    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one
    003 * or more contributor license agreements.  See the NOTICE file
    004 * distributed with this work for additional information
    005 * regarding copyright ownership.  The ASF licenses this file
    006 * to you under the Apache License, Version 2.0 (the
    007 * "License"); you may not use this file except in compliance
    008 * with the License.  You may obtain a copy of the License at
    009 *
    010 * http://www.apache.org/licenses/LICENSE-2.0
    011 *
    012 * Unless required by applicable law or agreed to in writing,
    013 * software distributed under the License is distributed on an
    014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    015 * KIND, either express or implied.  See the License for the
    016 * specific language governing permissions and limitations
    017 * under the License.
    018 */
    019package org.apache.commons.compress.compressors.bzip2;
    020
    021import java.io.IOException;
    022import java.io.OutputStream;
    023import java.util.Arrays;
    024
    025import org.apache.commons.compress.compressors.CompressorOutputStream;
    026
    027/**
    028 * An output stream that compresses into the BZip2 format into another stream.
    029 *
    030 * <p>
    031 * The compression requires large amounts of memory. Thus you should call the {@link #close() close()} method as soon as possible, to force
    032 * {@code BZip2CompressorOutputStream} to release the allocated memory.
    033 * </p>
    034 *
    035 * <p>
    036 * 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
    037 * compression ratio. You can avoid unnecessary memory allocation by avoiding using a blocksize which is bigger than the size of the input.
    038 * </p>
    039 *
    040 * <p>
    041 * You can compute the memory usage for compressing by the following formula:
    042 * </p>
    043 *
    044 * <pre>
    045 * &lt;code&gt;400k + (9 * blocksize)&lt;/code&gt;.
    046 * </pre>
    047 *
    048 * <p>
    049 * To get the memory required for decompression by {@link BZip2CompressorInputStream} use
    050 * </p>
    051 *
    052 * <pre>
    053 * &lt;code&gt;65k + (5 * blocksize)&lt;/code&gt;.
    054 * </pre>
    055 *
    056 * <table style="width:100%" border="1">
    057 * <caption>Memory usage by blocksize</caption>
    058 * <tr>
    059 * <th colspan="3">Memory usage by blocksize</th>
    060 * </tr>
    061 * <tr>
    062 * <th style="text-align: right">Blocksize</th>
    063 * <th style="text-align: right">Compression<br>
    064 * memory usage</th>
    065 * <th style="text-align: right">Decompression<br>
    066 * memory usage</th>
    067 * </tr>
    068 * <tr>
    069 * <td style="text-align: right">100k</td>
    070 * <td style="text-align: right">1300k</td>
    071 * <td style="text-align: right">565k</td>
    072 * </tr>
    073 * <tr>
    074 * <td style="text-align: right">200k</td>
    075 * <td style="text-align: right">2200k</td>
    076 * <td style="text-align: right">1065k</td>
    077 * </tr>
    078 * <tr>
    079 * <td style="text-align: right">300k</td>
    080 * <td style="text-align: right">3100k</td>
    081 * <td style="text-align: right">1565k</td>
    082 * </tr>
    083 * <tr>
    084 * <td style="text-align: right">400k</td>
    085 * <td style="text-align: right">4000k</td>
    086 * <td style="text-align: right">2065k</td>
    087 * </tr>
    088 * <tr>
    089 * <td style="text-align: right">500k</td>
    090 * <td style="text-align: right">4900k</td>
    091 * <td style="text-align: right">2565k</td>
    092 * </tr>
    093 * <tr>
    094 * <td style="text-align: right">600k</td>
    095 * <td style="text-align: right">5800k</td>
    096 * <td style="text-align: right">3065k</td>
    097 * </tr>
    098 * <tr>
    099 * <td style="text-align: right">700k</td>
    100 * <td style="text-align: right">6700k</td>
    101 * <td style="text-align: right">3565k</td>
    102 * </tr>
    103 * <tr>
    104 * <td style="text-align: right">800k</td>
    105 * <td style="text-align: right">7600k</td>
    106 * <td style="text-align: right">4065k</td>
    107 * </tr>
    108 * <tr>
    109 * <td style="text-align: right">900k</td>
    110 * <td style="text-align: right">8500k</td>
    111 * <td style="text-align: right">4565k</td>
    112 * </tr>
    113 * </table>
    114 *
    115 * <p>
    116 * For decompression {@code BZip2CompressorInputStream} allocates less memory if the bzipped input is smaller than one block.
    117 * </p>
    118 *
    119 * <p>
    120 * Instances of this class are not threadsafe.
    121 * </p>
    122 *
    123 * <p>
    124 * TODO: Update to BZip2 1.0.1
    125 * </p>
    126 *
    127 * @NotThreadSafe
    128 */
    129public class BZip2CompressorOutputStream extends CompressorOutputStream implements BZip2Constants {
    130
    131    static final class Data {
    132
    133        // with blockSize 900k
    134        /* maps unsigned byte => "does it occur in block" */
    135        final boolean[] inUse = new boolean[256]; // 256 byte
    136        final byte[] unseqToSeq = new byte[256]; // 256 byte
    137        final int[] mtfFreq = new int[MAX_ALPHA_SIZE]; // 1032 byte
    138        final byte[] selector = new byte[MAX_SELECTORS]; // 18002 byte
    139        final byte[] selectorMtf = new byte[MAX_SELECTORS]; // 18002 byte
    140
    141        final byte[] generateMTFValues_yy = new byte[256]; // 256 byte
    142        final byte[][] sendMTFValues_len = new byte[N_GROUPS][MAX_ALPHA_SIZE]; // 1548
    143        // byte
    144        final int[][] sendMTFValues_rfreq = new int[N_GROUPS][MAX_ALPHA_SIZE]; // 6192
    145        // byte
    146        final int[] sendMTFValues_fave = new int[N_GROUPS]; // 24 byte
    147        final short[] sendMTFValues_cost = new short[N_GROUPS]; // 12 byte
    148        final int[][] sendMTFValues_code = new int[N_GROUPS][MAX_ALPHA_SIZE]; // 6192
    149        // byte
    150        final byte[] sendMTFValues2_pos = new byte[N_GROUPS]; // 6 byte
    151        final boolean[] sentMTFValues4_inUse16 = new boolean[16]; // 16 byte
    152
    153        final int[] heap = new int[MAX_ALPHA_SIZE + 2]; // 1040 byte
    154        final int[] weight = new int[MAX_ALPHA_SIZE * 2]; // 2064 byte
    155        final int[] parent = new int[MAX_ALPHA_SIZE * 2]; // 2064 byte
    156
    157        // ------------
    158        // 333408 byte
    159
    160        /*
    161         * holds the RLEd block of original data starting at index 1. After sorting the last byte added to the buffer is at index 0.
