node_modules/gearhash-jit/dist/esm/index.js

/**
 * gearhash-jit — Fast GEAR rolling hash for content-defined chunking.
 *
 * Uses a tiny hand-written WASM module with native i64 arithmetic.
 * The hash state is kept as raw bytes in JS (avoiding BigInt in the hot path)
 * and written to WASM memory only for the `nextMatch` call.
 */
import { initWasm, wasmNextMatch, getView, HASH_OFFSET, MASK_OFFSET, INPUT_OFFSET, MAX_INPUT_SIZE, } from "./wasm.js";
export { GEAR_TABLE } from "./table.js";
export class Hasher {
    maskBytes;
    /**
     * The current 64-bit rolling hash state as 8 little-endian bytes.
     * Updated after every `nextMatch` call. Zeroed by `resetHash()`.
     */
    hash;
    constructor(mask) {
        initWasm();
        this.maskBytes = new Uint8Array(8);
        this.hash = new Uint8Array(8);
        new DataView(this.maskBytes.buffer).setBigUint64(0, mask, true);
    }
    /**
     * Scan `buf` for the next gear-hash match. The internal hash state
     * carries over between calls (for split-buffer scanning).
     *
     * @returns 1-based byte position of the match, or -1 if none found.
     */
    nextMatch(buf) {
        const len = buf.length;
        if (len === 0)
            return -1;
        if (len > MAX_INPUT_SIZE) {
            throw new RangeError(`Input too large: ${len} > ${MAX_INPUT_SIZE}`);
        }
        const view = getView();
        view.set(this.hash, HASH_OFFSET);
        view.set(this.maskBytes, MASK_OFFSET);
        view.set(buf, INPUT_OFFSET);
        const pos = wasmNextMatch(INPUT_OFFSET, len);
        this.hash.set(view.subarray(HASH_OFFSET, HASH_OFFSET + 8));
        return pos;
    }
    /** Reset rolling hash to zero (call when starting a new chunk). */
    resetHash() {
        this.hash.fill(0);
    }
}