/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you under the Apache License, Version 2.0 (the
    * "License"); you may not use this file except in compliance
    * with the License.  You may obtain a copy of the License at
    *
   *   https://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   */
  package org.apache.commons.compress.compressors.bzip2;
  
  import java.io.IOException;
  import java.io.OutputStream;
  import java.util.Arrays;
  
  import org.apache.commons.compress.compressors.CompressorOutputStream;
  
  /**
   * An output stream that compresses into the BZip2 format into another stream.
   *
   * <p>
   * The compression requires large amounts of memory. Thus you should call the {@link #close() close()} method as soon as possible, to force
   * {@code BZip2CompressorOutputStream} to release the allocated memory.
   * </p>
   *
   * <p>
   * You can shrink the amount of allocated memory and maybe raise the compression speed by choosing a lower blocksize, which in turn may cause a lower
   * compression ratio. You can avoid unnecessary memory allocation by avoiding using a blocksize which is bigger than the size of the input.
   * </p>
   *
   * <p>
   * You can compute the memory usage for compressing by the following formula:
   * </p>
   *
   * <pre>
   * &lt;code&gt;400k + (9 * blocksize)&lt;/code&gt;.
   * </pre>
   *
   * <p>
   * To get the memory required for decompression by {@link BZip2CompressorInputStream} use
   * </p>
   *
   * <pre>
   * &lt;code&gt;65k + (5 * blocksize)&lt;/code&gt;.
   * </pre>
   *
   * <table style="width:100%" border="1">
   * <caption>Memory usage by blocksize</caption>
   * <tr>
   * <th colspan="3">Memory usage by blocksize</th>
   * </tr>
   * <tr>
   * <th style="text-align: right">Blocksize</th>
   * <th style="text-align: right">Compression<br>
   * memory usage</th>
   * <th style="text-align: right">Decompression<br>
   * memory usage</th>
   * </tr>
   * <tr>
   * <td style="text-align: right">100k</td>
   * <td style="text-align: right">1300k</td>
   * <td style="text-align: right">565k</td>
   * </tr>
   * <tr>
   * <td style="text-align: right">200k</td>
   * <td style="text-align: right">2200k</td>
   * <td style="text-align: right">1065k</td>
   * </tr>
   * <tr>
   * <td style="text-align: right">300k</td>
   * <td style="text-align: right">3100k</td>
   * <td style="text-align: right">1565k</td>
   * </tr>
   * <tr>
   * <td style="text-align: right">400k</td>
   * <td style="text-align: right">4000k</td>
   * <td style="text-align: right">2065k</td>
   * </tr>
   * <tr>
   * <td style="text-align: right">500k</td>
   * <td style="text-align: right">4900k</td>
   * <td style="text-align: right">2565k</td>
   * </tr>
   * <tr>
   * <td style="text-align: right">600k</td>
   * <td style="text-align: right">5800k</td>
   * <td style="text-align: right">3065k</td>
   * </tr>
   * <tr>
   * <td style="text-align: right">700k</td>
  * <td style="text-align: right">6700k</td>
  * <td style="text-align: right">3565k</td>
  * </tr>
  * <tr>
  * <td style="text-align: right">800k</td>
  * <td style="text-align: right">7600k</td>
  * <td style="text-align: right">4065k</td>
  * </tr>
  * <tr>
  * <td style="text-align: right">900k</td>
  * <td style="text-align: right">8500k</td>
  * <td style="text-align: right">4565k</td>
  * </tr>
  * </table>
  *
  * <p>
  * For decompression {@code BZip2CompressorInputStream} allocates less memory if the bzipped input is smaller than one block.
  * </p>
  *
  * <p>
  * Instances of this class are not threadsafe.
  * </p>
  *
  * <p>
  * TODO: Update to BZip2 1.0.1
  * </p>
  *
  * @NotThreadSafe
  */
 public class BZip2CompressorOutputStream extends CompressorOutputStream<OutputStream> implements BZip2Constants {
 
     static final class Data {
 
         // with blockSize 900k
         /* maps unsigned byte => "does it occur in block" */
         final boolean[] inUse = new boolean[256]; // 256 byte
         final byte[] unseqToSeq = new byte[256]; // 256 byte
         final int[] mtfFreq = new int[MAX_ALPHA_SIZE]; // 1032 byte
         final byte[] selector = new byte[MAX_SELECTORS]; // 18002 byte
         final byte[] selectorMtf = new byte[MAX_SELECTORS]; // 18002 byte
 
