lukechilds
/
base64-js
mirror of https://github.com/lukechilds/base64-js.git
1
0
Fork 0
Code Issues Projects Releases Wiki Activity
Browse Source

use typedarray, about 15% faster

master
Dominic Tarr 11 years ago
parent
f617396dab
commit
3deb9b4365
1 changed files with 108 additions and 98 deletions
Whitespace
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
Split View
Diff Options
Show Stats Download Patch File Download Diff File
  1. 206
      lib/b64.js

206
lib/b64.js
View File

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

Write Preview
Loading…
Cancel
Save