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65 lines
1.7 KiB
65 lines
1.7 KiB
// @flow
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/* eslint-disable */
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// Inspired by https://github.com/garycourt/murmurhash-js
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// Ported from https://github.com/aappleby/smhasher/blob/61a0530f28277f2e850bfc39600ce61d02b518de/src/MurmurHash2.cpp#L37-L86
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export default function murmur2(str: string) {
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// 'm' and 'r' are mixing constants generated offline.
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// They're not really 'magic', they just happen to work well.
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// const m = 0x5bd1e995;
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// const r = 24;
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// Initialize the hash
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var h = 0
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// Mix 4 bytes at a time into the hash
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var k,
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i = 0,
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len = str.length
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for (; len >= 4; ++i, len -= 4) {
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k =
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(str.charCodeAt(i) & 0xff) |
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((str.charCodeAt(++i) & 0xff) << 8) |
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((str.charCodeAt(++i) & 0xff) << 16) |
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((str.charCodeAt(++i) & 0xff) << 24)
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k =
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/* Math.imul(k, m): */
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(k & 0xffff) * 0x5bd1e995 + (((k >>> 16) * 0xe995) << 16)
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k ^= /* k >>> r: */ k >>> 24
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h =
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/* Math.imul(k, m): */
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((k & 0xffff) * 0x5bd1e995 + (((k >>> 16) * 0xe995) << 16)) ^
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/* Math.imul(h, m): */
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((h & 0xffff) * 0x5bd1e995 + (((h >>> 16) * 0xe995) << 16))
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}
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// Handle the last few bytes of the input array
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switch (len) {
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case 3:
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h ^= (str.charCodeAt(i + 2) & 0xff) << 16
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case 2:
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h ^= (str.charCodeAt(i + 1) & 0xff) << 8
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case 1:
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h ^= str.charCodeAt(i) & 0xff
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h =
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/* Math.imul(h, m): */
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(h & 0xffff) * 0x5bd1e995 + (((h >>> 16) * 0xe995) << 16)
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}
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// Do a few final mixes of the hash to ensure the last few
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// bytes are well-incorporated.
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h ^= h >>> 13
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h =
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/* Math.imul(h, m): */
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(h & 0xffff) * 0x5bd1e995 + (((h >>> 16) * 0xe995) << 16)
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return ((h ^ (h >>> 15)) >>> 0).toString(36)
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}
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