/*
    * 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.commons.compress.compressors.bzip2;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.nio.ByteOrder;
  import java.util.Arrays;
  
  import org.apache.commons.compress.compressors.CompressorInputStream;
  import org.apache.commons.compress.utils.BitInputStream;
  import org.apache.commons.compress.utils.InputStreamStatistics;
  import org.apache.commons.io.input.CloseShieldInputStream;
  
  /**
   * An input stream that decompresses from the BZip2 format to be read as any other stream.
   *
   * @NotThreadSafe
   */
  public class BZip2CompressorInputStream extends CompressorInputStream implements BZip2Constants, InputStreamStatistics {
  
      private static final class Data {
  
          // (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
          final byte[] ll8; // 900000 byte
  
          // ---------------
          // 4560782 byte
          // ===============
  
          Data(final int blockSize100k) {
              this.ll8 = new byte[blockSize100k * 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.
           */
          int[] initTT(final 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;
         }
 
     }
 
     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 static boolean bsGetBit(final BitInputStream bin) throws IOException {
         return bsR(bin, 1) != 0;
     }
 
     private static int bsGetInt(final BitInputStream bin) throws IOException {
         return bsR(bin, 32);
     }
 
     private static char bsGetUByte(final BitInputStream bin) throws IOException {
         return (char) bsR(bin, 8);
     }
 
     /**
      * read bits from the input stream
      *
      * @param n the number of bits to read, must not exceed 32?
      * @return the requested bits combined into an int
      * @throws IOException
      */
     private static int bsR(final BitInputStream bin, final int n) throws IOException {
         final long thech = bin.readBits(n);
         if (thech < 0) {
             throw new IOException("Unexpected end of stream");
         }
         return (int) thech;
     }
 
     private static void checkBounds(final int checkVal, final int limitExclusive, final String name) throws IOException {
         if (checkVal < 0) {
             throw new IOException("Corrupted input, " + name + " value negative");
         }
         if (checkVal >= limitExclusive) {
             throw new IOException("Corrupted input, " + name + " value too big");
         }
     }
 
     /**
      * Called by createHuffmanDecodingTables() exclusively.
      */
     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) throws IOException {
         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++) {
             final int l = length[i];
             checkBounds(l, MAX_ALPHA_SIZE, "length");
             base[l + 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];
         }
     }
 
     /**
      * Checks if the signature matches what is expected for a bzip2 file.
      *
      * @param signature the bytes to check
      * @param length    the number of bytes to check
      * @return true, if this stream is a bzip2 compressed stream, false otherwise
      *
      * @since 1.1
      */
     public static boolean matches(final byte[] signature, final int length) {
         return length >= 3 && signature[0] == 'B' && signature[1] == 'Z' && signature[2] == 'h';
     }
 
     /**
      * 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;
 
     // Variables used by setup* methods exclusively
 
     private boolean blockRandomised;
     private final CRC crc = new CRC();
     private int nInUse;
     private BitInputStream bin;
     private final boolean decompressConcatenated;
     private int currentState = START_BLOCK_STATE;
     private int storedBlockCRC, storedCombinedCRC;
     private int computedCombinedCRC;
     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 BZip2CompressorInputStream.Data data;
 
     /**
      * Constructs a new BZip2CompressorInputStream which decompresses bytes read from the specified stream. This doesn't support decompressing concatenated .bz2
      * files.
      *
      * @param in the InputStream from which this object should be created
      * @throws IOException          if the stream content is malformed or an I/O error occurs.
      * @throws NullPointerException if {@code in == null}
      */
     public BZip2CompressorInputStream(final InputStream in) throws IOException {
         this(in, false);
     }
 
     /**
      * Constructs a new BZip2CompressorInputStream which decompresses bytes read from the specified stream.
      *
      * @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 {@code in == null}, the stream content is malformed, or an I/O error occurs.
      */
     public BZip2CompressorInputStream(final InputStream in, final boolean decompressConcatenated) throws IOException {
         this.bin = new BitInputStream(in == System.in ? CloseShieldInputStream.wrap(in) : in, ByteOrder.BIG_ENDIAN);
         this.decompressConcatenated = decompressConcatenated;
         init(true);
         initBlock();
     }
 
     @Override
     public void close() throws IOException {
         final BitInputStream inShadow = this.bin;
         if (inShadow != null) {
             try {
                 inShadow.close();
             } finally {
                 this.data = null;
                 this.bin = null;
             }
         }
     }
 
     private boolean complete() throws IOException {
         this.storedCombinedCRC = bsGetInt(bin);
         this.currentState = EOF;
         this.data = null;
         if (this.storedCombinedCRC != this.computedCombinedCRC) {
             throw new IOException("BZip2 CRC error");
         }
         // Look for the next .bz2 stream if decompressing
         // concatenated files.
         return !decompressConcatenated || !init(false);
     }
 
