multiformats
Version:
Interface for multihash, multicodec, multibase and CID
170 lines • 5.46 kB
JavaScript
/* eslint-disable */
// base-x encoding / decoding
// Copyright (c) 2018 base-x contributors
// Copyright (c) 2014-2018 The Bitcoin Core developers (base58.cpp)
// Distributed under the MIT software license, see the accompanying
// file LICENSE or http://www.opensource.org/licenses/mit-license.php.
/**
* @param {string} ALPHABET
* @param {any} name
*/
function base(ALPHABET, name) {
if (ALPHABET.length >= 255) {
throw new TypeError('Alphabet too long');
}
var BASE_MAP = new Uint8Array(256);
for (var j = 0; j < BASE_MAP.length; j++) {
BASE_MAP[j] = 255;
}
for (var i = 0; i < ALPHABET.length; i++) {
var x = ALPHABET.charAt(i);
var xc = x.charCodeAt(0);
if (BASE_MAP[xc] !== 255) {
throw new TypeError(x + ' is ambiguous');
}
BASE_MAP[xc] = i;
}
var BASE = ALPHABET.length;
var LEADER = ALPHABET.charAt(0);
var FACTOR = Math.log(BASE) / Math.log(256); // log(BASE) / log(256), rounded up
var iFACTOR = Math.log(256) / Math.log(BASE); // log(256) / log(BASE), rounded up
/**
* @param {any[] | Iterable<number>} source
*/
function encode(source) {
// @ts-ignore
if (source instanceof Uint8Array)
;
else if (ArrayBuffer.isView(source)) {
source = new Uint8Array(source.buffer, source.byteOffset, source.byteLength);
}
else if (Array.isArray(source)) {
source = Uint8Array.from(source);
}
if (!(source instanceof Uint8Array)) {
throw new TypeError('Expected Uint8Array');
}
if (source.length === 0) {
return '';
}
// Skip & count leading zeroes.
var zeroes = 0;
var length = 0;
var pbegin = 0;
var pend = source.length;
while (pbegin !== pend && source[pbegin] === 0) {
pbegin++;
zeroes++;
}
// Allocate enough space in big-endian base58 representation.
var size = ((pend - pbegin) * iFACTOR + 1) >>> 0;
var b58 = new Uint8Array(size);
// Process the bytes.
while (pbegin !== pend) {
var carry = source[pbegin];
// Apply "b58 = b58 * 256 + ch".
var i = 0;
for (var it1 = size - 1; (carry !== 0 || i < length) && (it1 !== -1); it1--, i++) {
carry += (256 * b58[it1]) >>> 0;
b58[it1] = (carry % BASE) >>> 0;
carry = (carry / BASE) >>> 0;
}
if (carry !== 0) {
throw new Error('Non-zero carry');
}
length = i;
pbegin++;
}
// Skip leading zeroes in base58 result.
var it2 = size - length;
while (it2 !== size && b58[it2] === 0) {
it2++;
}
// Translate the result into a string.
var str = LEADER.repeat(zeroes);
for (; it2 < size; ++it2) {
str += ALPHABET.charAt(b58[it2]);
}
return str;
}
/**
* @param {string | string[]} source
*/
function decodeUnsafe(source) {
if (typeof source !== 'string') {
throw new TypeError('Expected String');
}
if (source.length === 0) {
return new Uint8Array();
}
var psz = 0;
// Skip leading spaces.
if (source[psz] === ' ') {
return;
}
// Skip and count leading '1's.
var zeroes = 0;
var length = 0;
while (source[psz] === LEADER) {
zeroes++;
psz++;
}
// Allocate enough space in big-endian base256 representation.
var size = (((source.length - psz) * FACTOR) + 1) >>> 0; // log(58) / log(256), rounded up.
var b256 = new Uint8Array(size);
// Process the characters.
while (source[psz]) {
// Decode character
var carry = BASE_MAP[source.charCodeAt(psz)];
// Invalid character
if (carry === 255) {
return;
}
var i = 0;
for (var it3 = size - 1; (carry !== 0 || i < length) && (it3 !== -1); it3--, i++) {
carry += (BASE * b256[it3]) >>> 0;
b256[it3] = (carry % 256) >>> 0;
carry = (carry / 256) >>> 0;
}
if (carry !== 0) {
throw new Error('Non-zero carry');
}
length = i;
psz++;
}
// Skip trailing spaces.
if (source[psz] === ' ') {
return;
}
// Skip leading zeroes in b256.
var it4 = size - length;
while (it4 !== size && b256[it4] === 0) {
it4++;
}
var vch = new Uint8Array(zeroes + (size - it4));
var j = zeroes;
while (it4 !== size) {
vch[j++] = b256[it4++];
}
return vch;
}
/**
* @param {string | string[]} string
*/
function decode(string) {
var buffer = decodeUnsafe(string);
if (buffer) {
return buffer;
}
throw new Error(`Non-${name} character`);
}
return {
encode: encode,
decodeUnsafe: decodeUnsafe,
decode: decode
};
}
var src = base;
var _brrp__multiformats_scope_baseX = src;
export default _brrp__multiformats_scope_baseX;
//# sourceMappingURL=base-x.js.map