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.
70 #include "bzlib_private.h"
72 /*---------------------------------------------*/
73 /*--- Fallback O(N log(N)^2) sorting ---*/
74 /*--- algorithm, for repetitive blocks ---*/
75 /*---------------------------------------------*/
77 /*---------------------------------------------*/
80 void fallbackSimpleSort ( UInt32* fmap,
91 for ( i = hi-4; i >= lo; i-- ) {
94 for ( j = i+4; j <= hi && ec_tmp > eclass[fmap[j]]; j += 4 )
100 for ( i = hi-1; i >= lo; i-- ) {
102 ec_tmp = eclass[tmp];
103 for ( j = i+1; j <= hi && ec_tmp > eclass[fmap[j]]; j++ )
110 /*---------------------------------------------*/
111 #define fswap(zz1, zz2) \
112 { Int32 zztmp = zz1; zz1 = zz2; zz2 = zztmp; }
114 #define fvswap(zzp1, zzp2, zzn) \
116 Int32 yyp1 = (zzp1); \
117 Int32 yyp2 = (zzp2); \
120 fswap(fmap[yyp1], fmap[yyp2]); \
121 yyp1++; yyp2++; yyn--; \
126 #define fmin(a,b) ((a) < (b)) ? (a) : (b)
128 #define fpush(lz,hz) { stackLo[sp] = lz; \
132 #define fpop(lz,hz) { sp--; \
136 #define FALLBACK_QSORT_SMALL_THRESH 10
137 #define FALLBACK_QSORT_STACK_SIZE 100
141 void fallbackQSort3 ( UInt32* fmap,
146 Int32 unLo, unHi, ltLo, gtHi, n, m;
149 Int32 stackLo[FALLBACK_QSORT_STACK_SIZE];
150 Int32 stackHi[FALLBACK_QSORT_STACK_SIZE];
155 fpush ( loSt, hiSt );
159 AssertH ( sp < FALLBACK_QSORT_STACK_SIZE, 1004 );
162 if (hi - lo < FALLBACK_QSORT_SMALL_THRESH) {
163 fallbackSimpleSort ( fmap, eclass, lo, hi );
167 /* Random partitioning. Median of 3 sometimes fails to
168 avoid bad cases. Median of 9 seems to help but
169 looks rather expensive. This too seems to work but
170 is cheaper. Guidance for the magic constants
171 7621 and 32768 is taken from Sedgewick's algorithms
174 r = ((r * 7621) + 1) % 32768;
176 if (r3 == 0) med = eclass[fmap[lo]]; else
177 if (r3 == 1) med = eclass[fmap[(lo+hi)>>1]]; else
178 med = eclass[fmap[hi]];
185 if (unLo > unHi) break;
186 n = (Int32)eclass[fmap[unLo]] - (Int32)med;
188 fswap(fmap[unLo], fmap[ltLo]);
196 if (unLo > unHi) break;
197 n = (Int32)eclass[fmap[unHi]] - (Int32)med;
199 fswap(fmap[unHi], fmap[gtHi]);
206 if (unLo > unHi) break;
207 fswap(fmap[unLo], fmap[unHi]); unLo++; unHi--;
210 AssertD ( unHi == unLo-1, "fallbackQSort3(2)" );
212 if (gtHi < ltLo) continue;
214 n = fmin(ltLo-lo, unLo-ltLo); fvswap(lo, unLo-n, n);
215 m = fmin(hi-gtHi, gtHi-unHi); fvswap(unLo, hi-m+1, m);
217 n = lo + unLo - ltLo - 1;
218 m = hi - (gtHi - unHi) + 1;
220 if (n - lo > hi - m) {
235 #undef FALLBACK_QSORT_SMALL_THRESH
236 #undef FALLBACK_QSORT_STACK_SIZE
239 /*---------------------------------------------*/
242 eclass exists for [0 .. nblock-1]
243 ((UChar*)eclass) [0 .. nblock-1] holds block
244 ptr exists for [0 .. nblock-1]
247 ((UChar*)eclass) [0 .. nblock-1] holds block
248 All other areas of eclass destroyed
249 fmap [0 .. nblock-1] holds sorted order
250 bhtab [ 0 .. 2+(nblock/32) ] destroyed
253 #define SET_BH(zz) bhtab[(zz) >> 5] |= (1 << ((zz) & 31))
254 #define CLEAR_BH(zz) bhtab[(zz) >> 5] &= ~(1 << ((zz) & 31))
255 #define ISSET_BH(zz) (bhtab[(zz) >> 5] & (1 << ((zz) & 31)))
256 #define WORD_BH(zz) bhtab[(zz) >> 5]
257 #define UNALIGNED_BH(zz) ((zz) & 0x01f)
260 void fallbackSort ( UInt32* fmap,
268 Int32 H, i, j, k, l, r, cc, cc1;
271 UChar* eclass8 = (UChar*)eclass;
274 Initial 1-char radix sort to generate
275 initial fmap and initial BH bits.
