2
/*-------------------------------------------------------------*/
3
/*--- Block sorting machinery ---*/
4
/*--- blocksort.c ---*/
5
/*-------------------------------------------------------------*/
8
This file is a part of bzip2 and/or libbzip2, a program and
9
library for lossless, block-sorting data compression.
11
Copyright (C) 1996-2000 Julian R Seward. All rights reserved.
13
Redistribution and use in source and binary forms, with or without
14
modification, are permitted provided that the following conditions
17
1. Redistributions of source code must retain the above copyright
18
notice, this list of conditions and the following disclaimer.
20
2. The origin of this software must not be misrepresented; you must
21
not claim that you wrote the original software. If you use this
22
software in a product, an acknowledgment in the product
23
documentation would be appreciated but is not required.
25
3. Altered source versions must be plainly marked as such, and must
26
not be misrepresented as being the original software.
28
4. The name of the author may not be used to endorse or promote
29
products derived from this software without specific prior written
32
THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
33
OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
34
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
35
ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
36
DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
37
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
38
GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
39
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
40
WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
41
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
42
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
44
Julian Seward, Cambridge, UK.
46
bzip2/libbzip2 version 1.0 of 21 March 2000
48
This program is based on (at least) the work of:
58
For more information on these sources, see the manual.
60
To get some idea how the block sorting algorithms in this file
62
On the Performance of BWT Sorting Algorithms
63
in Proceedings of the IEEE Data Compression Conference 2000,
64
Snowbird, Utah, USA, 27-30 March 2000. The main sort in this
65
file implements the algorithm called cache in the paper.
69
#include "bzlib_private.h"
71
/*---------------------------------------------*/
72
/*--- Fallback O(N log(N)^2) sorting ---*/
73
/*--- algorithm, for repetitive blocks ---*/
74
/*---------------------------------------------*/
76
/*---------------------------------------------*/
79
void fallbackSimpleSort ( UInt32* fmap,
90
for ( i = hi-4; i >= lo; i-- ) {
93
for ( j = i+4; j <= hi && ec_tmp > eclass[fmap[j]]; j += 4 )
99
for ( i = hi-1; i >= lo; i-- ) {
101
ec_tmp = eclass[tmp];
102
for ( j = i+1; j <= hi && ec_tmp > eclass[fmap[j]]; j++ )
109
/*---------------------------------------------*/
110
#define fswap(zz1, zz2) \
111
{ Int32 zztmp = zz1; zz1 = zz2; zz2 = zztmp; }
113
#define fvswap(zzp1, zzp2, zzn) \
115
Int32 yyp1 = (zzp1); \
116
Int32 yyp2 = (zzp2); \
119
