private int sendMTFValues1()

in src/main/java/org/apache/commons/compress/compressors/bzip2/BZip2CompressorOutputStream.java [791:905]

• 84 lines of code
• 14 McCabe index (conditional complexity)

    private int sendMTFValues1(final int nGroups, final int alphaSize) {
        final Data dataShadow = this.data;
        final int[][] rfreq = dataShadow.sendMTFValues_rfreq;
        final int[] fave = dataShadow.sendMTFValues_fave;
        final short[] cost = dataShadow.sendMTFValues_cost;
        final char[] sfmap = dataShadow.sfmap;
        final byte[] selector = dataShadow.selector;
        final byte[][] len = dataShadow.sendMTFValues_len;
        final byte[] len_0 = len[0];
        final byte[] len_1 = len[1];
        final byte[] len_2 = len[2];
        final byte[] len_3 = len[3];
        final byte[] len_4 = len[4];
        final byte[] len_5 = len[5];
        final int nMTFShadow = this.nMTF;

        int nSelectors = 0;

        for (int iter = 0; iter < N_ITERS; iter++) {
            for (int t = nGroups; --t >= 0;) {
                fave[t] = 0;
                final int[] rfreqt = rfreq[t];
                for (int i = alphaSize; --i >= 0;) {
                    rfreqt[i] = 0;
                }
            }

            nSelectors = 0;

            for (int gs = 0; gs < this.nMTF;) {
                // Set group start & end marks.

                // Calculate the cost of this group as coded by each of the
                // coding tables.

                final int ge = Math.min(gs + G_SIZE - 1, nMTFShadow - 1);

                final byte mask = (byte) 0xff;
                if (nGroups == N_GROUPS) {
                    // unrolled version of the else-block

                    short cost0 = 0;
                    short cost1 = 0;
                    short cost2 = 0;
                    short cost3 = 0;
                    short cost4 = 0;
                    short cost5 = 0;

                    for (int i = gs; i <= ge; i++) {
                        final int icv = sfmap[i];
                        cost0 += (short) (len_0[icv] & mask);
                        cost1 += (short) (len_1[icv] & mask);
                        cost2 += (short) (len_2[icv] & mask);
                        cost3 += (short) (len_3[icv] & mask);
                        cost4 += (short) (len_4[icv] & mask);
                        cost5 += (short) (len_5[icv] & mask);
                    }

                    cost[0] = cost0;
                    cost[1] = cost1;
                    cost[2] = cost2;
                    cost[3] = cost3;
                    cost[4] = cost4;
                    cost[5] = cost5;

                } else {
                    for (int t = nGroups; --t >= 0;) {
                        cost[t] = 0;
                    }

                    for (int i = gs; i <= ge; i++) {
                        final int icv = sfmap[i];
                        for (int t = nGroups; --t >= 0;) {
                            cost[t] += (short) (len[t][icv] & mask);
                        }
                    }
                }

                /*
                 * Find the coding table which is best for this group, and record its identity in the selector table.
                 */
                int bt = -1;
                for (int t = nGroups, bc = 999999999; --t >= 0;) {
                    final int cost_t = cost[t];
                    if (cost_t < bc) {
                        bc = cost_t;
                        bt = t;
                    }
                }

                fave[bt]++;
                selector[nSelectors] = (byte) bt;
                nSelectors++;

                /*
                 * Increment the symbol frequencies for the selected table.
                 */
                final int[] rfreq_bt = rfreq[bt];
                for (int i = gs; i <= ge; i++) {
                    rfreq_bt[sfmap[i]]++;
                }

                gs = ge + 1;
            }

            /*
             * Recompute the tables based on the accumulated frequencies.
             */
            for (int t = 0; t < nGroups; t++) {
                hbMakeCodeLengths(len[t], rfreq[t], this.data, alphaSize, 20);
            }
        }

        return nSelectors;
    }