Method flushBlock

packages/alphatab/src/zip/DeflaterHuffman.ts:579–636

(stored: Uint8Array, storedOffset: number, storedLength: number, lastBlock: boolean)

    }

    public flushBlock(stored: Uint8Array, storedOffset: number, storedLength: number, lastBlock: boolean) {
        this._literalTree.freqs[DeflaterHuffman._eofSymbol]++;

        // Build trees
        this._literalTree.buildTree();
        this._distTree.buildTree();

        // Calculate bitlen frequency
        this._literalTree.calcBLFreq(this._blTree);
        this._distTree.calcBLFreq(this._blTree);

        // Build bitlen tree
        this._blTree.buildTree();

        let blTreeCodes = 4;
        for (let i = 18; i > blTreeCodes; i--) {
            if (this._blTree.length![DeflaterHuffman._blOrder[i]] > 0) {
                blTreeCodes = i + 1;
            }
        }
        let optLen =
            14 +
            blTreeCodes * 3 +
            this._blTree.getEncodedLength() +
            this._literalTree.getEncodedLength() +
            this._distTree.getEncodedLength() +
            this._extraBits;

        let staticLen = this._extraBits;
        for (let i = 0; i < DeflaterHuffman._literalNum; i++) {
            staticLen += this._literalTree.freqs[i] * DeflaterHuffman._staticLLength[i];
        }
        for (let i = 0; i < DeflaterHuffman._distNum; i++) {
            staticLen += this._distTree.freqs[i] * DeflaterHuffman._staticDLength[i];
        }
        if (optLen >= staticLen) {
            // Force static trees
            optLen = staticLen;
        }

        if (storedOffset >= 0 && storedLength + 4 < optLen >> 3) {
            // Store Block
            this.flushStoredBlock(stored, storedOffset, storedLength, lastBlock);
        } else if (optLen === staticLen) {
            // Encode with static tree
            this.pending.writeBits((DeflaterHuffman.staticTrees << 1) + (lastBlock ? 1 : 0), 3);
            this._literalTree.setStaticCodes(DeflaterHuffman._staticLCodes, DeflaterHuffman._staticLLength);
            this._distTree.setStaticCodes(DeflaterHuffman._staticDCodes, DeflaterHuffman._staticDLength);
            this.compressBlock();
            this.reset();
        } else {
            // Encode with dynamic tree
            this.pending.writeBits((DeflaterHuffman.dynTrees << 1) + (lastBlock ? 1 : 0), 3);
            this.sendAllTrees(blTreeCodes);
            this.compressBlock();
            this.reset();
        }
    }