/*
 *  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
 *
 *      http://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.
 *
 */

/*
 * This package is based on the work done by Keiron Liddle, Aftex Software
 * <keiron@aftexsw.com> to whom the Ant project is very grateful for his
 * great code.
 */
package org.apache.tools.bzip2;

import java.io.IOException;
import java.io.InputStream;

/**
 * An input stream that decompresses from the BZip2 format (without the file
 * header chars) to be read as any other stream.
 *
 * <p>The decompression requires large amounts of memory. Thus you
 * should call the {@link #close() close()} method as soon as
 * possible, to force <tt>CBZip2InputStream</tt> to release the
 * allocated memory.  See {@link CBZip2OutputStream
 * CBZip2OutputStream} for information about memory usage.</p>
 *
 * <p><tt>CBZip2InputStream</tt> reads bytes from the compressed
 * source stream via the single byte {@link java.io.InputStream#read()
 * read()} method exclusively. Thus you should consider to use a
 * buffered source stream.</p>
 * 
 * <p>Instances of this class are not threadsafe.</p>
 */
public class CBZip2InputStream extends InputStream implements BZip2Constants {

    /**
     * Index of the last char in the block, so the block size == last + 1.
     */
    private int  last;

    /**
     * Index in zptr[] of original string after sorting.
     */
    private int  origPtr;

    /**
     * always: in the range 0 .. 9.
     * The current block size is 100000 * this number.
     */
    private int blockSize100k;

    private boolean blockRandomised;

    private int bsBuff;
    private int bsLive;
    private final CRC crc = new CRC();

    private int nInUse;

    private InputStream in;
    private final boolean decompressConcatenated;

    private int currentChar = -1;

    private static final int EOF                  = 0;
    private static final int START_BLOCK_STATE = 1;
    private static final int RAND_PART_A_STATE = 2;
    private static final int RAND_PART_B_STATE = 3;
    private static final int RAND_PART_C_STATE = 4;
    private static final int NO_RAND_PART_A_STATE = 5;
    private static final int NO_RAND_PART_B_STATE = 6;
    private static final int NO_RAND_PART_C_STATE = 7;

    private int currentState = START_BLOCK_STATE;

    private int storedBlockCRC, storedCombinedCRC;
    private int computedBlockCRC, computedCombinedCRC;

    // Variables used by setup* methods exclusively

    private int su_count;
    private int su_ch2;
    private int su_chPrev;
    private int su_i2;
    private int su_j2;
    private int su_rNToGo;
    private int su_rTPos;
    private int su_tPos;
    private char su_z;

    /**
     * All memory intensive stuff.
     * This field is initialized by initBlock().
     */
    private CBZip2InputStream.Data data;

    /**
     * Constructs a new CBZip2InputStream which decompresses bytes read from
     * the specified stream. This doesn't suppprt decompressing
     * concatenated .bz2 files.
     *
     * <p>Although BZip2 headers are marked with the magic
     * <tt>"Bz"</tt> this constructor expects the next byte in the
     * stream to be the first one after the magic.  Thus callers have
     * to skip the first two bytes. Otherwise this constructor will
     * throw an exception. </p>
     * @param in 
     *
     * @throws IOException
     *  if the stream content is malformed or an I/O error occurs.
     * @throws NullPointerException
     *  if <tt>in == null</tt>
     */
    public CBZip2InputStream(final InputStream in) throws IOException {
        this(in, false);
    }

