Function hufCanonicalCodeTable

src/cpp/tool/tinyexr.h:8518–8557

    //

    static void hufCanonicalCodeTable(long long hcode[HUF_ENCSIZE]) {
        long long n[59];

        //
        // For each i from 0 through 58, count the
        // number of different codes of length i, and
        // store the count in n[i].
        //

        for (int i = 0; i <= 58; ++i) n[i] = 0;

        for (int i = 0; i < HUF_ENCSIZE; ++i) n[hcode[i]] += 1;

        //
        // For each i from 58 through 1, compute the
        // numerically lowest code with length i, and
        // store that code in n[i].
        //

        long long c = 0;

        for (int i = 58; i > 0; --i) {
            long long nc = ((c + n[i]) >> 1);
            n[i] = c;
            c = nc;
        }

        //
        // hcode[i] contains the length, l, of the
        // code for symbol i.  Assign the next available
        // code of length l to the symbol and store both
        // l and the code in hcode[i].
        //

        for (int i = 0; i < HUF_ENCSIZE; ++i) {
            int l = static_cast<int>(hcode[i]);

            if (l > 0) hcode[i] = l | (n[l]++ << 6);
        }
    }

    //
    // Compute Huffman codes (based on frq input) and store them in frq: