performed. In that case
- * @compressed_data and @compressed_len_ret will contain the compressed data and
- * its length. A return value of nonzero means that compressing the data did
- * not reduce its size, and @compressed_data will not contain the full
- * compressed data.
- */
-int lzx_compress(const void *__uncompressed_data, unsigned uncompressed_len,
- void *compressed_data, unsigned *compressed_len_ret)
-{
- struct output_bitstream ostream;
- u8 uncompressed_data[uncompressed_len + LZX_MAX_MATCH];
- struct lzx_freq_tables freq_tabs;
- struct lzx_codes codes;
- u32 match_tab[uncompressed_len];
- struct lru_queue queue;
- unsigned num_matches;
- unsigned compressed_len;
- unsigned i;
- int ret;
- int block_type = LZX_BLOCKTYPE_ALIGNED;
-
- if (uncompressed_len < 100)
- return 1;
-
- memset(&freq_tabs, 0, sizeof(freq_tabs));
- queue.R0 = 1;
- queue.R1 = 1;
- queue.R2 = 1;
-
- /* The input data must be preprocessed. To avoid changing the original
- * input, copy it to a temporary buffer. */
- memcpy(uncompressed_data, __uncompressed_data, uncompressed_len);
-
- /* Before doing any actual compression, do the call instruction (0xe8
- * byte) translation on the uncompressed data. */
- do_call_insn_preprocessing(uncompressed_data, uncompressed_len);
-
- /* Determine the sequence of matches and literals that will be output,
- * and in the process, keep counts of the number of times each symbol
- * will be output, so that the Huffman trees can be made. */
-
- num_matches = lz_analyze_block(uncompressed_data, uncompressed_len,
- match_tab, lzx_record_match,
- lzx_record_literal, &freq_tabs,
- &queue, freq_tabs.main_freq_table,
- &lzx_lz_params);
-
- lzx_make_huffman_codes(&freq_tabs, &codes);
-
- /* Initialize the output bitstream. */
- init_output_bitstream(&ostream, compressed_data, uncompressed_len - 1);
-
- /* The first three bits tell us what kind of block it is, and are one
- * of the LZX_BLOCKTYPE_* values. */
- bitstream_put_bits(&ostream, block_type, 3);
-
- /* The next bit indicates whether the block size is the default (32768),
- * indicated by a 1 bit, or whether the block size is given by the next
- * 16 bits, indicated by a 0 bit. */
- if (uncompressed_len == 32768) {
- bitstream_put_bits(&ostream, 1, 1);
- } else {
- bitstream_put_bits(&ostream, 0, 1);
- bitstream_put_bits(&ostream, uncompressed_len, 16);
- }
-
- /* Write out the aligned offset tree. Note that M$ lies and says that
- * the aligned offset tree comes after the length tree, but that is
- * wrong; it actually is before the main tree. */
- if (block_type == LZX_BLOCKTYPE_ALIGNED)
- for (i = 0; i < LZX_ALIGNEDTREE_NUM_SYMBOLS; i++)
- bitstream_put_bits(&ostream, codes.aligned_lens[i],
- LZX_ALIGNEDTREE_ELEMENT_SIZE);
-
- /* Write the pre-tree and lengths for the first LZX_NUM_CHARS symbols in the
- * main tree. */
- ret = lzx_write_compressed_tree(&ostream, codes.main_lens,
- LZX_NUM_CHARS);
- if (ret != 0)
- return ret;
-
- /* Write the pre-tree and symbols for the rest of the main tree. */
- ret = lzx_write_compressed_tree(&ostream, codes.main_lens +
- LZX_NUM_CHARS,
- LZX_MAINTREE_NUM_SYMBOLS -
- LZX_NUM_CHARS);
- if (ret != 0)
- return ret;
-
- /* Write the pre-tree and symbols for the length tree. */
- ret = lzx_write_compressed_tree(&ostream, codes.len_lens,
- LZX_LENTREE_NUM_SYMBOLS);
- if (ret != 0)
- return ret;
-
- /* Write the compressed literals. */
- ret = lzx_write_compressed_literals(&ostream, block_type,
- match_tab, num_matches, &codes);
- if (ret != 0)
- return ret;
-
- ret = flush_output_bitstream(&ostream);
- if (ret != 0)
- return ret;
-
- compressed_len = ostream.bit_output - (u8*)compressed_data;
-
- *compressed_len_ret = compressed_len;
-
-#ifdef ENABLE_VERIFY_COMPRESSION
- /* Verify that we really get the same thing back when decompressing. */
- u8 buf[uncompressed_len];
- ret = lzx_decompress(compressed_data, compressed_len, buf,
- uncompressed_len);
- if (ret != 0) {
- ERROR("lzx_compress(): Failed to decompress data we compressed");
- abort();
- }
-
- for (i = 0; i < uncompressed_len; i++) {
- if (buf[i] != *((u8*)__uncompressed_data + i)) {
- ERROR("lzx_compress(): Data we compressed didn't "
- "decompress to the original data (difference at "
- "byte %u of %u)", i + 1, uncompressed_len);
- abort();
- }
- }
-#endif
- return 0;
-}
projects / wimlib / blobdiff