         final byte[] generateMTFValues_yy = new byte[256]; // 256 byte
         final byte[][] sendMTFValues_len = new byte[N_GROUPS][MAX_ALPHA_SIZE]; // 1548
         // byte
         final int[][] sendMTFValues_rfreq = new int[N_GROUPS][MAX_ALPHA_SIZE]; // 6192
         // byte
         final int[] sendMTFValues_fave = new int[N_GROUPS]; // 24 byte
         final short[] sendMTFValues_cost = new short[N_GROUPS]; // 12 byte
         final int[][] sendMTFValues_code = new int[N_GROUPS][MAX_ALPHA_SIZE]; // 6192
         // byte
         final byte[] sendMTFValues2_pos = new byte[N_GROUPS]; // 6 byte
         final boolean[] sentMTFValues4_inUse16 = new boolean[16]; // 16 byte
 
         final int[] heap = new int[MAX_ALPHA_SIZE + 2]; // 1040 byte
         final int[] weight = new int[MAX_ALPHA_SIZE * 2]; // 2064 byte
         final int[] parent = new int[MAX_ALPHA_SIZE * 2]; // 2064 byte
 
         // ------------
         // 333408 byte
 
         /*
          * holds the RLEd block of original data starting at index 1. After sorting the last byte added to the buffer is at index 0.
          */
         final byte[] block; // 900021 byte
         /*
          * maps index in Burrows-Wheeler transformed block => index of byte in original block
          */
         final int[] fmap; // 3600000 byte
         final char[] sfmap; // 3600000 byte
         // ------------
         // 8433529 byte
         // ============
 
         /**
          * Index of original line in Burrows-Wheeler table.
          *
          * <p>
          * This is the index in fmap that points to the last byte of the original data.
          * </p>
          */
         int origPtr;
 
         Data(final int blockSize100k) {
             final int n = blockSize100k * BASEBLOCKSIZE;
             this.block = new byte[n + 1 + NUM_OVERSHOOT_BYTES];
             this.fmap = new int[n];
             this.sfmap = new char[2 * n];
         }
 
     }
 
     /**
      * The minimum supported blocksize {@code  == 1}.
      */
     public static final int MIN_BLOCKSIZE = 1;
 
     /**
      * The maximum supported blocksize {@code  == 9}.
      */
     public static final int MAX_BLOCKSIZE = 9;
     private static final int GREATER_ICOST = 15;
 
     private static final int LESSER_ICOST = 0;
 
     /**
      * Chooses a blocksize based on the given length of the data to compress.
      *
      * @return The blocksize, between {@link #MIN_BLOCKSIZE} and {@link #MAX_BLOCKSIZE} both inclusive. For a negative {@code inputLength} this method returns
      *         {@code MAX_BLOCKSIZE} always.
      *
      * @param inputLength The length of the data which will be compressed by {@code BZip2CompressorOutputStream}.
      */
     public static int chooseBlockSize(final long inputLength) {
         return inputLength > 0 ? (int) Math.min(inputLength / 132000 + 1, 9) : MAX_BLOCKSIZE;
     }
 
     private static void hbAssignCodes(final int[] code, final byte[] length, final int minLen, final int maxLen, final int alphaSize) {
         int vec = 0;
         for (int n = minLen; n <= maxLen; n++) {
             for (int i = 0; i < alphaSize; i++) {
                 if ((length[i] & 0xff) == n) {
                     code[i] = vec;
                     vec++;
                 }
             }
             vec <<= 1;
         }
     }
 
     private static void hbMakeCodeLengths(final byte[] len, final int[] freq, final Data dat, final int alphaSize, final int maxLen) {
         /*
          * Nodes and heap entries run from 1. Entry 0 for both the heap and nodes is a sentinel.
          */
         final int[] heap = dat.heap;
         final int[] weight = dat.weight;
         final int[] parent = dat.parent;
 
         for (int i = alphaSize; --i >= 0;) {
             weight[i + 1] = (freq[i] == 0 ? 1 : freq[i]) << 8;
         }
 
         for (boolean tooLong = true; tooLong;) {
             tooLong = false;
 
             int nNodes = alphaSize;
             int nHeap = 0;
             heap[0] = 0;
             weight[0] = 0;
             parent[0] = -2;
 
             for (int i = 1; i <= alphaSize; i++) {
                 parent[i] = -1;
                 nHeap++;
                 heap[nHeap] = i;
 
                 int zz = nHeap;
                 final int tmp = heap[zz];
                 while (weight[tmp] < weight[heap[zz >> 1]]) {
                     heap[zz] = heap[zz >> 1];
                     zz >>= 1;
                 }
                 heap[zz] = tmp;
             }
 
