6b1ac44aea
Notable changes: - Remove the `return this;` from the `MurmurHash3_64.update` method, since it's completely unused and doesn't make a lot of sense. - Remove the loop(s) from the `MurmurHash3_64.hexdigest` method, since creating a temporary array and then looping over it is wasteful given how simple this can be written with modern JavaScript.
133 lines
3.9 KiB
JavaScript
133 lines
3.9 KiB
JavaScript
/* Copyright 2014 Opera Software ASA
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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*
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* Based on https://code.google.com/p/smhasher/wiki/MurmurHash3.
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* Hashes roughly 100 KB per millisecond on i7 3.4 GHz.
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*/
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/* eslint no-var: error */
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import { isArrayBuffer, isString } from '../shared/util';
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const SEED = 0xc3d2e1f0;
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// Workaround for missing math precision in JS.
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const MASK_HIGH = 0xffff0000;
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const MASK_LOW = 0xffff;
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class MurmurHash3_64 {
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constructor(seed) {
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this.h1 = seed ? seed & 0xffffffff : SEED;
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this.h2 = seed ? seed & 0xffffffff : SEED;
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}
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update(input) {
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let data, length;
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if (isString(input)) {
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data = new Uint8Array(input.length * 2);
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length = 0;
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for (let i = 0, ii = input.length; i < ii; i++) {
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const code = input.charCodeAt(i);
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if (code <= 0xff) {
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data[length++] = code;
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} else {
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data[length++] = code >>> 8;
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data[length++] = code & 0xff;
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}
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}
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} else if (isArrayBuffer(input)) {
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data = input;
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length = data.byteLength;
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} else {
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throw new Error('Wrong data format in MurmurHash3_64_update. ' +
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'Input must be a string or array.');
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}
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const blockCounts = length >> 2;
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const tailLength = length - blockCounts * 4;
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// We don't care about endianness here.
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const dataUint32 = new Uint32Array(data.buffer, 0, blockCounts);
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let k1 = 0, k2 = 0;
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let h1 = this.h1, h2 = this.h2;
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const C1 = 0xcc9e2d51, C2 = 0x1b873593;
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const C1_LOW = C1 & MASK_LOW, C2_LOW = C2 & MASK_LOW;
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for (let i = 0; i < blockCounts; i++) {
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if (i & 1) {
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k1 = dataUint32[i];
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k1 = (k1 * C1 & MASK_HIGH) | (k1 * C1_LOW & MASK_LOW);
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k1 = k1 << 15 | k1 >>> 17;
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k1 = (k1 * C2 & MASK_HIGH) | (k1 * C2_LOW & MASK_LOW);
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h1 ^= k1;
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h1 = h1 << 13 | h1 >>> 19;
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h1 = h1 * 5 + 0xe6546b64;
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} else {
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k2 = dataUint32[i];
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k2 = (k2 * C1 & MASK_HIGH) | (k2 * C1_LOW & MASK_LOW);
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k2 = k2 << 15 | k2 >>> 17;
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k2 = (k2 * C2 & MASK_HIGH) | (k2 * C2_LOW & MASK_LOW);
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h2 ^= k2;
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h2 = h2 << 13 | h2 >>> 19;
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h2 = h2 * 5 + 0xe6546b64;
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}
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}
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k1 = 0;
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switch (tailLength) {
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case 3:
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k1 ^= data[blockCounts * 4 + 2] << 16;
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/* falls through */
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case 2:
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k1 ^= data[blockCounts * 4 + 1] << 8;
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/* falls through */
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case 1:
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k1 ^= data[blockCounts * 4];
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/* falls through */
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k1 = (k1 * C1 & MASK_HIGH) | (k1 * C1_LOW & MASK_LOW);
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k1 = k1 << 15 | k1 >>> 17;
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k1 = (k1 * C2 & MASK_HIGH) | (k1 * C2_LOW & MASK_LOW);
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if (blockCounts & 1) {
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h1 ^= k1;
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} else {
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h2 ^= k1;
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}
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}
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this.h1 = h1;
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this.h2 = h2;
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}
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hexdigest() {
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let h1 = this.h1, h2 = this.h2;
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h1 ^= h2 >>> 1;
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h1 = (h1 * 0xed558ccd & MASK_HIGH) | (h1 * 0x8ccd & MASK_LOW);
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h2 = (h2 * 0xff51afd7 & MASK_HIGH) |
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(((h2 << 16 | h1 >>> 16) * 0xafd7ed55 & MASK_HIGH) >>> 16);
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h1 ^= h2 >>> 1;
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h1 = (h1 * 0x1a85ec53 & MASK_HIGH) | (h1 * 0xec53 & MASK_LOW);
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h2 = (h2 * 0xc4ceb9fe & MASK_HIGH) |
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(((h2 << 16 | h1 >>> 16) * 0xb9fe1a85 & MASK_HIGH) >>> 16);
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h1 ^= h2 >>> 1;
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const hex1 = (h1 >>> 0).toString(16), hex2 = (h2 >>> 0).toString(16);
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return hex1.padStart(8, '0') + hex2.padStart(8, '0');
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}
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}
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export {
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MurmurHash3_64,
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};
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