xref: /oneTBB/examples/graph/fgbzip2/compress.cpp (revision b15aabb3)

/*
    Copyright (c) 2005-2021 Intel Corporation

    Licensed 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.
*/

/*-------------------------------------------------------------*/
/*--- Compression machinery (not incl block sorting)        ---*/
/*---                                          compress.cpp ---*/
/*-------------------------------------------------------------*/

/* ------------------------------------------------------------------
   The original source for this example:
   This file is part of bzip2/libbzip2, a program and library for
   lossless, block-sorting data compression.

   bzip2/libbzip2 version 1.0.6 of 6 September 2010
   Copyright (C) 1996-2010 Julian Seward <[email protected]>

   This program, "bzip2", the associated library "libbzip2", and all
   documentation, are copyright (C) 1996-2010 Julian R Seward.  All
   rights reserved.

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions
   are met:

   1. Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.

   2. The origin of this software must not be misrepresented; you must
   not claim that you wrote the original software.  If you use this
   software in a product, an acknowledgment in the product
   documentation would be appreciated but is not required.

   3. Altered source versions must be plainly marked as such, and must
   not be misrepresented as being the original software.

   4. The name of the author may not be used to endorse or promote
   products derived from this software without specific prior written
   permission.

   THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
   OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
   WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
   DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
   GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
   WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

   Julian Seward, [email protected]
   bzip2/libbzip2 version 1.0.6 of 6 September 2010
   ------------------------------------------------------------------ */

/* CHANGES
    0.9.0    -- original version.
    0.9.0a/b -- no changes in this file.
    0.9.0c   -- changed setting of nGroups in sendMTFValues()
                so as to do a bit better on small files
*/

#include "bzlib_private.hpp"

/*---------------------------------------------------*/
/*--- Bit stream I/O                              ---*/
/*---------------------------------------------------*/

/*---------------------------------------------------*/
void BZ2_bsInitWrite(EState* s) {
    s->bsLive = 0;
    s->bsBuff = 0;
}

/*---------------------------------------------------*/
static void bsFinishWrite(EState* s) {
    while (s->bsLive > 0) {
        s->zbits[s->numZ] = (UChar)(s->bsBuff >> 24);
        s->numZ++;
        s->bsBuff <<= 8;
        s->bsLive -= 8;
    }
}

/*---------------------------------------------------*/
#define bsNEEDW(nz)                                       \
    {                                                     \
        while (s->bsLive >= 8) {                          \
            s->zbits[s->numZ] = (UChar)(s->bsBuff >> 24); \
            s->numZ++;                                    \
            s->bsBuff <<= 8;                              \
            s->bsLive -= 8;                               \
        }                                                 \
    }

/*---------------------------------------------------*/
static __inline__ void bsW(EState* s, Int32 n, UInt32 v) {
    bsNEEDW(n);
    s->bsBuff |= (v << (32 - s->bsLive - n));
    s->bsLive += n;
}

/*---------------------------------------------------*/
static void bsPutUInt32(EState* s, UInt32 u) {
    bsW(s, 8, (u >> 24) & 0xffL);
    bsW(s, 8, (u >> 16) & 0xffL);
    bsW(s, 8, (u >> 8) & 0xffL);
    bsW(s, 8, u & 0xffL);
}

/*---------------------------------------------------*/
static void bsPutUChar(EState* s, UChar c) {
    bsW(s, 8, (UInt32)c);
}

/*---------------------------------------------------*/
/*--- The back end proper                         ---*/
/*---------------------------------------------------*/

/*---------------------------------------------------*/
static void makeMaps_e(EState* s) {
    Int32 i;
    s->nInUse = 0;
    for (i = 0; i < 256; i++)
        if (s->inUse[i]) {
            s->unseqToSeq[i] = s->nInUse;
            s->nInUse++;
        }
}

/*---------------------------------------------------*/
static void generateMTFValues(EState* s) {
    UChar yy[256];
    Int32 i, j;
    Int32 zPend;
    Int32 wr;
    Int32 EOB;

    /*
      After sorting (eg, here),
         s->arr1 [ 0 .. s->nblock-1 ] holds sorted order,
         and
         ((UChar*)s->arr2) [ 0 .. s->nblock-1 ]
         holds the original block data.

      The first thing to do is generate the MTF values,
      and put them in
         ((UInt16*)s->arr1) [ 0 .. s->nblock-1 ].
      Because there are strictly fewer or equal MTF values
      than block values, ptr values in this area are overwritten
      with MTF values only when they are no longer needed.

