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67bf71fe | 1 | /* Utilities for reading leb128 values. |
82704155 | 2 | Copyright (C) 2012-2019 Free Software Foundation, Inc. |
67bf71fe DD |
3 | |
4 | This file is part of the libiberty library. | |
5 | Libiberty is free software; you can redistribute it and/or | |
6 | modify it under the terms of the GNU Library General Public | |
7 | License as published by the Free Software Foundation; either | |
8 | version 2 of the License, or (at your option) any later version. | |
9 | ||
10 | Libiberty is distributed in the hope that it will be useful, | |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
13 | Library General Public License for more details. | |
14 | ||
15 | You should have received a copy of the GNU Library General Public | |
16 | License along with libiberty; see the file COPYING.LIB. If not, write | |
17 | to the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor, | |
18 | Boston, MA 02110-1301, USA. */ | |
19 | ||
20 | /* The functions defined here can be speed critical. | |
21 | Since they are all pretty small we keep things simple and just define | |
c81795e6 DE |
22 | them all as "static inline". |
23 | ||
24 | WARNING: This file is used by GDB which is stuck at C90. :-( | |
25 | Though it can use stdint.h, inttypes.h. | |
26 | Therefore if you want to add support for "long long" you need | |
27 | to wrap it in #ifdef CC_HAS_LONG_LONG. */ | |
67bf71fe DD |
28 | |
29 | #ifndef LEB128_H | |
30 | #define LEB128_H | |
31 | ||
32 | /* Get a definition for inline. */ | |
33 | #include "ansidecl.h" | |
34 | ||
35 | /* Get a definition for NULL, size_t. */ | |
36 | #include <stddef.h> | |
37 | ||
c81795e6 DE |
38 | #ifdef HAVE_STDINT_H |
39 | #include <stdint.h> | |
40 | #endif | |
41 | #ifdef HAVE_INTTYPES_H | |
42 | #include <inttypes.h> | |
43 | #endif | |
44 | ||
67bf71fe DD |
45 | /* Decode the unsigned LEB128 constant at BUF into the variable pointed to |
46 | by R, and return the number of bytes read. | |
47 | If we read off the end of the buffer, zero is returned, | |
48 | and nothing is stored in R. | |
49 | ||
50 | Note: The result is an int instead of a pointer to the next byte to be | |
51 | read to avoid const-vs-non-const problems. */ | |
52 | ||
53 | static inline size_t | |
c81795e6 DE |
54 | read_uleb128_to_uint64 (const unsigned char *buf, const unsigned char *buf_end, |
55 | uint64_t *r) | |
67bf71fe DD |
56 | { |
57 | const unsigned char *p = buf; | |
58 | unsigned int shift = 0; | |
c81795e6 | 59 | uint64_t result = 0; |
67bf71fe DD |
60 | unsigned char byte; |
61 | ||
62 | while (1) | |
63 | { | |
64 | if (p >= buf_end) | |
65 | return 0; | |
66 | ||
67 | byte = *p++; | |
c81795e6 | 68 | result |= ((uint64_t) (byte & 0x7f)) << shift; |
67bf71fe DD |
69 | if ((byte & 0x80) == 0) |
70 | break; | |
71 | shift += 7; | |
72 | } | |
73 | ||
74 | *r = result; | |
75 | return p - buf; | |
76 | } | |
77 | ||
78 | /* Decode the signed LEB128 constant at BUF into the variable pointed to | |
79 | by R, and return the number of bytes read. | |
80 | If we read off the end of the buffer, zero is returned, | |
81 | and nothing is stored in R. | |
82 | ||
83 | Note: The result is an int instead of a pointer to the next byte to be | |
84 | read to avoid const-vs-non-const problems. */ | |
85 | ||
86 | static inline size_t | |
c81795e6 DE |
87 | read_sleb128_to_int64 (const unsigned char *buf, const unsigned char *buf_end, |
88 | int64_t *r) | |
67bf71fe DD |
89 | { |
90 | const unsigned char *p = buf; | |
91 | unsigned int shift = 0; | |
c81795e6 | 92 | int64_t result = 0; |
67bf71fe DD |
93 | unsigned char byte; |
94 | ||
95 | while (1) | |
96 | { | |
97 | if (p >= buf_end) | |
98 | return 0; | |
99 | ||
100 | byte = *p++; | |
c81795e6 | 101 | result |= ((uint64_t) (byte & 0x7f)) << shift; |
67bf71fe DD |
102 | shift += 7; |
103 | if ((byte & 0x80) == 0) | |
104 | break; | |
105 | } | |
106 | if (shift < (sizeof (*r) * 8) && (byte & 0x40) != 0) | |
c81795e6 | 107 | result |= -(((uint64_t) 1) << shift); |
67bf71fe DD |
108 | |
109 | *r = result; | |
110 | return p - buf; | |
111 | } | |
112 | ||
113 | /* Return the number of bytes to read to skip past an LEB128 number in BUF. | |
114 | If the end isn't found before reaching BUF_END, return zero. | |
115 | ||
116 | Note: The result is an int instead of a pointer to the next byte to be | |
117 | read to avoid const-vs-non-const problems. */ | |
118 | ||
119 | static inline size_t | |
120 | skip_leb128 (const unsigned char *buf, const unsigned char *buf_end) | |
121 | { | |
122 | const unsigned char *p = buf; | |
123 | unsigned char byte; | |
124 | ||
125 | while (1) | |
126 | { | |
127 | if (p == buf_end) | |
128 | return 0; | |
129 | ||
130 | byte = *p++; | |
131 | if ((byte & 0x80) == 0) | |
132 | return p - buf; | |
133 | } | |
134 | } | |
135 | ||
136 | #endif /* LEB128_H */ |