     /**
      * Called by recvDecodingTables() exclusively.
      */
     private void createHuffmanDecodingTables(final int alphaSize, final int nGroups) throws IOException {
         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 endBlock() throws IOException {
         final int computedBlockCRC = this.crc.getValue();
         // A bad CRC is considered a fatal error.
         if (this.storedBlockCRC != 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;
             throw new IOException("BZip2 CRC error");
         }
         this.computedCombinedCRC = this.computedCombinedCRC << 1 | this.computedCombinedCRC >>> 31;
         this.computedCombinedCRC ^= computedBlockCRC;
     }
 
     private void getAndMoveToFrontDecode() throws IOException {
         final BitInputStream bin = this.bin;
         this.origPtr = bsR(bin, 24);
         recvDecodingTables();
         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();
         int lastShadow = -1;
         int zt = selector[groupNo] & 0xff;
         checkBounds(zt, N_GROUPS, "zt");
         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;
                         checkBounds(++groupNo, MAX_SELECTORS, "groupNo");
                         zt = selector[groupNo] & 0xff;
                         checkBounds(zt, N_GROUPS, "zt");
                         base_zt = base[zt];
                         limit_zt = limit[zt];
                         perm_zt = perm[zt];
                         minLens_zt = minLens[zt];
                     } else {
                         groupPos--;
                     }
 
                     int zn = minLens_zt;
                     checkBounds(zn, MAX_ALPHA_SIZE, "zn");
                     int zvec = bsR(bin, zn);
                     while (zvec > limit_zt[zn]) {
                         checkBounds(++zn, MAX_ALPHA_SIZE, "zn");
                         zvec = zvec << 1 | bsR(bin, 1);
                     }
                     final int tmp = zvec - base_zt[zn];
                     checkBounds(tmp, MAX_ALPHA_SIZE, "zvec");
                     nextSym = perm_zt[tmp];
                 }
                 checkBounds(s, this.data.ll8.length, "s");
 
                 final int yy0 = yy[0];
                 checkBounds(yy0, 256, "yy");
                 final byte ch = seqToUnseq[yy0];
                 unzftab[ch & 0xff] += s + 1;
 
                 final int from = ++lastShadow;
                 lastShadow += s;
                 checkBounds(lastShadow, this.data.ll8.length, "lastShadow");
                 Arrays.fill(ll8, from, lastShadow + 1, ch);
 
                 if (lastShadow >= limitLast) {
                     throw new IOException("Block overrun while expanding RLE in MTF, " + lastShadow + " exceeds " + limitLast);
                 }
             } else {
                 if (++lastShadow >= limitLast) {
                     throw new IOException("Block overrun in MTF, " + lastShadow + " exceeds " + limitLast);
                 }
                 checkBounds(nextSym, 256 + 1, "nextSym");
 
                 final char tmp = yy[nextSym - 1];
                 checkBounds(tmp, 256, "yy");
                 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;
                     checkBounds(++groupNo, MAX_SELECTORS, "groupNo");
                     zt = selector[groupNo] & 0xff;
                     checkBounds(zt, N_GROUPS, "zt");
                     base_zt = base[zt];
                     limit_zt = limit[zt];
                     perm_zt = perm[zt];
                     minLens_zt = minLens[zt];
                 } else {
                     groupPos--;
                 }
 
                 int zn = minLens_zt;
                 checkBounds(zn, MAX_ALPHA_SIZE, "zn");
                 int zvec = bsR(bin, zn);
                 while (zvec > limit_zt[zn]) {
                     checkBounds(++zn, MAX_ALPHA_SIZE, "zn");
                     zvec = zvec << 1 | bsR(bin, 1);
                 }
                 final int idx = zvec - base_zt[zn];
                 checkBounds(idx, MAX_ALPHA_SIZE, "zvec");
                 nextSym = perm_zt[idx];
             }
         }
 
         this.last = lastShadow;
     }
 
     private int getAndMoveToFrontDecode0() throws IOException {
         final Data dataShadow = this.data;
         final int zt = dataShadow.selector[0] & 0xff;
         checkBounds(zt, N_GROUPS, "zt");
         final int[] limit_zt = dataShadow.limit[zt];
         int zn = dataShadow.minLens[zt];
         checkBounds(zn, MAX_ALPHA_SIZE, "zn");
         int zvec = bsR(bin, zn);
         while (zvec > limit_zt[zn]) {
             checkBounds(++zn, MAX_ALPHA_SIZE, "zn");
             zvec = zvec << 1 | bsR(bin, 1);
         }
         final int tmp = zvec - dataShadow.base[zt][zn];
         checkBounds(tmp, MAX_ALPHA_SIZE, "zvec");
 