    162         */
    163        final byte[] block; // 900021 byte
    164        /*
    165         * maps index in Burrows-Wheeler transformed block => index of byte in original block
    166         */
    167        final int[] fmap; // 3600000 byte
    168        final char[] sfmap; // 3600000 byte
    169        // ------------
    170        // 8433529 byte
    171        // ============
    172
    173        /**
    174         * Index of original line in Burrows-Wheeler table.
    175         *
    176         * <p>
    177         * This is the index in fmap that points to the last byte of the original data.
    178         * </p>
    179         */
    180        int origPtr;
    181
    182        Data(final int blockSize100k) {
    183            final int n = blockSize100k * BZip2Constants.BASEBLOCKSIZE;
    184            this.block = new byte[n + 1 + NUM_OVERSHOOT_BYTES];
    185            this.fmap = new int[n];
    186            this.sfmap = new char[2 * n];
    187        }
    188
    189    }
    190
    191    /**
    192     * The minimum supported blocksize {@code  == 1}.
    193     */
    194    public static final int MIN_BLOCKSIZE = 1;
    195
    196    /**
    197     * The maximum supported blocksize {@code  == 9}.
    198     */
    199    public static final int MAX_BLOCKSIZE = 9;
    200    private static final int GREATER_ICOST = 15;
    201
    202    private static final int LESSER_ICOST = 0;
    203
    204    /**
    205     * Chooses a blocksize based on the given length of the data to compress.
    206     *
    207     * @return The blocksize, between {@link #MIN_BLOCKSIZE} and {@link #MAX_BLOCKSIZE} both inclusive. For a negative {@code inputLength} this method returns
    208     *         {@code MAX_BLOCKSIZE} always.
    209     *
    210     * @param inputLength The length of the data which will be compressed by {@code BZip2CompressorOutputStream}.
    211     */
    212    public static int chooseBlockSize(final long inputLength) {
    213        return inputLength > 0 ? (int) Math.min(inputLength / 132000 + 1, 9) : MAX_BLOCKSIZE;
    214    }
    215
    216    private static void hbAssignCodes(final int[] code, final byte[] length, final int minLen, final int maxLen, final int alphaSize) {
    217        int vec = 0;
    218        for (int n = minLen; n <= maxLen; n++) {
    219            for (int i = 0; i < alphaSize; i++) {
    220                if ((length[i] & 0xff) == n) {
    221                    code[i] = vec;
    222                    vec++;
    223                }
    224            }
    225            vec <<= 1;
    226        }
    227    }
    228
    229    private static void hbMakeCodeLengths(final byte[] len, final int[] freq, final Data dat, final int alphaSize, final int maxLen) {
    230        /*
    231         * Nodes and heap entries run from 1. Entry 0 for both the heap and nodes is a sentinel.
    232         */
    233        final int[] heap = dat.heap;
    234        final int[] weight = dat.weight;
    235        final int[] parent = dat.parent;
    236
    237        for (int i = alphaSize; --i >= 0;) {
    238            weight[i + 1] = (freq[i] == 0 ? 1 : freq[i]) << 8;
    239        }
    240
    241        for (boolean tooLong = true; tooLong;) {
    242            tooLong = false;
    243
    244            int nNodes = alphaSize;
    245            int nHeap = 0;
    246            heap[0] = 0;
    247            weight[0] = 0;
    248            parent[0] = -2;
    249
    250            for (int i = 1; i <= alphaSize; i++) {
    251                parent[i] = -1;
    252                nHeap++;
    253                heap[nHeap] = i;
    254
    255                int zz = nHeap;
    256                final int tmp = heap[zz];
    257                while (weight[tmp] < weight[heap[zz >> 1]]) {
    258                    heap[zz] = heap[zz >> 1];
    259                    zz >>= 1;
    260                }
    261                heap[zz] = tmp;
    262            }
    263
    264            while (nHeap > 1) {
    265                final int n1 = heap[1];
    266                heap[1] = heap[nHeap];
    267                nHeap--;
    268
    269                int yy = 0;
    270                int zz = 1;
    271                int tmp = heap[1];
    272
    273                while (true) {
    274                    yy = zz << 1;
    275
    276                    if (yy > nHeap) {
    277                        break;
    278                    }
    279
    280                    if (yy < nHeap && weight[heap[yy + 1]] < weight[heap[yy]]) {
    281                        yy++;
    282                    }
    283
    284                    if (weight[tmp] < weight[heap[yy]]) {
    285                        break;
    286                    }
    287
    288                    heap[zz] = heap[yy];
    289                    zz = yy;
    290                }
    291
    292                heap[zz] = tmp;
    293
    294                final int n2 = heap[1];
    295                heap[1] = heap[nHeap];
    296                nHeap--;
    297
    298                yy = 0;
    299                zz = 1;
    300                tmp = heap[1];
    301
    302                while (true) {
    303                    yy = zz << 1;
    304
    305                    if (yy > nHeap) {
    306                        break;
    307                    }
    308
    309                    if (yy < nHeap && weight[heap[yy + 1]] < weight[heap[yy]]) {
    310                        yy++;
    311                    }
    312
    313                    if (weight[tmp] < weight[heap[yy]]) {
    314                        break;
    315                    }
    316
    317                    heap[zz] = heap[yy];
    318                    zz = yy;
    319                }
    320
    321                heap[zz] = tmp;
    322                nNodes++;
    323                parent[n1] = parent[n2] = nNodes;
    324
    325                final int weight_n1 = weight[n1];
    326                final int weight_n2 = weight[n2];
    327                weight[nNodes] = (weight_n1 & 0xffffff00) + (weight_n2 & 0xffffff00) | 1 + Math.max(weight_n1 & 0x000000ff, weight_n2 & 0x000000ff);
    328
    329                parent[nNodes] = -1;
    330                nHeap++;
    331                heap[nHeap] = nNodes;
    332
    333                tmp = 0;
    334                zz = nHeap;
