mirror of
https://github.com/denoland/deno.git
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207 lines
6.6 KiB
TypeScript
207 lines
6.6 KiB
TypeScript
// Modified from https://github.com/beatgammit/base64-js
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// Copyright (c) 2014 Jameson Little. MIT License.
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const lookup: string[] = [];
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const revLookup: number[] = [];
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// RFC4648 base32
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const code = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
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for (let i = 0, len = code.length; i < len; ++i) {
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lookup[i] = code[i];
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revLookup[code.charCodeAt(i)] = i;
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}
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const placeHolderPadLookup = [0, 1, , 2, 3, , 4];
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function _getPadLen(placeHoldersLen: number): number {
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const maybeLen = placeHolderPadLookup[placeHoldersLen];
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if (typeof maybeLen !== "number") {
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throw new Error("Invalid pad length");
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}
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return maybeLen;
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}
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function getLens(b32: string): [number, number] {
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const len = b32.length;
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if (len % 8 > 0) {
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throw new Error("Invalid string. Length must be a multiple of 8");
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}
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let validLen = b32.indexOf("=");
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if (validLen === -1) validLen = len;
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const placeHoldersLen = validLen === len ? 0 : 8 - (validLen % 8);
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return [validLen, placeHoldersLen];
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}
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/**
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* Returns number of bytes encoded in the given RFC4648 base32 string input.
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* @param b32
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*/
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export function byteLength(b32: string): number {
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const [validLen, placeHoldersLen] = getLens(b32);
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return _byteLength(validLen, placeHoldersLen);
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}
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function _byteLength(validLen: number, placeHoldersLen: number): number {
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return ((validLen + placeHoldersLen) * 5) / 8 - _getPadLen(placeHoldersLen);
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}
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/**
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* Decodes a given RFC4648 base32 encoded string.
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* @param b32
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*/
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export function decode(b32: string): Uint8Array {
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let tmp: number;
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const [validLen, placeHoldersLen] = getLens(b32);
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const arr = new Uint8Array(_byteLength(validLen, placeHoldersLen));
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let curByte = 0;
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// if there are placeholders, only get up to the last complete 8 chars
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const len = placeHoldersLen > 0 ? validLen - 8 : validLen;
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let i: number;
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for (i = 0; i < len; i += 8) {
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tmp = (revLookup[b32.charCodeAt(i)] << 20) |
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(revLookup[b32.charCodeAt(i + 1)] << 15) |
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(revLookup[b32.charCodeAt(i + 2)] << 10) |
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(revLookup[b32.charCodeAt(i + 3)] << 5) |
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revLookup[b32.charCodeAt(i + 4)];
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arr[curByte++] = (tmp >> 17) & 0xff;
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arr[curByte++] = (tmp >> 9) & 0xff;
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arr[curByte++] = (tmp >> 1) & 0xff;
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tmp = ((tmp & 1) << 15) |
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(revLookup[b32.charCodeAt(i + 5)] << 10) |
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(revLookup[b32.charCodeAt(i + 6)] << 5) |
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revLookup[b32.charCodeAt(i + 7)];
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arr[curByte++] = (tmp >> 8) & 0xff;
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arr[curByte++] = tmp & 0xff;
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}
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if (placeHoldersLen === 1) {
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tmp = (revLookup[b32.charCodeAt(i)] << 20) |
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(revLookup[b32.charCodeAt(i + 1)] << 15) |
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(revLookup[b32.charCodeAt(i + 2)] << 10) |
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(revLookup[b32.charCodeAt(i + 3)] << 5) |
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revLookup[b32.charCodeAt(i + 4)];
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arr[curByte++] = (tmp >> 17) & 0xff;
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arr[curByte++] = (tmp >> 9) & 0xff;
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arr[curByte++] = (tmp >> 1) & 0xff;
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tmp = ((tmp & 1) << 7) |
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(revLookup[b32.charCodeAt(i + 5)] << 2) |
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(revLookup[b32.charCodeAt(i + 6)] >> 3);
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arr[curByte++] = tmp & 0xff;
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} else if (placeHoldersLen === 3) {
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tmp = (revLookup[b32.charCodeAt(i)] << 19) |
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(revLookup[b32.charCodeAt(i + 1)] << 14) |
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(revLookup[b32.charCodeAt(i + 2)] << 9) |
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(revLookup[b32.charCodeAt(i + 3)] << 4) |
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(revLookup[b32.charCodeAt(i + 4)] >> 1);
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arr[curByte++] = (tmp >> 16) & 0xff;
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arr[curByte++] = (tmp >> 8) & 0xff;
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arr[curByte++] = tmp & 0xff;
