cbzip2outputstream.java

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        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 = baseBlockSize * blockSize100k - 20;
    }

    private void endBlock() throws IOException {
        blockCRC = mCrc.getFinalCRC();
        combinedCRC = (combinedCRC << 1) | (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() throws IOException {
        /*
          Now another magic 48-bit number, 0x177245385090, to
          indicate the end of the last block.  (sqrt(pi), if
          you want to know.  I did want to use e, but it contains
          too much repetition -- 27 18 28 18 28 46 -- for me
          to feel statistically comfortable.  Call me paranoid.)
        */
        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(OutputStream f) {
        bsStream = f;
        bsLive = 0;
        bsBuff = 0;
        bytesOut = 0;
    }

    private void bsFinishedWithStream() throws IOException {
        while (bsLive > 0) {
            int ch = (bsBuff >> 24);
            try {
                bsStream.write(ch); // write 8-bit
            } catch (IOException e) {
                throw  e;
            }
            bsBuff <<= 8;
            bsLive -= 8;
            bytesOut++;
        }
    }

    private void bsW(int n, int v) throws IOException {
        while (bsLive >= 8) {
            int ch = (bsBuff >> 24);
            try {
                bsStream.write(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) throws IOException {
        bsW(8, c);
    }

    private void bsPutint(int u) throws IOException {
        bsW(8, (u >> 24) & 0xff);
        bsW(8, (u >> 16) & 0xff);
        bsW(8, (u >>  8) & 0xff);
        bsW(8,  u        & 0xff);
    }

    private void bsPutIntVS(int numBits, int c) throws IOException {
        bsW(numBits, c);
    }

    private void sendMTFValues() throws IOException {
        char len[][] = new char[N_GROUPS][MAX_ALPHA_SIZE];

        int v, t, i, j, gs, ge, totc, bt, bc, iter;
        int nSelectors = 0, alphaSize, minLen, maxLen, selCtr;
        int nGroups, nBytes;

        alphaSize = nInUse + 2;
        for (t = 0; t < 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 = new int[N_GROUPS][MAX_ALPHA_SIZE];
        int[] fave = new int[N_GROUPS];
        short[] cost = new short[N_GROUPS];
        /*
          Iterate up to N_ITERS times to improve the tables.
        */
        for (iter = 0; iter < 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 + 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 += len[0][icv];
                        cost1 += len[1][icv];
                        cost2 += len[2][icv];
                        cost3 += len[3][icv];
                        cost4 += len[4][icv];
                        cost5 += 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] += 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 / G_SIZE)))) {
            panic();
        }


        /* Compute MTF values for the selectors. */
        {
            char[] pos = new char[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 = new int[N_GROUPS][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. */
        {
            boolean[] inUse16 = new boolean[16];
            for (i = 0; i < 16; i++) {
                inUse16[i] = false;
                for (j = 0; j < 16; j++) {
                    if (inUse[i * 16 + j]) {
                        inUse16[i] = true;
                    }
                }
            }

            nBytes = bytesOut;
            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);
                        }
                    }
                }
            }