    /**
     * Constructs a new CBZip2InputStream which decompresses bytes
     * read from the specified stream.
     *
     * <p>Although BZip2 headers are marked with the magic
     * <tt>"Bz"</tt> this constructor expects the next byte in the
     * stream to be the first one after the magic.  Thus callers have
     * to skip the first two bytes. Otherwise this constructor will
     * throw an exception. </p>
     *
     * @param in the InputStream from which this object should be created
     * @param decompressConcatenated
     *                     if true, decompress until the end of the input;
     *                     if false, stop after the first .bz2 stream and
     *                     leave the input position to point to the next
     *                     byte after the .bz2 stream
     *
     * @throws IOException
     *             if the stream content is malformed or an I/O error occurs.
     * @throws NullPointerException
     *             if <tt>in == null</tt>
     */
    public CBZip2InputStream(final InputStream in,
                             final boolean decompressConcatenated)
            throws IOException {
        super();

        this.in = in;
        this.decompressConcatenated = decompressConcatenated;

        init(true);
        initBlock();
        setupBlock();
    }

  /** {@inheritDoc} */
  @Override
  public int read() throws IOException {
    if (this.in == null)
      throw new IOException("stream closed");
    return read0();
  }

    /*
     * (non-Javadoc)
     * 
     * @see java.io.InputStream#read(byte[], int, int)
     */
    @Override
    public int read(final byte[] dest, final 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 > dest.length) {
            throw new IndexOutOfBoundsException("offs(" + offs + ") + len("
                                                + len + ") > dest.length("
                                                + dest.length + ").");
        }
        if (this.in == null) {
            throw new IOException("stream closed");
        }

        final int hi = offs + len;
        int destOffs = offs;
        for (int b; (destOffs < hi) && ((b = read0()) >= 0);) {
            dest[destOffs++] = (byte) b;
        }

        return (destOffs == offs) ? -1 : (destOffs - offs);
    }

    private void makeMaps() {
        final boolean[] inUse   = this.data.inUse;
        final byte[] seqToUnseq = this.data.seqToUnseq;

        int nInUseShadow = 0;

        for (int i = 0; i < 256; i++) {
            if (inUse[i]) {
                seqToUnseq[nInUseShadow++] = (byte) i;
            }
        }

        this.nInUse = nInUseShadow;
    }

    private int read0() throws IOException {
        final int retChar = this.currentChar;

        switch (this.currentState) {
        case EOF:
            return -1;

        case START_BLOCK_STATE:
            throw new IllegalStateException();

        case RAND_PART_A_STATE:
            throw new IllegalStateException();

        case RAND_PART_B_STATE:
            setupRandPartB();
            break;

        case RAND_PART_C_STATE:
            setupRandPartC();
            break;

        case NO_RAND_PART_A_STATE:
            throw new IllegalStateException();

        case NO_RAND_PART_B_STATE:
            setupNoRandPartB();
            break;

        case NO_RAND_PART_C_STATE:
            setupNoRandPartC();
            break;

        default:
            throw new IllegalStateException();
        }

        return retChar;
    }

    private boolean init(boolean isFirstStream) throws IOException {
        if (null == in) {
            throw new IOException("No InputStream");
        }
        
        if (isFirstStream) {
            if (in.available() == 0) {
                throw new IOException("Empty InputStream");
            }
        } else {
            int magic0 = readByteAsInt();
            if (magic0 == -1) {
                return false;
            }
            int magic1 = readByteAsInt();
            if (magic0 != 'B' || magic1 != 'Z') {
                throw new IOException("Garbage after a valid BZip2 stream");
            }
        }

        int magic2 = readByteAsInt();
        if (magic2 != 'h') {
            throw new IOException(isFirstStream
                    ? "Stream is not in the BZip2 format"
                    : "Garbage after a valid BZip2 stream");
        }

        int blockSize = readByteAsInt();
        if ((blockSize < '1') || (blockSize > '9')) {
            throw new IOException("Stream is not BZip2 formatted: illegal "
                                  + "blocksize " + (char) blockSize);
        }

        this.blockSize100k = blockSize - '0';

        this.bsLive = 0;
        this.computedCombinedCRC = 0;

        return true;
    }

    public synchronized int readByteAsInt() throws IOException {
      /**
       * @j2sNative
       * 
       * return(this.in.readByteAsInt());
       */
      {
        return in.read();
      }
    }

  private void initBlock() throws IOException {
    char magic0;
    char magic1;
    char magic2;
    char magic3;
    char magic4;
    char magic5;

    while (true) {
      // Get the block magic bytes.
      magic0 = bsGetUByte();
      magic1 = bsGetUByte();
      magic2 = bsGetUByte();
      magic3 = bsGetUByte();
      magic4 = bsGetUByte();
      magic5 = bsGetUByte();

      // If isn't end of stream magic, break out of the loop.
      if (magic0 != 0x17 || magic1 != 0x72 || magic2 != 0x45 || magic3 != 0x38
          || magic4 != 0x50 || magic5 != 0x90) {
        break;
      }

      // End of stream was reached. Check the combined CRC and
      // advance to the next .bz2 stream if decoding concatenated
      // streams.
      if (complete()) {
        return;
      }
    }

    if (magic0 != 0x31 || // '1'
        magic1 != 0x41 || // ')'
        magic2 != 0x59 || // 'Y'
        magic3 != 0x26 || // '&'
        magic4 != 0x53 || // 'S'
        magic5 != 0x59 // 'Y'
    ) {
      this.currentState = EOF;
      throw new IOException("bad block header");
    }
    this.storedBlockCRC = bsGetInt();
    this.blockRandomised = bsR(1) == 1;

    /**
     * Allocate data here instead in constructor, so we do not allocate it if
     * the input file is empty.
     */
    if (this.data == null) {
      this.data = new Data(this.blockSize100k);
    }

    // currBlockNo++;
    getAndMoveToFrontDecode();

    this.crc.initialiseCRC();
    this.currentState = START_BLOCK_STATE;
  }

    private void endBlock() throws IOException {
        this.computedBlockCRC = this.crc.getFinalCRC();

        // A bad CRC is considered a fatal error.
        if (this.storedBlockCRC != this.computedBlockCRC) {
            // make next blocks readable without error
            // (repair feature, not yet documented, not tested)
            this.computedCombinedCRC
                = (this.storedCombinedCRC << 1)
                | (this.storedCombinedCRC >>> 31);
            this.computedCombinedCRC ^= this.storedBlockCRC;

            reportCRCError();
        }

        this.computedCombinedCRC
            = (this.computedCombinedCRC << 1)
            | (this.computedCombinedCRC >>> 31);
        this.computedCombinedCRC ^= this.computedBlockCRC;
    }

    private boolean complete() throws IOException {
        this.storedCombinedCRC = bsGetInt();
        this.currentState = EOF;
        this.data = null;

        if (this.storedCombinedCRC != this.computedCombinedCRC) {
            reportCRCError();
        }

        // Look for the next .bz2 stream if decompressing
        // concatenated files.
        return !decompressConcatenated || !init(false);
    }

    @Override
    public void close() throws IOException {
        InputStream inShadow = this.in;
        if (inShadow != null) {
            try {
                if (inShadow != System.in) {
                    inShadow.close();
                }
            } finally {
                this.data = null;
                this.in = null;
            }
        }
    }

    private int bsR(final int n) throws IOException {
        int bsLiveShadow = this.bsLive;
        int bsBuffShadow = this.bsBuff;

        if (bsLiveShadow < n) {
            final InputStream inShadow = this.in;
            do {
                int thech = readByteAsInt();//inShadow.read();

                if (thech < 0) {
                    throw new IOException("unexpected end of stream");
                }

                bsBuffShadow = (bsBuffShadow << 8) | thech;
                bsLiveShadow += 8;
            } while (bsLiveShadow < n);

            this.bsBuff = bsBuffShadow;
        }

        this.bsLive = bsLiveShadow - n;
        return (bsBuffShadow >> (bsLiveShadow - n)) & ((1 << n) - 1);
    }

    private boolean bsGetBit() throws IOException {
        int bsLiveShadow = this.bsLive;
        int bsBuffShadow = this.bsBuff;

        if (bsLiveShadow < 1) {
            int thech = readByteAsInt();

            if (thech < 0) {
                throw new IOException("unexpected end of stream");
            }

            bsBuffShadow = (bsBuffShadow << 8) | thech;
            bsLiveShadow += 8;
            this.bsBuff = bsBuffShadow;
        }

        this.bsLive = bsLiveShadow - 1;
        return ((bsBuffShadow >> (bsLiveShadow - 1)) & 1) != 0;
    }

    private char bsGetUByte() throws IOException {
        return (char) bsR(8);
    }

    private int bsGetInt() throws IOException {
        return (((((bsR(8) << 8) | bsR(8)) << 8) | bsR(8)) << 8) | bsR(8);
    }

    /**
     * Called by createHuffmanDecodingTables() exclusively.
     * @param limit 
     * @param base 
     * @param perm 
     * @param length 
     * @param minLen 
     * @param maxLen 
     * @param alphaSize 
     */
    private static void hbCreateDecodeTables(final int[] limit,
                                             final int[] base,
                                             final int[] perm,
                                             final char[] length,
                                             final int minLen,
                                             final int maxLen,
                                             final int alphaSize) {
        for (int i = minLen, pp = 0; i <= maxLen; i++) {
            for (int j = 0; j < alphaSize; j++) {
                if (length[j] == i) {
                    perm[pp++] = j;
                }
            }
        }

        for (int i = MAX_CODE_LEN; --i > 0;) {
            base[i] = 0;
            limit[i] = 0;
        }

        for (int i = 0; i < alphaSize; i++) {
            base[length[i] + 1]++;
        }

        for (int i = 1, b = base[0]; i < MAX_CODE_LEN; i++) {
            b += base[i];
            base[i] = b;
        }

        for (int i = minLen, vec = 0, b = base[i]; i <= maxLen; i++) {
            final int nb = base[i + 1];
            vec += nb - b;
            b = nb;
            limit[i] = vec - 1;
            vec <<= 1;
        }

        for (int i = minLen + 1; i <= maxLen; i++) {
            base[i] = ((limit[i - 1] + 1) << 1) - base[i];
        }
    }

    private void recvDecodingTables() throws IOException {
        final Data dataShadow     = this.data;
        final boolean[] inUse     = dataShadow.inUse;
        final byte[] pos          = dataShadow.recvDecodingTables_pos;
        final byte[] selector     = dataShadow.selector;
        final byte[] selectorMtf  = dataShadow.selectorMtf;

        int inUse16 = 0;

        /* Receive the mapping table */
        for (int i = 0; i < 16; i++) {
            if (bsGetBit()) {
                inUse16 |= 1 << i;
            }
        }

        for (int i = 256; --i >= 0;) {
            inUse[i] = false;
        }

        for (int i = 0; i < 16; i++) {
            if ((inUse16 & (1 << i)) != 0) {
                final int i16 = i << 4;
                for (int j = 0; j < 16; j++) {
                    if (bsGetBit()) {
                        inUse[i16 + j] = true;
                    }
                }
            }
        }

        makeMaps();
        final int alphaSize = this.nInUse + 2;

        /* Now the selectors */
        final int nGroups = bsR(3);
        final int nSelectors = bsR(15);

        for (int i = 0; i < nSelectors; i++) {
            int j = 0;
            while (bsGetBit()) {
                j++;
            }
            selectorMtf[i] = (byte) j;
        }

        /* Undo the MTF values for the selectors. */
        for (int v = nGroups; --v >= 0;) {
            pos[v] = (byte) v;
        }

        for (int i = 0; i < nSelectors; i++) {
            int v = selectorMtf[i] & 0xff;
            final byte tmp = pos[v];
            while (v > 0) {
                // nearly all times v is zero, 4 in most other cases
                pos[v] = pos[v - 1];
                v--;
            }
            pos[0] = tmp;
            selector[i] = tmp;
        }

        final char[][] len  = dataShadow.temp_charArray2d;

        /* Now the coding tables */
        for (int t = 0; t < nGroups; t++) {
            int curr = bsR(5);
            final char[] len_t = len[t];
            for (int i = 0; i < alphaSize; i++) {
                while (bsGetBit()) {
                    curr += bsGetBit() ? -1 : 1;
                }
                len_t[i] = (char) curr;
            }
        }

        // finally create the Huffman tables
        createHuffmanDecodingTables(alphaSize, nGroups);
    }

    /**
     * Called by recvDecodingTables() exclusively.
     * @param alphaSize 
     * @param nGroups 
     */
    private void createHuffmanDecodingTables(final int alphaSize,
                                             final int nGroups) {
        final Data dataShadow = this.data;
        final char[][] len  = dataShadow.temp_charArray2d;
        final int[] minLens = dataShadow.minLens;
        final int[][] limit = dataShadow.limit;
        final int[][] base  = dataShadow.base;
        final int[][] perm  = dataShadow.perm;

        for (int t = 0; t < nGroups; t++) {
            int minLen = 32;
            int maxLen = 0;
            final char[] len_t = len[t];
            for (int i = alphaSize; --i >= 0;) {
                final char lent = len_t[i];
                if (lent > maxLen) {
                    maxLen = lent;
                }
                if (lent < minLen) {
                    minLen = lent;
                }
            }
            hbCreateDecodeTables(limit[t], base[t], perm[t], len[t], minLen,
                                 maxLen, alphaSize);
            minLens[t] = minLen;
        }
    }

  private void getAndMoveToFrontDecode() throws IOException {
    this.origPtr = bsR(24);
    recvDecodingTables();

    final InputStream inShadow = this.in;
    final Data dataShadow = this.data;
    final byte[] ll8 = dataShadow.ll8;
    final int[] unzftab = dataShadow.unzftab;
    final byte[] selector = dataShadow.selector;
    final byte[] seqToUnseq = dataShadow.seqToUnseq;
    final char[] yy = dataShadow.getAndMoveToFrontDecode_yy;
    final int[] minLens = dataShadow.minLens;
    final int[][] limit = dataShadow.limit;
    final int[][] base = dataShadow.base;
    final int[][] perm = dataShadow.perm;
    final int limitLast = this.blockSize100k * 100000;

    /*
      Setting up the unzftab entries here is not strictly
      necessary, but it does save having to do it later
      in a separate pass, and so saves a block's worth of
      cache misses.
    */
    for (int i = 256; --i >= 0;) {
      yy[i] = (char) i;
      unzftab[i] = 0;
    }

    int groupNo = 0;
    int groupPos = G_SIZE - 1;
    final int eob = this.nInUse + 1;
    int nextSym = getAndMoveToFrontDecode0(0);
    int bsBuffShadow = this.bsBuff;
    int bsLiveShadow = this.bsLive;
    int lastShadow = -1;
    int zt = selector[groupNo] & 0xff;
    int[] base_zt = base[zt];
    int[] limit_zt = limit[zt];
    int[] perm_zt = perm[zt];
    int minLens_zt = minLens[zt];

    while (nextSym != eob) {
      if ((nextSym == RUNA) || (nextSym == RUNB)) {
        int s = -1;

        for (int n = 1; true; n <<= 1) {
          if (nextSym == RUNA) {
            s += n;
          } else if (nextSym == RUNB) {
            s += n << 1;
          } else {
            break;
          }

          if (groupPos == 0) {
            groupPos = G_SIZE - 1;
            zt = selector[++groupNo] & 0xff;
            base_zt = base[zt];
            limit_zt = limit[zt];
            perm_zt = perm[zt];
            minLens_zt = minLens[zt];
          } else {
            groupPos--;
          }

          int zn = minLens_zt;

