1 ///////////////////////////////////////////////////////////////////////////////
2 //
3 /// \file       powerpc.c
4 /// \brief      Filter for PowerPC (big endian) 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 powerpc_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 += 4) {
24 		// PowerPC branch 6(48) 24(Offset) 1(Abs) 1(Link)
25 		if ((buffer[i] >> 2) == 0x12
26 				&& ((buffer[i + 3] & 3) == 1)) {
27 
28 			const uint32_t src = ((buffer[i + 0] & 3) << 24)
29 					| (buffer[i + 1] << 16)
30 					| (buffer[i + 2] << 8)
31 					| (buffer[i + 3] & (~3));
32 
33 			uint32_t dest;
34 			if (is_encoder)
35 				dest = now_pos + (uint32_t)(i) + src;
36 			else
37 				dest = src - (now_pos + (uint32_t)(i));
38 
39 			buffer[i + 0] = 0x48 | ((dest >> 24) &  0x03);
40 			buffer[i + 1] = (dest >> 16);
41 			buffer[i + 2] = (dest >> 8);
42 			buffer[i + 3] &= 0x03;
43 			buffer[i + 3] |= dest;
44 		}
45 	}
46 
47 	return i;
48 }
49 
50 
51 static lzma_ret
52 powerpc_coder_init(lzma_next_coder *next, lzma_allocator *allocator,
53 		const lzma_filter_info *filters, bool is_encoder)
54 {
55 	return lzma_simple_coder_init(next, allocator, filters,
56 			&powerpc_code, 0, 4, 4, is_encoder);
57 }
58 
59 
60 extern lzma_ret
61 lzma_simple_powerpc_encoder_init(lzma_next_coder *next,
62 		lzma_allocator *allocator, const lzma_filter_info *filters)
63 {
64 	return powerpc_coder_init(next, allocator, filters, true);
65 }
66 
67 
68 extern lzma_ret
69 lzma_simple_powerpc_decoder_init(lzma_next_coder *next,
70 		lzma_allocator *allocator, const lzma_filter_info *filters)
71 {
72 	return powerpc_coder_init(next, allocator, filters, false);
73 }
74