Published
Edited
May 13, 2020
Importers
md`# bech32
Code copied from https://www.npmjs.com/package/bech32, v1.1.4`
bech32 = {
var ALPHABET = 'qpzry9x8gf2tvdw0s3jn54khce6mua7l';
// pre-compute lookup table
var ALPHABET_MAP = {};
for (var z = 0; z < ALPHABET.length; z++) {
var x = ALPHABET.charAt(z);
if (ALPHABET_MAP[x] !== undefined) throw new TypeError(x + ' is ambiguous');
ALPHABET_MAP[x] = z;
}
function polymodStep(pre) {
var b = pre >> 25;
return (
((pre & 0x1FFFFFF) << 5) ^
(-((b >> 0) & 1) & 0x3b6a57b2) ^
(-((b >> 1) & 1) & 0x26508e6d) ^
(-((b >> 2) & 1) & 0x1ea119fa) ^
(-((b >> 3) & 1) & 0x3d4233dd) ^
(-((b >> 4) & 1) & 0x2a1462b3)
);
}
function prefixChk(prefix) {
var chk = 1;
for (var i = 0; i < prefix.length; ++i) {
var c = prefix.charCodeAt(i);
if (c < 33 || c > 126) return 'Invalid prefix (' + prefix + ')';
chk = polymodStep(chk) ^ (c >> 5);
}
chk = polymodStep(chk);
for (i = 0; i < prefix.length; ++i) {
var v = prefix.charCodeAt(i);
chk = polymodStep(chk) ^ (v & 0x1f);
}
return chk;
}
function encode(prefix, words, LIMIT) {
LIMIT = LIMIT || 90;
if (prefix.length + 7 + words.length > LIMIT)
throw new TypeError('Exceeds length limit');
prefix = prefix.toLowerCase();
// determine chk mod
var chk = prefixChk(prefix);
if (typeof chk === 'string') throw new Error(chk);
var result = prefix + '1';
for (var i = 0; i < words.length; ++i) {
var x = words[i];
if (x >> 5 !== 0) throw new Error('Non 5-bit word');
chk = polymodStep(chk) ^ x;
result += ALPHABET.charAt(x);
}
for (i = 0; i < 6; ++i) {
chk = polymodStep(chk);
}
chk ^= 1;
for (i = 0; i < 6; ++i) {
var v = (chk >> ((5 - i) * 5)) & 0x1f;
result += ALPHABET.charAt(v);
}
return result;
}
function __decode(str, LIMIT) {
LIMIT = LIMIT || 90;
if (str.length < 8) return str + ' too short';
if (str.length > LIMIT) return 'Exceeds length limit';
// don't allow mixed case
var lowered = str.toLowerCase();
var uppered = str.toUpperCase();
if (str !== lowered && str !== uppered) return 'Mixed-case string ' + str;
str = lowered;
var split = str.lastIndexOf('1');
if (split === -1) return 'No separator character for ' + str;
if (split === 0) return 'Missing prefix for ' + str;
var prefix = str.slice(0, split);
var wordChars = str.slice(split + 1);
if (wordChars.length < 6) return 'Data too short';
var chk = prefixChk(prefix);
if (typeof chk === 'string') return chk;
var words = [];
for (var i = 0; i < wordChars.length; ++i) {
var c = wordChars.charAt(i);
var v = ALPHABET_MAP[c];
if (v === undefined) return 'Unknown character ' + c;
chk = polymodStep(chk) ^ v;
// not in the checksum?
if (i + 6 >= wordChars.length) continue;
words.push(v);
}
if (chk !== 1) return 'Invalid checksum for ' + str;
return { prefix: prefix, words: words };
}
function decodeUnsafe() {
var res = __decode.apply(null, arguments);
if (typeof res === 'object') return res;
}
function decode(str) {
var res = __decode.apply(null, arguments);
if (typeof res === 'object') return res;
throw new Error(res);
}
function convert(data, inBits, outBits, pad) {
var value = 0;
var bits = 0;
var maxV = (1 << outBits) - 1;
var result = [];
for (var i = 0; i < data.length; ++i) {
value = (value << inBits) | data[i];
bits += inBits;
while (bits >= outBits) {
bits -= outBits;
result.push((value >> bits) & maxV);
}
}
if (pad) {
if (bits > 0) {
result.push((value << (outBits - bits)) & maxV);
}
} else {
if (bits >= inBits) return 'Excess padding';
if ((value << (outBits - bits)) & maxV) return 'Non-zero padding';
}
return result;
}
function toWordsUnsafe(bytes) {
var res = convert(bytes, 8, 5, true);
if (Array.isArray(res)) return res;
}
function toWords(bytes) {
var res = convert(bytes, 8, 5, true);
if (Array.isArray(res)) return res;
throw new Error(res);
}
function fromWordsUnsafe(words) {
var res = convert(words, 5, 8, false);
if (Array.isArray(res)) return res;
}
function fromWords(words) {
var res = convert(words, 5, 8, false);
if (Array.isArray(res)) return res;
throw new Error(res);
}
return {
decodeUnsafe: decodeUnsafe,
decode: decode,
encode: encode,
toWordsUnsafe: toWordsUnsafe,
toWords: toWords,
fromWordsUnsafe: fromWordsUnsafe,
fromWords: fromWords
};
}
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