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-rw-r--r--crypto/bzip2/src/CBZip2OutputStream.cs1691
1 files changed, 1691 insertions, 0 deletions
diff --git a/crypto/bzip2/src/CBZip2OutputStream.cs b/crypto/bzip2/src/CBZip2OutputStream.cs
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+/*
+ * 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.
+ */
+
+using System;
+using System.IO;
+
+namespace Org.BouncyCastle.Apache.Bzip2
+{
+	/**
+    * An output stream that compresses into the BZip2 format (with the file
+    * header chars) into another stream.
+    *
+    * @author <a href="mailto:keiron@aftexsw.com">Keiron Liddle</a>
+    *
+    * TODO:    Update to BZip2 1.0.1
+    * <b>NB:</b> note this class has been modified to add a leading BZ to the
+    * start of the BZIP2 stream to make it compatible with other PGP programs.
+    */
+    public class CBZip2OutputStream : Stream 
+	{
+        protected const int SETMASK = (1 << 21);
+        protected const int CLEARMASK = (~SETMASK);
+        protected const int GREATER_ICOST = 15;
+        protected const int LESSER_ICOST = 0;
+        protected const int SMALL_THRESH = 20;
+        protected const int DEPTH_THRESH = 10;
+
+        /*
+        If you are ever unlucky/improbable enough
+        to get a stack overflow whilst sorting,
+        increase the following constant and try
+        again.  In practice I have never seen the
+        stack go above 27 elems, so the following
+        limit seems very generous.
+        */
+        protected const int QSORT_STACK_SIZE = 1000;
+        private bool finished;
+
+        private static void Panic() {
+            //System.out.Println("panic");
+            //throw new CError();
+        }
+
+        private void MakeMaps() {
+            int i;
+            nInUse = 0;
+            for (i = 0; i < 256; i++) {
+                if (inUse[i]) {
+                    seqToUnseq[nInUse] = (char) i;
+                    unseqToSeq[i] = (char) nInUse;
+                    nInUse++;
+                }
+            }
+        }
+
+        protected static void HbMakeCodeLengths(char[] len, int[] freq,
+                                                int alphaSize, int maxLen) {
+            /*
+            Nodes and heap entries run from 1.  Entry 0
+            for both the heap and nodes is a sentinel.
+            */
+            int nNodes, nHeap, n1, n2, i, j, k;
+            bool  tooLong;
+
+            int[] heap = new int[BZip2Constants.MAX_ALPHA_SIZE + 2];
+            int[] weight = new int[BZip2Constants.MAX_ALPHA_SIZE * 2];
+            int[] parent = new int[BZip2Constants.MAX_ALPHA_SIZE * 2];
+
+            for (i = 0; i < alphaSize; i++) {
+                weight[i + 1] = (freq[i] == 0 ? 1 : freq[i]) << 8;
+            }
+
+            while (true) {
+                nNodes = alphaSize;
+                nHeap = 0;
+
+                heap[0] = 0;
+                weight[0] = 0;
+                parent[0] = -2;
+
+                for (i = 1; i <= alphaSize; i++) {
+                    parent[i] = -1;
+                    nHeap++;
+                    heap[nHeap] = i;
+                    {
+                        int zz, tmp;
+                        zz = nHeap;
+                        tmp = heap[zz];
+                        while (weight[tmp] < weight[heap[zz >> 1]]) {
+                            heap[zz] = heap[zz >> 1];
+                            zz >>= 1;
+                        }
+                        heap[zz] = tmp;
+                    }
+                }
+                if (!(nHeap < (BZip2Constants.MAX_ALPHA_SIZE + 2))) {
+                    Panic();
+                }
+
+                while (nHeap > 1) {
+                    n1 = heap[1];
+                    heap[1] = heap[nHeap];
+                    nHeap--;
+                    {
+                        int zz = 0, yy = 0, tmp = 0;
+                        zz = 1;
+                        tmp = heap[zz];
+                        while (true) {
+                            yy = zz << 1;
+                            if (yy > nHeap) {
+                                break;
+                            }
+                            if (yy < nHeap
+                                && weight[heap[yy + 1]] < weight[heap[yy]]) {
+                                yy++;
+                            }
+                            if (weight[tmp] < weight[heap[yy]]) {
+                                break;
+                            }
+                            heap[zz] = heap[yy];
+                            zz = yy;
+                        }
+                        heap[zz] = tmp;
+                    }
+                    n2 = heap[1];
+                    heap[1] = heap[nHeap];
+                    nHeap--;
+                    {
+                        int zz = 0, yy = 0, tmp = 0;
+                        zz = 1;
+                        tmp = heap[zz];
+                        while (true) {
+                            yy = zz << 1;
+                            if (yy > nHeap) {
+                                break;
+                            }
+                            if (yy < nHeap
+                                && weight[heap[yy + 1]] < weight[heap[yy]]) {
+                                yy++;
+                            }
+                            if (weight[tmp] < weight[heap[yy]]) {
+                                break;
+                            }
+                            heap[zz] = heap[yy];
+                            zz = yy;
+                        }
+                        heap[zz] = tmp;
+                    }
+                    nNodes++;
+                    parent[n1] = parent[n2] = nNodes;
+
+                    weight[nNodes] = (int)((uint)((weight[n1] & 0xffffff00)
+                                    + (weight[n2] & 0xffffff00))
+                        | (uint)(1 + (((weight[n1] & 0x000000ff) >
+                                (weight[n2] & 0x000000ff)) ?
