X-Git-Url: https://wimlib.net/git/?p=wimlib;a=blobdiff_plain;f=src%2Flzx-common.c;h=b40f43d746dedccdb60a24e47bffcc219063e78f;hp=dfd6256b71b3396db6d7d7f847f826ae6482622d;hb=3872f9e0d30f6439b2a08e091fbd3df042841b6a;hpb=9bec19341aac9190cd0bd80a6937b02d923dd566 diff --git a/src/lzx-common.c b/src/lzx-common.c index dfd6256b..b40f43d7 100644 --- a/src/lzx-common.c +++ b/src/lzx-common.c @@ -1,41 +1,59 @@ /* - * lzx-common.c - Common data for LZX compression and decompression. + * lzx-common.c - Common code for LZX compression and decompression. */ /* - * Copyright (C) 2012, 2013 Eric Biggers + * Copyright (C) 2012, 2013, 2014 Eric Biggers * - * This file is part of wimlib, a library for working with WIM files. + * This file is free software; you can redistribute it and/or modify it under + * the terms of the GNU Lesser 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 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 + * This file 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 Lesser 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/. + * You should have received a copy of the GNU Lesser General Public License + * along with this file; if not, see http://www.gnu.org/licenses/. */ #ifdef HAVE_CONFIG_H # include "config.h" #endif +#include + +#include "wimlib/bitops.h" +#include "wimlib/endianness.h" #include "wimlib/lzx.h" +#include "wimlib/unaligned.h" +#include "wimlib/util.h" + +#ifdef __SSE2__ +# include +#endif -#ifdef USE_LZX_EXTRA_BITS_ARRAY -/* LZX uses what it calls 'position slots' to represent match offsets. - * What this means is that a small 'position slot' number and a small - * offset from that slot are encoded instead of one large offset for - * every match. - * - lzx_position_base is an index to the position slot bases - * - lzx_extra_bits states how many bits of offset-from-base data is needed. +/* Mapping: offset slot => first match offset that uses that offset slot. */ -const u8 lzx_extra_bits[] = { +const u32 lzx_offset_slot_base[LZX_MAX_OFFSET_SLOTS] = { + 0 , 1 , 2 , 3 , 4 , /* 0 --- 4 */ + 6 , 8 , 12 , 16 , 24 , /* 5 --- 9 */ + 32 , 48 , 64 , 96 , 128 , /* 10 --- 14 */ + 192 , 256 , 384 , 512 , 768 , /* 15 --- 19 */ + 1024 , 1536 , 2048 , 3072 , 4096 , /* 20 --- 24 */ + 6144 , 8192 , 12288 , 16384 , 24576 , /* 25 --- 29 */ + 32768 , 49152 , 65536 , 98304 , 131072 , /* 30 --- 34 */ + 196608 , 262144 , 393216 , 524288 , 655360 , /* 35 --- 39 */ + 786432 , 917504 , 1048576, 1179648, 1310720, /* 40 --- 44 */ + 1441792, 1572864, 1703936, 1835008, 1966080, /* 45 --- 49 */ + 2097152 /* 50 */ +}; + +/* Mapping: offset slot => how many extra bits must be read and added to the + * corresponding offset slot base to decode the match offset. */ +const u8 lzx_extra_offset_bits[LZX_MAX_OFFSET_SLOTS] = { 0 , 0 , 0 , 0 , 1 , 1 , 2 , 2 , 3 , 3 , 4 , 4 , 5 , 5 , 6 , @@ -48,19 +66,285 @@ const u8 lzx_extra_bits[] = { 17, 17, 17, 17, 17, 17 }; + +/* Round the specified compression block size (not LZX block size) up to the + * next valid LZX window size, and return its order (log2). Or, if the block + * size is 0 or greater than the largest valid LZX window size, return 0. */ +unsigned +lzx_get_window_order(size_t max_block_size) +{ + unsigned order; + + if (max_block_size == 0 || max_block_size > LZX_MAX_WINDOW_SIZE) + return 0; + + order = fls32(max_block_size); + + if (((u32)1 << order) != max_block_size) + order++; + + return max(order, LZX_MIN_WINDOW_ORDER); +} + +/* Given a valid LZX window order, return the number of symbols that will exist + * in the main Huffman code. */ +unsigned +lzx_get_num_main_syms(unsigned window_order) +{ + u32 window_size = (u32)1 << window_order; + + /* NOTE: the calculation *should* be as follows: + * + * u32 max_offset = window_size - LZX_MIN_MATCH_LEN; + * u32 max_adjusted_offset = max_offset + LZX_OFFSET_OFFSET; + * u32 num_offset_slots = 1 + lzx_get_offset_slot_raw(max_adjusted_offset); + * + * However since LZX_MIN_MATCH_LEN == LZX_OFFSET_OFFSET, we would get + * max_adjusted_offset == window_size, which would bump the number of + * offset slots up by 1 since every valid LZX window size is equal to a + * offset slot base value. The format doesn't do this, and instead + * disallows matches with minimum length and maximum offset. This sets + * max_adjusted_offset = window_size - 1, so instead we must calculate: + * + * num_offset_slots = 1 + lzx_get_offset_slot_raw(window_size - 1); + * + * ... which is the same as + * + * num_offset_slots = lzx_get_offset_slot_raw(window_size); + * + * ... since every valid window size is equal to an offset base value. + */ + unsigned num_offset_slots = lzx_get_offset_slot_raw(window_size); + + /* Now calculate the number of main symbols as LZX_NUM_CHARS literal + * symbols, plus 8 symbols per offset slot (since there are 8 possible + * length headers, and we need all (offset slot, length header) + * combinations). */ + return LZX_NUM_CHARS + (num_offset_slots << 3); +} + +static void +do_translate_target(void *target, s32 input_pos) +{ + s32 abs_offset, rel_offset; + + rel_offset = get_unaligned_u32_le(target); + if (rel_offset >= -input_pos && rel_offset < LZX_WIM_MAGIC_FILESIZE) { + if (rel_offset < LZX_WIM_MAGIC_FILESIZE - input_pos) { + /* "good translation" */ + abs_offset = rel_offset + input_pos; + } else { + /* "compensating translation" */ + abs_offset = rel_offset - LZX_WIM_MAGIC_FILESIZE; + } + put_unaligned_u32_le(abs_offset, target); + } +} + +static void +undo_translate_target(void *target, s32 input_pos) +{ + s32 abs_offset, rel_offset; + + abs_offset = get_unaligned_u32_le(target); + if (abs_offset >= 0) { + if (abs_offset < LZX_WIM_MAGIC_FILESIZE) { + /* "good translation" */ + rel_offset = abs_offset - input_pos; + put_unaligned_u32_le(rel_offset, target); + } + } else { + if (abs_offset >= -input_pos) { + /* "compensating translation" */ + rel_offset = abs_offset + LZX_WIM_MAGIC_FILESIZE; + put_unaligned_u32_le(rel_offset, target); + } + } +} + +/* + * Do or undo the 'E8' preprocessing used in LZX. Before compression, the + * uncompressed data is preprocessed by changing the targets of x86 CALL + * instructions from relative offsets to absolute offsets. After decompression, + * the translation is undone by changing the targets of x86 CALL instructions + * from absolute offsets to relative offsets. + * + * Note that despite its intent, E8 preprocessing can be done on any data even + * if it is not actually x86 machine code. In fact, E8 preprocessing appears to + * always be used in LZX-compressed resources in WIM files; there is no bit to + * indicate whether it is used or not, unlike in the LZX compressed format as + * used in cabinet files, where a bit is reserved for that purpose. + * + * E8 preprocessing is disabled in the last 6 bytes of the uncompressed data, + * which really means the 5-byte call instruction cannot start in the last 10 + * bytes of the uncompressed data. This is one of the errors in the LZX + * documentation. + * + * E8 preprocessing does not appear to be disabled after the 32768th chunk of a + * WIM resource, which apparently is another difference from the LZX compression + * used in cabinet files. + * + * E8 processing is supposed to take the file size as a parameter, as it is used + * in calculating the translated jump targets. But in WIM files, this file size + * is always the same (LZX_WIM_MAGIC_FILESIZE == 12000000). + */ +static void +lzx_e8_filter(u8 *data, u32 size, void (*process_target)(void *, s32)) +{ + +#if !defined(__SSE2__) && !defined(__AVX2__) + /* + * A worthwhile optimization is to push the end-of-buffer check into the + * relatively rare E8 case. This is possible if we replace the last six + * bytes of data with E8 bytes; then we are guaranteed to hit an E8 byte + * before reaching end-of-buffer. In addition, this scheme guarantees + * that no translation can begin following an E8 byte in the