    335                tmp = heap[zz];
    336                final int weight_tmp = weight[tmp];
    337                while (weight_tmp < weight[heap[zz >> 1]]) {
    338                    heap[zz] = heap[zz >> 1];
    339                    zz >>= 1;
    340                }
    341                heap[zz] = tmp;
    342
    343            }
    344
    345            for (int i = 1; i <= alphaSize; i++) {
    346                int j = 0;
    347                int k = i;
    348
    349                for (int parent_k; (parent_k = parent[k]) >= 0;) {
    350                    k = parent_k;
    351                    j++;
    352                }
    353
    354                len[i - 1] = (byte) j;
    355                if (j > maxLen) {
    356                    tooLong = true;
    357                }
    358            }
    359
    360            if (tooLong) {
    361                for (int i = 1; i < alphaSize; i++) {
    362                    int j = weight[i] >> 8;
    363                    j = 1 + (j >> 1);
    364                    weight[i] = j << 8;
    365                }
    366            }
    367        }
    368    }
    369
    370    /**
    371     * Index of the last char in the block, so the block size == last + 1.
    372     */
    373    private int last;
    374    /**
    375     * Always: in the range 0 .. 9. The current block size is 100000 * this number.
    376     */
    377    private final int blockSize100k;
    378
    379    private int bsBuff;
    380
    381    private int bsLive;
    382
    383    private final CRC crc = new CRC();
    384    private int nInUse;
    385
    386    private int nMTF;
    387    private int currentChar = -1;
    388    private int runLength;
    389
    390    private int blockCRC;
    391    private int combinedCRC;
    392
    393    private final int allowableBlockSize;
    394    /**
    395     * All memory intensive stuff.
    396     */
    397    private Data data;
    398
    399    private BlockSort blockSorter;
    400
    401    private OutputStream out;
    402
    403    private volatile boolean closed;
    404
    405    /**
    406     * Constructs a new {@code BZip2CompressorOutputStream} with a blocksize of 900k.
    407     *
    408     * @param out the destination stream.
    409     *
    410     * @throws IOException          if an I/O error occurs in the specified stream.
    411     * @throws NullPointerException if {@code out == null}.
    412     */
    413    public BZip2CompressorOutputStream(final OutputStream out) throws IOException {
    414        this(out, MAX_BLOCKSIZE);
    415    }
    416
    417    /**
    418     * Constructs a new {@code BZip2CompressorOutputStream} with specified blocksize.
    419     *
    420     * @param out       the destination stream.
    421     * @param blockSize the blockSize as 100k units.
    422     *
    423     * @throws IOException              if an I/O error occurs in the specified stream.
    424     * @throws IllegalArgumentException if {@code (blockSize &lt; 1) || (blockSize &gt; 9)}.
    425     * @throws NullPointerException     if {@code out == null}.
    426     *
    427     * @see #MIN_BLOCKSIZE
    428     * @see #MAX_BLOCKSIZE
    429     */
    430    public BZip2CompressorOutputStream(final OutputStream out, final int blockSize) throws IOException {
    431        if (blockSize < 1) {
    432            throw new IllegalArgumentException("blockSize(" + blockSize + ") < 1");
    433        }
    434        if (blockSize > 9) {
    435            throw new IllegalArgumentException("blockSize(" + blockSize + ") > 9");
    436        }
    437
    438        this.blockSize100k = blockSize;
    439        this.out = out;
    440
    441        /* 20 is just a paranoia constant */
    442        this.allowableBlockSize = this.blockSize100k * BZip2Constants.BASEBLOCKSIZE - 20;
    443        init();
    444    }
    445
    446    private void blockSort() {
    447        blockSorter.blockSort(data, last);
    448    }
    449
    450    private void bsFinishedWithStream() throws IOException {
    451        while (this.bsLive > 0) {
    452            final int ch = this.bsBuff >> 24;
    453            this.out.write(ch); // write 8-bit
    454            this.bsBuff <<= 8;
    455            this.bsLive -= 8;
    456        }
    457    }
    458
    459    private void bsPutInt(final int u) throws IOException {
    460        bsW(8, u >> 24 & 0xff);
    461        bsW(8, u >> 16 & 0xff);
    462        bsW(8, u >> 8 & 0xff);
    463        bsW(8, u & 0xff);
    464    }
    465
    466    private void bsPutUByte(final int c) throws IOException {
    467        bsW(8, c);
    468    }
    469
    470    private void bsW(final int n, final int v) throws IOException {
    471        final OutputStream outShadow = this.out;
    472        int bsLiveShadow = this.bsLive;
    473        int bsBuffShadow = this.bsBuff;
    474
    475        while (bsLiveShadow >= 8) {
    476            outShadow.write(bsBuffShadow >> 24); // write 8-bit
    477            bsBuffShadow <<= 8;
    478            bsLiveShadow -= 8;
    479        }
    480
    481        this.bsBuff = bsBuffShadow | v << 32 - bsLiveShadow - n;
    482        this.bsLive = bsLiveShadow + n;
    483    }
    484
    485    @Override
    486    public void close() throws IOException {
    487        if (!closed) {
    488            try (OutputStream outShadow = this.out) {
    489                finish();
    490            }
    491        }
    492    }
    493
    494    private void endBlock() throws IOException {
    495        this.blockCRC = this.crc.getValue();
    496        this.combinedCRC = this.combinedCRC << 1 | this.combinedCRC >>> 31;
    497        this.combinedCRC ^= this.blockCRC;
    498
    499        // empty block at end of file
    500        if (this.last == -1) {
    501            return;
    502        }
    503
    504        /* sort the block and establish posn of original string */
    505        blockSort();
    506
    507        /*
    508         * 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
    509         * 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,
    510         * 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
    511         * compression/ decompression doesn't rely on these statistical properties. They are only important when trying to recover blocks from damaged files.
