/**
 * Provides a bitwise input buffer supporting incremental bit loading and byte-aligned copying.
 *
 * @private
 */
export declare class _InBuffer {
    /**
     * Input byte buffer for bit-level reads.
     *
     * @private
     */
    _buffer: number[];
    /**
     * Start index of unread data in the buffer.
     *
     * @private
     */
    _begin: number;
    /**
     * End index of unread data in the buffer.
     *
     * @private
     */
    _end: number;
    /**
     * Bit buffer accumulating incoming bits.
     *
     * @private
     */
    _bBuffer: number;
    /**
     * Number of valid bits currently in the bit buffer.
     *
     * @private
     */
    _bInBuffer: number;
    constructor();
    /**
     * Gets the total number of full bytes currently available including pending bit buffer.
     *
     * @private
     * @returns {number} bytes.
     */
    readonly _bytes: number;
    /**
     * Indicates whether more input bytes are needed for further decoding.
     *
     * @private
     * @returns {boolean} needsInput.
     */
    _needsInput(): boolean;
    /**
     * Ensures the requested number of bits are available by pulling bytes into the bit buffer.
     *
     * @private
     * @param {number} count Number of bits required.
     * @returns {boolean} available.
     */
    _availableBits(count: number): boolean;
    /**
     * Loads up to 16 bits into the bit buffer and returns the current bit buffer value.
     *
     * @private
     * @returns {number} bitBuffer.
     */
    _load16Bits(): number;
    /**
     * Returns a bit mask with the lowest count bits set.
     *
     * @private
     * @param {number} count Number of low bits to set.
     * @returns {number} mask.
     */
    _getBitMask(count: number): number;
    /**
     * Retrieves the specified number of bits from the bit buffer and advances the bit position.
     *
     * @private
     * @param {number} count Number of bits to read.
     * @returns {number} value or -1 when insufficient bits.
     */
    _getBits(count: number): number;
    /**
     * Copies bytes into the target array from the buffered bits and underlying input, returning the count copied.
     *
     * @private
     * @param {number[]} output Destination buffer.
     * @param {number} offset Start index in the destination buffer.
     * @param {number} length Maximum number of bytes to copy.
     * @returns {number} copied.
     */
    _copyTo(output: number[], offset: number, length: number): number;
    /**
     * Sets the underlying input buffer range for subsequent bit loading operations.
     *
     * @private
     * @param {number[]} buffer Source input buffer.
     * @param {number} offset Start index of the input window.
     * @param {number} length Number of bytes available from offset.
     * @returns {void} nothing.
     */
    _setInput(buffer: number[], offset: number, length: number): void;
    /**
     * Skips the specified number of bits in the bit buffer.
     *
     * @private
     * @param {number} n Number of bits to skip.
     * @returns {void} nothing.
     */
    _skipBits(n: number): void;
    /**
     * Advances to the next byte boundary by discarding any remaining bits in the current byte.
     *
     * @private
     * @returns {void} nothing.
     */
    _skipByteBoundary(): void;
}