fswap(fmap[yyp1], fmap[yyp2]); \
120
yyp1++; yyp2++; yyn--; \
125
#define fmin(a,b) ((a) < (b)) ? (a) : (b)
127
#define fpush(lz,hz) { stackLo[sp] = lz; \
131
#define fpop(lz,hz) { sp--; \
135
#define FALLBACK_QSORT_SMALL_THRESH 10
136
#define FALLBACK_QSORT_STACK_SIZE 100
140
void fallbackQSort3 ( UInt32* fmap,
145
Int32 unLo, unHi, ltLo, gtHi, n, m;
148
Int32 stackLo[FALLBACK_QSORT_STACK_SIZE];
149
Int32 stackHi[FALLBACK_QSORT_STACK_SIZE];
154
fpush ( loSt, hiSt );
158
AssertH ( sp < FALLBACK_QSORT_STACK_SIZE, 1004 );
161
if (hi - lo < FALLBACK_QSORT_SMALL_THRESH) {
162
fallbackSimpleSort ( fmap, eclass, lo, hi );
166
/* Random partitioning. Median of 3 sometimes fails to
167
avoid bad cases. Median of 9 seems to help but
168
looks rather expensive. This too seems to work but
169
is cheaper. Guidance for the magic constants
170
7621 and 32768 is taken from Sedgewick's algorithms
173
r = ((r * 7621) + 1) % 32768;
175
if (r3 == 0) med = eclass[fmap[lo]]; else
176
if (r3 == 1) med = eclass[fmap[(lo+hi)>>1]]; else
177
med = eclass[fmap[hi]];
184
if (unLo > unHi) break;
185
n = (Int32)eclass[fmap[unLo]] - (Int32)med;
187
fswap(fmap[unLo], fmap[ltLo]);
195
if (unLo > unHi) break;
196
n = (Int32)eclass[fmap[unHi]] - (Int32)med;
198
fswap(fmap[unHi], fmap[gtHi]);
205
if (unLo > unHi) break;
206
fswap(fmap[unLo], fmap[unHi]); unLo++; unHi--;
209
AssertD ( unHi == unLo-1, "fallbackQSort3(2)" );
211
if (gtHi < ltLo) continue;
213
n = fmin(ltLo-lo, unLo-ltLo); fvswap(lo, unLo-n, n);
214
m = fmin(hi-gtHi, gtHi-unHi); fvswap(unLo, hi-m+1, m);
216
n = lo + unLo - ltLo - 1;
217
m = hi - (gtHi - unHi) + 1;
219
if (n - lo > hi - m) {
234
#undef FALLBACK_QSORT_SMALL_THRESH
235
#undef FALLBACK_QSORT_STACK_SIZE
238
/*---------------------------------------------*/
241
eclass exists for [0 .. nblock-1]
242
((UChar*)eclass) [0 .. nblock-1] holds block
243
ptr exists for [0 .. nblock-1]
246
((UChar*)eclass) [0 .. nblock-1] holds block
247
All other areas of eclass destroyed
248
fmap [0 .. nblock-1] holds sorted order
249
bhtab [ 0 .. 2+(nblock/32) ] destroyed
252
#define SET_BH(zz) bhtab[(zz) >> 5] |= (1 << ((zz) & 31))
253
#define CLEAR_BH(zz) bhtab[(zz) >> 5] &= ~(1 << ((zz) & 31))
254
#define ISSET_BH(zz) (bhtab[(zz) >> 5] & (1 << ((zz) & 31)))
255
#define WORD_BH(zz) bhtab[(zz) >> 5]
256
#define UNALIGNED_BH(zz) ((zz) & 0x01f)
259
void fallbackSort ( UInt32* fmap,
267
Int32 H, i, j, k, l, r, cc, cc1;
270
UChar* eclass8 = (UChar*)eclass;
273
Initial 1-char radix sort to generate
274
initial fmap and initial BH bits.
277
VPrintf0 ( " bucket sorting ...\n" );
278
for (i = 0; i < 257; i++) ftab[i] = 0;
279
for (i = 0; i < nblock; i++) ftab[eclass8[i]]++;
280
for (i = 0; i < 256; i++) ftabCopy[i] = ftab[i];
281
for (i = 1; i < 257; i++) ftab[i] += ftab[i-1];
283
for (i = 0; i < nblock; i++) {
290
nBhtab = 2 + (nblock / 32);
291
for (i = 0; i < nBhtab; i++) bhtab[i] = 0;
292
for (i = 0; i < 256; i++) SET_BH(ftab[i]);
295
Inductively refine the buckets. Kind-of an
296
"exponential radix sort" (!), inspired by the
297
Manber-Myers suffix array construction algorithm.