             while (nHeap > 1) {
                 final int n1 = heap[1];
                 heap[1] = heap[nHeap];
                 nHeap--;
 
                 int yy = 0;
                 int zz = 1;
                 int tmp = heap[1];
 
                 while (true) {
                     yy = zz << 1;
 
                     if (yy > nHeap) {
                         break;
                     }
 
                     if (yy < nHeap && weight[heap[yy + 1]] < weight[heap[yy]]) {
                         yy++;
                     }
 
                     if (weight[tmp] < weight[heap[yy]]) {
                         break;
                     }
 
                     heap[zz] = heap[yy];
                     zz = yy;
                 }
 
                 heap[zz] = tmp;
 
                 final int n2 = heap[1];
                 heap[1] = heap[nHeap];
                 nHeap--;
 
                 yy = 0;
                 zz = 1;
                 tmp = heap[1];
 
                 while (true) {
                     yy = zz << 1;
 
                     if (yy > nHeap) {
                         break;
                     }
 
                     if (yy < nHeap && weight[heap[yy + 1]] < weight[heap[yy]]) {
                         yy++;
                     }
 
                     if (weight[tmp] < weight[heap[yy]]) {
                         break;
                     }
 
                     heap[zz] = heap[yy];
                     zz = yy;
                 }
 
                 heap[zz] = tmp;
                 nNodes++;
                 parent[n1] = parent[n2] = nNodes;
 
                 final int weight_n1 = weight[n1];
                 final int weight_n2 = weight[n2];
                 weight[nNodes] = (weight_n1 & 0xffffff00) + (weight_n2 & 0xffffff00) | 1 + Math.max(weight_n1 & 0x000000ff, weight_n2 & 0x000000ff);
 
                 parent[nNodes] = -1;
                 nHeap++;
                 heap[nHeap] = nNodes;
 
                 tmp = 0;
                 zz = nHeap;
                 tmp = heap[zz];
                 final int weight_tmp = weight[tmp];
                 while (weight_tmp < weight[heap[zz >> 1]]) {
                     heap[zz] = heap[zz >> 1];
                     zz >>= 1;
                 }
                 heap[zz] = tmp;
 
             }
 
             for (int i = 1; i <= alphaSize; i++) {
                 int j = 0;
                 int k = i;
 
                 for (int parent_k; (parent_k = parent[k]) >= 0;) {
                     k = parent_k;
                     j++;
                 }
 
                 len[i - 1] = (byte) j;
                 if (j > maxLen) {
                     tooLong = true;
                 }
             }
 
             if (tooLong) {
                 for (int i = 1; i < alphaSize; i++) {
                     int j = weight[i] >> 8;
                     j = 1 + (j >> 1);
                     weight[i] = j << 8;
                 }
             }
         }
     }
 
     /**
      * Index of the last char in the block, so the block size == last + 1.
      */
     private int last;
     /**
      * Always: in the range 0 .. 9. The current block size is 100000 * this number.
      */
     private final int blockSize100k;
 
     private int bsBuff;
 
     private int bsLive;
 
     private final CRC crc = new CRC();
     private int nInUse;
 
     private int nMTF;
     private int currentChar = -1;
     private int runLength;
 
     private int combinedCRC;
 
     private final int allowableBlockSize;
     /**
      * All memory intensive stuff.
      */
     private Data data;
 
     private BlockSort blockSorter;
 
     /**
      * Constructs a new {@code BZip2CompressorOutputStream} with a blocksize of 900k.
      *
      * @param out the destination stream.
      * @throws IOException          if an I/O error occurs in the specified stream.
      * @throws NullPointerException if {@code out == null}.
      */
     public BZip2CompressorOutputStream(final OutputStream out) throws IOException {
         this(out, MAX_BLOCKSIZE);
     }
 
     /**
      * Constructs a new {@code BZip2CompressorOutputStream} with specified blocksize.
      *
      * @param out       the destination stream.
      * @param blockSize the blockSize as 100k units.
      * @throws IOException              if an I/O error occurs in the specified stream.
      * @throws IllegalArgumentException if {@code (blockSize &lt; 1) || (blockSize &gt; 9)}.
      * @throws NullPointerException     if {@code out == null}.
      * @see #MIN_BLOCKSIZE
      * @see #MAX_BLOCKSIZE
      */
     public BZip2CompressorOutputStream(final OutputStream out, final int blockSize) throws IOException {
         super(out);
         if (blockSize < 1) {
             throw new IllegalArgumentException("blockSize(" + blockSize + ") < 1");
         }
         if (blockSize > 9) {
             throw new IllegalArgumentException("blockSize(" + blockSize + ") > 9");
         }
         this.blockSize100k = blockSize;
         /* 20 is just a paranoia constant */
         this.allowableBlockSize = this.blockSize100k * BASEBLOCKSIZE - 20;
         init();
     }
 