      The final compressed bitstream is generated into the
      area starting at
         (UChar*) (&((UChar*)s->arr2)[s->nblock])

      These storage aliases are set up in bzCompressInit(),
      except for the last one, which is arranged in
      compressBlock().
   */
    UInt32* ptr = s->ptr;
    UChar* block = s->block;
    UInt16* mtfv = s->mtfv;

    makeMaps_e(s);
    EOB = s->nInUse + 1;

    for (i = 0; i <= EOB; i++)
        s->mtfFreq[i] = 0;

    wr = 0;
    zPend = 0;
    for (i = 0; i < s->nInUse; i++)
        yy[i] = (UChar)i;

    for (i = 0; i < s->nblock; i++) {
        UChar ll_i;
        AssertD(wr <= i, "generateMTFValues(1)");
        j = ptr[i] - 1;
        if (j < 0)
            j += s->nblock;
        ll_i = s->unseqToSeq[block[j]];
        AssertD(ll_i < s->nInUse, "generateMTFValues(2a)");

        if (yy[0] == ll_i) {
            zPend++;
        }
        else {
            if (zPend > 0) {
                zPend--;
                while (True) {
                    if (zPend & 1) {
                        mtfv[wr] = BZ_RUNB;
                        wr++;
                        s->mtfFreq[BZ_RUNB]++;
                    }
                    else {
                        mtfv[wr] = BZ_RUNA;
                        wr++;
                        s->mtfFreq[BZ_RUNA]++;
                    }
                    if (zPend < 2)
                        break;
                    zPend = (zPend - 2) / 2;
                };
                zPend = 0;
            }
            {
                UChar rtmp;
                UChar* ryy_j;
                UChar rll_i;
                rtmp = yy[1];
                yy[1] = yy[0];
                ryy_j = &(yy[1]);
                rll_i = ll_i;
                while (rll_i != rtmp) {
                    UChar rtmp2;
                    ryy_j++;
                    rtmp2 = rtmp;
                    rtmp = *ryy_j;
                    *ryy_j = rtmp2;
                };
                yy[0] = rtmp;
                j = ryy_j - &(yy[0]);
                mtfv[wr] = j + 1;
                wr++;
                s->mtfFreq[j + 1]++;
            }
        }
    }

    if (zPend > 0) {
        zPend--;
        while (True) {
            if (zPend & 1) {
                mtfv[wr] = BZ_RUNB;
                wr++;
                s->mtfFreq[BZ_RUNB]++;
            }
            else {
                mtfv[wr] = BZ_RUNA;
                wr++;
                s->mtfFreq[BZ_RUNA]++;
            }
            if (zPend < 2)
                break;
            zPend = (zPend - 2) / 2;
        };
        zPend = 0;
    }

    mtfv[wr] = EOB;
    wr++;
    s->mtfFreq[EOB]++;

    s->nMTF = wr;
}

/*---------------------------------------------------*/
#define BZ_LESSER_ICOST  0
#define BZ_GREATER_ICOST 15

static void sendMTFValues(EState* s) {
    Int32 t, i, j, k, gs, ge, totc, bt, bc;
    Int32 nSelectors, alphaSize, minLen, maxLen, selCtr;
    Int32 nGroups, nBytes;

    /*--
   UChar  len [BZ_N_GROUPS][BZ_MAX_ALPHA_SIZE];
   is a global since the decoder also needs it.

   Int32  code[BZ_N_GROUPS][BZ_MAX_ALPHA_SIZE];
   Int32  rfreq[BZ_N_GROUPS][BZ_MAX_ALPHA_SIZE];
   are also globals only used in this proc.
   Made global to keep stack frame size small.
   --*/

    UInt16 cost[BZ_N_GROUPS];
    Int32 fave[BZ_N_GROUPS];

    UInt16* mtfv = s->mtfv;

    if (s->verbosity >= 3)
        VPrintf3("      %d in block, %d after MTF & 1-2 coding, "
                 "%d+2 syms in use\n",
                 s->nblock,
                 s->nMTF,
                 s->nInUse);

    alphaSize = s->nInUse + 2;
    for (i = 0; i < BZ_N_GROUPS; i++)
        for (j = 0; j < alphaSize; j++)
            s->len[i][j] = BZ_GREATER_ICOST;

