124 lines
3.5 KiB
JavaScript
124 lines
3.5 KiB
JavaScript
var lookup = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
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;(function (exports) {
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'use strict';
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var Arr = (typeof Uint8Array !== 'undefined')
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? Uint8Array
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: Array
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var PLUS = '+'.charCodeAt(0)
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var SLASH = '/'.charCodeAt(0)
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var NUMBER = '0'.charCodeAt(0)
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var LOWER = 'a'.charCodeAt(0)
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var UPPER = 'A'.charCodeAt(0)
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var PLUS_URL_SAFE = '-'.charCodeAt(0)
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var SLASH_URL_SAFE = '_'.charCodeAt(0)
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function decode (elt) {
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var code = elt.charCodeAt(0)
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if (code === PLUS ||
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code === PLUS_URL_SAFE)
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return 62 // '+'
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if (code === SLASH ||
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code === SLASH_URL_SAFE)
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return 63 // '/'
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if (code < NUMBER)
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return -1 //no match
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if (code < NUMBER + 10)
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return code - NUMBER + 26 + 26
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if (code < UPPER + 26)
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return code - UPPER
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if (code < LOWER + 26)
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return code - LOWER + 26
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}
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function b64ToByteArray (b64) {
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var i, j, l, tmp, placeHolders, arr
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if (b64.length % 4 > 0) {
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throw new Error('Invalid string. Length must be a multiple of 4')
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}
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// the number of equal signs (place holders)
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// if there are two placeholders, than the two characters before it
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// represent one byte
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// if there is only one, then the three characters before it represent 2 bytes
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// this is just a cheap hack to not do indexOf twice
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var len = b64.length
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placeHolders = '=' === b64.charAt(len - 2) ? 2 : '=' === b64.charAt(len - 1) ? 1 : 0
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// base64 is 4/3 + up to two characters of the original data
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arr = new Arr(b64.length * 3 / 4 - placeHolders)
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// if there are placeholders, only get up to the last complete 4 chars
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l = placeHolders > 0 ? b64.length - 4 : b64.length
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var L = 0
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function push (v) {
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arr[L++] = v
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}
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for (i = 0, j = 0; i < l; i += 4, j += 3) {
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tmp = (decode(b64.charAt(i)) << 18) | (decode(b64.charAt(i + 1)) << 12) | (decode(b64.charAt(i + 2)) << 6) | decode(b64.charAt(i + 3))
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push((tmp & 0xFF0000) >> 16)
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push((tmp & 0xFF00) >> 8)
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push(tmp & 0xFF)
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}
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if (placeHolders === 2) {
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tmp = (decode(b64.charAt(i)) << 2) | (decode(b64.charAt(i + 1)) >> 4)
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push(tmp & 0xFF)
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} else if (placeHolders === 1) {
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tmp = (decode(b64.charAt(i)) << 10) | (decode(b64.charAt(i + 1)) << 4) | (decode(b64.charAt(i + 2)) >> 2)
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push((tmp >> 8) & 0xFF)
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push(tmp & 0xFF)
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}
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return arr
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}
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function uint8ToBase64 (uint8) {
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var i,
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extraBytes = uint8.length % 3, // if we have 1 byte left, pad 2 bytes
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output = "",
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temp, length
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function encode (num) {
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return lookup.charAt(num)
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}
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function tripletToBase64 (num) {
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return encode(num >> 18 & 0x3F) + encode(num >> 12 & 0x3F) + encode(num >> 6 & 0x3F) + encode(num & 0x3F)
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}
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// go through the array every three bytes, we'll deal with trailing stuff later
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for (i = 0, length = uint8.length - extraBytes; i < length; i += 3) {
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temp = (uint8[i] << 16) + (uint8[i + 1] << 8) + (uint8[i + 2])
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output += tripletToBase64(temp)
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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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switch (extraBytes) {
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case 1:
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temp = uint8[uint8.length - 1]
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output += encode(temp >> 2)
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output += encode((temp << 4) & 0x3F)
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output += '=='
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break
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case 2:
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temp = (uint8[uint8.length - 2] << 8) + (uint8[uint8.length - 1])
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output += encode(temp >> 10)
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output += encode((temp >> 4) & 0x3F)
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output += encode((temp << 2) & 0x3F)
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output += '='
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break
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}
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return output
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}
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exports.toByteArray = b64ToByteArray
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exports.fromByteArray = uint8ToBase64
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}(typeof exports === 'undefined' ? (this.base64js = {}) : exports))
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