+                                (weight[n1] & 0x000000ff) :
+                                (weight[n2] & 0x000000ff))));
+
+                    parent[nNodes] = -1;
+                    nHeap++;
+                    heap[nHeap] = nNodes;
+                    {
+                        int zz = 0, tmp = 0;
+                        zz = nHeap;
+                        tmp = heap[zz];
+                        while (weight[tmp] < weight[heap[zz >> 1]]) {
+                            heap[zz] = heap[zz >> 1];
+                            zz >>= 1;
+                        }
+                        heap[zz] = tmp;
+                    }
+                }
+                if (!(nNodes < (BZip2Constants.MAX_ALPHA_SIZE * 2))) {
+                    Panic();
+                }
+
+                tooLong = false;
+                for (i = 1; i <= alphaSize; i++) {
+                    j = 0;
+                    k = i;
+                    while (parent[k] >= 0) {
+                        k = parent[k];
+                        j++;
+                    }
+                    len[i - 1] = (char) j;
+                    if (j > maxLen) {
+                        tooLong = true;
+                    }
+                }
+
+                if (!tooLong) {
+                    break;
+                }
+
+                for (i = 1; i < alphaSize; i++) {
+                    j = weight[i] >> 8;
+                    j = 1 + (j / 2);
+                    weight[i] = j << 8;
+                }
+            }
+        }
+
+        /*
+        index of the last char in the block, so
+        the block size == last + 1.
+        */
+        int last;
+
+        /*
+        index in zptr[] of original string after sorting.
+        */
+        int origPtr;
+
+        /*
+        always: in the range 0 .. 9.
+        The current block size is 100000 * this number.
+        */
+        int blockSize100k;
+
+        bool blockRandomised;
+
+        int bytesOut;
+        int bsBuff;
+        int bsLive;
+        CRC mCrc = new CRC();
+
+        private bool[] inUse = new bool[256];
+        private int nInUse;
+
+        private char[] seqToUnseq = new char[256];
+        private char[] unseqToSeq = new char[256];
+
+        private char[] selector = new char[BZip2Constants.MAX_SELECTORS];
+        private char[] selectorMtf = new char[BZip2Constants.MAX_SELECTORS];
+
+        private char[] block;
+        private int[] quadrant;
+        private int[] zptr;
+        private short[] szptr;
+        private int[] ftab;
+
+        private int nMTF;
+
+        private int[] mtfFreq = new int[BZip2Constants.MAX_ALPHA_SIZE];
+
+        /*
+        * Used when sorting.  If too many long comparisons
+        * happen, we stop sorting, randomise the block
+        * slightly, and try again.
+        */
+        private int workFactor;
+        private int workDone;
+        private int workLimit;
+        private bool firstAttempt;
+        private int nBlocksRandomised;
+
+        private int currentChar = -1;
+        private int runLength = 0;
+
+        public CBZip2OutputStream(Stream inStream) : this(inStream, 9) {
+        }
+
+        public CBZip2OutputStream(Stream inStream, int inBlockSize)
+            {
+            block = null;
+            quadrant = null;
+            zptr = null;
+            ftab = null;
+
+            inStream.WriteByte((byte)'B');
+            inStream.WriteByte((byte)'Z');
+
+            BsSetStream(inStream);
+
+            workFactor = 50;
+            if (inBlockSize > 9) {
+                inBlockSize = 9;
+            }
+            if (inBlockSize < 1) {
+                inBlockSize = 1;
+            }
+            blockSize100k = inBlockSize;
+            AllocateCompressStructures();
+            Initialize();
+            InitBlock();
+        }
+
+        /**
+        *
+        * modified by Oliver Merkel, 010128
+        *
+        */
+        public override void WriteByte(byte bv) {
+            int b = (256 + bv) % 256;
+            if (currentChar != -1) {
+                if (currentChar == b) {
+                    runLength++;
+                    if (runLength > 254) {
+                        WriteRun();
+                        currentChar = -1;
+                        runLength = 0;
+                    }
+                } else {
+                    WriteRun();
+                    runLength = 1;
+                    currentChar = b;
+                }
+            } else {
+                currentChar = b;
+                runLength++;
+            }
+        }
+
+        private void WriteRun() {
+            if (last < allowableBlockSize) {
+                inUse[currentChar] = true;
+                for (int i = 0; i < runLength; i++) {
+                    mCrc.UpdateCRC((char) currentChar);
+                }
+                switch (runLength) {
+                case 1:
+                    last++;
+                    block[last + 1] = (char) currentChar;
+                    break;
+                case 2:
+                    last++;
+                    block[last + 1] = (char) currentChar;
+                    last++;
+                    block[last + 1] = (char) currentChar;
+                    break;
+                case 3:
+                    last++;
+                    block[last + 1] = (char) currentChar;
+                    last++;
+                    block[last + 1] = (char) currentChar;
+                    last++;
+                    block[last + 1] = (char) currentChar;
+                    break;
+                default:
+                    inUse[runLength - 4] = true;
+                    last++;
+                    block[last + 1] = (char) currentChar;
+                    last++;
+                    block[last + 1] = (char) currentChar;
+                    last++;
+                    block[last + 1] = (char) currentChar;
+                    last++;
+                    block[last + 1] = (char) currentChar;
+                    last++;
+                    block[last + 1] = (char) (runLength - 4);
+                    break;
+                }
+            } else {
+                EndBlock();
+                InitBlock();
+                WriteRun();
+            }
+        }
+
+        bool closed = false;
+
+//        protected void Finalize() {
+//            Close();
+//        }
+
+        public override void Close() {
+            if (closed) {
+                return;
+            }
+
+            Finish();
+
+            closed = true;
+            base.Close();
+            bsStream.Close();
+        }
+
+        public void Finish() {
+            if (finished) {
+                return;
+            }
+
+            if (runLength > 0) {
+                WriteRun();
+            }
+            currentChar = -1;
+            EndBlock();
+            EndCompression();
+            finished = true;
+            Flush();
+        }
+        
+        public override void Flush() {
+            bsStream.Flush();
+        }
+
+        private int blockCRC, combinedCRC;
+
+        private void Initialize() {
+            bytesOut = 0;
+            nBlocksRandomised = 0;
+
+            /* Write `magic' bytes h indicating file-format == huffmanised,
+            followed by a digit indicating blockSize100k.