          // Inlined:
          // int zvec = bsR(zn);
          while (bsLiveShadow < zn) {
            final int thech = readByteAsInt();//inShadow.read();
            if (thech < 0)
              throw new IOException("unexpected end of stream");

            bsBuffShadow = (bsBuffShadow << 8) | thech;
            bsLiveShadow += 8;
            continue;
          }
          int zvec = (bsBuffShadow >> (bsLiveShadow - zn)) & ((1 << zn) - 1);
          bsLiveShadow -= zn;

          while (zvec > limit_zt[zn]) {
            zn++;
            while (bsLiveShadow < 1) {
              final int thech = readByteAsInt();//inShadow.read();
              if (thech < 0)
                throw new IOException("unexpected end of stream");
              bsBuffShadow = (bsBuffShadow << 8) | thech;
              bsLiveShadow += 8;
              continue;
            }
            bsLiveShadow--;
            zvec = (zvec << 1) | ((bsBuffShadow >> bsLiveShadow) & 1);
          }
          nextSym = perm_zt[zvec - base_zt[zn]];
        }

        final byte ch = seqToUnseq[yy[0]];
        unzftab[ch & 0xff] += s + 1;

        while (s-- >= 0) {
          ll8[++lastShadow] = ch;
        }

        if (lastShadow >= limitLast) {
          throw new IOException("block overrun");
        }
      } else {
        if (++lastShadow >= limitLast) {
          throw new IOException("block overrun");
        }

        final char tmp = yy[nextSym - 1];
        unzftab[seqToUnseq[tmp] & 0xff]++;
        ll8[lastShadow] = seqToUnseq[tmp];

        /*
          This loop is hammered during decompression,
          hence avoid native method call overhead of
          System.arraycopy for very small ranges to copy.
        */
        if (nextSym <= 16) {
          for (int j = nextSym - 1; j > 0;) {
            yy[j] = yy[--j];
          }
        } else {
          System.arraycopy(yy, 0, yy, 1, nextSym - 1);
        }

        yy[0] = tmp;

        if (groupPos == 0) {
          groupPos = G_SIZE - 1;
          zt = selector[++groupNo] & 0xff;
          base_zt = base[zt];
          limit_zt = limit[zt];
          perm_zt = perm[zt];
          minLens_zt = minLens[zt];
        } else {
          groupPos--;
        }

        int zn = minLens_zt;

        // Inlined:
        // int zvec = bsR(zn);
        while (bsLiveShadow < zn) {
          final int thech = readByteAsInt();//inShadow.read();
          if (thech < 0)
            throw new IOException("unexpected end of stream");
          bsBuffShadow = (bsBuffShadow << 8) | thech;
          bsLiveShadow += 8;
          continue;
        }
        int zvec = (bsBuffShadow >> (bsLiveShadow - zn)) & ((1 << zn) - 1);
        bsLiveShadow -= zn;

        while (zvec > limit_zt[zn]) {
          zn++;
          while (bsLiveShadow < 1) {
            final int thech = readByteAsInt();//inShadow.read();
            if (thech <0) 
              throw new IOException("unexpected end of stream");
              bsBuffShadow = (bsBuffShadow << 8) | thech;
              bsLiveShadow += 8;
              continue;
          }
          bsLiveShadow--;
          zvec = (zvec << 1) | ((bsBuffShadow >> bsLiveShadow) & 1);
        }
        nextSym = perm_zt[zvec - base_zt[zn]];
      }
    }

    this.last = lastShadow;
    this.bsLive = bsLiveShadow;
    this.bsBuff = bsBuffShadow;
  }

  private int getAndMoveToFrontDecode0(final int groupNo) throws IOException {
    final InputStream inShadow = this.in;
    final Data dataShadow = this.data;
    final int zt = dataShadow.selector[groupNo] & 0xff;
    final int[] limit_zt = dataShadow.limit[zt];
    int zn = dataShadow.minLens[zt];
    int zvec = bsR(zn);
    int bsLiveShadow = this.bsLive;
    int bsBuffShadow = this.bsBuff;

    while (zvec > limit_zt[zn]) {
      zn++;
      while (bsLiveShadow < 1) {
        final int thech = readByteAsInt();//inShadow.read();

        if (thech < 0)
          throw new IOException("unexpected end of stream");

        bsBuffShadow = (bsBuffShadow << 8) | thech;
        bsLiveShadow += 8;
        continue;
      }
      bsLiveShadow--;
      zvec = (zvec << 1) | ((bsBuffShadow >> bsLiveShadow) & 1);
    }

