1 // SPDX-License-Identifier: 0BSD
2
3 ///////////////////////////////////////////////////////////////////////////////
4 //
5 /// \file armthumb.c
6 /// \brief Filter for ARM-Thumb binaries
7 ///
8 // Authors: Igor Pavlov
9 // Lasse Collin
10 //
11 ///////////////////////////////////////////////////////////////////////////////
12
13 #include "simple_private.h"
14
15
16 static size_t
armthumb_code(void * simple lzma_attribute ((__unused__)),uint32_t now_pos,bool is_encoder,uint8_t * buffer,size_t size)17 armthumb_code(void *simple lzma_attribute((__unused__)),
18 uint32_t now_pos, bool is_encoder,
19 uint8_t *buffer, size_t size)
20 {
21 size_t i;
22 for (i = 0; i + 4 <= size; i += 2) {
23 if ((buffer[i + 1] & 0xF8) == 0xF0
24 && (buffer[i + 3] & 0xF8) == 0xF8) {
25 uint32_t src = (((uint32_t)(buffer[i + 1]) & 7) << 19)
26 | ((uint32_t)(buffer[i + 0]) << 11)
27 | (((uint32_t)(buffer[i + 3]) & 7) << 8)
28 | (uint32_t)(buffer[i + 2]);
29
30 src <<= 1;
31
32 uint32_t dest;
33 if (is_encoder)
34 dest = now_pos + (uint32_t)(i) + 4 + src;
35 else
36 dest = src - (now_pos + (uint32_t)(i) + 4);
37
38 dest >>= 1;
39 buffer[i + 1] = 0xF0 | ((dest >> 19) & 0x7);
40 buffer[i + 0] = (dest >> 11);
41 buffer[i + 3] = 0xF8 | ((dest >> 8) & 0x7);
42 buffer[i + 2] = (dest);
43 i += 2;
44 }
45 }
46
47 return i;
48 }
49
50
51 static lzma_ret
armthumb_coder_init(lzma_next_coder * next,const lzma_allocator * allocator,const lzma_filter_info * filters,bool is_encoder)52 armthumb_coder_init(lzma_next_coder *next, const lzma_allocator *allocator,
53 const lzma_filter_info *filters, bool is_encoder)
54 {
55 return lzma_simple_coder_init(next, allocator, filters,
56 &armthumb_code, 0, 4, 2, is_encoder);
57 }
58
59
60 #ifdef HAVE_ENCODER_ARMTHUMB
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 #endif
69
70
71 #ifdef HAVE_DECODER_ARMTHUMB
72 extern lzma_ret
lzma_simple_armthumb_decoder_init(lzma_next_coder * next,const lzma_allocator * allocator,const lzma_filter_info * filters)73 lzma_simple_armthumb_decoder_init(lzma_next_coder *next,
74 const lzma_allocator *allocator,
75 const lzma_filter_info *filters)
76 {
77 return armthumb_coder_init(next, allocator, filters, false);
78 }
79 #endif
80