    512         */
    513        bsPutUByte(0x31);
    514        bsPutUByte(0x41);
    515        bsPutUByte(0x59);
    516        bsPutUByte(0x26);
    517        bsPutUByte(0x53);
    518        bsPutUByte(0x59);
    519
    520        /* Now the block's CRC, so it is in a known place. */
    521        bsPutInt(this.blockCRC);
    522
    523        /* Now a single bit indicating no randomisation. */
    524        bsW(1, 0);
    525
    526        /* Finally, block's contents proper. */
    527        moveToFrontCodeAndSend();
    528    }
    529
    530    private void endCompression() throws IOException {
    531        /*
    532         * 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
    533         * contains too much repetition -- 27 18 28 18 28 46 -- for me to feel statistically comfortable. Call me paranoid.)
    534         */
    535        bsPutUByte(0x17);
    536        bsPutUByte(0x72);
    537        bsPutUByte(0x45);
    538        bsPutUByte(0x38);
    539        bsPutUByte(0x50);
    540        bsPutUByte(0x90);
    541
    542        bsPutInt(this.combinedCRC);
    543        bsFinishedWithStream();
    544    }
    545
    546    public void finish() throws IOException {
    547        if (!closed) {
    548            closed = true;
    549            try {
    550                if (this.runLength > 0) {
    551                    writeRun();
    552                }
    553                this.currentChar = -1;
    554                endBlock();
    555                endCompression();
    556            } finally {
    557                this.out = null;
    558                this.blockSorter = null;
    559                this.data = null;
    560            }
    561        }
    562    }
    563
    564    @Override
    565    public void flush() throws IOException {
    566        final OutputStream outShadow = this.out;
    567        if (outShadow != null) {
    568            outShadow.flush();
    569        }
    570    }
    571
    572    /*
    573     * Performs Move-To-Front on the Burrows-Wheeler transformed buffer, storing the MTFed data in data.sfmap in RUNA/RUNB run-length-encoded form.
    574     *
    575     * <p>Keeps track of byte frequencies in data.mtfFreq at the same time.</p>
    576     */
    577    private void generateMTFValues() {
    578        final int lastShadow = this.last;
    579        final Data dataShadow = this.data;
    580        final boolean[] inUse = dataShadow.inUse;
    581        final byte[] block = dataShadow.block;
    582        final int[] fmap = dataShadow.fmap;
    583        final char[] sfmap = dataShadow.sfmap;
    584        final int[] mtfFreq = dataShadow.mtfFreq;
    585        final byte[] unseqToSeq = dataShadow.unseqToSeq;
    586        final byte[] yy = dataShadow.generateMTFValues_yy;
    587
    588        // make maps
    589        int nInUseShadow = 0;
    590        for (int i = 0; i < 256; i++) {
    591            if (inUse[i]) {
    592                unseqToSeq[i] = (byte) nInUseShadow;
    593                nInUseShadow++;
    594            }
    595        }
    596        this.nInUse = nInUseShadow;
    597
    598        final int eob = nInUseShadow + 1;
    599
    600        Arrays.fill(mtfFreq, 0, eob + 1, 0);
    601
    602        for (int i = nInUseShadow; --i >= 0;) {
    603            yy[i] = (byte) i;
    604        }
    605
    606        int wr = 0;
    607        int zPend = 0;
    608
    609        for (int i = 0; i <= lastShadow; i++) {
    610            final byte ll_i = unseqToSeq[block[fmap[i]] & 0xff];
    611            byte tmp = yy[0];
    612            int j = 0;
    613
    614            while (ll_i != tmp) {
    615                j++;
    616                final byte tmp2 = tmp;
    617                tmp = yy[j];
    618                yy[j] = tmp2;
    619            }
    620            yy[0] = tmp;
    621
    622            if (j == 0) {
    623                zPend++;
    624            } else {
    625                if (zPend > 0) {
    626                    zPend--;
    627                    while (true) {
    628                        if ((zPend & 1) == 0) {
    629                            sfmap[wr] = RUNA;
    630                            wr++;
    631                            mtfFreq[RUNA]++;
    632                        } else {
    633                            sfmap[wr] = RUNB;
    634                            wr++;
    635                            mtfFreq[RUNB]++;
    636                        }
    637
    638                        if (zPend < 2) {
    639                            break;
    640                        }
    641                        zPend = zPend - 2 >> 1;
    642                    }
    643                    zPend = 0;
    644                }
    645                sfmap[wr] = (char) (j + 1);
    646                wr++;
    647                mtfFreq[j + 1]++;
    648            }
    649        }
    650
    651        if (zPend > 0) {
    652            zPend--;
    653            while (true) {
    654                if ((zPend & 1) == 0) {
    655                    sfmap[wr] = RUNA;
    656                    wr++;
    657                    mtfFreq[RUNA]++;
    658                } else {
    659                    sfmap[wr] = RUNB;
    660                    wr++;
    661                    mtfFreq[RUNB]++;
    662                }
    663
    664                if (zPend < 2) {
    665                    break;
    666                }
    667                zPend = zPend - 2 >> 1;
    668            }
    669        }
    670
    671        sfmap[wr] = (char) eob;
    672        mtfFreq[eob]++;
    673        this.nMTF = wr + 1;
    674    }
    675
    676    /**
    677     * Returns the blocksize parameter specified at construction time.