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} else if (placeHoldersLen === 4) {
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tmp = (revLookup[b32.charCodeAt(i)] << 11) |
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(revLookup[b32.charCodeAt(i + 1)] << 6) |
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(revLookup[b32.charCodeAt(i + 2)] << 1) |
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(revLookup[b32.charCodeAt(i + 3)] >> 4);
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arr[curByte++] = (tmp >> 8) & 0xff;
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arr[curByte++] = tmp & 0xff;
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} else if (placeHoldersLen === 6) {
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tmp = (revLookup[b32.charCodeAt(i)] << 3) |
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(revLookup[b32.charCodeAt(i + 1)] >> 2);
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arr[curByte++] = tmp & 0xff;
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}
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return arr;
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}
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function encodeChunk(uint8: Uint8Array, start: number, end: number): string {
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let tmp: number;
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const output = [];
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for (let i = start; i < end; i += 5) {
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tmp = ((uint8[i] << 16) & 0xff0000) |
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((uint8[i + 1] << 8) & 0xff00) |
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(uint8[i + 2] & 0xff);
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output.push(lookup[(tmp >> 19) & 0x1f]);
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output.push(lookup[(tmp >> 14) & 0x1f]);
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output.push(lookup[(tmp >> 9) & 0x1f]);
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output.push(lookup[(tmp >> 4) & 0x1f]);
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tmp = ((tmp & 0xf) << 16) |
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((uint8[i + 3] << 8) & 0xff00) |
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(uint8[i + 4] & 0xff);
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output.push(lookup[(tmp >> 15) & 0x1f]);
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output.push(lookup[(tmp >> 10) & 0x1f]);
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output.push(lookup[(tmp >> 5) & 0x1f]);
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output.push(lookup[tmp & 0x1f]);
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}
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return output.join("");
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}
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/**
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* Encodes a given Uint8Array into RFC4648 base32 representation
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* @param uint8
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*/
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export function encode(uint8: Uint8Array): string {
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let tmp: number;
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const len = uint8.length;
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const extraBytes = len % 5;
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const parts = [];
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const maxChunkLength = 16385; // must be multiple of 5
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const len2 = len - extraBytes;
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// go through the array every 5 bytes, we'll deal with trailing stuff later
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for (let i = 0; i < len2; i += maxChunkLength) {
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parts.push(
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encodeChunk(
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uint8,
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i,
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i + maxChunkLength > len2 ? len2 : i + maxChunkLength,
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),
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);
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}
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// pad the end with zeros, but make sure to not forget the extra bytes
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if (extraBytes === 4) {
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tmp = ((uint8[len2] & 0xff) << 16) |
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((uint8[len2 + 1] & 0xff) << 8) |
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(uint8[len2 + 2] & 0xff);
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parts.push(lookup[(tmp >> 19) & 0x1f]);
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parts.push(lookup[(tmp >> 14) & 0x1f]);
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parts.push(lookup[(tmp >> 9) & 0x1f]);
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parts.push(lookup[(tmp >> 4) & 0x1f]);
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tmp = ((tmp & 0xf) << 11) | (uint8[len2 + 3] << 3);
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parts.push(lookup[(tmp >> 10) & 0x1f]);
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parts.push(lookup[(tmp >> 5) & 0x1f]);
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parts.push(lookup[tmp & 0x1f]);
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parts.push("=");
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} else if (extraBytes === 3) {
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tmp = ((uint8[len2] & 0xff) << 17) |
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((uint8[len2 + 1] & 0xff) << 9) |
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((uint8[len2 + 2] & 0xff) << 1);
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parts.push(lookup[(tmp >> 20) & 0x1f]);
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parts.push(lookup[(tmp >> 15) & 0x1f]);
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parts.push(lookup[(tmp >> 10) & 0x1f]);
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parts.push(lookup[(tmp >> 5) & 0x1f]);
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parts.push(lookup[tmp & 0x1f]);
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parts.push("===");
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} else if (extraBytes === 2) {
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tmp = ((uint8[len2] & 0xff) << 12) | ((uint8[len2 + 1] & 0xff) << 4);
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parts.push(lookup[(tmp >> 15) & 0x1f]);
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parts.push(lookup[(tmp >> 10) & 0x1f]);
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parts.push(lookup[(tmp >> 5) & 0x1f]);
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parts.push(lookup[tmp & 0x1f]);
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parts.push("====");
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} else if (extraBytes === 1) {
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tmp = (uint8[len2] & 0xff) << 2;
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parts.push(lookup[(tmp >> 5) & 0x1f]);
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parts.push(lookup[tmp & 0x1f]);
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parts.push("======");
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}
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return parts.join("");
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}
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