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
armthumb_code(void * simple lzma_attribute ((__unused__)),uint32_t now_pos,bool is_encoder,uint8_t * buffer,size_t size)18 armthumb_code(void *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 = (((uint32_t)(buffer[i + 1]) & 7) << 19)
27 | ((uint32_t)(buffer[i + 0]) << 11)
28 | (((uint32_t)(buffer[i + 3]) & 7) << 8)
29 | (uint32_t)(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
armthumb_coder_init(lzma_next_coder * next,const lzma_allocator * allocator,const lzma_filter_info * filters,bool is_encoder)53 armthumb_coder_init(lzma_next_coder *next, const 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
lzma_simple_armthumb_encoder_init(lzma_next_coder * next,const lzma_allocator * allocator,const lzma_filter_info * filters)62 lzma_simple_armthumb_encoder_init(lzma_next_coder *next,
63 const lzma_allocator *allocator,
64 const lzma_filter_info *filters)
65 {
66 return armthumb_coder_init(next, allocator, filters, true);
67 }
68
69
70 extern lzma_ret
lzma_simple_armthumb_decoder_init(lzma_next_coder * next,const lzma_allocator * allocator,const lzma_filter_info * filters)71 lzma_simple_armthumb_decoder_init(lzma_next_coder *next,
72 const lzma_allocator *allocator,
73 const lzma_filter_info *filters)
74 {
75 return armthumb_coder_init(next, allocator, filters, false);
76 }
77