         return dataShadow.perm[zt][tmp];
     }
 
     /**
      * @since 1.17
      */
     @Override
     public long getCompressedCount() {
         return bin.getBytesRead();
     }
 
     private boolean init(final boolean isFirstStream) throws IOException {
         if (null == bin) {
             throw new IOException("No InputStream");
         }
 
         if (!isFirstStream) {
             bin.clearBitCache();
         }
 
         final int magic0 = readNextByte(this.bin);
         if (magic0 == -1 && !isFirstStream) {
             return false;
         }
         final int magic1 = readNextByte(this.bin);
         final int magic2 = readNextByte(this.bin);
 
         if (magic0 != 'B' || magic1 != 'Z' || magic2 != 'h') {
             throw new IOException(isFirstStream ? "Stream is not in the BZip2 format" : "Garbage after a valid BZip2 stream");
         }
 
         final int blockSize = readNextByte(this.bin);
         if (blockSize < '1' || blockSize > '9') {
             throw new IOException("BZip2 block size is invalid");
         }
 
         this.blockSize100k = blockSize - '0';
 
         this.computedCombinedCRC = 0;
 
         return true;
     }
 
     private void initBlock() throws IOException {
         final BitInputStream bin = this.bin;
         char magic0;
         char magic1;
         char magic2;
         char magic3;
         char magic4;
         char magic5;
 
         while (true) {
             // Get the block magic bytes.
             magic0 = bsGetUByte(bin);
             magic1 = bsGetUByte(bin);
             magic2 = bsGetUByte(bin);
             magic3 = bsGetUByte(bin);
             magic4 = bsGetUByte(bin);
             magic5 = bsGetUByte(bin);
 
             // 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(bin);
         this.blockRandomised = bsR(bin, 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.reset();
         this.currentState = START_BLOCK_STATE;
     }
 
     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;
     }
 
     @Override
     public int read() throws IOException {
         if (this.bin != null) {
             final int r = read0();
             count(r < 0 ? -1 : 1);
             return r;
         }
         throw new IOException("Stream closed");
     }
 
     /*
      * (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.bin == null) {
             throw new IOException("Stream closed");
         }
         if (len == 0) {
             return 0;
         }
 
         final int hi = offs + len;
         int destOffs = offs;
         int b;
         while (destOffs < hi && (b = read0()) >= 0) {
             dest[destOffs++] = (byte) b;
             count(1);
         }
 
         return destOffs == offs ? -1 : destOffs - offs;
     }
 
     private int read0() throws IOException {
         switch (currentState) {
         case EOF:
             return -1;
 
         case START_BLOCK_STATE:
             return setupBlock();
 
         case RAND_PART_A_STATE:
             throw new IllegalStateException();
 
         case RAND_PART_B_STATE:
             return setupRandPartB();
 
         case RAND_PART_C_STATE:
             return setupRandPartC();
 
         case NO_RAND_PART_A_STATE:
             throw new IllegalStateException();
 
         case NO_RAND_PART_B_STATE:
             return setupNoRandPartB();
 
         case NO_RAND_PART_C_STATE:
             return setupNoRandPartC();
 
         default:
             throw new IllegalStateException();
         }
     }
 
     private int readNextByte(final BitInputStream in) throws IOException {
         final long b = in.readBits(8);
         return (int) b;
     }
 
     private void recvDecodingTables() throws IOException {
         final BitInputStream bin = this.bin;
         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(bin)) {
                 inUse16 |= 1 << i;
             }
         }
 
         Arrays.fill(inUse, 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(bin)) {
                         inUse[i16 + j] = true;
                     }
                 }
             }
         }
 
         makeMaps();
         final int alphaSize = this.nInUse + 2;
         /* Now the selectors */
         final int nGroups = bsR(bin, 3);
         final int selectors = bsR(bin, 15);
         if (selectors < 0) {
             throw new IOException("Corrupted input, nSelectors value negative");
         }
         checkBounds(alphaSize, MAX_ALPHA_SIZE + 1, "alphaSize");
         checkBounds(nGroups, N_GROUPS + 1, "nGroups");
 
