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/**
* 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;
}