minibzip2.cpp

minibzip2

   Int32  copyEnd  [256];
   UChar  c1;
   Int32  numQSorted;
   UInt16 s;
   if (verb >= 4) VPrintf0 ( "        main sort initialise ...\n" );

   /*-- set up the 2-byte frequency table --*/
   for (i = 65536; i >= 0; i--) ftab[i] = 0;

   j = block[0] << 8;
   i = nblock-1;
   for (; i >= 3; i -= 4) {
      quadrant[i] = 0;
      j = (j >> 8) | ( ((UInt16)block[i]) << 8);
      ftab[j]++;
      quadrant[i-1] = 0;
      j = (j >> 8) | ( ((UInt16)block[i-1]) << 8);
      ftab[j]++;
      quadrant[i-2] = 0;
      j = (j >> 8) | ( ((UInt16)block[i-2]) << 8);
      ftab[j]++;
      quadrant[i-3] = 0;
      j = (j >> 8) | ( ((UInt16)block[i-3]) << 8);
      ftab[j]++;
   }
   for (; i >= 0; i--) {
      quadrant[i] = 0;
      j = (j >> 8) | ( ((UInt16)block[i]) << 8);
      ftab[j]++;
   }

   /*-- (emphasises close relationship of block & quadrant) --*/
   for (i = 0; i < BZ_N_OVERSHOOT; i++) {
      block   [nblock+i] = block[i];
      quadrant[nblock+i] = 0;
   }

   if (verb >= 4) VPrintf0 ( "        bucket sorting ...\n" );

   /*-- Complete the initial radix sort --*/
   for (i = 1; i <= 65536; i++) ftab[i] += ftab[i-1];

   s = block[0] << 8;
   i = nblock-1;
   for (; i >= 3; i -= 4) {
      s = (s >> 8) | (block[i] << 8);
      j = ftab[s] -1;
      ftab[s] = j;
      ptr[j] = i;
      s = (s >> 8) | (block[i-1] << 8);
      j = ftab[s] -1;
      ftab[s] = j;
      ptr[j] = i-1;
      s = (s >> 8) | (block[i-2] << 8);
      j = ftab[s] -1;
      ftab[s] = j;
      ptr[j] = i-2;
      s = (s >> 8) | (block[i-3] << 8);
      j = ftab[s] -1;
      ftab[s] = j;
      ptr[j] = i-3;
   }
   for (; i >= 0; i--) {
      s = (s >> 8) | (block[i] << 8);
      j = ftab[s] -1;
      ftab[s] = j;
      ptr[j] = i;
   }

   /*--
      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++) {
      bigDone     [i] = False;
      runningOrder[i] = i;
   }

   {
      Int32 vv;
      Int32 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 ( BIGFREQ(runningOrder[j-h]) > BIGFREQ(vv) ) {
               runningOrder[j] = runningOrder[j-h];
               j = j - h;
               if (j <= (h - 1)) goto zero;
            }
            zero:
            runningOrder[j] = vv;
         }
      } while (h != 1);
   }

   /*--
      The main sorting loop.
   --*/

   numQSorted = 0;

   for (i = 0; i <= 255; i++) {

      /*--
         Process big buckets, starting with the least full.
         Basically this is a 3-step process in which we call
         mainQSort3 to sort the small buckets [ss, j], but
         also make a big effort to avoid the calls if we can.
      --*/
      ss = runningOrder[i];

      /*--
         Step 1:
         Complete the big bucket [ss] by quicksorting
         any unsorted small buckets [ss, j], for j != ss.  
         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++) {
         if (j != ss) {
            sb = (ss << 8) + j;
            if ( ! (ftab[sb] & SETMASK) ) {
               Int32 lo = ftab[sb]   & CLEARMASK;
               Int32 hi = (ftab[sb+1] & CLEARMASK) - 1;
               if (hi > lo) {
                  if (verb >= 4)
                     VPrintf4 ( "        qsort [0x%x, 0x%x]   "
                                "done %d   this %d\n",
                                ss, j, numQSorted, hi - lo + 1 );
                  mainQSort3 ( 
                     ptr, block, quadrant, nblock, 
                     lo, hi, BZ_N_RADIX, budget 
                  );   
                  numQSorted += (hi - lo + 1);
                  if (*budget < 0) return;
               }
            }
            ftab[sb] |= SETMASK;
         }
      }

