KiCad PCB EDA Suite
base64.cpp
Go to the documentation of this file.
1 /*
2  * This program source code file is part of KiCad, a free EDA CAD application.
3  *
4  * Copyright (C) 2019 KiCad Developers, see AUTHORS.txt for contributors.
5  *
6  * @author Seth Hillbrand <seth@kipro-pcb.com>
7  *
8  * This program is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU General Public License
10  * as published by the Free Software Foundation; either version 3
11  * of the License, or (at your option) any later version.
12  *
13  * This program is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16  * GNU General Public License for more details.
17  *
18  * You should have received a copy of the GNU General Public License along
19  * with this program. If not, see <http://www.gnu.org/licenses/>.
20  */
21 
22 
23 #include <base64.h>
24 
25 #include <cstdint>
26 #include <cstddef>
27 #include <limits>
28 #include <vector>
29 
30 namespace {
31 
32 static const uint8_t ENCODE_BASE64[64] = {
33  0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
34  0x49, 0x4A, 0x4B, 0x4C, 0x4D, 0x4E, 0x4F, 0x50,
35  0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58,
36  0x59, 0x5A, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66,
37  0x67, 0x68, 0x69, 0x6A, 0x6B, 0x6C, 0x6D, 0x6E,
38  0x6F, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76,
39  0x77, 0x78, 0x79, 0x7A, 0x30, 0x31, 0x32, 0x33,
40  0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x2B, 0x2F,
41 };
42 
43 static const uint8_t E = -1;
44 
45 static const uint8_t DECODE_BASE64[128] = {
46 /* 0x0 0x1 0x2 0x3 0x4 0x5 0x6 0x7 0x8 0x9 0xA 0xB 0xC 0xD 0xE 0xF */
47  E, E, E, E, E, E, E, E, E, E, E, E, E, E, E, E,
48  E, E, E, E, E, E, E, E, E, E, E, E, E, E, E, E,
49  E, E, E, E, E, E, E, E, E, E, E, 62, E, E, E, 63,
50  52, 53, 54, 55, 56, 57, 58, 59, 60, 61, E, E, E, E, E, E,
51  E, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
52  15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, E, E, E, E, E,
53  E, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
54  41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, E, E, E, E, E,
55 };
56 
57 } // namespace
58 
59 namespace base64
60 {
61  size_t encode_length( size_t aInputLen )
62  {
63  return 4 * ( ( aInputLen + 2 ) / 3 ) + ( aInputLen + 2 ) % 3 - 2;
64  }
65 
66 
67  size_t decode_length( size_t aInputLen )
68  {
69  if( aInputLen % 4 == 1 )
70  return 0;
71  else
72  return 3 * ( ( aInputLen + 2 ) / 4 ) + ( aInputLen + 2 ) % 4 - 2;
73  }
74 
75 
76  void encode( const std::vector<uint8_t>& aInput, std::vector<uint8_t>& aOutput )
77  {
78  size_t end = ( aInput.size() / 3 ) * 3;
79  aOutput.reserve( encode_length( aInput.size() ) );
80 
81  for( size_t i = 0; i < end; i += 3 )
82  {
83  unsigned value = ( aInput[i] << 16 ) | ( aInput[i + 1] << 8 ) | aInput[i + 2] ;
84 
85  aOutput.emplace_back( ENCODE_BASE64[( value >> 18 ) & 0x3F] );
86  aOutput.emplace_back( ENCODE_BASE64[( value >> 12 ) & 0x3F] );
87  aOutput.emplace_back( ENCODE_BASE64[( value >> 6 ) & 0x3F] );
88  aOutput.emplace_back( ENCODE_BASE64[value & 0x3F] );
89  }
90 
91  size_t remainder = aInput.size() - end;
92 
93  if( remainder )
94  {
95  unsigned value = aInput[end];
96 
97  if( remainder == 2 )
98  {
99  value = ( value << 10 ) | ( aInput[end + 1] << 2 );
100  aOutput.emplace_back( ENCODE_BASE64[( value >> 12 ) & 0x3F] );
101  }
102  else
103  {
104  value <<= 4;
105  }
106 
107  aOutput.emplace_back( ENCODE_BASE64[( value >> 6 ) & 0x3F] );
108  aOutput.emplace_back( ENCODE_BASE64[value & 0x3F] );
109  }
110  }
111 
112 
113  void decode(const std::vector<uint8_t>& aInput, std::vector<uint8_t>& aOutput )
114  {
115  size_t end = ( aInput.size() / 4 ) * 4;
116  size_t decode_size = decode_length( aInput.size() );
117 
118  if( !decode_size )
119  return;
120 
121  aOutput.reserve( decode_size );
122 
123  for( size_t i = 0; i < end; i++ )
124  {
125  unsigned value = ( DECODE_BASE64[aInput[i] & 0x7F] << 18 ) |
126  ( DECODE_BASE64[aInput[i + 1] & 0x7F] << 12 ) |
127  ( DECODE_BASE64[aInput[i + 2] & 0x7F] << 6 ) |
128  DECODE_BASE64[aInput[i + 3] & 0x7F];
129 
130  aOutput.emplace_back( ( value >> 16 ) & 0xff );
131  aOutput.emplace_back( ( value >> 8 ) & 0xff );
132  aOutput.emplace_back( value & 0xff );
133  }
134 
135  size_t remainder = aInput.size() - end;
136 
137  if( remainder )
138  {
139  unsigned value = ( ( DECODE_BASE64[aInput[end] & 0x7F] ) << 6 ) |
140  ( DECODE_BASE64[aInput[end + 1] & 0x7F] );
141 
142  if( remainder == 3 )
143  {
144  value = ( value << 6 ) | ( DECODE_BASE64[aInput[end + 2] & 0x7F] );
145  value >>= 2;
146 
147  aOutput.emplace_back( ( value >> 8 ) & 0xff );
148  }
149  else
150  {
151  value >>= 4;
152  }
153  aOutput[0] = value & 0xff ;
154  }
155  }
156 
157 } // base64
void encode(const std::vector< uint8_t > &aInput, std::vector< uint8_t > &aOutput)
Definition: base64.cpp:76
void decode(const std::vector< uint8_t > &aInput, std::vector< uint8_t > &aOutput)
Definition: base64.cpp:113
size_t decode_length(size_t aInputLen)
Definition: base64.cpp:67
size_t encode_length(size_t aInputLen)
Definition: base64.cpp:61