+            */
+            BsPutUChar('h');
+            BsPutUChar('0' + blockSize100k);
+
+            combinedCRC = 0;
+        }
+
+        private int allowableBlockSize;
+
+        private void InitBlock() {
+            //        blockNo++;
+            mCrc.InitialiseCRC();
+            last = -1;
+            //        ch = 0;
+
+            for (int i = 0; i < 256; i++) {
+                inUse[i] = false;
+            }
+
+            /* 20 is just a paranoia constant */
+            allowableBlockSize = BZip2Constants.baseBlockSize * blockSize100k - 20;
+        }
+
+        private void EndBlock() {
+            blockCRC = mCrc.GetFinalCRC();
+            combinedCRC = (combinedCRC << 1) | (int)(((uint)combinedCRC) >> 31);
+            combinedCRC ^= blockCRC;
+
+            /* sort the block and establish posn of original string */
+            DoReversibleTransformation();
+
+            /*
+            A 6-byte block header, the value chosen arbitrarily
+            as 0x314159265359 :-).  A 32 bit value does not really
+            give a strong enough guarantee that the value will not
+            appear by chance in the compressed datastream.  Worst-case
+            probability of this event, for a 900k block, is about
+            2.0e-3 for 32 bits, 1.0e-5 for 40 bits and 4.0e-8 for 48 bits.
+            For a compressed file of size 100Gb -- about 100000 blocks --
+            only a 48-bit marker will do.  NB: normal compression/
+            decompression do *not* rely on these statistical properties.
+            They are only important when trying to recover blocks from
+            damaged files.
+            */
+            BsPutUChar(0x31);
+            BsPutUChar(0x41);
+            BsPutUChar(0x59);
+            BsPutUChar(0x26);
+            BsPutUChar(0x53);
+            BsPutUChar(0x59);
+
+            /* Now the block's CRC, so it is in a known place. */
+            BsPutint(blockCRC);
+
+            /* Now a single bit indicating randomisation. */
+            if (blockRandomised) {
+                BsW(1, 1);
+                nBlocksRandomised++;
+            } else {
+                BsW(1, 0);
+            }
+
+            /* Finally, block's contents proper. */
+            MoveToFrontCodeAndSend();
+        }
+
+        private void EndCompression() {
+            /*
+            Now another magic 48-bit number, 0x177245385090, to
+            indicate the end of the last block.  (Sqrt(pi), if
+            you want to know.  I did want to use e, but it contains
+            too much repetition -- 27 18 28 18 28 46 -- for me
+            to feel statistically comfortable.  Call me paranoid.)
+            */
+            BsPutUChar(0x17);
+            BsPutUChar(0x72);
+            BsPutUChar(0x45);
+            BsPutUChar(0x38);
+            BsPutUChar(0x50);
+            BsPutUChar(0x90);
+
+            BsPutint(combinedCRC);
+
+            BsFinishedWithStream();
+        }
+
+        private void HbAssignCodes(int[] code, char[] length, int minLen,
+                                    int maxLen, int alphaSize) {
+            int n, vec, i;
+
+            vec = 0;
+            for (n = minLen; n <= maxLen; n++) {
+                for (i = 0; i < alphaSize; i++) {
+                    if (length[i] == n) {
+                        code[i] = vec;
+                        vec++;
+                    }
+                };
+                vec <<= 1;
+            }
+        }
+
+        private void BsSetStream(Stream f) {
+            bsStream = f;
+            bsLive = 0;
+            bsBuff = 0;
+            bytesOut = 0;
+        }
+
+        private void BsFinishedWithStream() {
+            while (bsLive > 0) {
+                int ch = (bsBuff >> 24);
+                try {
+                    bsStream.WriteByte((byte)ch); // write 8-bit
+                } catch (IOException e) {
+                    throw  e;
+                }
+                bsBuff <<= 8;
+                bsLive -= 8;
+                bytesOut++;
+            }
+        }
+
+        private void BsW(int n, int v) {
+            while (bsLive >= 8) {
+                int ch = (bsBuff >> 24);
+                try {
+                    bsStream.WriteByte((byte)ch); // write 8-bit
+                } catch (IOException e) {
+                    throw e;
+                }
+                bsBuff <<= 8;
+                bsLive -= 8;
+                bytesOut++;
+            }
+            bsBuff |= (v << (32 - bsLive - n));
+            bsLive += n;
+        }
+
+        private void BsPutUChar(int c) {
+            BsW(8, c);
+        }
+
+        private void BsPutint(int u) {
+            BsW(8, (u >> 24) & 0xff);
+            BsW(8, (u >> 16) & 0xff);
+            BsW(8, (u >>  8) & 0xff);
+            BsW(8,  u        & 0xff);
+        }
+
+        private void BsPutIntVS(int numBits, int c) {
+            BsW(numBits, c);
+        }
+
+        private void SendMTFValues() {
+            char[][] len = CBZip2InputStream.InitCharArray(BZip2Constants.N_GROUPS, BZip2Constants.MAX_ALPHA_SIZE);
+
+            int v, t, i, j, gs, ge, totc, bt, bc, iter;
+            int nSelectors = 0, alphaSize, minLen, maxLen, selCtr;
+            int nGroups;
+
+            alphaSize = nInUse + 2;
+            for (t = 0; t < BZip2Constants.N_GROUPS; t++) {
+                for (v = 0; v < alphaSize; v++) {
+                    len[t][v] = (char) GREATER_ICOST;
+                }
+            }
+
+            /* Decide how many coding tables to use */
+            if (nMTF <= 0) {
+                Panic();
+            }
+
+            if (nMTF < 200) {
+                nGroups = 2;
+            } else if (nMTF < 600) {
+                nGroups = 3;
+            } else if (nMTF < 1200) {
+                nGroups = 4;
+            } else if (nMTF < 2400) {
+                nGroups = 5;
+            } else {
+                nGroups = 6;
+            }
+
+            /* Generate an initial set of coding tables */ {
+                int nPart, remF, tFreq, aFreq;
+
+                nPart = nGroups;
+                remF  = nMTF;
+                gs = 0;
+                while (nPart > 0) {
+                    tFreq = remF / nPart;
+                    ge = gs - 1;
+                    aFreq = 0;
+                    while (aFreq < tFreq && ge < alphaSize - 1) {
+                        ge++;
+                        aFreq += mtfFreq[ge];
+                    }
+
+                    if (ge > gs && nPart != nGroups && nPart != 1
+                        && ((nGroups - nPart) % 2 == 1)) {
+                        aFreq -= mtfFreq[ge];
+                        ge--;
+                    }
+
+                    for (v = 0; v < alphaSize; v++) {
+                        if (v >= gs && v <= ge) {
+                            len[nPart - 1][v] = (char) LESSER_ICOST;
+                        } else {
+                            len[nPart - 1][v] = (char) GREATER_ICOST;
+                        }
+                    }
+
+                    nPart--;
+                    gs = ge + 1;
+                    remF -= aFreq;
+                }
+            }
+
+            int[][] rfreq = CBZip2InputStream.InitIntArray(BZip2Constants.N_GROUPS, BZip2Constants.MAX_ALPHA_SIZE);
+            int[] fave = new int[BZip2Constants.N_GROUPS];
+            short[] cost = new short[BZip2Constants.N_GROUPS];
+            /*
+            Iterate up to N_ITERS times to improve the tables.