    678     *
    679     * @return the blocksize parameter specified at construction time
    680     */
    681    public final int getBlockSize() {
    682        return this.blockSize100k;
    683    }
    684
    685    /**
    686     * 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
    687     * blockSize100k.
    688     *
    689     * @throws IOException if the magic bytes could not been written
    690     */
    691    private void init() throws IOException {
    692        bsPutUByte('B');
    693        bsPutUByte('Z');
    694
    695        this.data = new Data(this.blockSize100k);
    696        this.blockSorter = new BlockSort(this.data);
    697
    698        // huffmanized magic bytes
    699        bsPutUByte('h');
    700        bsPutUByte('0' + this.blockSize100k);
    701
    702        this.combinedCRC = 0;
    703        initBlock();
    704    }
    705
    706    private void initBlock() {
    707        // blockNo++;
    708        this.crc.reset();
    709        this.last = -1;
    710        // ch = 0;
    711
    712        final boolean[] inUse = this.data.inUse;
    713        for (int i = 256; --i >= 0;) {
    714            inUse[i] = false;
    715        }
    716
    717    }
    718
    719    private void moveToFrontCodeAndSend() throws IOException {
    720        bsW(24, this.data.origPtr);
    721        generateMTFValues();
    722        sendMTFValues();
    723    }
    724
    725    private void sendMTFValues() throws IOException {
    726        final byte[][] len = this.data.sendMTFValues_len;
    727        final int alphaSize = this.nInUse + 2;
    728
    729        for (int t = N_GROUPS; --t >= 0;) {
    730            final byte[] len_t = len[t];
    731            for (int v = alphaSize; --v >= 0;) {
    732                len_t[v] = GREATER_ICOST;
    733            }
    734        }
    735
    736        /* Decide how many coding tables to use */
    737        // assert (this.nMTF > 0) : this.nMTF;
    738        final int nGroups = this.nMTF < 200 ? 2 : this.nMTF < 600 ? 3 : this.nMTF < 1200 ? 4 : this.nMTF < 2400 ? 5 : 6;
    739
    740        /* Generate an initial set of coding tables */
    741        sendMTFValues0(nGroups, alphaSize);
    742
    743        /*
    744         * Iterate up to N_ITERS times to improve the tables.
    745         */
    746        final int nSelectors = sendMTFValues1(nGroups, alphaSize);
    747
    748        /* Compute MTF values for the selectors. */
    749        sendMTFValues2(nGroups, nSelectors);
    750
    751        /* Assign actual codes for the tables. */
    752        sendMTFValues3(nGroups, alphaSize);
    753
    754        /* Transmit the mapping table. */
    755        sendMTFValues4();
    756
    757        /* Now the selectors. */
    758        sendMTFValues5(nGroups, nSelectors);
    759
    760        /* Now the coding tables. */
    761        sendMTFValues6(nGroups, alphaSize);
    762
    763        /* And finally, the block data proper */
    764        sendMTFValues7();
    765    }
    766
    767    private void sendMTFValues0(final int nGroups, final int alphaSize) {
    768        final byte[][] len = this.data.sendMTFValues_len;
    769        final int[] mtfFreq = this.data.mtfFreq;
    770
    771        int remF = this.nMTF;
    772        int gs = 0;
    773
    774        for (int nPart = nGroups; nPart > 0; nPart--) {
    775            final int tFreq = remF / nPart;
    776            int ge = gs - 1;
    777            int aFreq = 0;
    778
    779            for (final int a = alphaSize - 1; aFreq < tFreq && ge < a;) {
    780                aFreq += mtfFreq[++ge];
    781            }
    782
    783            if (ge > gs && nPart != nGroups && nPart != 1 && (nGroups - nPart & 1) != 0) {
    784                aFreq -= mtfFreq[ge--];
    785            }
    786
    787            final byte[] len_np = len[nPart - 1];
    788            for (int v = alphaSize; --v >= 0;) {
    789                if (v >= gs && v <= ge) {
    790                    len_np[v] = LESSER_ICOST;
    791                } else {
    792                    len_np[v] = GREATER_ICOST;
    793                }
    794            }
    795
    796            gs = ge + 1;
    797            remF -= aFreq;
    798        }
    799    }
    800
    801    private int sendMTFValues1(final int nGroups, final int alphaSize) {
    802        final Data dataShadow = this.data;
    803        final int[][] rfreq = dataShadow.sendMTFValues_rfreq;
    804        final int[] fave = dataShadow.sendMTFValues_fave;
    805        final short[] cost = dataShadow.sendMTFValues_cost;
    806        final char[] sfmap = dataShadow.sfmap;
    807        final byte[] selector = dataShadow.selector;
    808        final byte[][] len = dataShadow.sendMTFValues_len;
    809        final byte[] len_0 = len[0];
    810        final byte[] len_1 = len[1];
    811        final byte[] len_2 = len[2];
    812        final byte[] len_3 = len[3];
    813        final byte[] len_4 = len[4];
    814        final byte[] len_5 = len[5];
    815        final int nMTFShadow = this.nMTF;
    816
    817        int nSelectors = 0;
    818
    819        for (int iter = 0; iter < N_ITERS; iter++) {
    820            for (int t = nGroups; --t >= 0;) {
    821                fave[t] = 0;
    822                final int[] rfreqt = rfreq[t];
    823                for (int i = alphaSize; --i >= 0;) {
    824                    rfreqt[i] = 0;
    825                }
    826            }
    827
    828            nSelectors = 0;
    829
    830            for (int gs = 0; gs < this.nMTF;) {
    831                // Set group start & end marks.