    this.bsLive = bsLiveShadow;
    this.bsBuff = bsBuffShadow;

    return dataShadow.perm[zt][zvec - dataShadow.base[zt][zn]];
  }

    private void setupBlock() throws IOException {
        if (this.data == null) {
            return;
        }

        final int[] cftab = this.data.cftab;
        final int[] tt    = this.data.initTT(this.last + 1);
        final byte[] ll8  = this.data.ll8;
        cftab[0] = 0;
        System.arraycopy(this.data.unzftab, 0, cftab, 1, 256);

        for (int i = 1, c = cftab[0]; i <= 256; i++) {
            c += cftab[i];
            cftab[i] = c;
        }

        for (int i = 0, lastShadow = this.last; i <= lastShadow; i++) {
            tt[cftab[ll8[i] & 0xff]++] = i;
        }

        if ((this.origPtr < 0) || (this.origPtr >= tt.length)) {
            throw new IOException("stream corrupted");
        }

        this.su_tPos = tt[this.origPtr];
        this.su_count = 0;
        this.su_i2 = 0;
        this.su_ch2 = 256;   /* not a char and not EOF */

        if (this.blockRandomised) {
            this.su_rNToGo = 0;
            this.su_rTPos = 0;
            setupRandPartA();
        } else {
            setupNoRandPartA();
        }
    }

    private void setupRandPartA() throws IOException {
        if (this.su_i2 <= this.last) {
            this.su_chPrev = this.su_ch2;
            int su_ch2Shadow = this.data.ll8[this.su_tPos] & 0xff;
            this.su_tPos = this.data.tt[this.su_tPos];
            if (this.su_rNToGo == 0) {
                this.su_rNToGo = BZip2Constants.rNums[this.su_rTPos] - 1;
                if (++this.su_rTPos == 512) {
                    this.su_rTPos = 0;
                }
            } else {
                this.su_rNToGo--;
            }
            this.su_ch2 = su_ch2Shadow ^= (this.su_rNToGo == 1) ? 1 : 0;
            this.su_i2++;
            this.currentChar = su_ch2Shadow;
            this.currentState = RAND_PART_B_STATE;
            this.crc.updateCRC(su_ch2Shadow);
        } else {
            endBlock();
            initBlock();
            setupBlock();
        }
    }

    private void setupNoRandPartA() throws IOException {
        if (this.su_i2 <= this.last) {
            this.su_chPrev = this.su_ch2;
            int su_ch2Shadow = this.data.ll8[this.su_tPos] & 0xff;
            this.su_ch2 = su_ch2Shadow;
            this.su_tPos = this.data.tt[this.su_tPos];
            this.su_i2++;
            this.currentChar = su_ch2Shadow;
            this.currentState = NO_RAND_PART_B_STATE;
            this.crc.updateCRC(su_ch2Shadow);
        } else {
            this.currentState = NO_RAND_PART_A_STATE;
            endBlock();
            initBlock();
            setupBlock();
        }
    }

    private void setupRandPartB() throws IOException {
        if (this.su_ch2 != this.su_chPrev) {
            this.currentState = RAND_PART_A_STATE;
            this.su_count = 1;
            setupRandPartA();
        } else if (++this.su_count >= 4) {
            this.su_z = (char) (this.data.ll8[this.su_tPos] & 0xff);
            this.su_tPos = this.data.tt[this.su_tPos];
            if (this.su_rNToGo == 0) {
                this.su_rNToGo = BZip2Constants.rNums[this.su_rTPos] - 1;
                if (++this.su_rTPos == 512) {
                    this.su_rTPos = 0;
                }
            } else {
                this.su_rNToGo--;
            }
            this.su_j2 = 0;
            this.currentState = RAND_PART_C_STATE;
            if (this.su_rNToGo == 1) {
                this.su_z ^= 1;
            }
            setupRandPartC();
        } else {
            this.currentState = RAND_PART_A_STATE;
            setupRandPartA();
        }
    }