+            */
+            for (iter = 0; iter < BZip2Constants.N_ITERS; iter++) {
+                for (t = 0; t < nGroups; t++) {
+                    fave[t] = 0;
+                }
+
+                for (t = 0; t < nGroups; t++) {
+                    for (v = 0; v < alphaSize; v++) {
+                        rfreq[t][v] = 0;
+                    }
+                }
+
+                nSelectors = 0;
+                totc = 0;
+                gs = 0;
+                while (true) {
+
+                    /* Set group start & end marks. */
+                    if (gs >= nMTF) {
+                        break;
+                    }
+                    ge = gs + BZip2Constants.G_SIZE - 1;
+                    if (ge >= nMTF) {
+                        ge = nMTF - 1;
+                    }
+
+                    /*
+                    Calculate the cost of this group as coded
+                    by each of the coding tables.
+                    */
+                    for (t = 0; t < nGroups; t++) {
+                        cost[t] = 0;
+                    }
+
+                    if (nGroups == 6) {
+                        short cost0, cost1, cost2, cost3, cost4, cost5;
+                        cost0 = cost1 = cost2 = cost3 = cost4 = cost5 = 0;
+                        for (i = gs; i <= ge; i++) {
+                            short icv = szptr[i];
+                            cost0 += (short)len[0][icv];
+                            cost1 += (short)len[1][icv];
+                            cost2 += (short)len[2][icv];
+                            cost3 += (short)len[3][icv];
+                            cost4 += (short)len[4][icv];
+                            cost5 += (short)len[5][icv];
+                        }
+                        cost[0] = cost0;
+                        cost[1] = cost1;
+                        cost[2] = cost2;
+                        cost[3] = cost3;
+                        cost[4] = cost4;
+                        cost[5] = cost5;
+                    } else {
+                        for (i = gs; i <= ge; i++) {
+                            short icv = szptr[i];
+                            for (t = 0; t < nGroups; t++) {
+                                cost[t] += (short)len[t][icv];
+                            }
+                        }
+                    }
+
+                    /*
+                    Find the coding table which is best for this group,
+                    and record its identity in the selector table.
+                    */
+                    bc = 999999999;
+                    bt = -1;
+                    for (t = 0; t < nGroups; t++) {
+                        if (cost[t] < bc) {
+                            bc = cost[t];
+                            bt = t;
+                        }
+                    };
+                    totc += bc;
+                    fave[bt]++;
+                    selector[nSelectors] = (char) bt;
+                    nSelectors++;
+
+                    /*
+                    Increment the symbol frequencies for the selected table.
+                    */
+                    for (i = gs; i <= ge; i++) {
+                        rfreq[bt][szptr[i]]++;
+                    }
+
+                    gs = ge + 1;
+                }
+
+                /*
+                Recompute the tables based on the accumulated frequencies.
+                */
+                for (t = 0; t < nGroups; t++) {
+                    HbMakeCodeLengths(len[t], rfreq[t], alphaSize, 20);
+                }
+            }
+
+            rfreq = null;
+            fave = null;
+            cost = null;
+
+            if (!(nGroups < 8)) {
+                Panic();
+            }
+            if (!(nSelectors < 32768 && nSelectors <= (2 + (900000 / BZip2Constants.G_SIZE)))) {
+                Panic();
+            }
+
+
+            /* Compute MTF values for the selectors. */
+            {
+                char[] pos = new char[BZip2Constants.N_GROUPS];
+                char ll_i, tmp2, tmp;
+                for (i = 0; i < nGroups; i++) {
+                    pos[i] = (char) i;
+                }
+                for (i = 0; i < nSelectors; i++) {
+                    ll_i = selector[i];
+                    j = 0;
+                    tmp = pos[j];
+                    while (ll_i != tmp) {
+                        j++;
+                        tmp2 = tmp;
+                        tmp = pos[j];
+                        pos[j] = tmp2;
+                    }
+                    pos[0] = tmp;
+                    selectorMtf[i] = (char) j;
+                }
+            }
+
+            int[][] code = CBZip2InputStream.InitIntArray(BZip2Constants.N_GROUPS, BZip2Constants.MAX_ALPHA_SIZE);
+
+            /* Assign actual codes for the tables. */
+            for (t = 0; t < nGroups; t++) {
+                minLen = 32;
+                maxLen = 0;
+                for (i = 0; i < alphaSize; i++) {
+                    if (len[t][i] > maxLen) {
+                        maxLen = len[t][i];
+                    }
+                    if (len[t][i] < minLen) {
+                        minLen = len[t][i];
+                    }
+                }
+                if (maxLen > 20) {
+                    Panic();
+                }
+                if (minLen < 1) {
+                    Panic();
+                }
+                HbAssignCodes(code[t], len[t], minLen, maxLen, alphaSize);
+            }
+
+            /* Transmit the mapping table. */
+            {
+                bool[] inUse16 = new bool[16];
+                for (i = 0; i < 16; i++) {
+                    inUse16[i] = false;
+                    for (j = 0; j < 16; j++) {
+                        if (inUse[i * 16 + j]) {
+                            inUse16[i] = true;
+                        }
+                    }
+                }
+
+				for (i = 0; i < 16; i++) {
+                    if (inUse16[i]) {
+                        BsW(1, 1);
+                    } else {
+                        BsW(1, 0);
+                    }
+                }
+
+                for (i = 0; i < 16; i++) {
+                    if (inUse16[i]) {
+                        for (j = 0; j < 16; j++) {
+                            if (inUse[i * 16 + j]) {
+                                BsW(1, 1);
+                            } else {
+                                BsW(1, 0);
+                            }
+                        }
+                    }
+                }
+
+            }
+
+            /* Now the selectors. */
+            BsW(3, nGroups);