     private void blockSort() {
         blockSorter.blockSort(data, last);
     }
 
     private void bsFinishedWithStream() throws IOException {
         while (this.bsLive > 0) {
             final int ch = this.bsBuff >> 24;
             this.out.write(ch); // write 8-bit
             this.bsBuff <<= 8;
             this.bsLive -= 8;
         }
     }
 
     private void bsPutInt(final int u) throws IOException {
         bsW(8, u >> 24 & 0xff);
         bsW(8, u >> 16 & 0xff);
         bsW(8, u >> 8 & 0xff);
         bsW(8, u & 0xff);
     }
 
     private void bsPutUByte(final int c) throws IOException {
         bsW(8, c);
     }
 
     private void bsW(final int n, final int v) throws IOException {
         final OutputStream outShadow = this.out;
         int bsLiveShadow = this.bsLive;
         int bsBuffShadow = this.bsBuff;
 
         while (bsLiveShadow >= 8) {
             outShadow.write(bsBuffShadow >> 24); // write 8-bit
             bsBuffShadow <<= 8;
             bsLiveShadow -= 8;
         }
 
         this.bsBuff = bsBuffShadow | v << 32 - bsLiveShadow - n;
         this.bsLive = bsLiveShadow + n;
     }
 
     @Override
     public void close() throws IOException {
         if (!isClosed()) {
             try {
                 finish();
             } finally {
                 super.close();
             }
         }
     }
 
     private void endBlock() throws IOException {
         final int blockCRC = this.crc.getValue();
         this.combinedCRC = this.combinedCRC << 1 | this.combinedCRC >>> 31;
         this.combinedCRC ^= blockCRC;
 
         // empty block at end of file
         if (this.last == -1) {
             return;
         }
 
         /* sort the block and establish posn of original string */
         blockSort();
 
         /*
          * A 6-byte block header, the value chosen arbitrarily as 0x314159265359 :-). A 32 bit value does not really give a strong enough guarantee that the
          * value will not appear by chance in the compressed data stream. Worst-case probability of this event, for a 900k block, is about 2.0e-3 for 32 bits,
          * 1.0e-5 for 40 bits and 4.0e-8 for 48 bits. For a compressed file of size 100Gb -- about 100000 blocks -- only a 48-bit marker will do. NB: normal
          * compression/ decompression doesn't rely on these statistical properties. They are only important when trying to recover blocks from damaged files.
          */
         bsPutUByte(0x31);
         bsPutUByte(0x41);
         bsPutUByte(0x59);
         bsPutUByte(0x26);
         bsPutUByte(0x53);
         bsPutUByte(0x59);
 
         /* Now the block's CRC, so it is in a known place. */
         bsPutInt(blockCRC);
 
         /* Now a single bit indicating no randomization. */
         bsW(1, 0);
 
         /* Finally, block's contents proper. */
         moveToFrontCodeAndSend();
     }
 
     private void endCompression() throws IOException {
         /*
          * Now another magic 48-bit number, 0x177245385090, to indicate the end of the last block. (sqrt(pi), if you want to know. I did want to use e, but it
          * contains too much repetition -- 27 18 28 18 28 46 -- for me to feel statistically comfortable. Call me paranoid.)
          */
         bsPutUByte(0x17);
         bsPutUByte(0x72);
         bsPutUByte(0x45);
         bsPutUByte(0x38);
         bsPutUByte(0x50);
         bsPutUByte(0x90);
 
         bsPutInt(this.combinedCRC);
         bsFinishedWithStream();
     }
 
     @Override
     public void finish() throws IOException {
         if (!isClosed()) {
             try {
                 if (this.runLength > 0) {
                     writeRun();
                 }
                 this.currentChar = -1;
                 endBlock();
                 endCompression();
             } finally {
                 this.blockSorter = null;
                 this.data = null;
             }
         }
     }
 
     @Override
     public void flush() throws IOException {
         if (out != null) {
             super.flush();
         }
     }
 
     /*
      * Performs Move-To-Front on the Burrows-Wheeler transformed buffer, storing the MTFed data in data.sfmap in RUNA/RUNB run-length-encoded form.
      *
      * <p>Keeps track of byte frequencies in data.mtfFreq at the same time.</p>
      */
     private void generateMTFValues() {
         final int lastShadow = this.last;
         final Data dataShadow = this.data;
         final boolean[] inUse = dataShadow.inUse;
         final byte[] block = dataShadow.block;
         final int[] fmap = dataShadow.fmap;
         final char[] sfmap = dataShadow.sfmap;
         final int[] mtfFreq = dataShadow.mtfFreq;
         final byte[] unseqToSeq = dataShadow.unseqToSeq;
         final byte[] yy = dataShadow.generateMTFValues_yy;
 
