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1 //===--- Base64.h - Base64 Encoder/Decoder ----------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file provides generic base64 encoder/decoder.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #ifndef LLVM_SUPPORT_BASE64_H
14 #define LLVM_SUPPORT_BASE64_H
15 
16 #include <string>
17 
18 namespace llvm {
19 
encodeBase64(InputBytes const & Bytes)20 template <class InputBytes> std::string encodeBase64(InputBytes const &Bytes) {
21   static const char Table[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
22                               "abcdefghijklmnopqrstuvwxyz"
23                               "0123456789+/";
24   std::string Buffer;
25   Buffer.resize(((Bytes.size() + 2) / 3) * 4);
26 
27   size_t i = 0, j = 0;
28   for (size_t n = Bytes.size() / 3 * 3; i < n; i += 3, j += 4) {
29     uint32_t x = ((unsigned char)Bytes[i] << 16) |
30                  ((unsigned char)Bytes[i + 1] << 8) |
31                  (unsigned char)Bytes[i + 2];
32     Buffer[j + 0] = Table[(x >> 18) & 63];
33     Buffer[j + 1] = Table[(x >> 12) & 63];
34     Buffer[j + 2] = Table[(x >> 6) & 63];
35     Buffer[j + 3] = Table[x & 63];
36   }
37   if (i + 1 == Bytes.size()) {
38     uint32_t x = ((unsigned char)Bytes[i] << 16);
39     Buffer[j + 0] = Table[(x >> 18) & 63];
40     Buffer[j + 1] = Table[(x >> 12) & 63];
41     Buffer[j + 2] = '=';
42     Buffer[j + 3] = '=';
43   } else if (i + 2 == Bytes.size()) {
44     uint32_t x =
45         ((unsigned char)Bytes[i] << 16) | ((unsigned char)Bytes[i + 1] << 8);
46     Buffer[j + 0] = Table[(x >> 18) & 63];
47     Buffer[j + 1] = Table[(x >> 12) & 63];
48     Buffer[j + 2] = Table[(x >> 6) & 63];
49     Buffer[j + 3] = '=';
50   }
51   return Buffer;
52 }
53 
54 } // end namespace llvm
55 
56 #endif
57