         // Don't fail on nSelectors overflowing boundaries but discard the values in overflow
         // See https://gnu.wildebeest.org/blog/mjw/2019/08/02/bzip2-and-the-cve-that-wasnt/
         // and https://sourceware.org/ml/bzip2-devel/2019-q3/msg00007.html
 
         for (int i = 0; i < selectors; i++) {
             int j = 0;
             while (bsGetBit(bin)) {
                 j++;
             }
             if (i < MAX_SELECTORS) {
                 selectorMtf[i] = (byte) j;
             }
         }
         final int nSelectors = Math.min(selectors, MAX_SELECTORS);
 
         /* 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;
             checkBounds(v, N_GROUPS, "selectorMtf");
             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(bin, 5);
             final char[] len_t = len[t];
             for (int i = 0; i < alphaSize; i++) {
                 while (bsGetBit(bin)) {
                     curr += bsGetBit(bin) ? -1 : 1;
                 }
                 len_t[i] = (char) curr;
             }
         }
 
         // finally create the Huffman tables
         createHuffmanDecodingTables(alphaSize, nGroups);
     }
 
     private int setupBlock() throws IOException {
         if (currentState == EOF || this.data == null) {
             return -1;
         }
 
         final int[] cftab = this.data.cftab;
         final int ttLen = this.last + 1;
         final int[] tt = this.data.initTT(ttLen);
         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++) {
             final int tmp = cftab[ll8[i] & 0xff]++;
             checkBounds(tmp, ttLen, "tt index");
             tt[tmp] = 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;
             return setupRandPartA();
         }
         return setupNoRandPartA();
     }
 
     private int setupNoRandPartA() throws IOException {
         if (this.su_i2 <= this.last) {
             this.su_chPrev = this.su_ch2;
             final int su_ch2Shadow = this.data.ll8[this.su_tPos] & 0xff;
             this.su_ch2 = su_ch2Shadow;
             checkBounds(this.su_tPos, this.data.tt.length, "su_tPos");
             this.su_tPos = this.data.tt[this.su_tPos];
             this.su_i2++;
             this.currentState = NO_RAND_PART_B_STATE;
             this.crc.update(su_ch2Shadow);
             return su_ch2Shadow;
         }
         this.currentState = NO_RAND_PART_A_STATE;
         endBlock();
         initBlock();
         return setupBlock();
     }
 
     private int setupNoRandPartB() throws IOException {
         if (this.su_ch2 != this.su_chPrev) {
             this.su_count = 1;
             return setupNoRandPartA();
         }
         if (++this.su_count >= 4) {
             checkBounds(this.su_tPos, this.data.ll8.length, "su_tPos");
             this.su_z = (char) (this.data.ll8[this.su_tPos] & 0xff);
             this.su_tPos = this.data.tt[this.su_tPos];
             this.su_j2 = 0;
             return setupNoRandPartC();
         }
         return setupNoRandPartA();
     }
 
     private int setupNoRandPartC() throws IOException {
         if (this.su_j2 < this.su_z) {
             final int su_ch2Shadow = this.su_ch2;
             this.crc.update(su_ch2Shadow);
             this.su_j2++;
             this.currentState = NO_RAND_PART_C_STATE;
             return su_ch2Shadow;
         }
         this.su_i2++;
         this.su_count = 0;
         return setupNoRandPartA();
     }
 
     private int 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;
             checkBounds(this.su_tPos, this.data.tt.length, "su_tPos");
             this.su_tPos = this.data.tt[this.su_tPos];
             if (this.su_rNToGo == 0) {
                 this.su_rNToGo = Rand.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.currentState = RAND_PART_B_STATE;
             this.crc.update(su_ch2Shadow);
             return su_ch2Shadow;
         }
         endBlock();
         initBlock();
         return setupBlock();
     }
 
     private int setupRandPartB() throws IOException {
         if (this.su_ch2 != this.su_chPrev) {
             this.currentState = RAND_PART_A_STATE;
             this.su_count = 1;
             return setupRandPartA();
         }
         if (++this.su_count < 4) {
             this.currentState = RAND_PART_A_STATE;
             return setupRandPartA();
         }
         this.su_z = (char) (this.data.ll8[this.su_tPos] & 0xff);
         checkBounds(this.su_tPos, this.data.tt.length, "su_tPos");
         this.su_tPos = this.data.tt[this.su_tPos];
         if (this.su_rNToGo == 0) {
             this.su_rNToGo = Rand.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;
         }
         return setupRandPartC();
     }
 
     private int setupRandPartC() throws IOException {
         if (this.su_j2 < this.su_z) {
             this.crc.update(this.su_ch2);
             this.su_j2++;
             return this.su_ch2;
         }
         this.currentState = RAND_PART_A_STATE;
         this.su_i2++;
         this.su_count = 0;
         return setupRandPartA();
     }
 }