278 VPrintf0 ( " bucket sorting ...\n" );
279 for (i = 0; i < 257; i++) ftab[i] = 0;
280 for (i = 0; i < nblock; i++) ftab[eclass8[i]]++;
281 for (i = 0; i < 256; i++) ftabCopy[i] = ftab[i];
282 for (i = 1; i < 257; i++) ftab[i] += ftab[i-1];
284 for (i = 0; i < nblock; i++) {
291 nBhtab = 2 + (nblock / 32);
292 for (i = 0; i < nBhtab; i++) bhtab[i] = 0;
293 for (i = 0; i < 256; i++) SET_BH(ftab[i]);
296 Inductively refine the buckets. Kind-of an
297 "exponential radix sort" (!), inspired by the
298 Manber-Myers suffix array construction algorithm.
301 /*-- set sentinel bits for block-end detection --*/
302 for (i = 0; i < 32; i++) {
303 SET_BH(nblock + 2*i);
304 CLEAR_BH(nblock + 2*i + 1);
307 /*-- the log(N) loop --*/
312 VPrintf1 ( " depth %6d has ", H );
315 for (i = 0; i < nblock; i++) {
316 if (ISSET_BH(i)) j = i;
317 k = fmap[i] - H; if (k < 0) k += nblock;
325 /*-- find the next non-singleton bucket --*/
327 while (ISSET_BH(k) && UNALIGNED_BH(k)) k++;
329 while (WORD_BH(k) == 0xffffffff) k += 32;
330 while (ISSET_BH(k)) k++;
333 if (l >= nblock) break;
334 while (!ISSET_BH(k) && UNALIGNED_BH(k)) k++;
336 while (WORD_BH(k) == 0x00000000) k += 32;
337 while (!ISSET_BH(k)) k++;
340 if (r >= nblock) break;
342 /*-- now [l, r] bracket current bucket --*/
344 nNotDone += (r - l + 1);
345 fallbackQSort3 ( fmap, eclass, l, r );
347 /*-- scan bucket and generate header bits-- */
349 for (i = l; i <= r; i++) {
350 cc1 = eclass[fmap[i]];
351 if (cc != cc1) { SET_BH(i); cc = cc1; };
357 VPrintf1 ( "%6d unresolved strings\n", nNotDone );
360 if (H > nblock || nNotDone == 0) break;
364 Reconstruct the original block in
365 eclass8 [0 .. nblock-1], since the
366 previous phase destroyed it.
