1207753Smm/////////////////////////////////////////////////////////////////////////////// 2207753Smm// 3207753Smm/// \file x86.c 4207753Smm/// \brief Filter for x86 binaries (BCJ filter) 5207753Smm/// 6207753Smm// Authors: Igor Pavlov 7207753Smm// Lasse Collin 8207753Smm// 9207753Smm// This file has been put into the public domain. 10207753Smm// You can do whatever you want with this file. 11207753Smm// 12207753Smm/////////////////////////////////////////////////////////////////////////////// 13207753Smm 14207753Smm#include "simple_private.h" 15207753Smm 16207753Smm 17207753Smm#define Test86MSByte(b) ((b) == 0 || (b) == 0xFF) 18207753Smm 19207753Smm 20207753Smmstruct lzma_simple_s { 21207753Smm uint32_t prev_mask; 22207753Smm uint32_t prev_pos; 23207753Smm}; 24207753Smm 25207753Smm 26207753Smmstatic size_t 27207753Smmx86_code(lzma_simple *simple, uint32_t now_pos, bool is_encoder, 28207753Smm uint8_t *buffer, size_t size) 29207753Smm{ 30207753Smm static const bool MASK_TO_ALLOWED_STATUS[8] 31207753Smm = { true, true, true, false, true, false, false, false }; 32207753Smm 33207753Smm static const uint32_t MASK_TO_BIT_NUMBER[8] 34207753Smm = { 0, 1, 2, 2, 3, 3, 3, 3 }; 35207753Smm 36207753Smm uint32_t prev_mask = simple->prev_mask; 37207753Smm uint32_t prev_pos = simple->prev_pos; 38207753Smm 39207753Smm if (size < 5) 40207753Smm return 0; 41207753Smm 42207753Smm if (now_pos - prev_pos > 5) 43207753Smm prev_pos = now_pos - 5; 44207753Smm 45207753Smm const size_t limit = size - 5; 46207753Smm size_t buffer_pos = 0; 47207753Smm 48207753Smm while (buffer_pos <= limit) { 49207753Smm uint8_t b = buffer[buffer_pos]; 50207753Smm if (b != 0xE8 && b != 0xE9) { 51207753Smm ++buffer_pos; 52207753Smm continue; 53207753Smm } 54207753Smm 55207753Smm const uint32_t offset = now_pos + (uint32_t)(buffer_pos) 56207753Smm - prev_pos; 57207753Smm prev_pos = now_pos + (uint32_t)(buffer_pos); 58207753Smm 59207753Smm if (offset > 5) { 60207753Smm prev_mask = 0; 61207753Smm } else { 62207753Smm for (uint32_t i = 0; i < offset; ++i) { 63207753Smm prev_mask &= 0x77; 64207753Smm prev_mask <<= 1; 65207753Smm } 66207753Smm } 67207753Smm 68207753Smm b = buffer[buffer_pos + 4]; 69207753Smm 70207753Smm if (Test86MSByte(b) 71207753Smm && MASK_TO_ALLOWED_STATUS[(prev_mask >> 1) & 0x7] 72207753Smm && (prev_mask >> 1) < 0x10) { 73207753Smm 74207753Smm uint32_t src = ((uint32_t)(b) << 24) 75207753Smm | ((uint32_t)(buffer[buffer_pos + 3]) << 16) 76207753Smm | ((uint32_t)(buffer[buffer_pos + 2]) << 8) 77207753Smm | (buffer[buffer_pos + 1]); 78207753Smm 79207753Smm uint32_t dest; 80207753Smm while (true) { 81207753Smm if (is_encoder) 82207753Smm dest = src + (now_pos + (uint32_t)( 83207753Smm buffer_pos) + 5); 84207753Smm else 85207753Smm dest = src - (now_pos + (uint32_t)( 86207753Smm buffer_pos) + 5); 87207753Smm 88207753Smm if (prev_mask == 0) 89207753Smm break; 90207753Smm 91207753Smm const uint32_t i = MASK_TO_BIT_NUMBER[ 92207753Smm prev_mask >> 1]; 93207753Smm 94207753Smm b = (uint8_t)(dest >> (24 - i * 8)); 95207753Smm 96207753Smm if (!Test86MSByte(b)) 97207753Smm break; 98207753Smm 99207753Smm src = dest ^ ((1 << (32 - i * 8)) - 1); 100207753Smm } 101207753Smm 102207753Smm buffer[buffer_pos + 4] 103207753Smm = (uint8_t)(~(((dest >> 24) & 1) - 1)); 104207753Smm buffer[buffer_pos + 3] = (uint8_t)(dest >> 16); 105207753Smm buffer[buffer_pos + 2] = (uint8_t)(dest >> 8); 106207753Smm buffer[buffer_pos + 1] = (uint8_t)(dest); 107207753Smm buffer_pos += 5; 108207753Smm prev_mask = 0; 109207753Smm 110207753Smm } else { 111207753Smm ++buffer_pos; 112207753Smm prev_mask |= 1; 113207753Smm if (Test86MSByte(b)) 114207753Smm prev_mask |= 0x10; 115207753Smm } 116207753Smm } 117207753Smm 118207753Smm simple->prev_mask = prev_mask; 119207753Smm simple->prev_pos = prev_pos; 120207753Smm 121207753Smm return buffer_pos; 122207753Smm} 123207753Smm 124207753Smm 125207753Smmstatic lzma_ret 126207753Smmx86_coder_init(lzma_next_coder *next, lzma_allocator *allocator, 127207753Smm const lzma_filter_info *filters, bool is_encoder) 128207753Smm{ 129207753Smm const lzma_ret ret = lzma_simple_coder_init(next, allocator, filters, 130207753Smm &x86_code, sizeof(lzma_simple), 5, 1, is_encoder); 131207753Smm 132207753Smm if (ret == LZMA_OK) { 133207753Smm next->coder->simple->prev_mask = 0; 134207753Smm next->coder->simple->prev_pos = (uint32_t)(-5); 135207753Smm } 136207753Smm 137207753Smm return ret; 138207753Smm} 139207753Smm 140207753Smm 141207753Smmextern lzma_ret 142207753Smmlzma_simple_x86_encoder_init(lzma_next_coder *next, lzma_allocator *allocator, 143207753Smm const lzma_filter_info *filters) 144207753Smm{ 145207753Smm return x86_coder_init(next, allocator, filters, true); 146207753Smm} 147207753Smm 148207753Smm 149207753Smmextern lzma_ret 150207753Smmlzma_simple_x86_decoder_init(lzma_next_coder *next, lzma_allocator *allocator, 151207753Smm const lzma_filter_info *filters) 152207753Smm{ 153207753Smm return x86_coder_init(next, allocator, filters, false); 154207753Smm} 155