      AssertH ( !bigDone[ss], 1006 );

      /*--
         Step 2:
         Now scan this big bucket [ss] so as to synthesise the
         sorted order for small buckets [t, ss] for all t,
         including, magically, the bucket [ss,ss] too.
         This will avoid doing Real Work in subsequent Step 1's.
      --*/
      {
         for (j = 0; j <= 255; j++) {
            copyStart[j] =  ftab[(j << 8) + ss]     & CLEARMASK;
            copyEnd  [j] = (ftab[(j << 8) + ss + 1] & CLEARMASK) - 1;
         }
         for (j = ftab[ss << 8] & CLEARMASK; j < copyStart[ss]; j++) {
            k = ptr[j]-1; if (k < 0) k += nblock;
            c1 = block[k];
            if (!bigDone[c1])
               ptr[ copyStart[c1]++ ] = k;
         }
         for (j = (ftab[(ss+1) << 8] & CLEARMASK) - 1; j > copyEnd[ss]; j--) {
            k = ptr[j]-1; if (k < 0) k += nblock;
            c1 = block[k];
            if (!bigDone[c1]) 
               ptr[ copyEnd[c1]-- ] = k;
         }
      }

      AssertH ( (copyStart[ss]-1 == copyEnd[ss])
                || 
                /* Extremely rare case missing in bzip2-1.0.0 and 1.0.1.
                   Necessity for this case is demonstrated by compressing 
                   a sequence of approximately 48.5 million of character 
                   251; 1.0.0/1.0.1 will then die here. */
                (copyStart[ss] == 0 && copyEnd[ss] == nblock-1),
                1007 )

      for (j = 0; j <= 255; j++) ftab[(j << 8) + ss] |= SETMASK;

      /*--
         Step 3:
         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.

         The quadrant array provides a way to incrementally
         cache sort orderings, as they appear, so as to 
         make subsequent comparisons in fullGtU() complete
         faster.  For repetitive blocks this makes a big
         difference (but not big enough to be able to avoid
         the fallback sorting mechanism, exponential radix sort).

         The precise meaning is: at all times:

            for 0 <= i < nblock and 0 <= j <= nblock

            if block[i] != block[j], 

               then the relative values of quadrant[i] and 
                    quadrant[j] are meaningless.

               else {
                  if quadrant[i] < quadrant[j]
                     then the string starting at i lexicographically
                     precedes the string starting at j

                  else if quadrant[i] > quadrant[j]
                     then the string starting at j lexicographically
                     precedes the string starting at i

                  else
                     the relative ordering of the strings starting
                     at i and j has not yet been determined.
               }
      --*/
      bigDone[ss] = True;

      if (i < 255) {
         Int32 bbStart  = ftab[ss << 8] & CLEARMASK;
         Int32 bbSize   = (ftab[(ss+1) << 8] & CLEARMASK) - bbStart;
         Int32 shifts   = 0;

         while ((bbSize >> shifts) > 65534) shifts++;

         for (j = bbSize-1; j >= 0; j--) {
            Int32 a2update     = ptr[bbStart + j];
            UInt16 qVal        = (UInt16)(j >> shifts);
            quadrant[a2update] = qVal;
            if (a2update < BZ_N_OVERSHOOT)
               quadrant[a2update + nblock] = qVal;
         }
         AssertH ( ((bbSize-1) >> shifts) <= 65535, 1002 );
      }

   }

   if (verb >= 4)
      VPrintf3 ( "        %d pointers, %d sorted, %d scanned\n",
                 nblock, numQSorted, nblock - numQSorted );
}

#undef BIGFREQ
#undef SETMASK
#undef CLEARMASK


/*---------------------------------------------*/
/* Pre:
      nblock > 0
      arr2 exists for [0 .. nblock-1 +N_OVERSHOOT]
      ((UChar*)arr2)  [0 .. nblock-1] holds block
      arr1 exists for [0 .. nblock-1]