    private void setupRandPartC() throws IOException {
        if (this.su_j2 < this.su_z) {
            this.currentChar = this.su_ch2;
            this.crc.updateCRC(this.su_ch2);
            this.su_j2++;
        } else {
            this.currentState = RAND_PART_A_STATE;
            this.su_i2++;
            this.su_count = 0;
            setupRandPartA();
        }
    }

    private void setupNoRandPartB() throws IOException {
        if (this.su_ch2 != this.su_chPrev) {
            this.su_count = 1;
            setupNoRandPartA();
        } else if (++this.su_count >= 4) {
            this.su_z = (char) (this.data.ll8[this.su_tPos] & 0xff);
            this.su_tPos = this.data.tt[this.su_tPos];
            this.su_j2 = 0;
            setupNoRandPartC();
        } else {
            setupNoRandPartA();
        }
    }

    private void setupNoRandPartC() throws IOException {
        if (this.su_j2 < this.su_z) {
            int su_ch2Shadow = this.su_ch2;
            this.currentChar = su_ch2Shadow;
            this.crc.updateCRC(su_ch2Shadow);
            this.su_j2++;
            this.currentState = NO_RAND_PART_C_STATE;
        } else {
            this.su_i2++;
            this.su_count = 0;
            setupNoRandPartA();
        }
    }

    private static final class Data extends Object {

        // (with blockSize 900k)
        final boolean[] inUse   = new boolean[256];                                   //      256 byte

        final byte[] seqToUnseq   = new byte[256];                                    //      256 byte
        final byte[] selector     = new byte[MAX_SELECTORS];                          //    18002 byte
        final byte[] selectorMtf  = new byte[MAX_SELECTORS];                          //    18002 byte

        /**
         * Freq table collected to save a pass over the data during
         * decompression.
         */
        final int[] unzftab = new int[256];                                           //     1024 byte

        final int[][] limit = new int[N_GROUPS][MAX_ALPHA_SIZE];                      //     6192 byte
        final int[][] base  = new int[N_GROUPS][MAX_ALPHA_SIZE];                      //     6192 byte
        final int[][] perm  = new int[N_GROUPS][MAX_ALPHA_SIZE];                      //     6192 byte
        final int[] minLens = new int[N_GROUPS];                                      //       24 byte

        final int[]     cftab     = new int[257];                                     //     1028 byte
        final char[]    getAndMoveToFrontDecode_yy = new char[256];                   //      512 byte
        final char[][]  temp_charArray2d  = new char[N_GROUPS][MAX_ALPHA_SIZE];       //     3096 byte
        final byte[] recvDecodingTables_pos = new byte[N_GROUPS];                     //        6 byte
        //---------------
        //    60798 byte

        int[] tt;                                                                     //  3600000 byte
        byte[] ll8;                                                                   //   900000 byte
        //---------------
        //  4560782 byte
        //===============

        Data(int blockSize100k) {
            super();

            this.ll8 = new byte[blockSize100k * BZip2Constants.baseBlockSize];
        }

        /**
         * Initializes the {@link #tt} array.
         *
         * This method is called when the required length of the array
         * is known.  I don't initialize it at construction time to
         * avoid unnecessary memory allocation when compressing small
         * files.
         * @param length 
         * @return int array
         */
        final int[] initTT(int length) {
            int[] ttShadow = this.tt;

            // tt.length should always be >= length, but theoretically
            // it can happen, if the compressor mixed small and large
            // blocks.  Normally only the last block will be smaller
            // than others.
            if ((ttShadow == null) || (ttShadow.length < length)) {
                this.tt = ttShadow = new int[length];
            }

            return ttShadow;
        }

    }

    @SuppressWarnings("unused")
    private static void reportCRCError() throws IOException {
        // The clean way would be to throw an exception.
        //throw new IOException("crc error");

        // Just print a message, like the previous versions of this class did
        System.err.println("BZip2 CRC error");
    }

}