From: Eric Biggers Date: Sun, 1 Jun 2014 20:42:02 +0000 (-0500) Subject: Share most e8 processing code between LZX compressor and decompressor X-Git-Tag: v1.7.0~66 X-Git-Url: https://wimlib.net/git/?a=commitdiff_plain;h=a20052d2eaf44eb0466972826f8f9e0c3bcb92d2;p=wimlib Share most e8 processing code between LZX compressor and decompressor --- diff --git a/include/wimlib/lzx.h b/include/wimlib/lzx.h index 1f4c1e3f..7104dc14 100644 --- a/include/wimlib/lzx.h +++ b/include/wimlib/lzx.h @@ -157,4 +157,10 @@ lzx_lru_queue_init(struct lzx_lru_queue *queue) queue->R[i] = 1; } +extern void +lzx_do_e8_preprocessing(u8 *data, s32 size); + +extern void +lzx_undo_e8_preprocessing(u8 *data, s32 size); + #endif /* _WIMLIB_LZX_H */ diff --git a/src/lzx-common.c b/src/lzx-common.c index 2fd54c18..24bf9974 100644 --- a/src/lzx-common.c +++ b/src/lzx-common.c @@ -25,9 +25,14 @@ # include "config.h" #endif +#include "wimlib/endianness.h" #include "wimlib/lzx.h" #include "wimlib/util.h" +#ifdef __SSE2__ +# include +#endif + /* 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 @@ -112,3 +117,184 @@ lzx_get_num_main_syms(u32 window_size) * combinations). */ return LZX_NUM_CHARS + (num_position_slots << 3); } + +static void +do_translate_target(s32 *target, s32 input_pos) +{ + s32 abs_offset, rel_offset; + + /* XXX: This assumes unaligned memory accesses are okay. */ + rel_offset = le32_to_cpu(*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; + } + *target = cpu_to_le32(abs_offset); + } +} + +static void +undo_translate_target(s32 *target, s32 input_pos) +{ + s32 abs_offset, rel_offset; + + /* XXX: This assumes unaligned memory accesses are okay. */ + abs_offset = le32_to_cpu(*target); + if (abs_offset >= 0) { + if (abs_offset < LZX_WIM_MAGIC_FILESIZE) { + /* "good translation" */ + rel_offset = abs_offset - input_pos; + + *target = cpu_to_le32(rel_offset); + } + } else { + if (abs_offset >= -input_pos) { + /* "compensating translation" */ + rel_offset = abs_offset + LZX_WIM_MAGIC_FILESIZE; + + *target = cpu_to_le32(rel_offset); + } + } +} + +/* + * 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 +#ifndef __SSE2__ +inline /* Although inlining the 'process_target' function still speeds up the + SSE2 case, it bloats the binary more. */ +#endif +void +lzx_e8_filter(u8 *data, s32 size, void (*process_target)(s32 *, s32)) +{ +#ifdef __SSE2__ + /* SSE2 vectorized implementation for x86_64. This speeds up LZX + * decompression by about 5-8% overall. (Usually --- the performance + * actually regresses slightly in the degenerate case that the data + * consists entirely of 0xe8 bytes. Also, this optimization affects + * compression as well, but the percentage improvement is less because + * LZX compression is much slower than LZX decompression. ) */ + __m128i *p128 = (__m128i *)data; + u32 valid_mask = 0xFFFFFFFF; + + if (size >= 32 && (uintptr_t)data % 16 == 0) { + __m128i * const end128 = p128 + size / 16 - 1; + + /* Create a vector of all 0xe8 bytes */ + const __m128i e8_bytes = _mm_set1_epi8(0xe8); + + /* Iterate through the 16-byte vectors in the input. */ + do { + /* Compare the current 16-byte vector with the vector of + * all 0xe8 bytes. This produces 0xff where the byte is + * 0xe8 and 0x00 where it is not. */ + __m128i cmpresult = _mm_cmpeq_epi8(*p128, e8_bytes); + + /* Map the comparison results into a single 16-bit + * number. It will contain a 1 bit when the + * corresponding byte in the current 16-byte vector is + * an e8 byte. Note: the low-order bit corresponds to + * the first (lowest address) byte. */ + u32 e8_mask = _mm_movemask_epi8(cmpresult); + + if (!e8_mask) { + /* If e8_mask is 0, then none of these 16 bytes + * have value 0xe8. No e8 translation is + * needed, and there is no restriction that + * carries over to the next 16 bytes. */ + valid_mask = 0xFFFFFFFF; + } else { + /* At least one byte has value 0xe8. + * + * The AND with valid_mask accounts