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