1 /////////////////////////////////////////////////////////////////////////////// 2 // 3 /// \file armthumb.c 4 /// \brief Filter for ARM-Thumb binaries 5 /// 6 // Authors: Igor Pavlov 7 // Lasse Collin 8 // 9 // This file has been put into the public domain. 10 // You can do whatever you want with this file. 11 // 12 /////////////////////////////////////////////////////////////////////////////// 13 14 #include "simple_private.h" 15 16 17 static size_t 18 armthumb_code(lzma_simple *simple lzma_attribute((__unused__)), 19 uint32_t now_pos, bool is_encoder, 20 uint8_t *buffer, size_t size) 21 { 22 size_t i; 23 for (i = 0; i + 4 <= size; i += 2) { 24 if ((buffer[i + 1] & 0xF8) == 0xF0 25 && (buffer[i + 3] & 0xF8) == 0xF8) { 26 uint32_t src = ((buffer[i + 1] & 0x7) << 19) 27 | (buffer[i + 0] << 11) 28 | ((buffer[i + 3] & 0x7) << 8) 29 | (buffer[i + 2]); 30 31 src <<= 1; 32 33 uint32_t dest; 34 if (is_encoder) 35 dest = now_pos + (uint32_t)(i) + 4 + src; 36 else 37 dest = src - (now_pos + (uint32_t)(i) + 4); 38 39 dest >>= 1; 40 buffer[i + 1] = 0xF0 | ((dest >> 19) & 0x7); 41 buffer[i + 0] = (dest >> 11); 42 buffer[i + 3] = 0xF8 | ((dest >> 8) & 0x7); 43 buffer[i + 2] = (dest); 44 i += 2; 45 } 46 } 47 48 return i; 49 } 50 51 52 static lzma_ret 53 armthumb_coder_init(lzma_next_coder *next, lzma_allocator *allocator, 54 const lzma_filter_info *filters, bool is_encoder) 55 { 56 return lzma_simple_coder_init(next, allocator, filters, 57 &armthumb_code, 0, 4, 2, is_encoder); 58 } 59 60 61 extern lzma_ret 62 lzma_simple_armthumb_encoder_init(lzma_next_coder *next, 63 lzma_allocator *allocator, const lzma_filter_info *filters) 64 { 65 return armthumb_coder_init(next, allocator, filters, true); 66 } 67 68 69 extern lzma_ret 70 lzma_simple_armthumb_decoder_init(lzma_next_coder *next, 71 lzma_allocator *allocator, const lzma_filter_info *filters) 72 { 73 return armthumb_coder_init(next, allocator, filters, false); 74 } 75