         // make maps
         int nInUseShadow = 0;
         for (int i = 0; i < 256; i++) {
             if (inUse[i]) {
                 unseqToSeq[i] = (byte) nInUseShadow;
                 nInUseShadow++;
             }
         }
         this.nInUse = nInUseShadow;
 
         final int eob = nInUseShadow + 1;
 
         Arrays.fill(mtfFreq, 0, eob + 1, 0);
 
         for (int i = nInUseShadow; --i >= 0;) {
             yy[i] = (byte) i;
         }
 
         int wr = 0;
         int zPend = 0;
 
         for (int i = 0; i <= lastShadow; i++) {
             final byte ll_i = unseqToSeq[block[fmap[i]] & 0xff];
             byte tmp = yy[0];
             int j = 0;
 
             while (ll_i != tmp) {
                 j++;
                 final byte tmp2 = tmp;
                 tmp = yy[j];
                 yy[j] = tmp2;
             }
             yy[0] = tmp;
 
             if (j == 0) {
                 zPend++;
             } else {
                 if (zPend > 0) {
                     zPend--;
                     while (true) {
                         if ((zPend & 1) == 0) {
                             sfmap[wr] = RUNA;
                             wr++;
                             mtfFreq[RUNA]++;
                         } else {
                             sfmap[wr] = RUNB;
                             wr++;
                             mtfFreq[RUNB]++;
                         }
 
                         if (zPend < 2) {
                             break;
                         }
                         zPend = zPend - 2 >> 1;
                     }
                     zPend = 0;
                 }
                 sfmap[wr] = (char) (j + 1);
                 wr++;
                 mtfFreq[j + 1]++;
             }
         }
 
         if (zPend > 0) {
             zPend--;
             while (true) {
                 if ((zPend & 1) == 0) {
                     sfmap[wr] = RUNA;
                     wr++;
                     mtfFreq[RUNA]++;
                 } else {
                     sfmap[wr] = RUNB;
                     wr++;
                     mtfFreq[RUNB]++;
                 }
 
                 if (zPend < 2) {
                     break;
                 }
                 zPend = zPend - 2 >> 1;
             }
         }
 
         sfmap[wr] = (char) eob;
         mtfFreq[eob]++;
         this.nMTF = wr + 1;
     }
 
     /**
      * Returns the blocksize parameter specified at construction time.
      *
      * @return the blocksize parameter specified at construction time
      */
     public final int getBlockSize() {
         return this.blockSize100k;
     }
 
     /**
      * Writes magic bytes like BZ on the first position of the stream and bytes indicating the file-format, which is huffmanized, followed by a digit indicating
      * blockSize100k.
      *
      * @throws IOException if the magic bytes could not been written
      */
     private void init() throws IOException {
         bsPutUByte('B');
         bsPutUByte('Z');
 
         this.data = new Data(this.blockSize100k);
         this.blockSorter = new BlockSort(this.data);
 
         // huffmanized magic bytes
         bsPutUByte('h');
         bsPutUByte('0' + this.blockSize100k);
 
         this.combinedCRC = 0;
         initBlock();
     }
 
     private void initBlock() {
         // blockNo++;
         this.crc.reset();
         this.last = -1;
         // ch = 0;
 
         final boolean[] inUse = this.data.inUse;
         for (int i = 256; --i >= 0;) {
             inUse[i] = false;
         }
 
     }
 
     private void moveToFrontCodeAndSend() throws IOException {
         bsW(24, this.data.origPtr);
         generateMTFValues();
         sendMTFValues();
     }
 
     private void sendMTFValues() throws IOException {
         final byte[][] len = this.data.sendMTFValues_len;
         final int alphaSize = this.nInUse + 2;
 
         for (int t = N_GROUPS; --t >= 0;) {
             final byte[] len_t = len[t];
             for (int v = alphaSize; --v >= 0;) {
                 len_t[v] = GREATER_ICOST;
             }
         }
 
         /* Decide how many coding tables to use */
         // assert (this.nMTF > 0) : this.nMTF;
         final int nGroups = this.nMTF < 200 ? 2 : this.nMTF < 600 ? 3 : this.nMTF < 1200 ? 4 : this.nMTF < 2400 ? 5 : 6;
 
         /* Generate an initial set of coding tables */
         sendMTFValues0(nGroups, alphaSize);
 