+            BsW(15, nSelectors);
+            for (i = 0; i < nSelectors; i++) {
+                for (j = 0; j < selectorMtf[i]; j++) {
+                    BsW(1, 1);
+                }
+                BsW(1, 0);
+            }
+
+            /* Now the coding tables. */
+            for (t = 0; t < nGroups; t++) {
+                int curr = len[t][0];
+                BsW(5, curr);
+                for (i = 0; i < alphaSize; i++) {
+                    while (curr < len[t][i]) {
+                        BsW(2, 2);
+                        curr++; /* 10 */
+                    }
+                    while (curr > len[t][i]) {
+                        BsW(2, 3);
+                        curr--; /* 11 */
+                    }
+                    BsW(1, 0);
+                }
+            }
+
+            /* And finally, the block data proper */
+            selCtr = 0;
+            gs = 0;
+            while (true) {
+                if (gs >= nMTF) {
+                    break;
+                }
+                ge = gs + BZip2Constants.G_SIZE - 1;
+                if (ge >= nMTF) {
+                    ge = nMTF - 1;
+                }
+                for (i = gs; i <= ge; i++) {
+                    BsW(len[selector[selCtr]][szptr[i]],
+                        code[selector[selCtr]][szptr[i]]);
+                }
+
+                gs = ge + 1;
+                selCtr++;
+            }
+            if (!(selCtr == nSelectors)) {
+                Panic();
+            }
+        }
+
+        private void MoveToFrontCodeAndSend() {
+            BsPutIntVS(24, origPtr);
+            GenerateMTFValues();
+            SendMTFValues();
+        }
+
+        private Stream bsStream;
+
+        private void SimpleSort(int lo, int hi, int d) {
+            int i, j, h, bigN, hp;
+            int v;
+
+            bigN = hi - lo + 1;
+            if (bigN < 2) {
+                return;
+            }
+
+            hp = 0;
+            while (incs[hp] < bigN) {
+                hp++;
+            }
+            hp--;
+
+            for (; hp >= 0; hp--) {
+                h = incs[hp];
+
+                i = lo + h;
+                while (true) {
+                    /* copy 1 */
+                    if (i > hi) {
+                        break;
+                    }
+                    v = zptr[i];
+                    j = i;
+                    while (FullGtU(zptr[j - h] + d, v + d)) {
+                        zptr[j] = zptr[j - h];
+                        j = j - h;
+                        if (j <= (lo + h - 1)) {
+                            break;
+                        }
+                    }
+                    zptr[j] = v;
+                    i++;
+
+                    /* copy 2 */
+                    if (i > hi) {
+                        break;
+                    }
+                    v = zptr[i];
+                    j = i;
+                    while (FullGtU(zptr[j - h] + d, v + d)) {
+                        zptr[j] = zptr[j - h];
+                        j = j - h;
+                        if (j <= (lo + h - 1)) {
+                            break;
+                        }
+                    }
+                    zptr[j] = v;
+                    i++;
+
+                    /* copy 3 */
+                    if (i > hi) {
+                        break;
+                    }
+                    v = zptr[i];
+                    j = i;
+                    while (FullGtU(zptr[j - h] + d, v + d)) {
+                        zptr[j] = zptr[j - h];
+                        j = j - h;
+                        if (j <= (lo + h - 1)) {
+                            break;
+                        }
+                    }
+                    zptr[j] = v;
+                    i++;
+
+                    if (workDone > workLimit && firstAttempt) {
+                        return;
+                    }
+                }
+            }
+        }
+
+        private void Vswap(int p1, int p2, int n) {
+            int temp = 0;
+            while (n > 0) {
+                temp = zptr[p1];
+                zptr[p1] = zptr[p2];
+                zptr[p2] = temp;
+                p1++;
+                p2++;
+                n--;
+            }
+        }
+
+        private char Med3(char a, char b, char c) {
+            char t;
+            if (a > b) {
+                t = a;
+                a = b;
+                b = t;
+            }
+            if (b > c) {
+                t = b;
+                b = c;
+                c = t;
+            }
+            if (a > b) {
+                b = a;
+            }
+            return b;
+        }
+
+        internal class StackElem {
+            internal int ll;
+            internal int hh;
+            internal int dd;
+        }
+
+        private void QSort3(int loSt, int hiSt, int dSt) {
+            int unLo, unHi, ltLo, gtHi, med, n, m;
+            int sp, lo, hi, d;
+            StackElem[] stack = new StackElem[QSORT_STACK_SIZE];
+            for (int count = 0; count < QSORT_STACK_SIZE; count++) {
+                stack[count] = new StackElem();
+            }
+
+            sp = 0;
+
+            stack[sp].ll = loSt;
+            stack[sp].hh = hiSt;
+            stack[sp].dd = dSt;
+            sp++;
+
+            while (sp > 0) {
+                if (sp >= QSORT_STACK_SIZE) {
+                    Panic();
+                }
+
+                sp--;
+                lo = stack[sp].ll;
+                hi = stack[sp].hh;
+                d = stack[sp].dd;
+
+                if (hi - lo < SMALL_THRESH || d > DEPTH_THRESH) {
+                    SimpleSort(lo, hi, d);
+                    if (workDone > workLimit && firstAttempt) {
+                        return;
+                    }
+                    continue;
+                }
+
+                med = Med3(block[zptr[lo] + d + 1],
+                        block[zptr[hi            ] + d  + 1],
+                        block[zptr[(lo + hi) >> 1] + d + 1]);
+
+                unLo = ltLo = lo;
+                unHi = gtHi = hi;
+
+                while (true) {
+                    while (true) {
+                        if (unLo > unHi) {
+                            break;
+                        }
+                        n = ((int) block[zptr[unLo] + d + 1]) - med;
+                        if (n == 0) {
+                            int temp = 0;
+                            temp = zptr[unLo];
+                            zptr[unLo] = zptr[ltLo];
+                            zptr[ltLo] = temp;
+                            ltLo++;
+                            unLo++;
