/**
 * Compress a block of data using LZ4 block compression.
 * Returns the full ClickHouse compressed block including checksum.
 *
 * Format:
 *   checksum (16 bytes, CityHash128 of the rest)
 *   compression_method (1 byte, 0x82 for LZ4)
 *   compressed_size (4 bytes LE, includes header)
 *   uncompressed_size (4 bytes LE)
 *   compressed_data (bytes)
 */
export declare function compressBlock(data: Buffer): Buffer;
/**
 * Decompress a ClickHouse compressed block.
 * Expects the full block including checksum.
 * Returns the decompressed data.
 */
export declare function decompressBlock(buf: Buffer, offset?: number): {
    data: Buffer;
    bytesRead: number;
};
/**
 * Pure JS LZ4 block compression (simplified).
 * Uses a hash table for match finding.
 */
export declare function lz4CompressBlock(input: Buffer): Buffer;
/**
 * Pure JS LZ4 block decompression.
 */
export declare function lz4DecompressBlock(input: Buffer, uncompressedSize: number): Buffer;