         /*
          * Iterate up to N_ITERS times to improve the tables.
          */
         final int nSelectors = sendMTFValues1(nGroups, alphaSize);
 
         /* Compute MTF values for the selectors. */
         sendMTFValues2(nGroups, nSelectors);
 
         /* Assign actual codes for the tables. */
         sendMTFValues3(nGroups, alphaSize);
 
         /* Transmit the mapping table. */
         sendMTFValues4();
 
         /* Now the selectors. */
         sendMTFValues5(nGroups, nSelectors);
 
         /* Now the coding tables. */
         sendMTFValues6(nGroups, alphaSize);
 
         /* And finally, the block data proper */
         sendMTFValues7();
     }
 
     private void sendMTFValues0(final int nGroups, final int alphaSize) {
         final byte[][] len = this.data.sendMTFValues_len;
         final int[] mtfFreq = this.data.mtfFreq;
 
         int remF = this.nMTF;
         int gs = 0;
 
         for (int nPart = nGroups; nPart > 0; nPart--) {
             final int tFreq = remF / nPart;
             int ge = gs - 1;
             int aFreq = 0;
 
             for (final int a = alphaSize - 1; aFreq < tFreq && ge < a;) {
                 aFreq += mtfFreq[++ge];
             }
 
             if (ge > gs && nPart != nGroups && nPart != 1 && (nGroups - nPart & 1) != 0) {
                 aFreq -= mtfFreq[ge--];
             }
 
             final byte[] len_np = len[nPart - 1];
             for (int v = alphaSize; --v >= 0;) {
                 if (v >= gs && v <= ge) {
                     len_np[v] = LESSER_ICOST;
                 } else {
                     len_np[v] = GREATER_ICOST;
                 }
             }
 
             gs = ge + 1;
             remF -= aFreq;
         }
     }
 
     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;
     }
 
     private void sendMTFValues2(final int nGroups, final int nSelectors) {
         // assert (nGroups < 8) : nGroups;
 
         final Data dataShadow = this.data;
         final byte[] pos = dataShadow.sendMTFValues2_pos;
 
         for (int i = nGroups; --i >= 0;) {
             pos[i] = (byte) i;
         }
 
         for (int i = 0; i < nSelectors; i++) {
             final byte ll_i = dataShadow.selector[i];
             byte tmp = pos[0];
             int j = 0;
 
             while (ll_i != tmp) {
                 j++;
                 final byte tmp2 = tmp;
                 tmp = pos[j];
                 pos[j] = tmp2;
             }
 
             pos[0] = tmp;
             dataShadow.selectorMtf[i] = (byte) j;
         }
     }
 
     private void sendMTFValues3(final int nGroups, final int alphaSize) {
         final int[][] code = this.data.sendMTFValues_code;
         final byte[][] len = this.data.sendMTFValues_len;
 
         for (int t = 0; t < nGroups; t++) {
             int minLen = 32;
             int maxLen = 0;
             final byte[] len_t = len[t];
             for (int i = alphaSize; --i >= 0;) {
                 final int l = len_t[i] & 0xff;
                 if (l > maxLen) {
                     maxLen = l;
                 }
                 if (l < minLen) {
                     minLen = l;
                 }
             }
 
             // assert (maxLen <= 20) : maxLen;
             // assert (minLen >= 1) : minLen;
 
             hbAssignCodes(code[t], len[t], minLen, maxLen, alphaSize);
         }
     }
 
     private void sendMTFValues4() throws IOException {
         final boolean[] inUse = this.data.inUse;
         final boolean[] inUse16 = this.data.sentMTFValues4_inUse16;
 
         for (int i = 16; --i >= 0;) {
             inUse16[i] = false;
             final int i16 = i * 16;
             for (int j = 16; --j >= 0;) {
                 if (inUse[i16 + j]) {
                     inUse16[i] = true;
                     break;
                 }
             }
         }
 
         for (int i = 0; i < 16; i++) {
             bsW(1, inUse16[i] ? 1 : 0);
         }
 
         final OutputStream outShadow = this.out;
         int bsLiveShadow = this.bsLive;
         int bsBuffShadow = this.bsBuff;
 
         for (int i = 0; i < 16; i++) {
             if (inUse16[i]) {
                 final int i16 = i * 16;
                 for (int j = 0; j < 16; j++) {
                     // inlined: bsW(1, inUse[i16 + j] ? 1 : 0);
                     while (bsLiveShadow >= 8) {
                         outShadow.write(bsBuffShadow >> 24); // write 8-bit
                         bsBuffShadow <<= 8;
                         bsLiveShadow -= 8;
                     }
                     if (inUse[i16 + j]) {
                         bsBuffShadow |= 1 << 32 - bsLiveShadow - 1;
                     }
                     bsLiveShadow++;
                 }
             }
         }
 