    832
    833                // Calculate the cost of this group as coded by each of the
    834                // coding tables.
    835
    836                final int ge = Math.min(gs + G_SIZE - 1, nMTFShadow - 1);
    837
    838                final byte mask = (byte) 0xff;
    839                if (nGroups == N_GROUPS) {
    840                    // unrolled version of the else-block
    841
    842                    short cost0 = 0;
    843                    short cost1 = 0;
    844                    short cost2 = 0;
    845                    short cost3 = 0;
    846                    short cost4 = 0;
    847                    short cost5 = 0;
    848
    849                    for (int i = gs; i <= ge; i++) {
    850                        final int icv = sfmap[i];
    851                        cost0 += (short) (len_0[icv] & mask);
    852                        cost1 += (short) (len_1[icv] & mask);
    853                        cost2 += (short) (len_2[icv] & mask);
    854                        cost3 += (short) (len_3[icv] & mask);
    855                        cost4 += (short) (len_4[icv] & mask);
    856                        cost5 += (short) (len_5[icv] & mask);
    857                    }
    858
    859                    cost[0] = cost0;
    860                    cost[1] = cost1;
    861                    cost[2] = cost2;
    862                    cost[3] = cost3;
    863                    cost[4] = cost4;
    864                    cost[5] = cost5;
    865
    866                } else {
    867                    for (int t = nGroups; --t >= 0;) {
    868                        cost[t] = 0;
    869                    }
    870
    871                    for (int i = gs; i <= ge; i++) {
    872                        final int icv = sfmap[i];
    873                        for (int t = nGroups; --t >= 0;) {
    874                            cost[t] += (short) (len[t][icv] & mask);
    875                        }
    876                    }
    877                }
    878
    879                /*
    880                 * Find the coding table which is best for this group, and record its identity in the selector table.
    881                 */
    882                int bt = -1;
    883                for (int t = nGroups, bc = 999999999; --t >= 0;) {
    884                    final int cost_t = cost[t];
    885                    if (cost_t < bc) {
    886                        bc = cost_t;
    887                        bt = t;
    888                    }
    889                }
    890
    891                fave[bt]++;
    892                selector[nSelectors] = (byte) bt;
    893                nSelectors++;
    894
    895                /*
    896                 * Increment the symbol frequencies for the selected table.
    897                 */
    898                final int[] rfreq_bt = rfreq[bt];
    899                for (int i = gs; i <= ge; i++) {
    900                    rfreq_bt[sfmap[i]]++;
    901                }
    902
    903                gs = ge + 1;
    904            }
    905
    906            /*
    907             * Recompute the tables based on the accumulated frequencies.
    908             */
    909            for (int t = 0; t < nGroups; t++) {
    910                hbMakeCodeLengths(len[t], rfreq[t], this.data, alphaSize, 20);
    911            }
    912        }
    913
    914        return nSelectors;
    915    }
    916
    917    private void sendMTFValues2(final int nGroups, final int nSelectors) {
    918        // assert (nGroups < 8) : nGroups;
    919
    920        final Data dataShadow = this.data;
    921        final byte[] pos = dataShadow.sendMTFValues2_pos;
    922
    923        for (int i = nGroups; --i >= 0;) {
    924            pos[i] = (byte) i;
    925        }
    926
    927        for (int i = 0; i < nSelectors; i++) {
    928            final byte ll_i = dataShadow.selector[i];
    929            byte tmp = pos[0];
    930            int j = 0;
    931
    932            while (ll_i != tmp) {
    933                j++;
    934                final byte tmp2 = tmp;
    935                tmp = pos[j];
    936                pos[j] = tmp2;
    937            }
    938
    939            pos[0] = tmp;
    940            dataShadow.selectorMtf[i] = (byte) j;
    941        }
    942    }
    943
    944    private void sendMTFValues3(final int nGroups, final int alphaSize) {
    945        final int[][] code = this.data.sendMTFValues_code;
    946        final byte[][] len = this.data.sendMTFValues_len;
    947
    948        for (int t = 0; t < nGroups; t++) {
    949            int minLen = 32;
    950            int maxLen = 0;
    951            final byte[] len_t = len[t];
    952            for (int i = alphaSize; --i >= 0;) {
    953                final int l = len_t[i] & 0xff;
    954                if (l > maxLen) {
    955                    maxLen = l;
    956                }
    957                if (l < minLen) {
    958                    minLen = l;
    959                }
    960            }
    961
    962            // assert (maxLen <= 20) : maxLen;
    963            // assert (minLen >= 1) : minLen;
    964
    965            hbAssignCodes(code[t], len[t], minLen, maxLen, alphaSize);
    966        }
    967    }
    968
    969    private void sendMTFValues4() throws IOException {
    970        final boolean[] inUse = this.data.inUse;
    971        final boolean[] inUse16 = this.data.sentMTFValues4_inUse16;
    972
    973        for (int i = 16; --i >= 0;) {
    974            inUse16[i] = false;
    975            final int i16 = i * 16;
    976            for (int j = 16; --j >= 0;) {
    977                if (inUse[i16 + j]) {
    978                    inUse16[i] = true;
    979                    break;
    980                }
    981            }
    982        }
    983
    984        for (int i = 0; i < 16; i++) {
