lukechilds
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base64-js
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use typedarray, about 15% faster

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Dominic Tarr 11 years ago
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3deb9b4365
1 changed files with 108 additions and 98 deletions
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  1. 206
      lib/b64.js

206
lib/b64.js
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@ -1,103 +1,113 @@
(function (exports) { (function (exports) {
'use strict'; 'use strict';
var lookup = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'; var lookup = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
function b64ToByteArray(b64) { function decode (c) {
var i, j, l, tmp, placeHolders, arr; return indexOf(lookup, c)
}
if (b64.length % 4 > 0) {
throw 'Invalid string. Length must be a multiple of 4'; function b64ToByteArray(b64) {
} var i, j, l, tmp, placeHolders, arr;
// the number of equal signs (place holders) if (b64.length % 4 > 0) {
// if there are two placeholders, than the two characters before it throw 'Invalid string. Length must be a multiple of 4';
// represent one byte }
// if there is only one, then the three characters before it represent 2 bytes
// this is just a cheap hack to not do indexOf twice // the number of equal signs (place holders)
placeHolders = indexOf(b64, '='); // if there are two placeholders, than the two characters before it
placeHolders = placeHolders > 0 ? b64.length - placeHolders : 0; // represent one byte
// if there is only one, then the three characters before it represent 2 bytes
// base64 is 4/3 + up to two characters of the original data // this is just a cheap hack to not do indexOf twice
arr = [];//new Uint8Array(b64.length * 3 / 4 - placeHolders); placeHolders = indexOf(b64, '=');
placeHolders = placeHolders > 0 ? b64.length - placeHolders : 0;
// if there are placeholders, only get up to the last complete 4 chars
l = placeHolders > 0 ? b64.length - 4 : b64.length; // base64 is 4/3 + up to two characters of the original data
arr = new Uint8Array(b64.length * 3 / 4 - placeHolders);
for (i = 0, j = 0; i < l; i += 4, j += 3) {
tmp = (indexOf(lookup, b64.charAt(i)) << 18) | (indexOf(lookup, b64.charAt(i + 1)) << 12) | (indexOf(lookup, b64.charAt(i + 2)) << 6) | indexOf(lookup, b64.charAt(i + 3)); // if there are placeholders, only get up to the last complete 4 chars
arr.push((tmp & 0xFF0000) >> 16); l = placeHolders > 0 ? b64.length - 4 : b64.length;
arr.push((tmp & 0xFF00) >> 8);
arr.push(tmp & 0xFF); var L = 0
}
function push (v) {
if (placeHolders === 2) { arr[L++] = v
tmp = (indexOf(lookup, b64.charAt(i)) << 2) | (indexOf(lookup, b64.charAt(i + 1)) >> 4); }
arr.push(tmp & 0xFF);
} else if (placeHolders === 1) { for (i = 0, j = 0; i < l; i += 4, j += 3) {
tmp = (indexOf(lookup, b64.charAt(i)) << 10) | (indexOf(lookup, b64.charAt(i + 1)) << 4) | (indexOf(lookup, b64.charAt(i + 2)) >> 2); tmp = (decode(b64.charAt(i)) << 18) | (indexOf(lookup, b64.charAt(i + 1)) << 12) | (decode(b64.charAt(i + 2)) << 6) | decode(b64.charAt(i + 3));
arr.push((tmp >> 8) & 0xFF); push((tmp & 0xFF0000) >> 16);
arr.push(tmp & 0xFF); push((tmp & 0xFF00) >> 8);
} push(tmp & 0xFF);
}
return arr;
} if (placeHolders === 2) {
tmp = (decode(b64.charAt(i)) << 2) | (decode(b64.charAt(i + 1)) >> 4);
function uint8ToBase64(uint8) { push(tmp & 0xFF);
var i, } else if (placeHolders === 1) {
extraBytes = uint8.length % 3, // if we have 1 byte left, pad 2 bytes tmp = (indexOf(lookup, b64.charAt(i)) << 10) | (indexOf(lookup, b64.charAt(i + 1)) << 4) | (indexOf(lookup, b64.charAt(i + 2)) >> 2);
output = "", push((tmp >> 8) & 0xFF);
temp, length; push(tmp & 0xFF);
}
function tripletToBase64 (num) {
return lookup.charAt(num >> 18 & 0x3F) + lookup.charAt(num >> 12 & 0x3F) + lookup.charAt(num >> 6 & 0x3F) + lookup.charAt(num & 0x3F); return arr;
}; }
// go through the array every three bytes, we'll deal with trailing stuff later function uint8ToBase64(uint8) {
for (i = 0, length = uint8.length - extraBytes; i < length; i += 3) { var i,
temp = (uint8[i] << 16) + (uint8[i + 1] << 8) + (uint8[i + 2]); extraBytes = uint8.length % 3, // if we have 1 byte left, pad 2 bytes
output += tripletToBase64(temp); output = "",
} temp, length;
// pad the end with zeros, but make sure to not forget the extra bytes function tripletToBase64 (num) {
switch (extraBytes) { return lookup.charAt(num >> 18 & 0x3F) + lookup.charAt(num >> 12 & 0x3F) + lookup.charAt(num >> 6 & 0x3F) + lookup.charAt(num & 0x3F);
case 1: };
temp = uint8[uint8.length - 1];
output += lookup.charAt(temp >> 2); // go through the array every three bytes, we'll deal with trailing stuff later
output += lookup.charAt((temp << 4) & 0x3F); for (i = 0, length = uint8.length - extraBytes; i < length; i += 3) {
output += '=='; temp = (uint8[i] << 16) + (uint8[i + 1] << 8) + (uint8[i + 2]);
break; output += tripletToBase64(temp);
case 2: }
temp = (uint8[uint8.length - 2] << 8) + (uint8[uint8.length - 1]);
output += lookup.charAt(temp >> 10); // pad the end with zeros, but make sure to not forget the extra bytes
output += lookup.charAt((temp >> 4) & 0x3F); switch (extraBytes) {
output += lookup.charAt((temp << 2) & 0x3F); case 1:
output += '='; temp = uint8[uint8.length - 1];
break; output += lookup.charAt(temp >> 2);
} output += lookup.charAt((temp << 4) & 0x3F);
output += '==';
return output; break;
} case 2:
temp = (uint8[uint8.length - 2] << 8) + (uint8[uint8.length - 1]);
module.exports.toByteArray = b64ToByteArray; output += lookup.charAt(temp >> 10);
module.exports.fromByteArray = uint8ToBase64; output += lookup.charAt((temp >> 4) & 0x3F);
output += lookup.charAt((temp << 2) & 0x3F);
output += '=';
break;
}
return output;
}
module.exports.toByteArray = b64ToByteArray;
module.exports.fromByteArray = uint8ToBase64;
}()); }());
function indexOf (arr, elt /*, from*/) { function indexOf (arr, elt /*, from*/) {
var len = arr.length; var len = arr.length;
var from = Number(arguments[1]) || 0; var from = Number(arguments[1]) || 0;
from = (from < 0) from = (from < 0)
? Math.ceil(from) ? Math.ceil(from)
: Math.floor(from); : Math.floor(from);
if (from < 0) if (from < 0)
from += len; from += len;
for (; from < len; from++) { for (; from < len; from++) {
if ((typeof arr === 'string' && arr.charAt(from) === elt) || if ((typeof arr === 'string' && arr.charAt(from) === elt) ||
(typeof arr !== 'string' && arr[from] === elt)) { (typeof arr !== 'string' && arr[from] === elt)) {
return from; return from;
} }
} }
return -1; return -1;
} }

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