    /*--- Decide how many coding tables to use ---*/
    AssertH(s->nMTF > 0, 3001);
    if (s->nMTF < 200)
        nGroups = 2;
    else if (s->nMTF < 600)
        nGroups = 3;
    else if (s->nMTF < 1200)
        nGroups = 4;
    else if (s->nMTF < 2400)
        nGroups = 5;
    else
        nGroups = 6;

    /*--- Generate an initial set of coding tables ---*/
    {
        Int32 nPart, remF, tFreq, aFreq;

        nPart = nGroups;
        remF = s->nMTF;
        gs = 0;
        while (nPart > 0) {
            tFreq = remF / nPart;
            ge = gs - 1;
            aFreq = 0;
            while (aFreq < tFreq && ge < alphaSize - 1) {
                ge++;
                aFreq += s->mtfFreq[ge];
            }

            if (ge > gs && nPart != nGroups && nPart != 1 && ((nGroups - nPart) % 2 == 1)) {
                aFreq -= s->mtfFreq[ge];
                ge--;
            }

            if (s->verbosity >= 3)
                VPrintf5("      initial group %d, [%d .. %d], "
                         "has %d syms (%4.1f%%)\n",
                         nPart,
                         gs,
                         ge,
                         aFreq,
                         (100.0 * (float)aFreq) / (float)(s->nMTF));

            for (i = 0; i < alphaSize; i++)
                if (i >= gs && i <= ge)
                    s->len[nPart - 1][i] = BZ_LESSER_ICOST;
                else
                    s->len[nPart - 1][i] = BZ_GREATER_ICOST;

            nPart--;
            gs = ge + 1;
            remF -= aFreq;
        }
    }

    /*---
      Iterate up to BZ_N_ITERS times to improve the tables.
   ---*/
    for (k = 0; k < BZ_N_ITERS; k++) {
        for (i = 0; i < nGroups; i++)
            fave[i] = 0;

        for (i = 0; i < nGroups; i++)
            for (j = 0; j < alphaSize; j++)
                s->rfreq[i][j] = 0;

        /*---
        Set up an auxiliary length table which is used to fast-track
	the common case (nGroups == 6).
      ---*/
        if (nGroups == 6) {
            for (i = 0; i < alphaSize; i++) {
                s->len_pack[i][0] = (s->len[1][i] << 16) | s->len[0][i];
                s->len_pack[i][1] = (s->len[3][i] << 16) | s->len[2][i];
                s->len_pack[i][2] = (s->len[5][i] << 16) | s->len[4][i];
            }
        }

        nSelectors = 0;
        totc = 0;
        gs = 0;
        while (True) {
            /*--- Set group start & end marks. --*/
            if (gs >= s->nMTF)
                break;
            ge = gs + BZ_G_SIZE - 1;
            if (ge >= s->nMTF)
                ge = s->nMTF - 1;

            /*--
            Calculate the cost of this group as coded
            by each of the coding tables.
         --*/
            for (i = 0; i < nGroups; i++)
                cost[i] = 0;

            if (nGroups == 6 && 50 == ge - gs + 1) {
                /*--- fast track the common case ---*/
                UInt32 cost01, cost23, cost45;
                UInt16 icv;
                cost01 = cost23 = cost45 = 0;

#define BZ_ITER(nn)                \
    icv = mtfv[gs + (nn)];         \
    cost01 += s->len_pack[icv][0]; \
    cost23 += s->len_pack[icv][1]; \
    cost45 += s->len_pack[icv][2];

                BZ_ITER(0);
                BZ_ITER(1);
                BZ_ITER(2);
                BZ_ITER(3);
                BZ_ITER(4);
                BZ_ITER(5);
                BZ_ITER(6);
                BZ_ITER(7);
                BZ_ITER(8);
                BZ_ITER(9);
                BZ_ITER(10);
                BZ_ITER(11);
                BZ_ITER(12);
                BZ_ITER(13);
                BZ_ITER(14);
                BZ_ITER(15);
                BZ_ITER(16);
                BZ_ITER(17);
                BZ_ITER(18);
                BZ_ITER(19);
                BZ_ITER(20);
                BZ_ITER(21);
                BZ_ITER(22);
                BZ_ITER(23);
                BZ_ITER(24);
                BZ_ITER(25);
                BZ_ITER(26);
                BZ_ITER(27);
                BZ_ITER(28);
                BZ_ITER(29);
                BZ_ITER(30);
                BZ_ITER(31);
                BZ_ITER(32);
                BZ_ITER(33);
                BZ_ITER(34);
                BZ_ITER(35);
                BZ_ITER(36);
                BZ_ITER(37);
                BZ_ITER(38);
                BZ_ITER(39);
                BZ_ITER(40);
                BZ_ITER(41);
                BZ_ITER(42);
                BZ_ITER(43);
                BZ_ITER(44);
                BZ_ITER(45);
                BZ_ITER(46);
                BZ_ITER(47);
                BZ_ITER(48);
                BZ_ITER(49);