    985            bsW(1, inUse16[i] ? 1 : 0);
    986        }
    987
    988        final OutputStream outShadow = this.out;
    989        int bsLiveShadow = this.bsLive;
    990        int bsBuffShadow = this.bsBuff;
    991
    992        for (int i = 0; i < 16; i++) {
    993            if (inUse16[i]) {
    994                final int i16 = i * 16;
    995                for (int j = 0; j < 16; j++) {
    996                    // inlined: bsW(1, inUse[i16 + j] ? 1 : 0);
    997                    while (bsLiveShadow >= 8) {
    998                        outShadow.write(bsBuffShadow >> 24); // write 8-bit
    999                        bsBuffShadow <<= 8;
    1000                        bsLiveShadow -= 8;
    1001                    }
    1002                    if (inUse[i16 + j]) {
    1003                        bsBuffShadow |= 1 << 32 - bsLiveShadow - 1;
    1004                    }
    1005                    bsLiveShadow++;
    1006                }
    1007            }
    1008        }
    1009
    1010        this.bsBuff = bsBuffShadow;
    1011        this.bsLive = bsLiveShadow;
    1012    }
    1013
    1014    private void sendMTFValues5(final int nGroups, final int nSelectors) throws IOException {
    1015        bsW(3, nGroups);
    1016        bsW(15, nSelectors);
    1017
    1018        final OutputStream outShadow = this.out;
    1019        final byte[] selectorMtf = this.data.selectorMtf;
    1020
    1021        int bsLiveShadow = this.bsLive;
    1022        int bsBuffShadow = this.bsBuff;
    1023
    1024        for (int i = 0; i < nSelectors; i++) {
    1025            for (int j = 0, hj = selectorMtf[i] & 0xff; j < hj; j++) {
    1026                // inlined: bsW(1, 1);
    1027                while (bsLiveShadow >= 8) {
    1028                    outShadow.write(bsBuffShadow >> 24);
    1029                    bsBuffShadow <<= 8;
    1030                    bsLiveShadow -= 8;
    1031                }
    1032                bsBuffShadow |= 1 << 32 - bsLiveShadow - 1;
    1033                bsLiveShadow++;
    1034            }
    1035
    1036            // inlined: bsW(1, 0);
    1037            while (bsLiveShadow >= 8) {
    1038                outShadow.write(bsBuffShadow >> 24);
    1039                bsBuffShadow <<= 8;
    1040                bsLiveShadow -= 8;
    1041            }
    1042            // bsBuffShadow |= 0 << (32 - bsLiveShadow - 1);
    1043            bsLiveShadow++;
    1044        }
    1045
    1046        this.bsBuff = bsBuffShadow;
    1047        this.bsLive = bsLiveShadow;
    1048    }
    1049
    1050    private void sendMTFValues6(final int nGroups, final int alphaSize) throws IOException {
    1051        final byte[][] len = this.data.sendMTFValues_len;
    1052        final OutputStream outShadow = this.out;
    1053
    1054        int bsLiveShadow = this.bsLive;
    1055        int bsBuffShadow = this.bsBuff;
    1056
    1057        for (int t = 0; t < nGroups; t++) {
    1058            final byte[] len_t = len[t];
    1059            int curr = len_t[0] & 0xff;
    1060
    1061            // inlined: bsW(5, curr);
    1062            while (bsLiveShadow >= 8) {
    1063                outShadow.write(bsBuffShadow >> 24); // write 8-bit
    1064                bsBuffShadow <<= 8;
    1065                bsLiveShadow -= 8;
    1066            }
    1067            bsBuffShadow |= curr << 32 - bsLiveShadow - 5;
    1068            bsLiveShadow += 5;
    1069
    1070            for (int i = 0; i < alphaSize; i++) {
    1071                final int lti = len_t[i] & 0xff;
    1072                while (curr < lti) {
    1073                    // inlined: bsW(2, 2);
    1074                    while (bsLiveShadow >= 8) {
    1075                        outShadow.write(bsBuffShadow >> 24); // write 8-bit
    1076                        bsBuffShadow <<= 8;
    1077                        bsLiveShadow -= 8;
    1078                    }
    1079                    bsBuffShadow |= 2 << 32 - bsLiveShadow - 2;
    1080                    bsLiveShadow += 2;
    1081
    1082                    curr++; /* 10 */
    1083                }
    1084
    1085                while (curr > lti) {
    1086                    // inlined: bsW(2, 3);
    1087                    while (bsLiveShadow >= 8) {
    1088                        outShadow.write(bsBuffShadow >> 24); // write 8-bit
    1089                        bsBuffShadow <<= 8;
    1090                        bsLiveShadow -= 8;
    1091                    }
    1092                    bsBuffShadow |= 3 << 32 - bsLiveShadow - 2;
    1093                    bsLiveShadow += 2;
    1094
    1095                    curr--; /* 11 */
    1096                }
    1097
    1098                // inlined: bsW(1, 0);
    1099                while (bsLiveShadow >= 8) {
    1100                    outShadow.write(bsBuffShadow >> 24); // write 8-bit
    1101                    bsBuffShadow <<= 8;
    1102                    bsLiveShadow -= 8;
    1103                }
    1104                // bsBuffShadow |= 0 << (32 - bsLiveShadow - 1);
    1105                bsLiveShadow++;
    1106            }
    1107        }
    1108
    1109        this.bsBuff = bsBuffShadow;
    1110        this.bsLive = bsLiveShadow;
    1111    }
    1112
    1113    private void sendMTFValues7() throws IOException {
    1114        final Data dataShadow = this.data;
    1115        final byte[][] len = dataShadow.sendMTFValues_len;
    1116        final int[][] code = dataShadow.sendMTFValues_code;
    1117        final OutputStream outShadow = this.out;
    1118        final byte[] selector = dataShadow.selector;
    1119        final char[] sfmap = dataShadow.sfmap;
    1120        final int nMTFShadow = this.nMTF;
    1121
    1122        int selCtr = 0;
    1123
    1124        int bsLiveShadow = this.bsLive;
    1125        int bsBuffShadow = this.bsBuff;
    1126
