1 | /**
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2 | * @preserve
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3 | * JS Implementation of incremental MurmurHash3 (r150) (as of May 10, 2013)
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4 | *
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5 | * @author <a href="mailto:jensyt@gmail.com">Jens Taylor</a>
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6 | * @see http://github.com/homebrewing/brauhaus-diff
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7 | * @author <a href="mailto:gary.court@gmail.com">Gary Court</a>
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8 | * @see http://github.com/garycourt/murmurhash-js
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9 | * @author <a href="mailto:aappleby@gmail.com">Austin Appleby</a>
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10 | * @see http://sites.google.com/site/murmurhash/
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11 | */
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12 | (function(){
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13 | var cache;
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14 |
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15 | // Call this function without `new` to use the cached object (good for
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16 | // single-threaded environments), or with `new` to create a new object.
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17 | //
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18 | // @param {string} key A UTF-16 or ASCII string
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19 | // @param {number} seed An optional positive integer
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20 | // @return {object} A MurmurHash3 object for incremental hashing
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21 | function MurmurHash3(key, seed) {
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22 | var m = this instanceof MurmurHash3 ? this : cache;
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23 | m.reset(seed)
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24 | if (typeof key === 'string' && key.length > 0) {
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25 | m.hash(key);
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26 | }
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27 |
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28 | if (m !== this) {
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29 | return m;
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30 | }
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31 | };
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32 |
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33 | // Incrementally add a string to this hash
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34 | //
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35 | // @param {string} key A UTF-16 or ASCII string
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36 | // @return {object} this
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37 | MurmurHash3.prototype.hash = function(key) {
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38 | var h1, k1, i, top, len;
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39 |
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40 | len = key.length;
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41 | this.len += len;
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42 |
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43 | k1 = this.k1;
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44 | i = 0;
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45 | switch (this.rem) {
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46 | case 0: k1 ^= len > i ? (key.charCodeAt(i++) & 0xffff) : 0;
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47 | case 1: k1 ^= len > i ? (key.charCodeAt(i++) & 0xffff) << 8 : 0;
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48 | case 2: k1 ^= len > i ? (key.charCodeAt(i++) & 0xffff) << 16 : 0;
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49 | case 3:
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50 | k1 ^= len > i ? (key.charCodeAt(i) & 0xff) << 24 : 0;
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51 | k1 ^= len > i ? (key.charCodeAt(i++) & 0xff00) >> 8 : 0;
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52 | }
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53 |
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54 | this.rem = (len + this.rem) & 3; // & 3 is same as % 4
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55 | len -= this.rem;
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56 | if (len > 0) {
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57 | h1 = this.h1;
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58 | while (1) {
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59 | k1 = (k1 * 0x2d51 + (k1 & 0xffff) * 0xcc9e0000) & 0xffffffff;
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60 | k1 = (k1 << 15) | (k1 >>> 17);
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61 | k1 = (k1 * 0x3593 + (k1 & 0xffff) * 0x1b870000) & 0xffffffff;
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62 |
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63 | h1 ^= k1;
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64 | h1 = (h1 << 13) | (h1 >>> 19);
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65 | h1 = (h1 * 5 + 0xe6546b64) & 0xffffffff;
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66 |
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67 | if (i >= len) {
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68 | break;
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69 | }
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70 |
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71 | k1 = ((key.charCodeAt(i++) & 0xffff)) ^
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72 | ((key.charCodeAt(i++) & 0xffff) << 8) ^
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73 | ((key.charCodeAt(i++) & 0xffff) << 16);
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74 | top = key.charCodeAt(i++);
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75 | k1 ^= ((top & 0xff) << 24) ^
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76 | ((top & 0xff00) >> 8);
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77 | }
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78 |
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79 | k1 = 0;
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80 | switch (this.rem) {
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81 | case 3: k1 ^= (key.charCodeAt(i + 2) & 0xffff) << 16;
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82 | case 2: k1 ^= (key.charCodeAt(i + 1) & 0xffff) << 8;
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83 | case 1: k1 ^= (key.charCodeAt(i) & 0xffff);
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84 | }
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85 |
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86 | this.h1 = h1;
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87 | }
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88 |
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89 | this.k1 = k1;
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90 | return this;
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91 | };
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92 |
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93 | // Get the result of this hash
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94 | //
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95 | // @return {number} The 32-bit hash
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96 | MurmurHash3.prototype.result = function() {
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97 | var k1, h1;
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98 |
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99 | k1 = this.k1;
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100 | h1 = this.h1;
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101 |
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102 | if (k1 > 0) {
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103 | k1 = (k1 * 0x2d51 + (k1 & 0xffff) * 0xcc9e0000) & 0xffffffff;
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104 | k1 = (k1 << 15) | (k1 >>> 17);
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105 | k1 = (k1 * 0x3593 + (k1 & 0xffff) * 0x1b870000) & 0xffffffff;
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106 | h1 ^= k1;
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107 | }
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108 |
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109 | h1 ^= this.len;
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110 |
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111 | h1 ^= h1 >>> 16;
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112 | h1 = (h1 * 0xca6b + (h1 & 0xffff) * 0x85eb0000) & 0xffffffff;
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113 | h1 ^= h1 >>> 13;
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114 | h1 = (h1 * 0xae35 + (h1 & 0xffff) * 0xc2b20000) & 0xffffffff;
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115 | h1 ^= h1 >>> 16;
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116 |
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117 | return h1 >>> 0;
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118 | };
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119 |
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120 | // Reset the hash object for reuse
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121 | //
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122 | // @param {number} seed An optional positive integer
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123 | MurmurHash3.prototype.reset = function(seed) {
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124 | this.h1 = typeof seed === 'number' ? seed : 0;
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125 | this.rem = this.k1 = this.len = 0;
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126 | return this;
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127 | };
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128 |
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129 | // A cached object to use. This can be safely used if you're in a single-
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130 | // threaded environment, otherwise you need to create new hashes to use.
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131 | cache = new MurmurHash3();
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132 |
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133 | if (typeof(module) != 'undefined') {
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134 | module.exports = MurmurHash3;
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135 | } else {
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136 | this.MurmurHash3 = MurmurHash3;
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137 | }
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138 | }());
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