export declare const MAX_DECOMPRESSED_BLOCK_SIZE: number;
/** True if using native lz4-napi, false if using WASM */
export declare let usingNativeLz4: boolean;
/** True if using native zstd-napi, false if using WASM */
export declare let usingNativeZstd: boolean;
export declare function init(): Promise<void>;
export declare function concat(arrays: Uint8Array<ArrayBufferLike>[]): Uint8Array<ArrayBufferLike>;
export declare function readUInt32LE(arr: Uint8Array, offset: number): number;
export declare function writeUInt32LE(arr: Uint8Array, value: number, offset: number): void;
export declare const Method: {
    readonly None: 2;
    readonly LZ4: 130;
    readonly ZSTD: 144;
};
export type MethodCode = (typeof Method)[keyof typeof Method];
export type Compression = false | "lz4" | "zstd" | {
    method: "zstd";
    level?: number;
};
export declare function toMethodCode(compression: Compression): MethodCode;
/** ZSTD compression level, defined only for the `{ method: "zstd", level }` form. */
export declare function compressionLevel(compression: Compression): number | undefined;
export declare function cityHash128LE(bytes: Uint8Array): Uint8Array;
/**
 * Raw LZ4 block compression (no ClickHouse block wrapper, no frame headers).
 * Used internally for ClickHouse native block format.
 */
export declare function lz4CompressRaw(raw: Uint8Array): Uint8Array;
/**
 * LZ4 frame compression for HTTP Content-Encoding.
 * Produces standard LZ4 frame format with magic number and checksums.
 * Only available with lz4-napi (Node.js), not in WASM builds.
 */
export declare function lz4CompressFrame(raw: Uint8Array): Uint8Array;
/**
 * Raw ZSTD compression (no ClickHouse block wrapper).
 * Use for HTTP Content-Encoding compression.
 */
export declare function zstdCompressRaw(raw: Uint8Array, level?: number): Uint8Array;
/**
 * Encode a block with ClickHouse native compression format.
 * @param raw - Uncompressed data
 * @param compression - Compression method; the `{ method: "zstd", level }` form carries a ZSTD level
 * @returns Compressed block with checksum header
 */
export declare function encodeBlock(raw: Uint8Array, compression?: Compression): Uint8Array;
/** Calculate required buffer size for encodeBlock output */
export declare function decodeBlock(block: Uint8Array): Uint8Array;
export declare function decodeBlocks(data: Uint8Array): Uint8Array;
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