300
/*-- set sentinel bits for block-end detection --*/
301
for (i = 0; i < 32; i++) {
302
SET_BH(nblock + 2*i);
303
CLEAR_BH(nblock + 2*i + 1);
306
/*-- the log(N) loop --*/
311
VPrintf1 ( " depth %6d has ", H );
314
for (i = 0; i < nblock; i++) {
315
if (ISSET_BH(i)) j = i;
316
k = fmap[i] - H; if (k < 0) k += nblock;
324
/*-- find the next non-singleton bucket --*/
326
while (ISSET_BH(k) && UNALIGNED_BH(k)) k++;
328
while (WORD_BH(k) == 0xffffffff) k += 32;
329
while (ISSET_BH(k)) k++;
332
if (l >= nblock) break;
333
while (!ISSET_BH(k) && UNALIGNED_BH(k)) k++;
335
while (WORD_BH(k) == 0x00000000) k += 32;
336
while (!ISSET_BH(k)) k++;
339
if (r >= nblock) break;
341
/*-- now [l, r] bracket current bucket --*/
343
nNotDone += (r - l + 1);
344
fallbackQSort3 ( fmap, eclass, l, r );
346
/*-- scan bucket and generate header bits-- */
348
for (i = l; i <= r; i++) {
349
cc1 = eclass[fmap[i]];
350
if (cc != cc1) { SET_BH(i); cc = cc1; };
356
VPrintf1 ( "%6d unresolved strings\n", nNotDone );
359
if (H > nblock || nNotDone == 0) break;
363
Reconstruct the original block in
364
eclass8 [0 .. nblock-1], since the
365
previous phase destroyed it.
368
VPrintf0 ( " reconstructing block ...\n" );
370
for (i = 0; i < nblock; i++) {
371
while (ftabCopy[j] == 0) j++;
373
eclass8[fmap[i]] = (UChar)j;
375
AssertH ( j < 256, 1005 );
385
/*---------------------------------------------*/
386
/*--- The main, O(N^2 log(N)) sorting ---*/
387
/*--- algorithm. Faster for "normal" ---*/
388
/*--- non-repetitive blocks. ---*/
389
/*---------------------------------------------*/
391
/*---------------------------------------------*/
394
Bool mainGtU ( UInt32 i1,
405
AssertD ( i1 != i2, "mainGtU" );
407
c1 = block[i1]; c2 = block[i2];
408
if (c1 != c2) return (c1 > c2);
411
c1 = block[i1]; c2 = block[i2];
412
if (c1 != c2) return (c1 > c2);
415
c1 = block[i1]; c2 = block[i2];
416
if (c1 != c2) return (c1 > c2);
419
c1 = block[i1]; c2 = block[i2];
420
if (c1 != c2) return (c1 > c2);
423
c1 = block[i1]; c2 = block[i2];
424
if (c1 != c2) return (c1 > c2);
427
c1 = block[i1]; c2 = block[i2];
428
if (c1 != c2) return (c1 > c2);
431
c1 = block[i1]; c2 = block[i2];
432
if (c1 != c2) return (c1 > c2);
435
c1 = block[i1]; c2 = block[i2];
436
if (c1 != c2) return (c1 > c2);
439
c1 = block[i1]; c2 = block[i2];
440
if (c1 != c2) return (c1 > c2);
443
c1 = block[i1]; c2 = block[i2];
444
if (c1 != c2) return (c1 > c2);
447
c1 = block[i1]; c2 = block[i2];
448
if (c1 != c2) return (c1 > c2);
451
c1 = block[i1]; c2 = block[i2];
452
if (c1 != c2) return (c1 > c2);
459
c1 = block[i1]; c2 = block[i2];
460
if (c1 != c2) return (c1 > c2);
461
s1 = quadrant[i1]; s2 = quadrant[i2];
462
if (s1 != s2) return (s1 > s2);
465
c1 = block[i1]; c2 = block[i2];
466
if (c1 != c2) return (c1 > c2);
467
s1 = quadrant[i1]; s2 = quadrant[i2];
468
if (s1 != s2) return (s1 > s2);
471
c1 = block[i1]; c2 = block[i2];
472
if (c1 != c2) return (c1 > c2);
473
s1 = quadrant[i1]; s2 = quadrant[i2];
474
if (s1 != s2) return (s1 > s2);
477
c1 = block[i1]; c2 = block[i2];
478
if (c1 != c2) return (c1 > c2);
479
s1 = quadrant[i1]; s2 = quadrant[i2];
480
if (s1 != s2) return (s1 > s2);
483
c1 = block[i1]; c2 = block[i2];
484
if (c1 != c2) return (c1 > c2);
485
s1 = quadrant[i1]; s2 = quadrant[i2];
486
if (s1 != s2) return (s1 > s2);
489
c1 = block[i1]; c2 = block[i2];
490
if (c1 != c2) return (c1 > c2);
491
s1 = quadrant[i1]; s2 = quadrant[i2];
492
if (s1 != s2) return (s1 > s2);
495
c1 = block[i1]; c2 = block[i2];
496
if (c1 != c2) return (c1 > c2);
497
s1 = quadrant[i1]; s2 = quadrant[i2];
498
if (s1 != s2) return (s1 > s2);
501
c1 = block[i1]; c2 = block[i2];
502
if (c1 != c2) return (c1 > c2);
503
s1 = quadrant[i1]; s2 = quadrant[i2];
504
if (s1 != s2) return (s1 > s2);
507
if (i1 >= nblock) i1 -= nblock;
508
if (i2 >= nblock) i2 -= nblock;
519
/*---------------------------------------------*/
521
Knuth's increments seem to work better
522
than Incerpi-Sedgewick here. Possibly
523
because the number of elems to sort is
524
usually small, typically <= 20.