for the fact + * that we can't start an e8 translation that + * overlaps the previous one. */ + while ((e8_mask &= valid_mask)) { + + /* Count the number of trailing zeroes + * in e8_mask. This will produce the + * index of the byte, within the 16, at + * which the next e8 translation should + * be done. */ + u32 bit = __builtin_ctz(e8_mask); + + /* Do (or undo) the e8 translation. */ + u8 *p8 = (u8 *)p128 + bit; + (*process_target)((s32 *)(p8 + 1), + p8 - data); + + /* Don't start an e8 translation in the + * next 4 bytes. */ + valid_mask &= ~((u32)0x1F << bit); + } + /* Moving on to the next vector. Shift and set + * valid_mask accordingly. */ + valid_mask >>= 16; + valid_mask |= 0xFFFF0000; + } + } while (++p128 < end128); + } + + u8 *p8 = (u8 *)p128; + while (!(valid_mask & 1)) { + p8++; + valid_mask >>= 1; + } +#else /* __SSE2__ */ + u8 *p8 = data; +#endif /* !__SSE2__ */ + + if (size > 10) { + /* Finish any bytes that weren't processed by the vectorized + * implementation. */ + u8 *p8_end = data + size - 10; + do { + if (*p8 == 0xe8) { + (*process_target)((s32 *)(p8 + 1), p8 - data); + p8 += 5; + } else { + p8++; + } + } while (p8 < p8_end); + } +} + +void +lzx_do_e8_preprocessing(u8 *data, s32 size) +{ + lzx_e8_filter(data, size, do_translate_target); +} + +void +lzx_undo_e8_preprocessing(u8 *data, s32 size) +{ + lzx_e8_filter(data, size, undo_translate_target); +} diff --git a/src/lzx-compress.c b/src/lzx-compress.c index d71c28dd..c86b03ca 100644 --- a/src/lzx-compress.c +++ b/src/lzx-compress.c @@ -1491,40 +1491,6 @@ lzx_prepare_block_fast(struct lzx_compressor * ctx) ctx->num_blocks = 1; } -static void -do_call_insn_translation(u32 *call_insn_target, int input_pos, - s32 file_size) -{ - s32 abs_offset; - s32 rel_offset; - - rel_offset = le32_to_cpu(*call_insn_target); - if (rel_offset >= -input_pos && rel_offset < file_size) { - if (rel_offset < file_size - input_pos) { - /* "good translation" */ - abs_offset = rel_offset + input_pos; - } else { - /* "compensating translation" */ - abs_offset = rel_offset - file_size; - } - *call_insn_target = cpu_to_le32(abs_offset); - } -} - -/* This is the reverse of undo_call_insn_preprocessing() in lzx-decompress.c. - * See the comment above that function for more information. */ -static void -do_call_insn_preprocessing(u8 data[], int size) -{ - for (int i = 0; i < size - 10; i++) { - if (data[i] == 0xe8) { - do_call_insn_translation((u32*)&data[i + 1], i, - LZX_WIM_MAGIC_FILESIZE); - i += 4; - } - } -} - static size_t lzx_compress(const void *uncompressed_data, size_t uncompressed_size, void *compressed_data, size_t compressed_size_avail, void *_ctx) @@ -1561,7 +1527,7 @@ lzx_compress(const void *uncompressed_data, size_t uncompressed_size, /* Before doing any actual compression, do the call instruction (0xe8 * byte) translation on the uncompressed data. */ - do_call_insn_preprocessing(ctx->window, ctx->window_size); + lzx_do_e8_preprocessing(ctx->window, ctx->window_size); LZX_DEBUG("Preparing blocks..."); diff --git a/src/lzx-decompress.c b/src/lzx-decompress.c index 7389c7c4..bbb10514 100644 --- a/src/lzx-decompress.c +++ b/src/lzx-decompress.c @@ -115,10 +115,6 @@ #include -#ifdef __SSE2__ -# include -#endif - /* Huffman decoding tables and maps from symbols to code lengths. */ struct lzx_tables { @@ -647,149 +643,6 @@ lzx_decode_match(unsigned main_element, int block_type, return match_len; } -static void -undo_call_insn_translation(u32 *call_insn_target, s32 input_pos) -{ - s32 abs_offset; - s32 rel_offset; - - abs_offset = le32_to_cpu(*call_insn_target); - if (abs_offset >= 0) { - if (abs_offset < LZX_WIM_MAGIC_FILESIZE) { - /* "good translation" */ - rel_offset = abs_offset - input_pos; - - *call_insn_target = cpu_to_le32(rel_offset); - } - } else { - if (abs_offset >= -input_pos) { - /* "compensating translation" */ - rel_offset = abs_offset + LZX_WIM_MAGIC_FILESIZE; - - *call_insn_target = cpu_to_le32(rel_offset); - } - } -} - -/* Undo the 'E8' preprocessing, where the targets of x86 CALL instructions were - * changed from relative offsets to absolute offsets. - * - * Note that this call instruction preprocessing can and will be used on any - * data even if it is not actually x86 machine code. In fact, this type of - * 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. - * - * Call instruction 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. - * - * Call instruction preprocessing does not appear to be disabled after the - * 32768th chunk of a WIM stream, which is apparently is yet another difference - * from the LZX compression used in cabinet files. - * - * Call instruction 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 -undo_call_insn_preprocessing(u8 *uncompressed_data, size_t uncompressed_size) -{ -#ifdef __SSE2__ - - /* SSE2 vectorized implementation for x86_64. This speeds up LZX - * decompression by about 5-8% overall. (Usually --- the performance - * actually regresses slightly in the degenerate case that the data - * consists entirely of 0xe8 bytes.) */ - __m128i *p128 = (__m128i *)uncompressed_data; - u32 valid_mask = 0xFFFFFFFF; - - if (uncompressed_size >= 32 && - ((uintptr_t)uncompressed_data % 16 == 0)) - { - __m128i * const end128 = p128 + uncompressed_size / 16 - 1; - - /* Create a vector of all 0xe8 bytes */ - const __m128i e8_bytes = _mm_set1_epi8(0xe8); - - /* Iterate through the 16-byte vectors in the input. */ - do { - /* Compare the current 16-byte vector with the vector of - * all 0xe8 bytes. This produces 0xff where the byte is - * 0xe8 and 0x00 where it is not. */ - __m128i cmpresult = _mm_cmpeq_epi8(*p128, e8_bytes); - - /* Map the comparison results into a single 16-bit - * number. It will contain a 1 bit when the - * corresponding byte in the current 16-byte vector is - * an e8 byte. Note: the low-order bit corresponds to - * the first (lowest address) byte. */ - u32 e8_mask = _mm_movemask_epi8(cmpresult); - - if (!e8_mask) { - /* If e8_mask is 0, then none of these 16 bytes - * have value 0xe8. No e8 translation is - * needed, and there is no restriction that - * carries over to the next 16 bytes. */ - valid_mask = 0xFFFFFFFF; - } else { - /* At least one byte has value 0xe8. - * - * The AND with valid_mask accounts for the fact - * that we can't start an e8 translation that - * overlaps the previous one. */ - while ((e8_mask &= valid_mask)) { - - /* Count the number of trailing zeroes - * in e8_mask. This will produce the - * index of the byte, within the 16, at - * which the next e8 translation should - * be done. */ - u32 bit = __builtin_ctz(e8_mask); - - /* Do the e8 translation. */ - u8 *p8 = (u8 *)p128 + bit; - undo_call_insn_translation((s32 *)(p8 + 1), - p8 - uncompressed_data); - - /* Don't start an e8 translation in the - * next 4 bytes. */ - valid_mask &= ~((u32)0x1F << bit); - } - /* Moving on to the next vector. Shift and set - * valid_mask accordingly. */ - valid_mask >>= 16; - valid_mask |= 0xFFFF0000; - } - } while (++p128 < end128); - } - - u8 *p8 = (u8 *)p128; - while (!(valid_mask & 1)) { - p8++; - valid_mask >>= 1; - } -#else /* __SSE2__ */ - u8 *p8 = uncompressed_data; -#endif /* !__SSE2__ */ - - if (uncompressed_size > 10) { - /* Finish any bytes that weren't processed by the vectorized - * implementation. */ - u8 *p8_end = uncompressed_data + uncompressed_size - 10; - do { - if (*p8 == 0xe8) { - undo_call_insn_translation((s32 *)(p8 + 1), - p8 - uncompressed_data); - p8 += 5; - } else { - p8++; - } - } while (p8 < p8_end); - } -} - /* * Decompresses an LZX-compressed block of data from which the header has already * been read. @@ -947,7 +800,7 @@ lzx_decompress(const void *compressed_data, size_t compressed_size, } } if (e8_preprocessing_done) - undo_call_insn_preprocessing(uncompressed_data, uncompressed_size); + lzx_undo_e8_preprocessing(uncompressed_data, uncompressed_size); return 0; }