| /** |
| * Base-N/Base-X encoding/decoding functions. |
| * |
| * Original implementation from base-x: |
| * https://github.com/cryptocoinjs/base-x |
| * |
| * Which is MIT licensed: |
| * |
| * The MIT License (MIT) |
| * |
| * Copyright base-x contributors (c) 2016 |
| * |
| * Permission is hereby granted, free of charge, to any person obtaining a copy |
| * of this software and associated documentation files (the "Software"), to deal |
| * in the Software without restriction, including without limitation the rights |
| * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
| * copies of the Software, and to permit persons to whom the Software is |
| * furnished to do so, subject to the following conditions: |
| * |
| * The above copyright notice and this permission notice shall be included in |
| * all copies or substantial portions of the Software. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
| * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING |
| * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER |
| * DEALINGS IN THE SOFTWARE. |
| */ |
| var api = {}; |
| module.exports = api; |
| |
| // baseN alphabet indexes |
| var _reverseAlphabets = {}; |
| |
| /** |
| * BaseN-encodes a Uint8Array using the given alphabet. |
| * |
| * @param input the Uint8Array to encode. |
| * @param maxline the maximum number of encoded characters per line to use, |
| * defaults to none. |
| * |
| * @return the baseN-encoded output string. |
| */ |
| api.encode = function(input, alphabet, maxline) { |
| if(typeof alphabet !== 'string') { |
| throw new TypeError('"alphabet" must be a string.'); |
| } |
| if(maxline !== undefined && typeof maxline !== 'number') { |
| throw new TypeError('"maxline" must be a number.'); |
| } |
| |
| var output = ''; |
| |
| if(!(input instanceof Uint8Array)) { |
| // assume forge byte buffer |
| output = _encodeWithByteBuffer(input, alphabet); |
| } else { |
| var i = 0; |
| var base = alphabet.length; |
| var first = alphabet.charAt(0); |
| var digits = [0]; |
| for(i = 0; i < input.length; ++i) { |
| for(var j = 0, carry = input[i]; j < digits.length; ++j) { |
| carry += digits[j] << 8; |
| digits[j] = carry % base; |
| carry = (carry / base) | 0; |
| } |
| |
| while(carry > 0) { |
| digits.push(carry % base); |
| carry = (carry / base) | 0; |
| } |
| } |
| |
| // deal with leading zeros |
| for(i = 0; input[i] === 0 && i < input.length - 1; ++i) { |
| output += first; |
| } |
| // convert digits to a string |
| for(i = digits.length - 1; i >= 0; --i) { |
| output += alphabet[digits[i]]; |
| } |
| } |
| |
| if(maxline) { |
| var regex = new RegExp('.{1,' + maxline + '}', 'g'); |
| output = output.match(regex).join('\r\n'); |
| } |
| |
| return output; |
| }; |
| |
| /** |
| * Decodes a baseN-encoded (using the given alphabet) string to a |
| * Uint8Array. |
| * |
| * @param input the baseN-encoded input string. |
| * |
| * @return the Uint8Array. |
| */ |
| api.decode = function(input, alphabet) { |
| if(typeof input !== 'string') { |
| throw new TypeError('"input" must be a string.'); |
| } |
| if(typeof alphabet !== 'string') { |
| throw new TypeError('"alphabet" must be a string.'); |
| } |
| |
| var table = _reverseAlphabets[alphabet]; |
| if(!table) { |
| // compute reverse alphabet |
| table = _reverseAlphabets[alphabet] = []; |
| for(var i = 0; i < alphabet.length; ++i) { |
| table[alphabet.charCodeAt(i)] = i; |
| } |
| } |
| |
| // remove whitespace characters |
| input = input.replace(/\s/g, ''); |
| |
| var base = alphabet.length; |
| var first = alphabet.charAt(0); |
| var bytes = [0]; |
| for(var i = 0; i < input.length; i++) { |
| var value = table[input.charCodeAt(i)]; |
| if(value === undefined) { |
| return; |
| } |
| |
| for(var j = 0, carry = value; j < bytes.length; ++j) { |
| carry += bytes[j] * base; |
| bytes[j] = carry & 0xff; |
| carry >>= 8; |
| } |
| |
| while(carry > 0) { |
| bytes.push(carry & 0xff); |
| carry >>= 8; |
| } |
| } |
| |
| // deal with leading zeros |
| for(var k = 0; input[k] === first && k < input.length - 1; ++k) { |
| bytes.push(0); |
| } |
| |
| if(typeof Buffer !== 'undefined') { |
| return Buffer.from(bytes.reverse()); |
| } |
| |
| return new Uint8Array(bytes.reverse()); |
| }; |
| |
| function _encodeWithByteBuffer(input, alphabet) { |
| var i = 0; |
| var base = alphabet.length; |
| var first = alphabet.charAt(0); |
| var digits = [0]; |
| for(i = 0; i < input.length(); ++i) { |
| for(var j = 0, carry = input.at(i); j < digits.length; ++j) { |
| carry += digits[j] << 8; |
| digits[j] = carry % base; |
| carry = (carry / base) | 0; |
| } |
| |
| while(carry > 0) { |
| digits.push(carry % base); |
| carry = (carry / base) | 0; |
| } |
| } |
| |
| var output = ''; |
| |
| // deal with leading zeros |
| for(i = 0; input.at(i) === 0 && i < input.length() - 1; ++i) { |
| output += first; |
| } |
| // convert digits to a string |
| for(i = digits.length - 1; i >= 0; --i) { |
| output += alphabet[digits[i]]; |
| } |
| |
| return output; |
| } |