    1127        for (int gs = 0; gs < nMTFShadow;) {
    1128            final int ge = Math.min(gs + G_SIZE - 1, nMTFShadow - 1);
    1129            final int selector_selCtr = selector[selCtr] & 0xff;
    1130            final int[] code_selCtr = code[selector_selCtr];
    1131            final byte[] len_selCtr = len[selector_selCtr];
    1132
    1133            while (gs <= ge) {
    1134                final int sfmap_i = sfmap[gs];
    1135
    1136                //
    1137                // inlined: bsW(len_selCtr[sfmap_i] & 0xff,
    1138                // code_selCtr[sfmap_i]);
    1139                //
    1140                while (bsLiveShadow >= 8) {
    1141                    outShadow.write(bsBuffShadow >> 24);
    1142                    bsBuffShadow <<= 8;
    1143                    bsLiveShadow -= 8;
    1144                }
    1145                final int n = len_selCtr[sfmap_i] & 0xFF;
    1146                bsBuffShadow |= code_selCtr[sfmap_i] << 32 - bsLiveShadow - n;
    1147                bsLiveShadow += n;
    1148
    1149                gs++;
    1150            }
    1151
    1152            gs = ge + 1;
    1153            selCtr++;
    1154        }
    1155
    1156        this.bsBuff = bsBuffShadow;
    1157        this.bsLive = bsLiveShadow;
    1158    }
    1159
    1160    @Override
    1161    public void write(final byte[] buf, int offs, final int len) throws IOException {
    1162        if (offs < 0) {
    1163            throw new IndexOutOfBoundsException("offs(" + offs + ") < 0.");
    1164        }
    1165        if (len < 0) {
    1166            throw new IndexOutOfBoundsException("len(" + len + ") < 0.");
    1167        }
    1168        if (offs + len > buf.length) {
    1169            throw new IndexOutOfBoundsException("offs(" + offs + ") + len(" + len + ") > buf.length(" + buf.length + ").");
    1170        }
    1171        if (closed) {
    1172            throw new IOException("Stream closed");
    1173        }
    1174
    1175        for (final int hi = offs + len; offs < hi;) {
    1176            write0(buf[offs++]);
    1177        }
    1178    }
    1179
    1180    @Override
    1181    public void write(final int b) throws IOException {
    1182        if (closed) {
    1183            throw new IOException("Closed");
    1184        }
    1185        write0(b);
    1186    }
    1187
    1188    /**
    1189     * Keeps track of the last bytes written and implicitly performs run-length encoding as the first step of the bzip2 algorithm.
    1190     */
    1191    private void write0(int b) throws IOException {
    1192        if (this.currentChar != -1) {
    1193            b &= 0xff;
    1194            if (this.currentChar == b) {
    1195                if (++this.runLength > 254) {
    1196                    writeRun();
    1197                    this.currentChar = -1;
    1198                    this.runLength = 0;
    1199                }
    1200                // else nothing to do
    1201            } else {
    1202                writeRun();
    1203                this.runLength = 1;
    1204                this.currentChar = b;
    1205            }
    1206        } else {
    1207            this.currentChar = b & 0xff;
    1208            this.runLength++;
    1209        }
    1210    }
    1211
    1212    /**
    1213     * 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
    1214     * identical bytes).
    1215     *
    1216     * <p>
    1217     * Flushes the current block before writing data if it is full.
    1218     * </p>
    1219     *
    1220     * <p>
    1221     * "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
    1222     * to point to the last index written minus 1.
    1223     * </p>
    1224     */
    1225    private void writeRun() throws IOException {
    1226        final int lastShadow = this.last;
    1227
    1228        if (lastShadow < this.allowableBlockSize) {
    1229            final int currentCharShadow = this.currentChar;
    1230            final Data dataShadow = this.data;
    1231            dataShadow.inUse[currentCharShadow] = true;
    1232            final byte ch = (byte) currentCharShadow;
    1233
    1234            int runLengthShadow = this.runLength;
    1235            this.crc.update(currentCharShadow, runLengthShadow);
    1236
    1237            switch (runLengthShadow) {
    1238            case 1:
    1239                dataShadow.block[lastShadow + 2] = ch;
    1240                this.last = lastShadow + 1;
    1241                break;
    1242
    1243            case 2:
    1244                dataShadow.block[lastShadow + 2] = ch;
    1245                dataShadow.block[lastShadow + 3] = ch;
    1246                this.last = lastShadow + 2;
    1247                break;
    1248
    1249            case 3: {
    1250                final byte[] block = dataShadow.block;
    1251                block[lastShadow + 2] = ch;
    1252                block[lastShadow + 3] = ch;
    1253                block[lastShadow + 4] = ch;
    1254                this.last = lastShadow + 3;
    1255            }
    1256                break;
    1257
    1258            default: {
    1259                runLengthShadow -= 4;
    1260                dataShadow.inUse[runLengthShadow] = true;
    1261                final byte[] block = dataShadow.block;
    1262                block[lastShadow + 2] = ch;
    1263                block[lastShadow + 3] = ch;
    1264                block[lastShadow + 4] = ch;
    1265                block[lastShadow + 5] = ch;
    1266                block[lastShadow + 6] = (byte) runLengthShadow;
    1267                this.last = lastShadow + 5;
    1268            }
    1269                break;
    1270
    1271            }
    1272        } else {
    1273            endBlock();
    1274            initBlock();
    1275            writeRun();
    1276        }
    1277    }
    1278
    1279}