   Post:
      ((UChar*)arr2) [0 .. nblock-1] holds block
      All other areas of block destroyed
      ftab [ 0 .. 65536 ] destroyed
      arr1 [0 .. nblock-1] holds sorted order
*/
void BZ2_blockSort ( EState* s )
{
   UInt32* ptr    = s->ptr; 
   UChar*  block  = s->block;
   UInt32* ftab   = s->ftab;
   Int32   nblock = s->nblock;
   Int32   verb   = s->verbosity;
   Int32   wfact  = s->workFactor;
   UInt16* quadrant;
   Int32   budget;
   Int32   budgetInit;
   Int32   i;

   if (nblock < 10000) {
      fallbackSort ( s->arr1, s->arr2, ftab, nblock, verb );
   } else {
      /* Calculate the location for quadrant, remembering to get
         the alignment right.  Assumes that &(block[0]) is at least
         2-byte aligned -- this should be ok since block is really
         the first section of arr2.
      */
      i = nblock+BZ_N_OVERSHOOT;
      if (i & 1) i++;
      quadrant = (UInt16*)(&(block[i]));

      /* (wfact-1) / 3 puts the default-factor-30
         transition point at very roughly the same place as 
         with v0.1 and v0.9.0.  
         Not that it particularly matters any more, since the
         resulting compressed stream is now the same regardless
         of whether or not we use the main sort or fallback sort.
      */
      if (wfact < 1  ) wfact = 1;
      if (wfact > 100) wfact = 100;
      budgetInit = nblock * ((wfact-1) / 3);
      budget = budgetInit;

      mainSort ( ptr, block, quadrant, ftab, nblock, verb, &budget );
      if (verb >= 3) 
         VPrintf3 ( "      %d work, %d block, ratio %5.2f\n",
                    budgetInit - budget,
                    nblock, 
                    (float)(budgetInit - budget) /
                    (float)(nblock==0 ? 1 : nblock) ); 
      if (budget < 0) {
         if (verb >= 2) 
            VPrintf0 ( "    too repetitive; using fallback"
                       " sorting algorithm\n" );
         fallbackSort ( s->arr1, s->arr2, ftab, nblock, verb );
      }
   }

   s->origPtr = -1;
   for (i = 0; i < s->nblock; i++)
      if (ptr[i] == 0)
         { s->origPtr = i; break; };

   AssertH( s->origPtr != -1, 1003 );
}


/*-------------------------------------------------------------*/
/*--- end                                       blocksort.c ---*/
/*-------------------------------------------------------------*/

/*-------------------------------------------------------------*/
/*--- Table for randomising repetitive blocks               ---*/
/*---                                           randtable.c ---*/
/*-------------------------------------------------------------*/

/*--
  This file is a part of bzip2 and/or libbzip2, a program and
  library for lossless, block-sorting data compression.

  Copyright (C) 1996-2002 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, Cambridge, UK.
  [e-mail]
  bzip2/libbzip2 version 1.0 of 21 March 2000

  This program is based on (at least) the work of:
     Mike Burrows
     David Wheeler
     Peter Fenwick
     Alistair Moffat
     Radford Neal
     Ian H. Witten
     Robert Sedgewick
     Jon L. Bentley

  For more information on these sources, see the manual.
--*/


#include "bzlib_private.h"


/*---------------------------------------------*/
Int32 BZ2_rNums[512] = { 
   619, 720, 127, 481, 931, 816, 813, 233, 566, 247, 
   985, 724, 205, 454, 863, 491, 741, 242, 949, 214, 
   733, 859, 335, 708, 621, 574, 73, 654, 730, 472, 
   419, 436, 278, 496, 867, 210, 399, 680, 480, 51, 
   878, 465, 811, 169, 869, 675, 611, 697, 867, 561, 
   862, 687, 507, 283, 482, 129, 807, 591, 733, 623, 
   150, 238, 59, 379, 684, 877, 625, 169, 643, 105, 
   170, 607, 520, 932, 727, 476, 693, 425, 174, 647, 
   73, 122, 335, 530, 442, 853, 695, 249, 445, 515,