527
Int32 incs[14] = { 1, 4, 13, 40, 121, 364, 1093, 3280,
528
9841, 29524, 88573, 265720,
532
void mainSimpleSort ( UInt32* ptr,
541
Int32 i, j, h, bigN, hp;
545
if (bigN < 2) return;
548
while (incs[hp] < bigN) hp++;
551
for (; hp >= 0; hp--) {
562
ptr[j-h]+d, v+d, block, quadrant, nblock, budget
566
if (j <= (lo + h - 1)) break;
576
ptr[j-h]+d, v+d, block, quadrant, nblock, budget
580
if (j <= (lo + h - 1)) break;
590
ptr[j-h]+d, v+d, block, quadrant, nblock, budget
594
if (j <= (lo + h - 1)) break;
599
if (*budget < 0) return;
605
/*---------------------------------------------*/
607
The following is an implementation of
608
an elegant 3-way quicksort for strings,
609
described in a paper "Fast Algorithms for
610
Sorting and Searching Strings", by Robert
611
Sedgewick and Jon L. Bentley.
614
#define mswap(zz1, zz2) \
615
{ Int32 zztmp = zz1; zz1 = zz2; zz2 = zztmp; }
617
#define mvswap(zzp1, zzp2, zzn) \
619
Int32 yyp1 = (zzp1); \
620
Int32 yyp2 = (zzp2); \
623
mswap(ptr[yyp1], ptr[yyp2]); \
624
yyp1++; yyp2++; yyn--; \
630
UChar mmed3 ( UChar a, UChar b, UChar c )
633
if (a > b) { t = a; a = b; b = t; };
641
#define mmin(a,b) ((a) < (b)) ? (a) : (b)
643
#define mpush(lz,hz,dz) { stackLo[sp] = lz; \
648
#define mpop(lz,hz,dz) { sp--; \
654
#define mnextsize(az) (nextHi[az]-nextLo[az])
656
#define mnextswap(az,bz) \
658
tz = nextLo[az]; nextLo[az] = nextLo[bz]; nextLo[bz] = tz; \
659
tz = nextHi[az]; nextHi[az] = nextHi[bz]; nextHi[bz] = tz; \
660
tz = nextD [az]; nextD [az] = nextD [bz]; nextD [bz] = tz; }
663
#define MAIN_QSORT_SMALL_THRESH 20
664
#define MAIN_QSORT_DEPTH_THRESH (BZ_N_RADIX + BZ_N_QSORT)
665
#define MAIN_QSORT_STACK_SIZE 100
668
void mainQSort3 ( UInt32* ptr,
677
Int32 unLo, unHi, ltLo, gtHi, n, m, med;
680
Int32 stackLo[MAIN_QSORT_STACK_SIZE];
681
Int32 stackHi[MAIN_QSORT_STACK_SIZE];
682
Int32 stackD [MAIN_QSORT_STACK_SIZE];
689
mpush ( loSt, hiSt, dSt );
693
AssertH ( sp < MAIN_QSORT_STACK_SIZE, 1001 );
696
if (hi - lo < MAIN_QSORT_SMALL_THRESH ||
697
d > MAIN_QSORT_DEPTH_THRESH) {
698
mainSimpleSort ( ptr, block, quadrant, nblock, lo, hi, d, budget );
699
if (*budget < 0) return;
704
mmed3 ( block[ptr[ lo ]+d],
706
block[ptr[ (lo+hi)>>1 ]+d] );
713
if (unLo > unHi) break;
714
n = ((Int32)block[ptr[unLo]+d]) - med;
716
mswap(ptr[unLo], ptr[ltLo]);
717
ltLo++; unLo++; continue;
723
if (unLo > unHi) break;
724
n = ((Int32)block[ptr[unHi]+d]) - med;
726
mswap(ptr[unHi], ptr[gtHi]);
727
gtHi--; unHi--; continue;
732
if (unLo > unHi) break;
733
mswap(ptr[unLo], ptr[unHi]); unLo++; unHi--;
736
AssertD ( unHi == unLo-1, "mainQSort3(2)" );
