source: trunk/libs/newlib/src/include/leb128.h @ 666

Last change on this file since 666 was 444, checked in by satin@…, 6 years ago

add newlib,libalmos-mkh, restructure shared_syscalls.h and mini-libc

File size: 3.7 KB
Line 
1/* Utilities for reading leb128 values.
2   Copyright (C) 2012-2015 Free Software Foundation, Inc.
3
4This file is part of the libiberty library.
5Libiberty is free software; you can redistribute it and/or
6modify it under the terms of the GNU Library General Public
7License as published by the Free Software Foundation; either
8version 2 of the License, or (at your option) any later version.
9
10Libiberty is distributed in the hope that it will be useful,
11but WITHOUT ANY WARRANTY; without even the implied warranty of
12MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13Library General Public License for more details.
14
15You should have received a copy of the GNU Library General Public
16License along with libiberty; see the file COPYING.LIB.  If not, write
17to the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
18Boston, 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
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.  */
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
38#ifdef HAVE_STDINT_H
39#include <stdint.h>
40#endif
41#ifdef HAVE_INTTYPES_H
42#include <inttypes.h>
43#endif
44
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
53static inline size_t
54read_uleb128_to_uint64 (const unsigned char *buf, const unsigned char *buf_end,
55                        uint64_t *r)
56{
57  const unsigned char *p = buf;
58  unsigned int shift = 0;
59  uint64_t result = 0;
60  unsigned char byte;
61
62  while (1)
63    {
64      if (p >= buf_end)
65        return 0;
66
67      byte = *p++;
68      result |= ((uint64_t) (byte & 0x7f)) << shift;
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
86static inline size_t
87read_sleb128_to_int64 (const unsigned char *buf, const unsigned char *buf_end,
88                       int64_t *r)
89{
90  const unsigned char *p = buf;
91  unsigned int shift = 0;
92  int64_t result = 0;
93  unsigned char byte;
94
95  while (1)
96    {
97      if (p >= buf_end)
98        return 0;
99
100      byte = *p++;
101      result |= ((uint64_t) (byte & 0x7f)) << shift;
102      shift += 7;
103      if ((byte & 0x80) == 0)
104        break;
105    }
106  if (shift < (sizeof (*r) * 8) && (byte & 0x40) != 0)
107    result |= -(((uint64_t) 1) << shift);
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
119static inline size_t
120skip_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 */
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