+                            continue;
+                        };
+                        if (n >  0) {
+                            break;
+                        }
+                        unLo++;
+                    }
+                    while (true) {
+                        if (unLo > unHi) {
+                            break;
+                        }
+                        n = ((int) block[zptr[unHi] + d + 1]) - med;
+                        if (n == 0) {
+                            int temp = 0;
+                            temp = zptr[unHi];
+                            zptr[unHi] = zptr[gtHi];
+                            zptr[gtHi] = temp;
+                            gtHi--;
+                            unHi--;
+                            continue;
+                        };
+                        if (n <  0) {
+                            break;
+                        }
+                        unHi--;
+                    }
+                    if (unLo > unHi) {
+                        break;
+                    }
+                    int tempx = zptr[unLo];
+                    zptr[unLo] = zptr[unHi];
+                    zptr[unHi] = tempx;
+                    unLo++;
+                    unHi--;
+                }
+
+                if (gtHi < ltLo) {
+                    stack[sp].ll = lo;
+                    stack[sp].hh = hi;
+                    stack[sp].dd = d + 1;
+                    sp++;
+                    continue;
+                }
+
+                n = ((ltLo - lo) < (unLo - ltLo)) ? (ltLo - lo) : (unLo - ltLo);
+                Vswap(lo, unLo - n, n);
+                m = ((hi - gtHi) < (gtHi - unHi)) ? (hi - gtHi) : (gtHi - unHi);
+                Vswap(unLo, hi - m + 1, m);
+
+                n = lo + unLo - ltLo - 1;
+                m = hi - (gtHi - unHi) + 1;
+
+                stack[sp].ll = lo;
+                stack[sp].hh = n;
+                stack[sp].dd = d;
+                sp++;
+
+                stack[sp].ll = n + 1;
+                stack[sp].hh = m - 1;
+                stack[sp].dd = d + 1;
+                sp++;
+
+                stack[sp].ll = m;
+                stack[sp].hh = hi;
+                stack[sp].dd = d;
+                sp++;
+            }
+        }
+
+        private void MainSort() {
+            int i, j, ss, sb;
+            int[] runningOrder = new int[256];
+            int[] copy = new int[256];
+            bool[] bigDone = new bool[256];
+            int c1, c2;
+            int numQSorted;
+
+            /*
+            In the various block-sized structures, live data runs
+            from 0 to last+NUM_OVERSHOOT_BYTES inclusive.  First,
+            set up the overshoot area for block.
+            */
+
+            //   if (verbosity >= 4) fprintf ( stderr, "   sort initialise ...\n" );
+            for (i = 0; i < BZip2Constants.NUM_OVERSHOOT_BYTES; i++) {
+                block[last + i + 2] = block[(i % (last + 1)) + 1];
+            }
+            for (i = 0; i <= last + BZip2Constants.NUM_OVERSHOOT_BYTES; i++) {
+                quadrant[i] = 0;
+            }
+
+            block[0] = (char) (block[last + 1]);
+
+            if (last < 4000) {
+                /*
+                Use SimpleSort(), since the full sorting mechanism
+                has quite a large constant overhead.
+                */
+                for (i = 0; i <= last; i++) {
+                    zptr[i] = i;
+                }
+                firstAttempt = false;
+                workDone = workLimit = 0;
+                SimpleSort(0, last, 0);
+            } else {
+                numQSorted = 0;
+                for (i = 0; i <= 255; i++) {
+                    bigDone[i] = false;
+                }
+
+                for (i = 0; i <= 65536; i++) {
+                    ftab[i] = 0;
+                }
+
+                c1 = block[0];
+                for (i = 0; i <= last; i++) {
+                    c2 = block[i + 1];
+                    ftab[(c1 << 8) + c2]++;
+                    c1 = c2;
+                }
+
+                for (i = 1; i <= 65536; i++) {
+                    ftab[i] += ftab[i - 1];
+                }
+
+                c1 = block[1];
+                for (i = 0; i < last; i++) {
+                    c2 = block[i + 2];
+                    j = (c1 << 8) + c2;
+                    c1 = c2;
+                    ftab[j]--;
+                    zptr[ftab[j]] = i;
+                }
+
+                j = ((block[last + 1]) << 8) + (block[1]);
+                ftab[j]--;
+                zptr[ftab[j]] = last;
+
+                /*
+                Now ftab contains the first loc of every small bucket.
+                Calculate the running order, from smallest to largest
+                big bucket.
+                */
+
+                for (i = 0; i <= 255; i++) {
+                    runningOrder[i] = i;
+                }
+
+                {
+                    int vv;
+                    int h = 1;
+                    do {
+                        h = 3 * h + 1;
+                    }
+                    while (h <= 256);
+                    do {
+                        h = h / 3;
+                        for (i = h; i <= 255; i++) {
+                            vv = runningOrder[i];
+                            j = i;
+                            while ((ftab[((runningOrder[j - h]) + 1) << 8]
+                                    - ftab[(runningOrder[j - h]) << 8]) >
+                                (ftab[((vv) + 1) << 8] - ftab[(vv) << 8])) {
+                                runningOrder[j] = runningOrder[j - h];
+                                j = j - h;
+                                if (j <= (h - 1)) {
+                                    break;
+                                }
+                            }
+                            runningOrder[j] = vv;
+                        }
+                    } while (h != 1);
+                }
+
+                /*
+                The main sorting loop.
+                */
+                for (i = 0; i <= 255; i++) {
+
+                    /*
+                    Process big buckets, starting with the least full.
+                    */
+                    ss = runningOrder[i];
+
+                    /*
+                    Complete the big bucket [ss] by quicksorting
+                    any unsorted small buckets [ss, j].  Hopefully
+                    previous pointer-scanning phases have already
+                    completed many of the small buckets [ss, j], so
+                    we don't have to sort them at all.