#undef BZ_ITER

                cost[0] = cost01 & 0xffff;
                cost[1] = cost01 >> 16;
                cost[2] = cost23 & 0xffff;
                cost[3] = cost23 >> 16;
                cost[4] = cost45 & 0xffff;
                cost[5] = cost45 >> 16;
            }
            else {
                /*--- slow version which correctly handles all situations ---*/
                for (i = gs; i <= ge; i++) {
                    UInt16 icv = mtfv[i];
                    for (j = 0; j < nGroups; j++)
                        cost[j] += s->len[j][icv];
                }
            }

            /*--
            Find the coding table which is best for this group,
            and record its identity in the selector table.
         --*/
            bc = 999999999;
            bt = -1;
            for (i = 0; i < nGroups; i++)
                if (cost[i] < bc) {
                    bc = cost[i];
                    bt = i;
                };
            totc += bc;
            fave[bt]++;
            s->selector[nSelectors] = bt;
            nSelectors++;

            /*--
            Increment the symbol frequencies for the selected table.
          --*/
            if (nGroups == 6 && 50 == ge - gs + 1) {
                /*--- fast track the common case ---*/

#define BZ_ITUR(nn) s->rfreq[bt][mtfv[gs + (nn)]]++

                BZ_ITUR(0);
                BZ_ITUR(1);
                BZ_ITUR(2);
                BZ_ITUR(3);
                BZ_ITUR(4);
                BZ_ITUR(5);
                BZ_ITUR(6);
                BZ_ITUR(7);
                BZ_ITUR(8);
                BZ_ITUR(9);
                BZ_ITUR(10);
                BZ_ITUR(11);
                BZ_ITUR(12);
                BZ_ITUR(13);
                BZ_ITUR(14);
                BZ_ITUR(15);
                BZ_ITUR(16);
                BZ_ITUR(17);
                BZ_ITUR(18);
                BZ_ITUR(19);
                BZ_ITUR(20);
                BZ_ITUR(21);
                BZ_ITUR(22);
                BZ_ITUR(23);
                BZ_ITUR(24);
                BZ_ITUR(25);
                BZ_ITUR(26);
                BZ_ITUR(27);
                BZ_ITUR(28);
                BZ_ITUR(29);
                BZ_ITUR(30);
                BZ_ITUR(31);
                BZ_ITUR(32);
                BZ_ITUR(33);
                BZ_ITUR(34);
                BZ_ITUR(35);
                BZ_ITUR(36);
                BZ_ITUR(37);
                BZ_ITUR(38);
                BZ_ITUR(39);
                BZ_ITUR(40);
                BZ_ITUR(41);
                BZ_ITUR(42);
                BZ_ITUR(43);
                BZ_ITUR(44);
                BZ_ITUR(45);
                BZ_ITUR(46);
                BZ_ITUR(47);
                BZ_ITUR(48);
                BZ_ITUR(49);

#undef BZ_ITUR
            }
            else {
                /*--- slow version which correctly handles all situations ---*/
                for (i = gs; i <= ge; i++)
                    s->rfreq[bt][mtfv[i]]++;
            }

            gs = ge + 1;
        }
        if (s->verbosity >= 3) {
            VPrintf2("      pass %d: size is %d, grp uses are ", k + 1, totc / 8);
            for (i = 0; i < nGroups; i++)
                VPrintf1("%d ", fave[i]);
            VPrintf0("\n");
        }

        /*--
        Recompute the tables based on the accumulated frequencies.
      --*/
        /* maxLen was changed from 20 to 17 in bzip2-1.0.3.  See
         comment in huffman.c for details. */
        for (i = 0; i < nGroups; i++)
            BZ2_hbMakeCodeLengths(&(s->len[i][0]), &(s->rfreq[i][0]), alphaSize, 17 /*20*/);
    }

    AssertH(nGroups < 8, 3002);
    AssertH(nSelectors < 32768 && nSelectors <= (2 + (900000 / BZ_G_SIZE)), 3003);

