152 lines
3.8 KiB
JavaScript
152 lines
3.8 KiB
JavaScript
|
'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('')
|
||
|
}
|