/**
 * Arbitrary-precision integer helper using decimal digit arrays for internal math.
 *
 * @private
 */
export declare class _PdfBigInt {
    private digits;
    constructor(decimalStr?: string);
    /**
     * Parse a decimal string into an internal reversed-digit array.
     *
     * @private
     * @param {string} str - Decimal string to parse.
     * @returns {number[]} Reversed array of decimal digits.
     */
    _parseDecimalString(str: string): number[];
    /**
     * Serialize the internal big integer to its decimal string representation.
     *
     * @private
     * @returns {string} Decimal string representation of the integer.
     */
    _toString(): string;
    /**
     * Convert the internal decimal representation to a JavaScript `bigint`.
     *
     * @private
     * @returns {bigint} The numeric value as a `bigint`.
     */
    _toBigInt(): bigint;
    /**
     * Add a small integer value to this big integer (in-place).
     *
     * @private
     * @param {number} n - Small integer to add.
     * @returns {void}
     */
    _add(n: number): void;
    /**
     * Multiply this big integer by 256 (in-place), used when decoding binary data.
     *
     * @private
     * @returns {void}
     */
    _multiply(): void;
    /**
     * Compute the bit-length of the integer value.
     *
     * @private
     * @returns {number} Number of bits required to represent the value.
     */
    _bitLength(): number;
}