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- 'use strict'
- exports.byteLength = byteLength
- exports.toByteArray = toByteArray
- exports.fromByteArray = fromByteArray
- var lookup = []
- var revLookup = []
- var Arr = typeof Uint8Array !== 'undefined' ? Uint8Array : Array
- var code = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
- for (var i = 0, len = code.length; i < len; ++i) {
- lookup[i] = code[i]
- revLookup[code.charCodeAt(i)] = i
- }
- // Support decoding URL-safe base64 strings, as Node.js does.
- // See: https://en.wikipedia.org/wiki/Base64#URL_applications
- revLookup['-'.charCodeAt(0)] = 62
- revLookup['_'.charCodeAt(0)] = 63
- function getLens (b64) {
- var len = b64.length
- if (len % 4 > 0) {
- throw new Error('Invalid string. Length must be a multiple of 4')
- }
- // Trim off extra bytes after placeholder bytes are found
- // See: https://github.com/beatgammit/base64-js/issues/42
- var validLen = b64.indexOf('=')
- if (validLen === -1) validLen = len
- var placeHoldersLen = validLen === len
- ? 0
- : 4 - (validLen % 4)
- return [validLen, placeHoldersLen]
- }
- // base64 is 4/3 + up to two characters of the original data
- function byteLength (b64) {
- var lens = getLens(b64)
- var validLen = lens[0]
- var placeHoldersLen = lens[1]
- return ((validLen + placeHoldersLen) * 3 / 4) - placeHoldersLen
- }
- function _byteLength (b64, validLen, placeHoldersLen) {
- return ((validLen + placeHoldersLen) * 3 / 4) - placeHoldersLen
- }
- function toByteArray (b64) {
- var tmp
- var lens = getLens(b64)
- var validLen = lens[0]
- var placeHoldersLen = lens[1]
- var arr = new Arr(_byteLength(b64, validLen, placeHoldersLen))
- var curByte = 0
- // if there are placeholders, only get up to the last complete 4 chars
- var len = placeHoldersLen > 0
- ? validLen - 4
- : validLen
- for (var i = 0; i < len; i += 4) {
- tmp =
- (revLookup[b64.charCodeAt(i)] << 18) |
- (revLookup[b64.charCodeAt(i + 1)] << 12) |
- (revLookup[b64.charCodeAt(i + 2)] << 6) |
- revLookup[b64.charCodeAt(i + 3)]
- arr[curByte++] = (tmp >> 16) & 0xFF
- arr[curByte++] = (tmp >> 8) & 0xFF
- arr[curByte++] = tmp & 0xFF
- }
- if (placeHoldersLen === 2) {
- tmp =
- (revLookup[b64.charCodeAt(i)] << 2) |
- (revLookup[b64.charCodeAt(i + 1)] >> 4)
- arr[curByte++] = tmp & 0xFF
- }
- if (placeHoldersLen === 1) {
- tmp =
- (revLookup[b64.charCodeAt(i)] << 10) |
- (revLookup[b64.charCodeAt(i + 1)] << 4) |
- (revLookup[b64.charCodeAt(i + 2)] >> 2)
- arr[curByte++] = (tmp >> 8) & 0xFF
- arr[curByte++] = tmp & 0xFF
- }
- return arr
- }
- function tripletToBase64 (num) {
- return lookup[num >> 18 & 0x3F] +
- lookup[num >> 12 & 0x3F] +
- lookup[num >> 6 & 0x3F] +
- lookup[num & 0x3F]
- }
- function encodeChunk (uint8, start, end) {
- var tmp
- var output = []
- for (var i = start; i < end; i += 3) {
- tmp =
- ((uint8[i] << 16) & 0xFF0000) +
- ((uint8[i + 1] << 8) & 0xFF00) +
- (uint8[i + 2] & 0xFF)
- output.push(tripletToBase64(tmp))
- }
- return output.join('')
- }
- function fromByteArray (uint8) {
- var tmp
- var len = uint8.length
- var extraBytes = len % 3 // if we have 1 byte left, pad 2 bytes
- var parts = []
- var maxChunkLength = 16383 // must be multiple of 3
- // go through the array every three bytes, we'll deal with trailing stuff later
- for (var i = 0, len2 = len - extraBytes; 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 === 1) {
- tmp = uint8[len - 1]
- parts.push(
- lookup[tmp >> 2] +
- lookup[(tmp << 4) & 0x3F] +
- '=='
- )
- } else if (extraBytes === 2) {
- tmp = (uint8[len - 2] << 8) + uint8[len - 1]
- parts.push(
- lookup[tmp >> 10] +
- lookup[(tmp >> 4) & 0x3F] +
- lookup[(tmp << 2) & 0x3F] +
- '='
- )
- }
- return parts.join('')
- }
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