43 lines
1.2 KiB
JavaScript
43 lines
1.2 KiB
JavaScript
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/**
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* Copyright 2013-present, Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under the BSD-style license found in the
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* LICENSE file in the root directory of this source tree. An additional grant
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* of patent rights can be found in the PATENTS file in the same directory.
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*
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*
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*/
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'use strict';
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var MOD = 65521;
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// adler32 is not cryptographically strong, and is only used to sanity check that
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// markup generated on the server matches the markup generated on the client.
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// This implementation (a modified version of the SheetJS version) has been optimized
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// for our use case, at the expense of conforming to the adler32 specification
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// for non-ascii inputs.
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function adler32(data) {
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var a = 1;
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var b = 0;
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var i = 0;
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var l = data.length;
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var m = l & ~0x3;
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while (i < m) {
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var n = Math.min(i + 4096, m);
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for (; i < n; i += 4) {
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b += (a += data.charCodeAt(i)) + (a += data.charCodeAt(i + 1)) + (a += data.charCodeAt(i + 2)) + (a += data.charCodeAt(i + 3));
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}
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a %= MOD;
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b %= MOD;
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}
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for (; i < l; i++) {
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b += a += data.charCodeAt(i);
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}
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a %= MOD;
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b %= MOD;
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return a | b << 16;
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}
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module.exports = adler32;
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