last 10 + * bytes because a 4-byte offset containing E8 as its high byte is a + * large negative number that is not valid for translation. That is + * exactly what we need. + */ + u8 *tail; + u8 saved_bytes[6]; + u8 *p; + + if (size <= 10) + return; + + tail = &data[size - 6]; + memcpy(saved_bytes, tail, 6); + memset(tail, 0xE8, 6); + p = data; + for (;;) { + while (*p != 0xE8) + p++; + if (p >= tail) + break; + (*process_target)(p + 1, p - data); + p += 5; + } + memcpy(tail, saved_bytes, 6); +#else + /* SSE2 or AVX-2 optimized version for x86_64 */ + + u8 *p = data; + u64 valid_mask = ~0; + + if (size <= 10) + return; +#ifdef __AVX2__ +# define ALIGNMENT_REQUIRED 32 +#else +# define ALIGNMENT_REQUIRED 16 #endif -const u32 lzx_position_base[] = { - 0 , 1 , 2 , 3 , 4 , - 6 , 8 , 12 , 16 , 24 , - 32 , 48 , 64 , 96 , 128 , - 192 , 256 , 384 , 512 , 768 , - 1024 , 1536 , 2048 , 3072 , 4096 , - 6144 , 8192 , 12288 , 16384 , 24576 , - 32768 , 49152 , 65536 , 98304 , 131072 , - 196608 , 262144 , 393216 , 524288 , 655360 , - 786432 , 917504 , 1048576, 1179648, 1310720, - 1441792, 1572864, 1703936, 1835008, 1966080, - 2097152 -}; + /* Process one byte at a time until the pointer is properly aligned. */ + while ((uintptr_t)p % ALIGNMENT_REQUIRED != 0) { + if (p >= data + size - 10) + return; + if (*p == 0xE8 && (valid_mask & 1)) { + (*process_target)(p + 1, p - data); + valid_mask &= ~0x1F; + } + p++; + valid_mask >>= 1; + valid_mask |= (u64)1 << 63; + } + + if (data + size - p >= 64) { + + /* Vectorized processing */ + + /* Note: we use a "trap" E8 byte to eliminate the need to check + * for end-of-buffer in the inner loop. This byte is carefully + * positioned so that it will never be changed by a previous + * translation before it is detected. */ + + u8 *trap = p + ((data + size - p) & ~31) - 32 + 4; + u8 saved_byte = *trap; + *trap = 0xE8; + + for (;;) { + u32 e8_mask; + u8 *orig_p = p; + #ifdef __SSE2__ + const __m128i e8_bytes = _mm_set1_epi8(0xE8); + for (;;) { + /* Read the next 32 bytes of data and test them + * for E8 bytes. */ + __m128i bytes1 = *(const __m128i *)p; + __m128i bytes2 = *(const __m128i *)(p + 16); + __m128i cmpresult1 = _mm_cmpeq_epi8(bytes1, e8_bytes); + __m128i cmpresult2 = _mm_cmpeq_epi8(bytes2, e8_bytes); + u32 mask1 = _mm_movemask_epi8(cmpresult1); + u32 mask2 = _mm_movemask_epi8(cmpresult2); + /* The masks have a bit set for each E8 byte. + * We stay in this fast inner loop as long as + * there are no E8 bytes. */ + if (mask1 | mask2) { + e8_mask = mask1 | (mask2 << 16); + break; + } + p += 32; + } + #else + /* AVX-2 */ + const __m256i e8_bytes = _mm256_set1_epi8(0xE8); + for (;;) { + __m256i bytes = *(const __m256i *)p; + __m256i cmpresult = _mm256_cmpeq_epi8(bytes, e8_bytes); + e8_mask = _mm256_movemask_epi8(cmpresult); + if (e8_mask) + break; + p += 32; + } + #endif + + /* Did we pass over data with no E8 bytes? */ + if (p != orig_p) + valid_mask = ~0; + + /* Are we nearing end-of-buffer? */ + if (p == trap - 4) + break; + + /* Process the E8 bytes. However, the AND with + * 'valid_mask' ensures we never process an E8 byte that + * was itself part of a translation target. */ + while ((e8_mask &= valid_mask)) { + unsigned bit = ffs32(e8_mask); + (*process_target)(p + bit + 1, p + bit - data); + valid_mask &= ~((u64)0x1F << bit); + } + + valid_mask >>= 32; + valid_mask |= 0xFFFFFFFF00000000; + p += 32; + } + + *trap = saved_byte; + } + + /* Approaching the end of the buffer; process one byte a time. */ + while (p < data + size - 10) { + if (*p == 0xE8 && (valid_mask & 1)) { + (*process_target)(p + 1, p - data); + valid_mask &= ~0x1F; + } + p++; + valid_mask >>= 1; + valid_mask |= (u64)1 << 63; + } +#endif /* __SSE2__ || __AVX2__ */ +} + +void +lzx_do_e8_preprocessing(u8 *data, u32 size) +{ + lzx_e8_filter(data, size, do_translate_target); +} +void +lzx_undo_e8_preprocessing(u8 *data, u32 size) +{ + lzx_e8_filter(data, size, undo_translate_target); +}