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/**
* Deterministic string hashing and sub-seed derivation. Shared between the
* PRNG and any other system that needs stable-across-runs uint32 from
* string keys.
*/
/**
* xmur3 string hash. Returns a uint32. Pure function — same input always
* produces the same output.
*/
export function hashString(input: string): number {
let h = 1779033703 ^ input.length
for (let i = 0; i < input.length; i++) {
h = Math.imul(h ^ input.charCodeAt(i), 3432918353)
h = (h << 13) | (h >>> 19)
}
h = Math.imul(h ^ (h >>> 16), 2246822507)
h = Math.imul(h ^ (h >>> 13), 3266489909)
h ^= h >>> 16
return h >>> 0
}
/**
* Derive a child seed from a parent seed and a label. Stable: same
* (parentSeed, label) always produces the same child seed, which is what
* lets Tier 3 NPCs be regenerated on demand from their (world, identity)
* tuple without storing their state.
*/
export function deriveSeed(parentSeed: number, label: string): number {
return hashString(`${parentSeed >>> 0}:${label}`)
}
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