    /*--- Compute MTF values for the selectors. ---*/
    {
        UChar pos[BZ_N_GROUPS], ll_i, tmp2, tmp;
        for (i = 0; i < nGroups; i++)
            pos[i] = i;
        for (i = 0; i < nSelectors; i++) {
            ll_i = s->selector[i];
            j = 0;
            tmp = pos[j];
            while (ll_i != tmp) {
                j++;
                tmp2 = tmp;
                tmp = pos[j];
                pos[j] = tmp2;
            };
            pos[0] = tmp;
            s->selectorMtf[i] = j;
        }
    };

    /*--- Assign actual codes for the tables. --*/
    for (j = 0; j < nGroups; j++) {
        minLen = 32;
        maxLen = 0;
        for (i = 0; i < alphaSize; i++) {
            if (s->len[j][i] > maxLen)
                maxLen = s->len[j][i];
            if (s->len[j][i] < minLen)
                minLen = s->len[j][i];
        }
        AssertH(!(maxLen > 17 /*20*/), 3004);
        AssertH(!(minLen < 1), 3005);
        BZ2_hbAssignCodes(&(s->code[j][0]), &(s->len[j][0]), minLen, maxLen, alphaSize);
    }

    /*--- Transmit the mapping table. ---*/
    {
        Bool inUse16[16];
        for (i = 0; i < 16; i++) {
            inUse16[i] = False;
            for (j = 0; j < 16; j++)
                if (s->inUse[i * 16 + j])
                    inUse16[i] = True;
        }

        nBytes = s->numZ;
        for (i = 0; i < 16; i++)
            if (inUse16[i])
                bsW(s, 1, 1);
            else
                bsW(s, 1, 0);

        for (i = 0; i < 16; i++)
            if (inUse16[i])
                for (j = 0; j < 16; j++) {
                    if (s->inUse[i * 16 + j])
                        bsW(s, 1, 1);
                    else
                        bsW(s, 1, 0);
                }

        if (s->verbosity >= 3)
            VPrintf1("      bytes: mapping %d, ", s->numZ - nBytes);
    }

    /*--- Now the selectors. ---*/
    nBytes = s->numZ;
    bsW(s, 3, nGroups);
    bsW(s, 15, nSelectors);
    for (i = 0; i < nSelectors; i++) {
        for (j = 0; j < s->selectorMtf[i]; j++)
            bsW(s, 1, 1);
        bsW(s, 1, 0);
    }
    if (s->verbosity >= 3)
        VPrintf1("selectors %d, ", s->numZ - nBytes);

    /*--- Now the coding tables. ---*/
    nBytes = s->numZ;

    for (t = 0; t < nGroups; t++) {
        Int32 curr = s->len[t][0];
        bsW(s, 5, curr);
        for (i = 0; i < alphaSize; i++) {
            while (curr < s->len[t][i]) {
                bsW(s, 2, 2);
                curr++; /* 10 */
            };
            while (curr > s->len[t][i]) {
                bsW(s, 2, 3);
                curr--; /* 11 */
            };
            bsW(s, 1, 0);
        }
    }

    if (s->verbosity >= 3)
        VPrintf1("code lengths %d, ", s->numZ - nBytes);

    /*--- And finally, the block data proper ---*/
    nBytes = s->numZ;
    selCtr = 0;
    gs = 0;
    while (True) {
        if (gs >= s->nMTF)
            break;
        ge = gs + BZ_G_SIZE - 1;
        if (ge >= s->nMTF)
            ge = s->nMTF - 1;
        AssertH(s->selector[selCtr] < nGroups, 3006);

        if (nGroups == 6 && 50 == ge - gs + 1) {
            /*--- fast track the common case ---*/
            UInt16 mtfv_i;
            UChar* s_len_sel_selCtr = &(s->len[s->selector[selCtr]][0]);
            Int32* s_code_sel_selCtr = &(s->code[s->selector[selCtr]][0]);

#define BZ_ITAH(nn)           \
    mtfv_i = mtfv[gs + (nn)]; \
    bsW(s, s_len_sel_selCtr[mtfv_i], s_code_sel_selCtr[mtfv_i])