         this.bsBuff = bsBuffShadow;
         this.bsLive = bsLiveShadow;
     }
 
     private void sendMTFValues5(final int nGroups, final int nSelectors) throws IOException {
         bsW(3, nGroups);
         bsW(15, nSelectors);
 
         final OutputStream outShadow = this.out;
         final byte[] selectorMtf = this.data.selectorMtf;
 
         int bsLiveShadow = this.bsLive;
         int bsBuffShadow = this.bsBuff;
 
         for (int i = 0; i < nSelectors; i++) {
             for (int j = 0, hj = selectorMtf[i] & 0xff; j < hj; j++) {
                 // inlined: bsW(1, 1);
                 while (bsLiveShadow >= 8) {
                     outShadow.write(bsBuffShadow >> 24);
                     bsBuffShadow <<= 8;
                     bsLiveShadow -= 8;
                 }
                 bsBuffShadow |= 1 << 32 - bsLiveShadow - 1;
                 bsLiveShadow++;
             }
 
             // inlined: bsW(1, 0);
             while (bsLiveShadow >= 8) {
                 outShadow.write(bsBuffShadow >> 24);
                 bsBuffShadow <<= 8;
                 bsLiveShadow -= 8;
             }
             // bsBuffShadow |= 0 << (32 - bsLiveShadow - 1);
             bsLiveShadow++;
         }
 
         this.bsBuff = bsBuffShadow;
         this.bsLive = bsLiveShadow;
     }
 
     private void sendMTFValues6(final int nGroups, final int alphaSize) throws IOException {
         final byte[][] len = this.data.sendMTFValues_len;
         final OutputStream outShadow = this.out;
 
         int bsLiveShadow = this.bsLive;
         int bsBuffShadow = this.bsBuff;
 
         for (int t = 0; t < nGroups; t++) {
             final byte[] len_t = len[t];
             int curr = len_t[0] & 0xff;
 
             // inlined: bsW(5, curr);
             while (bsLiveShadow >= 8) {
                 outShadow.write(bsBuffShadow >> 24); // write 8-bit
                 bsBuffShadow <<= 8;
                 bsLiveShadow -= 8;
             }
             bsBuffShadow |= curr << 32 - bsLiveShadow - 5;
             bsLiveShadow += 5;
 
             for (int i = 0; i < alphaSize; i++) {
                 final int lti = len_t[i] & 0xff;
                 while (curr < lti) {
                     // inlined: bsW(2, 2);
                     while (bsLiveShadow >= 8) {
                         outShadow.write(bsBuffShadow >> 24); // write 8-bit
                         bsBuffShadow <<= 8;
                         bsLiveShadow -= 8;
                     }
                     bsBuffShadow |= 2 << 32 - bsLiveShadow - 2;
                     bsLiveShadow += 2;
 
                     curr++; /* 10 */
                 }
 
                 while (curr > lti) {
                     // inlined: bsW(2, 3);
                     while (bsLiveShadow >= 8) {
                         outShadow.write(bsBuffShadow >> 24); // write 8-bit
                         bsBuffShadow <<= 8;
                         bsLiveShadow -= 8;
                     }
                     bsBuffShadow |= 3 << 32 - bsLiveShadow - 2;
                     bsLiveShadow += 2;
 
                     curr--; /* 11 */
                 }
 
                 // inlined: bsW(1, 0);
                 while (bsLiveShadow >= 8) {
                     outShadow.write(bsBuffShadow >> 24); // write 8-bit
                     bsBuffShadow <<= 8;
                     bsLiveShadow -= 8;
                 }
                 // bsBuffShadow |= 0 << (32 - bsLiveShadow - 1);
                 bsLiveShadow++;
             }
         }
 
         this.bsBuff = bsBuffShadow;
         this.bsLive = bsLiveShadow;
     }
 
     private void sendMTFValues7() throws IOException {
         final Data dataShadow = this.data;
         final byte[][] len = dataShadow.sendMTFValues_len;
         final int[][] code = dataShadow.sendMTFValues_code;
         final OutputStream outShadow = this.out;
         final byte[] selector = dataShadow.selector;
         final char[] sfmap = dataShadow.sfmap;
         final int nMTFShadow = this.nMTF;
 
         int selCtr = 0;
 
         int bsLiveShadow = this.bsLive;
         int bsBuffShadow = this.bsBuff;
 
         for (int gs = 0; gs < nMTFShadow;) {
             final int ge = Math.min(gs + G_SIZE - 1, nMTFShadow - 1);
             final int selector_selCtr = selector[selCtr] & 0xff;
             final int[] code_selCtr = code[selector_selCtr];
             final byte[] len_selCtr = len[selector_selCtr];
 
             while (gs <= ge) {
                 final int sfmap_i = sfmap[gs];
 
