| // Copyright (c) 2015, the Dart project authors. Please see the AUTHORS file |
| // for details. All rights reserved. Use of this source code is governed by a |
| // BSD-style license that can be found in the LICENSE file. |
| |
| library base64; |
| |
| import 'dart:typed_data'; |
| |
| const _decodeTable = |
| const [null, null, null, null, null, null, null, null, |
| null, null, null, null, null, null, null, null, |
| null, null, null, null, null, null, null, null, |
| null, null, null, null, null, null, null, null, |
| null, null, null, null, null, null, null, null, |
| null, null, null, 62, null, null, null, 63, |
| 52, 53, 54, 55, 56, 57, 58, 59, |
| 60, 61, null, null, null, 0, null, null, |
| null, 0, 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, null, null, null, null, null, |
| null, 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]; |
| |
| Uint8List decodeBase64(String s) { |
| if (s.length % 4 != 0) throw "Malformed Base64: $s"; |
| |
| var odd_bits = 0; |
| if (s[s.length - 1] == '=') { |
| if (s[s.length - 2] == '=') { |
| odd_bits = 2; |
| } else { |
| odd_bits = 1; |
| } |
| } |
| |
| var decodedByteLength = s.length ~/ 4 * 3 - odd_bits; |
| var result = new Uint8List(decodedByteLength); |
| var limit = s.length; |
| if (odd_bits != 0) { |
| limit = limit - 4; |
| } |
| |
| var i = 0, j = 0; |
| while (i < limit) { |
| var triple = _decodeTable[s.codeUnitAt(i++)]; |
| triple = (triple << 6) | _decodeTable[s.codeUnitAt(i++)]; |
| triple = (triple << 6) | _decodeTable[s.codeUnitAt(i++)]; |
| triple = (triple << 6) | _decodeTable[s.codeUnitAt(i++)]; |
| result[j++] = triple >> 16; |
| result[j++] = (triple >> 8) & 255; |
| result[j++] = triple & 255; |
| } |
| |
| if (odd_bits != 0) { |
| var triple = _decodeTable[s.codeUnitAt(i++)]; |
| triple = (triple << 6) | _decodeTable[s.codeUnitAt(i++)]; |
| triple = (triple << 6) | _decodeTable[s.codeUnitAt(i++)]; |
| triple = (triple << 6) | _decodeTable[s.codeUnitAt(i++)]; |
| result[j++] = triple >> 16; |
| if (odd_bits == 1) { |
| result[j++] = (triple >> 8) & 255; |
| } |
| } |
| assert(j == decodedByteLength); |
| return result; |
| } |