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| 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 } |
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