File: int_encoding.cc

package info (click to toggle)
binutils 2.28-5
  • links: PTS, VCS
  • area: main
  • in suites: stretch
  • size: 271,848 kB
  • sloc: ansic: 1,419,727; asm: 623,424; cpp: 125,042; exp: 64,226; makefile: 56,536; sh: 21,234; lisp: 15,206; yacc: 14,889; perl: 2,111; ada: 1,681; lex: 1,645; pascal: 1,438; cs: 879; sed: 195; python: 154; xml: 95; awk: 25
file content (134 lines) | stat: -rw-r--r-- 3,553 bytes parent folder | download
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
// int_encoding.cc -- variable length and unaligned integer encoding support.

// Copyright (C) 2009-2017 Free Software Foundation, Inc.
// Written by Doug Kwan <dougkwan@google.com> by refactoring scattered
// contents from other files in gold.  Original code written by Ian
// Lance Taylor <iant@google.com> and Caleb Howe <cshowe@google.com>.

// This file is part of gold.

// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
// MA 02110-1301, USA.

#include "gold.h"

#include <vector>

#include "int_encoding.h"

namespace gold {

// Read an unsigned LEB128 number.  Each byte contains 7 bits of
// information, plus one bit saying whether the number continues or
// not.  BYTE contains the first byte of the number, and is guaranteed
// to have the continuation bit set.

uint64_t
read_unsigned_LEB_128_x(const unsigned char* buffer, size_t* len,
			unsigned char byte)
{
  uint64_t result = static_cast<uint64_t>(byte & 0x7f);
  size_t num_read = 1;
  unsigned int shift = 7;

  do
    {
      if (num_read > 64 / 7 + 1)
        {
          gold_warning(_("Unusually large LEB128 decoded, "
			 "debug information may be corrupted"));
          break;
        }
      byte = *buffer++;
      num_read++;
      result |= (static_cast<uint64_t>(byte & 0x7f)) << shift;
      shift += 7;
    }
  while (byte & 0x80);

  *len = num_read;

  return result;
}

// Read a signed LEB128 number.  These are like regular LEB128
// numbers, except the last byte may have a sign bit set.
// BYTE contains the first byte of the number, and is guaranteed
// to have the continuation bit set.

int64_t
read_signed_LEB_128_x(const unsigned char* buffer, size_t* len,
		      unsigned char byte)
{
  int64_t result = static_cast<uint64_t>(byte & 0x7f);
  int shift = 7;
  size_t num_read = 1;

  do
    {
      if (num_read > 64 / 7 + 1)
        {
          gold_warning(_("Unusually large LEB128 decoded, "
			 "debug information may be corrupted"));
          break;
        }
      byte = *buffer++;
      num_read++;
      result |= (static_cast<uint64_t>(byte & 0x7f) << shift);
      shift += 7;
    }
  while (byte & 0x80);

  if ((shift < 8 * static_cast<int>(sizeof(result))) && (byte & 0x40))
    result |= -((static_cast<int64_t>(1)) << shift);
  *len = num_read;
  return result;
}

void
write_unsigned_LEB_128(std::vector<unsigned char>* buffer, uint64_t value)
{
  do
    {
      unsigned char current_byte = value & 0x7f;
      value >>= 7;
      if (value != 0)
        {
          current_byte |= 0x80;
        }
      buffer->push_back(current_byte);
    }
  while (value != 0);
}

size_t
get_length_as_unsigned_LEB_128(uint64_t value)
{
  size_t length = 0;
  do
    {
      unsigned char current_byte = value & 0x7f;
      value >>= 7;
      if (value != 0)
        {
          current_byte |= 0x80;
        }
      length++;
    }
  while (value != 0);
  return length;
}

} // End namespace gold.