Class Inflate

packages/alphatab/src/zip/Inflate.ts:93–407

 * @internal
 */
export class Inflate {
    private static _lenExtraBitsTbl: number[] = [
        0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0, -1, -1
    ];
    private static _lenBaseValTbl: number[] = [
        3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31, 35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227,
        258
    ];
    private static _distExtraBitsTbl: number[] = [
        0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 10, 10, 11, 11, 12, 12, 13, 13, -1, -1
    ];
    private static _distBaseValTbl: number[] = [
        1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193, 257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097,
        6145, 8193, 12289, 16385, 24577
    ];
    private static _codeLengthsPos: number[] = [16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15];

    private static _fixedHuffman: Huffman = Inflate._buildFixedHuffman();

    private static _buildFixedHuffman(): Huffman {
        const a: number[] = [];
        for (let n: number = 0; n < 288; n++) {
            a.push(n <= 143 ? 8 : n <= 255 ? 9 : n <= 279 ? 7 : 8);
        }
        return HuffTools.make(a, 0, 288, 10);
    }

    private _nbits: number = 0;
    private _bits: number = 0;
    private _state: InflateState = InflateState.Block;
    private _isFinal: boolean = false;
    private _huffman: Huffman = Inflate._fixedHuffman;
    private _huffdist: Huffman | null = null;
    private _len: number = 0;
    private _dist: number = 0;
    private _needed: number = 0;
    private _output: Uint8Array | null = null;
    private _outpos: number = 0;
    private _input: IReadable;
    private _lengths: number[] = [];
    private _window: InflateWindow = new InflateWindow();

    public constructor(readable: IReadable) {
        this._input = readable;
        for (let i: number = 0; i < 19; i++) {
            this._lengths.push(-1);
        }
    }

    public readBytes(b: Uint8Array, pos: number, len: number): number {
        this._needed = len;
        this._outpos = pos;
        this._output = b;
        if (len > 0) {
            while (this._inflateLoop()) {
                // inflating...
            }
        }