            BZ_ITAH(0);
            BZ_ITAH(1);
            BZ_ITAH(2);
            BZ_ITAH(3);
            BZ_ITAH(4);
            BZ_ITAH(5);
            BZ_ITAH(6);
            BZ_ITAH(7);
            BZ_ITAH(8);
            BZ_ITAH(9);
            BZ_ITAH(10);
            BZ_ITAH(11);
            BZ_ITAH(12);
            BZ_ITAH(13);
            BZ_ITAH(14);
            BZ_ITAH(15);
            BZ_ITAH(16);
            BZ_ITAH(17);
            BZ_ITAH(18);
            BZ_ITAH(19);
            BZ_ITAH(20);
            BZ_ITAH(21);
            BZ_ITAH(22);
            BZ_ITAH(23);
            BZ_ITAH(24);
            BZ_ITAH(25);
            BZ_ITAH(26);
            BZ_ITAH(27);
            BZ_ITAH(28);
            BZ_ITAH(29);
            BZ_ITAH(30);
            BZ_ITAH(31);
            BZ_ITAH(32);
            BZ_ITAH(33);
            BZ_ITAH(34);
            BZ_ITAH(35);
            BZ_ITAH(36);
            BZ_ITAH(37);
            BZ_ITAH(38);
            BZ_ITAH(39);
            BZ_ITAH(40);
            BZ_ITAH(41);
            BZ_ITAH(42);
            BZ_ITAH(43);
            BZ_ITAH(44);
            BZ_ITAH(45);
            BZ_ITAH(46);
            BZ_ITAH(47);
            BZ_ITAH(48);
            BZ_ITAH(49);

#undef BZ_ITAH
        }
        else {
            /*--- slow version which correctly handles all situations ---*/
            for (i = gs; i <= ge; i++) {
                bsW(s, s->len[s->selector[selCtr]][mtfv[i]], s->code[s->selector[selCtr]][mtfv[i]]);
            }
        }

        gs = ge + 1;
        selCtr++;
    }
    AssertH(selCtr == nSelectors, 3007);

    if (s->verbosity >= 3)
        VPrintf1("codes %d\n", s->numZ - nBytes);
}

/*---------------------------------------------------*/
void BZ2_compressBlock(EState* s, Bool is_last_block) {
    if (s->nblock > 0) {
        BZ_FINALISE_CRC(s->blockCRC);
        s->combinedCRC = (s->combinedCRC << 1) | (s->combinedCRC >> 31);
        s->combinedCRC ^= s->blockCRC;
        if (s->blockNo > 1)
            s->numZ = 0;

        if (s->verbosity >= 2)
            VPrintf4("    block %d: crc = 0x%08x, "
                     "combined CRC = 0x%08x, size = %d\n",
                     s->blockNo,
                     s->blockCRC,
                     s->combinedCRC,
                     s->nblock);

        BZ2_blockSort(s);
    }

    s->zbits = (UChar*)(&((UChar*)s->arr2)[s->nblock]);

    /*-- If this is the first block, create the stream header. --*/
    if (s->blockNo == 1) {
        BZ2_bsInitWrite(s);
        bsPutUChar(s, BZ_HDR_B);
        bsPutUChar(s, BZ_HDR_Z);
        bsPutUChar(s, BZ_HDR_h);
        bsPutUChar(s, (UChar)(BZ_HDR_0 + s->blockSize100k));
    }

    if (s->nblock > 0) {
        bsPutUChar(s, 0x31);
        bsPutUChar(s, 0x41);
        bsPutUChar(s, 0x59);
        bsPutUChar(s, 0x26);
        bsPutUChar(s, 0x53);
        bsPutUChar(s, 0x59);

        /*-- Now the block's CRC, so it is in a known place. --*/
        bsPutUInt32(s, s->blockCRC);

        /*--
         Now a single bit indicating (non-)randomisation.
         As of version 0.9.5, we use a better sorting algorithm
         which makes randomisation unnecessary.  So always set
         the randomised bit to 'no'.  Of course, the decoder
         still needs to be able to handle randomised blocks
         so as to maintain backwards compatibility with
         older versions of bzip2.
      --*/
        bsW(s, 1, 0);

        bsW(s, 24, s->origPtr);
        generateMTFValues(s);
        sendMTFValues(s);
    }

    /*-- If this is the last block, add the stream trailer. --*/
    if (is_last_block) {
        bsPutUChar(s, 0x17);
        bsPutUChar(s, 0x72);
        bsPutUChar(s, 0x45);
        bsPutUChar(s, 0x38);
        bsPutUChar(s, 0x50);
        bsPutUChar(s, 0x90);
        bsPutUInt32(s, s->combinedCRC);
        if (s->verbosity >= 2)
            VPrintf1("    final combined CRC = 0x%08x\n   ", s->combinedCRC);
        bsFinishWrite(s);
    }
}

/*-------------------------------------------------------------*/
/*--- end                                        compress.c ---*/
/*-------------------------------------------------------------*/