29 lines
1.4 KiB
TypeScript
29 lines
1.4 KiB
TypeScript
// cyrb53 (c) 2018 bryc (github.com/bryc). License: Public domain. Attribution appreciated.
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// A fast and simple 64-bit (or 53-bit) string hash function with decent collision resistance.
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// Largely inspired by MurmurHash2/3, but with a focus on speed/simplicity.
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// See https://stackoverflow.com/questions/7616461/generate-a-hash-from-string-in-javascript/52171480#52171480
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// https://github.com/bryc/code/blob/master/jshash/experimental/cyrb53.js
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export default function cyrb64(str: string, seed = 0) {
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let h1 = 0xdeadbeef ^ seed, h2 = 0x41c6ce57 ^ seed;
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for (let i = 0, ch; i < str.length; i++) {
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ch = str.charCodeAt(i);
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h1 = Math.imul(h1 ^ ch, 2654435761);
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h2 = Math.imul(h2 ^ ch, 1597334677);
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}
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h1 = Math.imul(h1 ^ (h1 >>> 16), 2246822507);
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h1 ^= Math.imul(h2 ^ (h2 >>> 13), 3266489909);
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h2 = Math.imul(h2 ^ (h2 >>> 16), 2246822507);
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h2 ^= Math.imul(h1 ^ (h1 >>> 13), 3266489909);
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// For a single 53-bit numeric return value we could return
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// 4294967296 * (2097151 & h2) + (h1 >>> 0);
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// but we instead return the full 64-bit value:
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return [h2 >>> 0, h1 >>> 0];
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}
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// An improved, *insecure* 64-bit hash that's short, fast, and has no dependencies.
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// Output is always 14 characters.
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export function cyrb64Hash(str: string, seed = 0) {
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const [h2, h1] = cyrb64(str, seed);
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return h2.toString(36).padStart(7, "0") + h1.toString(36).padStart(7, "0");
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}
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