lib/core/murmurhash3.js

/**
 * @licstart The following is the entire license notice for the
 * Javascript code in this page
 *
 * Copyright 2020 Mozilla Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * @licend The above is the entire license notice for the
 * Javascript code in this page
 */
"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.MurmurHash3_64 = void 0;

var _util = require("../shared/util.js");

const SEED = 0xc3d2e1f0;
const MASK_HIGH = 0xffff0000;
const MASK_LOW = 0xffff;

class MurmurHash3_64 {
  constructor(seed) {
    this.h1 = seed ? seed & 0xffffffff : SEED;
    this.h2 = seed ? seed & 0xffffffff : SEED;
  }

  update(input) {
    let data, length;

    if ((0, _util.isString)(input)) {
      data = new Uint8Array(input.length * 2);
      length = 0;

      for (let i = 0, ii = input.length; i < ii; i++) {
        const code = input.charCodeAt(i);

        if (code <= 0xff) {
          data[length++] = code;
        } else {
          data[length++] = code >>> 8;
          data[length++] = code & 0xff;
        }
      }
    } else if ((0, _util.isArrayBuffer)(input)) {
      data = input;
      length = data.byteLength;
    } else {
      throw new Error("Wrong data format in MurmurHash3_64_update. " + "Input must be a string or array.");
    }

    const blockCounts = length >> 2;
    const tailLength = length - blockCounts * 4;
    const dataUint32 = new Uint32Array(data.buffer, 0, blockCounts);
    let k1 = 0,
        k2 = 0;
    let h1 = this.h1,
        h2 = this.h2;
    const C1 = 0xcc9e2d51,
          C2 = 0x1b873593;
    const C1_LOW = C1 & MASK_LOW,
          C2_LOW = C2 & MASK_LOW;

    for (let i = 0; i < blockCounts; i++) {
      if (i & 1) {
        k1 = dataUint32[i];
        k1 = k1 * C1 & MASK_HIGH | k1 * C1_LOW & MASK_LOW;
        k1 = k1 << 15 | k1 >>> 17;
        k1 = k1 * C2 & MASK_HIGH | k1 * C2_LOW & MASK_LOW;
        h1 ^= k1;
        h1 = h1 << 13 | h1 >>> 19;
        h1 = h1 * 5 + 0xe6546b64;
      } else {
        k2 = dataUint32[i];
        k2 = k2 * C1 & MASK_HIGH | k2 * C1_LOW & MASK_LOW;
        k2 = k2 << 15 | k2 >>> 17;
        k2 = k2 * C2 & MASK_HIGH | k2 * C2_LOW & MASK_LOW;
        h2 ^= k2;
        h2 = h2 << 13 | h2 >>> 19;
        h2 = h2 * 5 + 0xe6546b64;
      }
    }

    k1 = 0;

    switch (tailLength) {
      case 3:
        k1 ^= data[blockCounts * 4 + 2] << 16;

      case 2:
        k1 ^= data[blockCounts * 4 + 1] << 8;

      case 1:
        k1 ^= data[blockCounts * 4];
        k1 = k1 * C1 & MASK_HIGH | k1 * C1_LOW & MASK_LOW;
        k1 = k1 << 15 | k1 >>> 17;
        k1 = k1 * C2 & MASK_HIGH | k1 * C2_LOW & MASK_LOW;

        if (blockCounts & 1) {
          h1 ^= k1;
        } else {
          h2 ^= k1;
        }

    }

    this.h1 = h1;
    this.h2 = h2;
  }

  hexdigest() {
    let h1 = this.h1,
        h2 = this.h2;
    h1 ^= h2 >>> 1;
    h1 = h1 * 0xed558ccd & MASK_HIGH | h1 * 0x8ccd & MASK_LOW;
    h2 = h2 * 0xff51afd7 & MASK_HIGH | ((h2 << 16 | h1 >>> 16) * 0xafd7ed55 & MASK_HIGH) >>> 16;
    h1 ^= h2 >>> 1;
    h1 = h1 * 0x1a85ec53 & MASK_HIGH | h1 * 0xec53 & MASK_LOW;
    h2 = h2 * 0xc4ceb9fe & MASK_HIGH | ((h2 << 16 | h1 >>> 16) * 0xb9fe1a85 & MASK_HIGH) >>> 16;
    h1 ^= h2 >>> 1;
    const hex1 = (h1 >>> 0).toString(16),
          hex2 = (h2 >>> 0).toString(16);
    return hex1.padStart(8, "0") + hex2.padStart(8, "0");
  }

}

exports.MurmurHash3_64 = MurmurHash3_64;