deno.land / std@0.167.0 / encoding / base32.ts
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/** * {@linkcode encode} and {@linkcode decode} for * [base32](https://en.wikipedia.org/wiki/Base32) encoding. * * Modified from https://github.com/beatgammit/base64-js * * This module is browser compatible. * * @example * ```ts * import { * decode, * encode, * } from "https://deno.land/std@$STD_VERSION/encoding/base32.ts"; * * const b32Repr = "RC2E6GA="; * * const binaryData = decode(b32Repr); * console.log(binaryData); * // => Uint8Array [ 136, 180, 79, 24 ] * * console.log(encode(binaryData)); * // => RC2E6GA= * ``` * * @module */
const lookup: string[] = [];const revLookup: number[] = [];
// RFC4648 base32const code = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";for (let i = 0, len = code.length; i < len; ++i) { lookup[i] = code[i]; revLookup[code.charCodeAt(i)] = i;}
const placeHolderPadLookup = [0, 1, , 2, 3, , 4];function _getPadLen(placeHoldersLen: number): number { const maybeLen = placeHolderPadLookup[placeHoldersLen]; if (typeof maybeLen !== "number") { throw new Error("Invalid pad length"); } return maybeLen;}
function getLens(b32: string): [number, number] { const len = b32.length;
if (len % 8 > 0) { throw new Error("Invalid string. Length must be a multiple of 8"); }
let validLen = b32.indexOf("="); if (validLen === -1) validLen = len;
const placeHoldersLen = validLen === len ? 0 : 8 - (validLen % 8);
return [validLen, placeHoldersLen];}
/** * Returns number of bytes encoded in the given RFC4648 base32 string input. * @param b32 */export function byteLength(b32: string): number { const [validLen, placeHoldersLen] = getLens(b32); return _byteLength(validLen, placeHoldersLen);}
function _byteLength(validLen: number, placeHoldersLen: number): number { return ((validLen + placeHoldersLen) * 5) / 8 - _getPadLen(placeHoldersLen);}
/** * Decodes a given RFC4648 base32 encoded string. * @param b32 */export function decode(b32: string): Uint8Array { let tmp: number; const [validLen, placeHoldersLen] = getLens(b32);
const arr = new Uint8Array(_byteLength(validLen, placeHoldersLen));
let curByte = 0;
// if there are placeholders, only get up to the last complete 8 chars const len = placeHoldersLen > 0 ? validLen - 8 : validLen;
let i: number; for (i = 0; i < len; i += 8) { tmp = (revLookup[b32.charCodeAt(i)] << 20) | (revLookup[b32.charCodeAt(i + 1)] << 15) | (revLookup[b32.charCodeAt(i + 2)] << 10) | (revLookup[b32.charCodeAt(i + 3)] << 5) | revLookup[b32.charCodeAt(i + 4)]; arr[curByte++] = (tmp >> 17) & 0xff; arr[curByte++] = (tmp >> 9) & 0xff; arr[curByte++] = (tmp >> 1) & 0xff;
tmp = ((tmp & 1) << 15) | (revLookup[b32.charCodeAt(i + 5)] << 10) | (revLookup[b32.charCodeAt(i + 6)] << 5) | revLookup[b32.charCodeAt(i + 7)]; arr[curByte++] = (tmp >> 8) & 0xff; arr[curByte++] = tmp & 0xff; }
if (placeHoldersLen === 1) { tmp = (revLookup[b32.charCodeAt(i)] << 20) | (revLookup[b32.charCodeAt(i + 1)] << 15) | (revLookup[b32.charCodeAt(i + 2)] << 10) | (revLookup[b32.charCodeAt(i + 3)] << 5) | revLookup[b32.charCodeAt(i + 4)]; arr[curByte++] = (tmp >> 17) & 0xff; arr[curByte++] = (tmp >> 9) & 0xff; arr[curByte++] = (tmp >> 1) & 0xff; tmp = ((tmp & 1) << 7) | (revLookup[b32.charCodeAt(i + 5)] << 2) | (revLookup[b32.charCodeAt(i + 6)] >> 3); arr[curByte++] = tmp & 0xff; } else if (placeHoldersLen === 3) { tmp = (revLookup[b32.charCodeAt(i)] << 19) | (revLookup[b32.charCodeAt(i + 1)] << 14) | (revLookup[b32.charCodeAt(i + 2)] << 9) | (revLookup[b32.charCodeAt(i + 3)] << 4) | (revLookup[b32.charCodeAt(i + 4)] >> 1); arr[curByte++] = (tmp >> 16) & 0xff; arr[curByte++] = (tmp >> 8) & 0xff; arr[curByte++] = tmp & 0xff; } else if (placeHoldersLen === 4) { tmp = (revLookup[b32.charCodeAt(i)] << 11) | (revLookup[b32.charCodeAt(i + 1)] << 6) | (revLookup[b32.charCodeAt(i + 2)] << 1) | (revLookup[b32.charCodeAt(i + 3)] >> 4); arr[curByte++] = (tmp >> 8) & 0xff; arr[curByte++] = tmp & 0xff; } else if (placeHoldersLen === 6) { tmp = (revLookup[b32.charCodeAt(i)] << 3) | (revLookup[b32.charCodeAt(i + 1)] >> 2); arr[curByte++] = tmp & 0xff; }
return arr;}
function encodeChunk(uint8: Uint8Array, start: number, end: number): string { let tmp: number; const output = []; for (let i = start; i < end; i += 5) { tmp = ((uint8[i] << 16) & 0xff0000) | ((uint8[i + 1] << 8) & 0xff00) | (uint8[i + 2] & 0xff); output.push(lookup[(tmp >> 19) & 0x1f]); output.push(lookup[(tmp >> 14) & 0x1f]); output.push(lookup[(tmp >> 9) & 0x1f]); output.push(lookup[(tmp >> 4) & 0x1f]); tmp = ((tmp & 0xf) << 16) | ((uint8[i + 3] << 8) & 0xff00) | (uint8[i + 4] & 0xff); output.push(lookup[(tmp >> 15) & 0x1f]); output.push(lookup[(tmp >> 10) & 0x1f]); output.push(lookup[(tmp >> 5) & 0x1f]); output.push(lookup[tmp & 0x1f]); } return output.join("");}
/** * Encodes a given Uint8Array into RFC4648 base32 representation * @param uint8 */export function encode(uint8: Uint8Array): string { let tmp: number; const len = uint8.length; const extraBytes = len % 5; const parts = []; const maxChunkLength = 16385; // must be multiple of 5 const len2 = len - extraBytes;
// go through the array every 5 bytes, we'll deal with trailing stuff later for (let i = 0; i < len2; i += maxChunkLength) { parts.push( encodeChunk( uint8, i, i + maxChunkLength > len2 ? len2 : i + maxChunkLength, ), ); }
// pad the end with zeros, but make sure to not forget the extra bytes if (extraBytes === 4) { tmp = ((uint8[len2] & 0xff) << 16) | ((uint8[len2 + 1] & 0xff) << 8) | (uint8[len2 + 2] & 0xff); parts.push(lookup[(tmp >> 19) & 0x1f]); parts.push(lookup[(tmp >> 14) & 0x1f]); parts.push(lookup[(tmp >> 9) & 0x1f]); parts.push(lookup[(tmp >> 4) & 0x1f]); tmp = ((tmp & 0xf) << 11) | (uint8[len2 + 3] << 3); parts.push(lookup[(tmp >> 10) & 0x1f]); parts.push(lookup[(tmp >> 5) & 0x1f]); parts.push(lookup[tmp & 0x1f]); parts.push("="); } else if (extraBytes === 3) { tmp = ((uint8[len2] & 0xff) << 17) | ((uint8[len2 + 1] & 0xff) << 9) | ((uint8[len2 + 2] & 0xff) << 1); parts.push(lookup[(tmp >> 20) & 0x1f]); parts.push(lookup[(tmp >> 15) & 0x1f]); parts.push(lookup[(tmp >> 10) & 0x1f]); parts.push(lookup[(tmp >> 5) & 0x1f]); parts.push(lookup[tmp & 0x1f]); parts.push("==="); } else if (extraBytes === 2) { tmp = ((uint8[len2] & 0xff) << 12) | ((uint8[len2 + 1] & 0xff) << 4); parts.push(lookup[(tmp >> 15) & 0x1f]); parts.push(lookup[(tmp >> 10) & 0x1f]); parts.push(lookup[(tmp >> 5) & 0x1f]); parts.push(lookup[tmp & 0x1f]); parts.push("===="); } else if (extraBytes === 1) { tmp = (uint8[len2] & 0xff) << 2; parts.push(lookup[(tmp >> 5) & 0x1f]); parts.push(lookup[tmp & 0x1f]); parts.push("======"); }
return parts.join("");}
std
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