743
n = mmin(ltLo-lo, unLo-ltLo); mvswap(lo, unLo-n, n);
744
m = mmin(hi-gtHi, gtHi-unHi); mvswap(unLo, hi-m+1, m);
746
n = lo + unLo - ltLo - 1;
747
m = hi - (gtHi - unHi) + 1;
749
nextLo[0] = lo; nextHi[0] = n; nextD[0] = d;
750
nextLo[1] = m; nextHi[1] = hi; nextD[1] = d;
751
nextLo[2] = n+1; nextHi[2] = m-1; nextD[2] = d+1;
753
if (mnextsize(0) < mnextsize(1)) mnextswap(0,1);
754
if (mnextsize(1) < mnextsize(2)) mnextswap(1,2);
755
if (mnextsize(0) < mnextsize(1)) mnextswap(0,1);
757
AssertD (mnextsize(0) >= mnextsize(1), "mainQSort3(8)" );
758
AssertD (mnextsize(1) >= mnextsize(2), "mainQSort3(9)" );
760
mpush (nextLo[0], nextHi[0], nextD[0]);
761
mpush (nextLo[1], nextHi[1], nextD[1]);
762
mpush (nextLo[2], nextHi[2], nextD[2]);
773
#undef MAIN_QSORT_SMALL_THRESH
774
#undef MAIN_QSORT_DEPTH_THRESH
775
#undef MAIN_QSORT_STACK_SIZE
778
/*---------------------------------------------*/
781
block32 exists for [0 .. nblock-1 +N_OVERSHOOT]
782
((UChar*)block32) [0 .. nblock-1] holds block
783
ptr exists for [0 .. nblock-1]
786
((UChar*)block32) [0 .. nblock-1] holds block
787
All other areas of block32 destroyed
788
ftab [0 .. 65536 ] destroyed
789
ptr [0 .. nblock-1] holds sorted order
790
if (*budget < 0), sorting was abandoned
793
#define BIGFREQ(b) (ftab[((b)+1) << 8] - ftab[(b) << 8])
794
#define SETMASK (1 << 21)
795
#define CLEARMASK (~(SETMASK))
798
void mainSort ( UInt32* ptr,
806
Int32 i, j, k, ss, sb;
807
Int32 runningOrder[256];
809
Int32 copyStart[256];
814
if (verb >= 4) VPrintf0 ( " main sort initialise ...\n" );
816
/*-- set up the 2-byte frequency table --*/
817
for (i = 65536; i >= 0; i--) ftab[i] = 0;
821
for (; i >= 3; i -= 4) {
823
j = (j >> 8) | ( ((UInt16)block[i]) << 8);
826
j = (j >> 8) | ( ((UInt16)block[i-1]) << 8);
829
j = (j >> 8) | ( ((UInt16)block[i-2]) << 8);
832
j = (j >> 8) | ( ((UInt16)block[i-3]) << 8);
835
for (; i >= 0; i--) {
837
j = (j >> 8) | ( ((UInt16)block[i]) << 8);
841
/*-- (emphasises close relationship of block & quadrant) --*/
842
for (i = 0; i < BZ_N_OVERSHOOT; i++) {
843
block [nblock+i] = block[i];
844
quadrant[nblock+i] = 0;
847
if (verb >= 4) VPrintf0 ( " bucket sorting ...\n" );
849
/*-- Complete the initial radix sort --*/
850
for (i = 1; i <= 65536; i++) ftab[i] += ftab[i-1];
854
for (; i >= 3; i -= 4) {
855
s = (s >> 8) | (block[i] << 8);
859
s = (s >> 8) | (block[i-1] << 8);
863
s = (s >> 8) | (block[i-2] << 8);
867
s = (s >> 8) | (block[i-3] << 8);
872
for (; i >= 0; i--) {
873
s = (s >> 8) | (block[i] << 8);
880
Now ftab contains the first loc of every small bucket.
