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

"use strict";
/**
 * 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.
 */
Object.defineProperty(exports, "__esModule", { value: true });
exports.Hasher = exports.GEAR_TABLE = void 0;
const wasm_js_1 = require("./wasm.js");
var table_js_1 = require("./table.js");
Object.defineProperty(exports, "GEAR_TABLE", { enumerable: true, get: function () { return table_js_1.GEAR_TABLE; } });
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) {
        (0, wasm_js_1.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 > wasm_js_1.MAX_INPUT_SIZE) {
            throw new RangeError(`Input too large: ${len} > ${wasm_js_1.MAX_INPUT_SIZE}`);
        }
        const view = (0, wasm_js_1.getView)();
        view.set(this.hash, wasm_js_1.HASH_OFFSET);
        view.set(this.maskBytes, wasm_js_1.MASK_OFFSET);
        view.set(buf, wasm_js_1.INPUT_OFFSET);
        const pos = (0, wasm_js_1.wasmNextMatch)(wasm_js_1.INPUT_OFFSET, len);
        this.hash.set(view.subarray(wasm_js_1.HASH_OFFSET, wasm_js_1.HASH_OFFSET + 8));
        return pos;
    }
    /** Reset rolling hash to zero (call when starting a new chunk). */
    resetHash() {
        this.hash.fill(0);
    }
}
exports.Hasher = Hasher;