Method calcBLFreq

packages/alphatab/src/zip/DeflaterHuffman.ts:311–352

* Scan a literal or distance tree to determine the frequencies of the codes * in the bit length tree. * @param blTree

(blTree: Tree)

     * @param blTree
     */
    public calcBLFreq(blTree: Tree) {
        let maxCount: number; /* max repeat count */
        let minCount: number; /* min repeat count */
        let count: number; /* repeat count of the current code */
        let curlen = -1; /* length of current code */

        let i = 0;
        while (i < this.numCodes) {
            count = 1;
            const nextlen = this.length![i];
            if (nextlen === 0) {
                maxCount = 138;
                minCount = 3;
            } else {
                maxCount = 6;
                minCount = 3;
                if (curlen !== nextlen) {
                    blTree.freqs[nextlen]++;
                    count = 0;
                }
            }
            curlen = nextlen;
            i++;

            while (i < this.numCodes && curlen === this.length![i]) {
                i++;
                if (++count >= maxCount) {
                    break;
                }
            }

            if (count < minCount) {
                blTree.freqs[curlen] += count;
            } else if (curlen !== 0) {
                blTree.freqs[Tree._repeat3To6]++;
            } else if (count <= 10) {
                blTree.freqs[Tree._repeat3To10]++;
            } else {
                blTree.freqs[Tree._repeat11To138]++;
            }
        }
    }

    /**
     * Set static codes and length