881
Calculate the running order, from smallest to largest
884
for (i = 0; i <= 255; i++) {
892
do h = 3 * h + 1; while (h <= 256);
895
for (i = h; i <= 255; i++) {
896
vv = runningOrder[i];
898
while ( BIGFREQ(runningOrder[j-h]) > BIGFREQ(vv) ) {
899
runningOrder[j] = runningOrder[j-h];
901
if (j <= (h - 1)) goto zero;
904
runningOrder[j] = vv;
910
The main sorting loop.
915
for (i = 0; i <= 255; i++) {
918
Process big buckets, starting with the least full.
919
Basically this is a 3-step process in which we call
920
mainQSort3 to sort the small buckets [ss, j], but
921
also make a big effort to avoid the calls if we can.
923
ss = runningOrder[i];
927
Complete the big bucket [ss] by quicksorting
928
any unsorted small buckets [ss, j], for j != ss.
929
Hopefully previous pointer-scanning phases have already
930
completed many of the small buckets [ss, j], so
931
we don't have to sort them at all.
933
for (j = 0; j <= 255; j++) {
936
if ( ! (ftab[sb] & SETMASK) ) {
937
Int32 lo = ftab[sb] & CLEARMASK;
938
Int32 hi = (ftab[sb+1] & CLEARMASK) - 1;
941
VPrintf4 ( " qsort [0x%x, 0x%x] "
943
ss, j, numQSorted, hi - lo + 1 );
945
ptr, block, quadrant, nblock,
946
lo, hi, BZ_N_RADIX, budget
948
numQSorted += (hi - lo + 1);
949
if (*budget < 0) return;
956
AssertH ( !bigDone[ss], 1006 );
960
Now scan this big bucket [ss] so as to synthesise the
961
sorted order for small buckets [t, ss] for all t,
962
including, magically, the bucket [ss,ss] too.
963
This will avoid doing Real Work in subsequent Step 1's.
966
for (j = 0; j <= 255; j++) {
967
copyStart[j] = ftab[(j << 8) + ss] & CLEARMASK;
968
copyEnd [j] = (ftab[(j << 8) + ss + 1] & CLEARMASK) - 1;
970
for (j = ftab[ss << 8] & CLEARMASK; j < copyStart[ss]; j++) {
971
k = ptr[j]-1; if (k < 0) k += nblock;
974
ptr[ copyStart[c1]++ ] = k;
976
for (j = (ftab[(ss+1) << 8] & CLEARMASK) - 1; j > copyEnd[ss]; j--) {
977
k = ptr[j]-1; if (k < 0) k += nblock;
980
ptr[ copyEnd[c1]-- ] = k;
984
AssertH ( copyStart[ss]-1 == copyEnd[ss], 1007 );
986
for (j = 0; j <= 255; j++) ftab[(j << 8) + ss] |= SETMASK;
990
The [ss] big bucket is now done. Record this fact,
991
and update the quadrant descriptors. Remember to
992
update quadrants in the overshoot area too, if
993
necessary. The "if (i < 255)" test merely skips
994
this updating for the last bucket processed, since
995
updating for the last bucket is pointless.
997
The quadrant array provides a way to incrementally
998
cache sort orderings, as they appear, so as to
999
make subsequent comparisons in fullGtU() complete
1000
faster. For repetitive blocks this makes a big
1001
difference (but not big enough to be able to avoid
1002
the fallback sorting mechanism, exponential radix sort).
