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79 lines
2.1 KiB
79 lines
2.1 KiB
13 years ago
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(function (exports) {
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'use strict';
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var lookup = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
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function b64ToByteArray(b64) {
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var i, l, tmp, hasPadding, arr = [];
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if (i % 4 > 0) {
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throw 'Invalid string. Length must be a multiple of 4';
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}
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hasPadding = /=$/.test(b64);
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l = hasPadding ? b64.length - 4: b64.length;
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for (i = 0; i < l; i += 4) {
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tmp = (lookup.indexOf(b64[i]) << 18) | (lookup.indexOf(b64[i + 1]) << 12) | (lookup.indexOf(b64[i + 2]) << 6) | lookup.indexOf(b64[i + 3]);
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arr.push((tmp & 0xFF0000) >> 16);
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arr.push((tmp & 0xFF00) >> 8);
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arr.push(tmp & 0xFF);
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}
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if (hasPadding) {
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b64 = b64.substring(i, b64.indexOf('='));
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if (b64.length === 2) {
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tmp = (lookup.indexOf(b64[0]) << 2) | (lookup.indexOf(b64[1]) >> 4);
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arr.push(tmp & 0xFF);
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} else {
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tmp = (lookup.indexOf(b64[0]) << 10) | (lookup.indexOf(b64[1]) << 4) | (lookup.indexOf(b64[2]) >> 2);
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arr.push((tmp >> 8) & 0xFF);
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arr.push(tmp & 0xFF);
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}
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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 tripletToBase64 (num) {
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return lookup[num >> 18 & 0x3F] + lookup[num >> 12 & 0x3F] + lookup[num >> 6 & 0x3F] + lookup[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 += lookup[temp >> 2];
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output += lookup[(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 += lookup[temp >> 10];
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output += lookup[(temp >> 4) & 0x3F];
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output += lookup[(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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module.exports.toByteArray = b64ToByteArray;
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module.exports.fromByteArray = uint8ToBase64;
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}());
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