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Diffstat (limited to '')
| -rw-r--r-- | src/liblzma/simple/x86.c | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/src/liblzma/simple/x86.c b/src/liblzma/simple/x86.c new file mode 100644 index 00000000..a48a5750 --- /dev/null +++ b/src/liblzma/simple/x86.c @@ -0,0 +1,161 @@ +/////////////////////////////////////////////////////////////////////////////// +// +/// \file x86.c +/// \brief Filter for x86 binaries (BCJ filter) +// +// Copyright (C) 1999-2006 Igor Pavlov +// Copyright (C) 2007 Lasse Collin +// +// This library 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 2.1 of the License, or (at your option) any later version. +// +// This library 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. +// +/////////////////////////////////////////////////////////////////////////////// + +#include "simple_private.h" + + +#define Test86MSByte(b) ((b) == 0 || (b) == 0xFF) + + +struct lzma_simple_s { + uint32_t prev_mask; + uint32_t prev_pos; +}; + + +static size_t +x86_code(lzma_simple *simple, uint32_t now_pos, bool is_encoder, + uint8_t *buffer, size_t size) +{ + static const bool MASK_TO_ALLOWED_STATUS[8] + = { true, true, true, false, true, false, false, false }; + + static const uint32_t MASK_TO_BIT_NUMBER[8] + = { 0, 1, 2, 2, 3, 3, 3, 3 }; + + uint32_t prev_mask = simple->prev_mask; + uint32_t prev_pos = simple->prev_pos; + + if (size < 5) + return 0; + + if (now_pos - prev_pos > 5) + prev_pos = now_pos - 5; + + const size_t limit = size - 5; + size_t buffer_pos = 0; + + while (buffer_pos <= limit) { + uint8_t b = buffer[buffer_pos]; + if (b != 0xE8 && b != 0xE9) { + ++buffer_pos; + continue; + } + + const uint32_t offset = now_pos + (uint32_t)(buffer_pos) + - prev_pos; + prev_pos = now_pos + (uint32_t)(buffer_pos); + + if (offset > 5) { + prev_mask = 0; + } else { + for (uint32_t i = 0; i < offset; ++i) { + prev_mask &= 0x77; + prev_mask <<= 1; + } + } + + b = buffer[buffer_pos + 4]; + + if (Test86MSByte(b) + && MASK_TO_ALLOWED_STATUS[(prev_mask >> 1) & 0x7] + && (prev_mask >> 1) < 0x10) { + + uint32_t src = ((uint32_t)(b) << 24) + | ((uint32_t)(buffer[buffer_pos + 3]) << 16) + | ((uint32_t)(buffer[buffer_pos + 2]) << 8) + | (buffer[buffer_pos + 1]); + + uint32_t dest; + while (true) { + if (is_encoder) + dest = src + (now_pos + (uint32_t)( + buffer_pos) + 5); + else + dest = src - (now_pos + (uint32_t)( + buffer_pos) + 5); + + if (prev_mask == 0) + break; + + const uint32_t i = MASK_TO_BIT_NUMBER[ + prev_mask >> 1]; + + b = (uint8_t)(dest >> (24 - i * 8)); + + if (!Test86MSByte(b)) + break; + + src = dest ^ ((1 << (32 - i * 8)) - 1); + } + + buffer[buffer_pos + 4] + = (uint8_t)(~(((dest >> 24) & 1) - 1)); + buffer[buffer_pos + 3] = (uint8_t)(dest >> 16); + buffer[buffer_pos + 2] = (uint8_t)(dest >> 8); + buffer[buffer_pos + 1] = (uint8_t)(dest); + buffer_pos += 5; + prev_mask = 0; + + } else { + ++buffer_pos; + prev_mask |= 1; + if (Test86MSByte(b)) + prev_mask |= 0x10; + } + } + + simple->prev_mask = prev_mask; + simple->prev_pos = prev_pos; + + return buffer_pos; +} + + +static lzma_ret +x86_coder_init(lzma_next_coder *next, lzma_allocator *allocator, + const lzma_filter_info *filters, bool is_encoder) +{ + const lzma_ret ret = lzma_simple_coder_init(next, allocator, filters, + &x86_code, sizeof(lzma_simple), 5, is_encoder); + + if (ret == LZMA_OK) { + next->coder->simple->prev_mask = 0; + next->coder->simple->prev_pos = (uint32_t)(-5); + } + + return ret; +} + + +extern lzma_ret +lzma_simple_x86_encoder_init(lzma_next_coder *next, lzma_allocator *allocator, + const lzma_filter_info *filters) +{ + return x86_coder_init(next, allocator, filters, true); +} + + +extern lzma_ret +lzma_simple_x86_decoder_init(lzma_next_coder *next, lzma_allocator *allocator, + const lzma_filter_info *filters) +{ + return x86_coder_init(next, allocator, filters, false); +} |