1004
The precise meaning is: at all times:
1006
for 0 <= i < nblock and 0 <= j <= nblock
1008
if block[i] != block[j],
1010
then the relative values of quadrant[i] and
1011
quadrant[j] are meaningless.
1014
if quadrant[i] < quadrant[j]
1015
then the string starting at i lexicographically
1016
precedes the string starting at j
1018
else if quadrant[i] > quadrant[j]
1019
then the string starting at j lexicographically
1020
precedes the string starting at i
1023
the relative ordering of the strings starting
1024
at i and j has not yet been determined.
1030
Int32 bbStart = ftab[ss << 8] & CLEARMASK;
1031
Int32 bbSize = (ftab[(ss+1) << 8] & CLEARMASK) - bbStart;
1034
while ((bbSize >> shifts) > 65534) shifts++;
1036
for (j = bbSize-1; j >= 0; j--) {
1037
Int32 a2update = ptr[bbStart + j];
1038
UInt16 qVal = (UInt16)(j >> shifts);
1039
quadrant[a2update] = qVal;
1040
if (a2update < BZ_N_OVERSHOOT)
1041
quadrant[a2update + nblock] = qVal;
1043
AssertH ( ((bbSize-1) >> shifts) <= 65535, 1002 );
1049
VPrintf3 ( " %d pointers, %d sorted, %d scanned\n",
1050
nblock, numQSorted, nblock - numQSorted );
1058
/*---------------------------------------------*/
1061
arr2 exists for [0 .. nblock-1 +N_OVERSHOOT]
1062
((UChar*)arr2) [0 .. nblock-1] holds block
1063
arr1 exists for [0 .. nblock-1]
1066
((UChar*)arr2) [0 .. nblock-1] holds block
1067
All other areas of block destroyed
1068
ftab [ 0 .. 65536 ] destroyed
1069
arr1 [0 .. nblock-1] holds sorted order
1071
void BZ2_blockSort ( EState* s )
1073
UInt32* ptr = s->ptr;
1074
UChar* block = s->block;
1075
UInt32* ftab = s->ftab;
1076
Int32 nblock = s->nblock;
1077
Int32 verb = s->verbosity;
1078
Int32 wfact = s->workFactor;
1084
if (nblock < 10000) {
1085
fallbackSort ( s->arr1, s->arr2, ftab, nblock, verb );
1087
/* Calculate the location for quadrant, remembering to get
1088
the alignment right. Assumes that &(block[0]) is at least
1089
2-byte aligned -- this should be ok since block is really
1090
the first section of arr2.
1092
i = nblock+BZ_N_OVERSHOOT;
1094
quadrant = (UInt16*)(&(block[i]));
1096
/* (wfact-1) / 3 puts the default-factor-30
1097
transition point at very roughly the same place as
1098
with v0.1 and v0.9.0.
1099
Not that it particularly matters any more, since the
1100
resulting compressed stream is now the same regardless
1101
of whether or not we use the main sort or fallback sort.
1103
if (wfact < 1 ) wfact = 1;
1104
if (wfact > 100) wfact = 100;
1105
budgetInit = nblock * ((wfact-1) / 3);
1106
budget = budgetInit;
1108
mainSort ( ptr, block, quadrant, ftab, nblock, verb, &budget );
1110
VPrintf3 ( " %d work, %d block, ratio %5.2f\n",
1111
budgetInit - budget,
1113
(float)(budgetInit - budget) /
1114
(float)(nblock==0 ? 1 : nblock) );
1117
VPrintf0 ( " too repetitive; using fallback"
1118
" sorting algorithm\n" );
1119
fallbackSort ( s->arr1, s->arr2, ftab, nblock, verb );
1124
for (i = 0; i < s->nblock; i++)
1126
{ s->origPtr = i; break; };
1128
AssertH( s->origPtr != -1, 1003 );
1132
/*-------------------------------------------------------------*/
1133
/*--- end blocksort.c ---*/
1134
/*-------------------------------------------------------------*/