+                    */
+                    for (j = 0; j <= 255; j++) {
+                        sb = (ss << 8) + j;
+                        if (!((ftab[sb] & SETMASK) == SETMASK)) {
+                            int lo = ftab[sb] & CLEARMASK;
+                            int hi = (ftab[sb + 1] & CLEARMASK) - 1;
+                            if (hi > lo) {
+                                QSort3(lo, hi, 2);
+                                numQSorted += (hi - lo + 1);
+                                if (workDone > workLimit && firstAttempt) {
+                                    return;
+                                }
+                            }
+                            ftab[sb] |= SETMASK;
+                        }
+                    }
+
+                    /*
+                    The ss big bucket is now done.  Record this fact,
+                    and update the quadrant descriptors.  Remember to
+                    update quadrants in the overshoot area too, if
+                    necessary.  The "if (i < 255)" test merely skips
+                    this updating for the last bucket processed, since
+                    updating for the last bucket is pointless.
+                    */
+                    bigDone[ss] = true;
+
+                    if (i < 255) {
+                        int bbStart  = ftab[ss << 8] & CLEARMASK;
+                        int bbSize   = (ftab[(ss + 1) << 8] & CLEARMASK) - bbStart;
+                        int shifts   = 0;
+
+                        while ((bbSize >> shifts) > 65534) {
+                            shifts++;
+                        }
+
+                        for (j = 0; j < bbSize; j++) {
+                            int a2update = zptr[bbStart + j];
+                            int qVal = (j >> shifts);
+                            quadrant[a2update] = qVal;
+                            if (a2update < BZip2Constants.NUM_OVERSHOOT_BYTES) {
+                                quadrant[a2update + last + 1] = qVal;
+                            }
+                        }
+
+                        if (!(((bbSize - 1) >> shifts) <= 65535)) {
+                            Panic();
+                        }
+                    }
+
+                    /*
+                    Now scan this big bucket so as to synthesise the
+                    sorted order for small buckets [t, ss] for all t != ss.
+                    */
+                    for (j = 0; j <= 255; j++) {
+                        copy[j] = ftab[(j << 8) + ss] & CLEARMASK;
+                    }
+
+                    for (j = ftab[ss << 8] & CLEARMASK;
+                        j < (ftab[(ss + 1) << 8] & CLEARMASK); j++) {
+                        c1 = block[zptr[j]];
+                        if (!bigDone[c1]) {
+                            zptr[copy[c1]] = zptr[j] == 0 ? last : zptr[j] - 1;
+                            copy[c1]++;
+                        }
+                    }
+
+                    for (j = 0; j <= 255; j++) {
+                        ftab[(j << 8) + ss] |= SETMASK;
+                    }
+                }
+            }
+        }
+
+        private void RandomiseBlock() {
+            int i;
+            int rNToGo = 0;
+            int rTPos  = 0;
+            for (i = 0; i < 256; i++) {
+                inUse[i] = false;
+            }
+
+            for (i = 0; i <= last; i++) {
+                if (rNToGo == 0) {
+                    rNToGo = (char) BZip2Constants.rNums[rTPos];
+                    rTPos++;
+                    if (rTPos == 512) {
+                        rTPos = 0;
+                    }
+                }
+                rNToGo--;
+                block[i + 1] ^= (char)((rNToGo == 1) ? 1 : 0);
+                // handle 16 bit signed numbers
+                block[i + 1] &= (char)0xFF;
+
+                inUse[block[i + 1]] = true;
+            }
+        }
+
+        private void DoReversibleTransformation() {
+            int i;
+
+            workLimit = workFactor * last;
+            workDone = 0;
+            blockRandomised = false;
+            firstAttempt = true;
+
+            MainSort();
+
+            if (workDone > workLimit && firstAttempt) {
+                RandomiseBlock();
+                workLimit = workDone = 0;
+                blockRandomised = true;
+                firstAttempt = false;
+                MainSort();
+            }
+
+            origPtr = -1;
+            for (i = 0; i <= last; i++) {
+                if (zptr[i] == 0) {
+                    origPtr = i;
+                    break;
+                }
+            };
+
+            if (origPtr == -1) {
+                Panic();
+            }
+        }
+
+        private bool FullGtU(int i1, int i2) {
+            int k;
+            char c1, c2;
+            int s1, s2;
+
+            c1 = block[i1 + 1];
+            c2 = block[i2 + 1];
+            if (c1 != c2) {
+                return (c1 > c2);
+            }
+            i1++;
+            i2++;
+
+            c1 = block[i1 + 1];
+            c2 = block[i2 + 1];
+            if (c1 != c2) {
+                return (c1 > c2);
+            }
+            i1++;
+            i2++;
+
+            c1 = block[i1 + 1];
+            c2 = block[i2 + 1];
+            if (c1 != c2) {
+                return (c1 > c2);
+            }
+            i1++;
+            i2++;
+
+            c1 = block[i1 + 1];
+            c2 = block[i2 + 1];
+            if (c1 != c2) {
+                return (c1 > c2);
+            }
+            i1++;
+            i2++;
+
+            c1 = block[i1 + 1];
+            c2 = block[i2 + 1];
+            if (c1 != c2) {
+                return (c1 > c2);
+            }
+            i1++;
+            i2++;
+
+            c1 = block[i1 + 1];
+            c2 = block[i2 + 1];
+            if (c1 != c2) {
+                return (c1 > c2);
+            }
+            i1++;
+            i2++;
+
+            k = last + 1;
+
+            do {
+                c1 = block[i1 + 1];
+                c2 = block[i2 + 1];
+                if (c1 != c2) {
+                    return (c1 > c2);
+                }
+                s1 = quadrant[i1];
+                s2 = quadrant[i2];
+                if (s1 != s2) {
+                    return (s1 > s2);
+                }
+                i1++;
+                i2++;
+
+                c1 = block[i1 + 1];
+                c2 = block[i2 + 1];
+                if (c1 != c2) {
+                    return (c1 > c2);
+                }
+                s1 = quadrant[i1];
+                s2 = quadrant[i2];
+                if (s1 != s2) {
+                    return (s1 > s2);
+                }
+                i1++;
+                i2++;
+
+                c1 = block[i1 + 1];
+                c2 = block[i2 + 1];
+                if (c1 != c2) {
+                    return (c1 > c2);
+                }
+                s1 = quadrant[i1];
+                s2 = quadrant[i2];
+                if (s1 != s2) {
+                    return (s1 > s2);
+                }
+                i1++;
+                i2++;
+
+                c1 = block[i1 + 1];
+                c2 = block[i2 + 1];
+                if (c1 != c2) {
+                    return (c1 > c2);
+                }
+                s1 = quadrant[i1];
+                s2 = quadrant[i2];
+                if (s1 != s2) {
+                    return (s1 > s2);
+                }
+                i1++;
+                i2++;
+
+                if (i1 > last) {
+                    i1 -= last;
+                    i1--;
+                };
+                if (i2 > last) {
+                    i2 -= last;
+                    i2--;
+                };
+
+                k -= 4;
+                workDone++;
+            } while (k >= 0);
+
+            return false;
+        }
+
+        /*
+        Knuth's increments seem to work better
+        than Incerpi-Sedgewick here.  Possibly
+        because the number of elems to sort is
+        usually small, typically <= 20.
