Codex
35 lines
952 B
JavaScript
35 lines
952 B
JavaScript
function mix32(value) {
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let mixed = value >>> 0;
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mixed ^= mixed >>> 16;
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mixed = Math.imul(mixed, 0x7feb352d);
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mixed ^= mixed >>> 15;
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mixed = Math.imul(mixed, 0x846ca68b);
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mixed ^= mixed >>> 16;
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return mixed >>> 0;
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}
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export function hashString(value) {
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let hash = 2166136261;
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for (let index = 0; index < value.length; index += 1) {
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hash ^= value.charCodeAt(index);
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hash = Math.imul(hash, 16777619);
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}
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return hash >>> 0;
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}
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export function whiteNoiseAt(seed, sampleIndex) {
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const mixed = mix32((seed >>> 0) ^ Math.imul(sampleIndex + 1, 0x9e3779b1));
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return (mixed / 0xffffffff) * 2 - 1;
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}
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export function pinkNoiseAt(seed, sampleIndex) {
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let total = 0;
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let weight = 0;
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for (let octave = 0; octave < 8; octave += 1) {
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const octaveWeight = 1 / (octave + 1);
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total += whiteNoiseAt(seed + octave * 0x1f123bb5, sampleIndex >> octave) * octaveWeight;
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weight += octaveWeight;
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}
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return total / weight;
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}
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