                 //
                 // inlined: bsW(len_selCtr[sfmap_i] & 0xff,
                 // code_selCtr[sfmap_i]);
                 //
                 while (bsLiveShadow >= 8) {
                     outShadow.write(bsBuffShadow >> 24);
                     bsBuffShadow <<= 8;
                     bsLiveShadow -= 8;
                 }
                 final int n = len_selCtr[sfmap_i] & 0xFF;
                 bsBuffShadow |= code_selCtr[sfmap_i] << 32 - bsLiveShadow - n;
                 bsLiveShadow += n;
 
                 gs++;
             }
 
             gs = ge + 1;
             selCtr++;
         }
 
         this.bsBuff = bsBuffShadow;
         this.bsLive = bsLiveShadow;
     }
 
     @Override
     public void write(final byte[] buf, int offs, final int len) throws IOException {
         if (offs < 0) {
             throw new IndexOutOfBoundsException("offs(" + offs + ") < 0.");
         }
         if (len < 0) {
             throw new IndexOutOfBoundsException("len(" + len + ") < 0.");
         }
         if (offs + len > buf.length) {
             throw new IndexOutOfBoundsException("offs(" + offs + ") + len(" + len + ") > buf.length(" + buf.length + ").");
         }
         checkOpen();
         for (final int hi = offs + len; offs < hi;) {
             write0(buf[offs++]);
         }
     }
 
     @Override
     public void write(final int b) throws IOException {
         checkOpen();
         write0(b);
     }
 
     /**
      * Keeps track of the last bytes written and implicitly performs run-length encoding as the first step of the bzip2 algorithm.
      */
     private void write0(int b) throws IOException {
         if (this.currentChar != -1) {
             b &= 0xff;
             if (this.currentChar == b) {
                 if (++this.runLength > 254) {
                     writeRun();
                     this.currentChar = -1;
                     this.runLength = 0;
                 }
                 // else nothing to do
             } else {
                 writeRun();
                 this.runLength = 1;
                 this.currentChar = b;
             }
         } else {
             this.currentChar = b & 0xff;
             this.runLength++;
         }
     }
 
     /**
      * Writes the current byte to the buffer, run-length encoding it if it has been repeated at least four times (the first step RLEs sequences of four
      * identical bytes).
      *
      * <p>
      * Flushes the current block before writing data if it is full.
      * </p>
      *
      * <p>
      * "write to the buffer" means adding to data.buffer starting two steps "after" this.last - initially starting at index 1 (not 0) - and updating this.last
      * to point to the last index written minus 1.
      * </p>
      */
     private void writeRun() throws IOException {
         final int lastShadow = this.last;
 
         if (lastShadow < this.allowableBlockSize) {
             final int currentCharShadow = this.currentChar;
             final Data dataShadow = this.data;
             dataShadow.inUse[currentCharShadow] = true;
             final byte ch = (byte) currentCharShadow;
 
             int runLengthShadow = this.runLength;
             this.crc.update(currentCharShadow, runLengthShadow);
 
             switch (runLengthShadow) {
             case 1:
                 dataShadow.block[lastShadow + 2] = ch;
                 this.last = lastShadow + 1;
                 break;
 
             case 2:
                 dataShadow.block[lastShadow + 2] = ch;
                 dataShadow.block[lastShadow + 3] = ch;
                 this.last = lastShadow + 2;
                 break;
 
             case 3: {
                 final byte[] block = dataShadow.block;
                 block[lastShadow + 2] = ch;
                 block[lastShadow + 3] = ch;
                 block[lastShadow + 4] = ch;
                 this.last = lastShadow + 3;
             }
                 break;
 
             default: {
                 runLengthShadow -= 4;
                 dataShadow.inUse[runLengthShadow] = true;
                 final byte[] block = dataShadow.block;
                 block[lastShadow + 2] = ch;
                 block[lastShadow + 3] = ch;
                 block[lastShadow + 4] = ch;
                 block[lastShadow + 5] = ch;
                 block[lastShadow + 6] = (byte) runLengthShadow;
                 this.last = lastShadow + 5;
             }
                 break;
 
             }
         } else {
             endBlock();
             initBlock();
             writeRun();
         }
     }
 
 }