+        */
+        private int[] incs = { 1, 4, 13, 40, 121, 364, 1093, 3280,
+                            9841, 29524, 88573, 265720,
+                            797161, 2391484 };
+
+        private void AllocateCompressStructures() {
+            int n = BZip2Constants.baseBlockSize * blockSize100k;
+            block = new char[(n + 1 + BZip2Constants.NUM_OVERSHOOT_BYTES)];
+            quadrant = new int[(n + BZip2Constants.NUM_OVERSHOOT_BYTES)];
+            zptr = new int[n];
+            ftab = new int[65537];
+
+            if (block == null || quadrant == null || zptr == null
+                || ftab == null) {
+                //int totalDraw = (n + 1 + NUM_OVERSHOOT_BYTES) + (n + NUM_OVERSHOOT_BYTES) + n + 65537;
+                //compressOutOfMemory ( totalDraw, n );
+            }
+
+            /*
+            The back end needs a place to store the MTF values
+            whilst it calculates the coding tables.  We could
+            put them in the zptr array.  However, these values
+            will fit in a short, so we overlay szptr at the
+            start of zptr, in the hope of reducing the number
+            of cache misses induced by the multiple traversals
+            of the MTF values when calculating coding tables.
+            Seems to improve compression speed by about 1%.
+            */
+            //    szptr = zptr;
+
+
+            szptr = new short[2 * n];
+        }
+
+        private void GenerateMTFValues() {
+            char[] yy = new char[256];
+            int  i, j;
+            char tmp;
+            char tmp2;
+            int zPend;
+            int wr;
+            int EOB;
+
+            MakeMaps();
+            EOB = nInUse + 1;
+
+            for (i = 0; i <= EOB; i++) {
+                mtfFreq[i] = 0;
+            }
+
+            wr = 0;
+            zPend = 0;
+            for (i = 0; i < nInUse; i++) {
+                yy[i] = (char) i;
+            }
+
+
+            for (i = 0; i <= last; i++) {
+                char ll_i;
+
+                ll_i = unseqToSeq[block[zptr[i]]];
+
+                j = 0;
+                tmp = yy[j];
+                while (ll_i != tmp) {
+                    j++;
+                    tmp2 = tmp;
+                    tmp = yy[j];
+                    yy[j] = tmp2;
+                };
+                yy[0] = tmp;
+
+                if (j == 0) {
+                    zPend++;
+                } else {
+                    if (zPend > 0) {
+                        zPend--;
+                        while (true) {
+                            switch (zPend % 2) {
+                            case 0:
+                                szptr[wr] = (short) BZip2Constants.RUNA;
+                                wr++;
+                                mtfFreq[BZip2Constants.RUNA]++;
+                                break;
+                            case 1:
+                                szptr[wr] = (short) BZip2Constants.RUNB;
+                                wr++;
+                                mtfFreq[BZip2Constants.RUNB]++;
+                                break;
+                            };
+                            if (zPend < 2) {
+                                break;
+                            }
+                            zPend = (zPend - 2) / 2;
+                        };
+                        zPend = 0;
+                    }
+                    szptr[wr] = (short) (j + 1);
+                    wr++;
+                    mtfFreq[j + 1]++;
+                }
+            }
+
+            if (zPend > 0) {
+                zPend--;
+                while (true) {
+                    switch (zPend % 2) {
+                    case 0:
+                        szptr[wr] = (short) BZip2Constants.RUNA;
+                        wr++;
+                        mtfFreq[BZip2Constants.RUNA]++;
+                        break;
+                    case 1:
+                        szptr[wr] = (short) BZip2Constants.RUNB;
+                        wr++;
+                        mtfFreq[BZip2Constants.RUNB]++;
+                        break;
+                    }
+                    if (zPend < 2) {
+                        break;
+                    }
+                    zPend = (zPend - 2) / 2;
+                }
+            }
+
+            szptr[wr] = (short) EOB;
+            wr++;
+            mtfFreq[EOB]++;
+
+            nMTF = wr;
+        }
+
+        public override int Read(byte[] buffer, int offset, int count) {
+            return 0;
+        }
+    
+        public override long Seek(long offset, SeekOrigin origin) {
+            return 0;
+        }
+    
+        public override void SetLength(long value) {
+        }
+    
+        public override void Write(byte[] buffer, int offset, int count) {
+            for (int k = 0; k < count; ++k) {
+                WriteByte(buffer[k + offset]);
+            }
+        }
+    
+        public override bool CanRead {
+            get {
+                return false;
+            }
+        }
+    
+        public override bool CanSeek {
+            get {
+                return false;
+            }
+        }
+    
+        public override bool CanWrite {
+            get {
+                return true;
+            }
+        }
+    
+        public override long Length {
+            get {
+                return 0;
+            }
+        }
+    
+        public override long Position {
+            get {
+                return 0;
+            }
+            set {
+            }
+        }
+    }
+}
\ No newline at end of file