369 VPrintf0 ( " reconstructing block ...\n" );
371 for (i = 0; i < nblock; i++) {
372 while (ftabCopy[j] == 0) j++;
374 eclass8[fmap[i]] = (UChar)j;
376 AssertH ( j < 256, 1005 );
386 /*---------------------------------------------*/
387 /*--- The main, O(N^2 log(N)) sorting ---*/
388 /*--- algorithm. Faster for "normal" ---*/
389 /*--- non-repetitive blocks. ---*/
390 /*---------------------------------------------*/
392 /*---------------------------------------------*/
395 Bool mainGtU ( UInt32 i1,
406 AssertD ( i1 != i2, "mainGtU" );
408 c1 = block[i1]; c2 = block[i2];
409 if (c1 != c2) return (c1 > c2);
412 c1 = block[i1]; c2 = block[i2];
413 if (c1 != c2) return (c1 > c2);
416 c1 = block[i1]; c2 = block[i2];
417 if (c1 != c2) return (c1 > c2);
420 c1 = block[i1]; c2 = block[i2];
421 if (c1 != c2) return (c1 > c2);
424 c1 = block[i1]; c2 = block[i2];
425 if (c1 != c2) return (c1 > c2);
428 c1 = block[i1]; c2 = block[i2];
429 if (c1 != c2) return (c1 > c2);
432 c1 = block[i1]; c2 = block[i2];
433 if (c1 != c2) return (c1 > c2);
436 c1 = block[i1]; c2 = block[i2];
437 if (c1 != c2) return (c1 > c2);
440 c1 = block[i1]; c2 = block[i2];
441 if (c1 != c2) return (c1 > c2);
444 c1 = block[i1]; c2 = block[i2];
445 if (c1 != c2) return (c1 > c2);
448 c1 = block[i1]; c2 = block[i2];
449 if (c1 != c2) return (c1 > c2);
452 c1 = block[i1]; c2 = block[i2];
453 if (c1 != c2) return (c1 > c2);
460 c1 = block[i1]; c2 = block[i2];
461 if (c1 != c2) return (c1 > c2);
462 s1 = quadrant[i1]; s2 = quadrant[i2];
463 if (s1 != s2) return (s1 > s2);
466 c1 = block[i1]; c2 = block[i2];
467 if (c1 != c2) return (c1 > c2);
468 s1 = quadrant[i1]; s2 = quadrant[i2];
469 if (s1 != s2) return (s1 > s2);
472 c1 = block[i1]; c2 = block[i2];
473 if (c1 != c2) return (c1 > c2);
474 s1 = quadrant[i1]; s2 = quadrant[i2];
475 if (s1 != s2) return (s1 > s2);
478 c1 = block[i1]; c2 = block[i2];
479 if (c1 != c2) return (c1 > c2);
480 s1 = quadrant[i1]; s2 = quadrant[i2];
481 if (s1 != s2) return (s1 > s2);
484 c1 = block[i1]; c2 = block[i2];
485 if (c1 != c2) return (c1 > c2);
486 s1 = quadrant[i1]; s2 = quadrant[i2];
487 if (s1 != s2) return (s1 > s2);
490 c1 = block[i1]; c2 = block[i2];
491 if (c1 != c2) return (c1 > c2);
492 s1 = quadrant[i1]; s2 = quadrant[i2];
493 if (s1 != s2) return (s1 > s2);
496 c1 = block[i1]; c2 = block[i2];
497 if (c1 != c2) return (c1 > c2);
498 s1 = quadrant[i1]; s2 = quadrant[i2];
499 if (s1 != s2) return (s1 > s2);
502 c1 = block[i1]; c2 = block[i2];
503 if (c1 != c2) return (c1 > c2);
504 s1 = quadrant[i1]; s2 = quadrant[i2];
505 if (s1 != s2) return (s1 > s2);
508 if (i1 >= nblock) i1 -= nblock;
509 if (i2 >= nblock) i2 -= nblock;
520 /*---------------------------------------------*/
522 Knuth's increments seem to work better
523 than Incerpi-Sedgewick here. Possibly
524 because the number of elems to sort is
525 usually small, typically <= 20.
528 Int32 incs[14] = { 1, 4, 13, 40, 121, 364, 1093, 3280,
529 9841, 29524, 88573, 265720,
533 void mainSimpleSort ( UInt32* ptr,
542 Int32 i, j, h, bigN, hp;
546 if (bigN < 2) return;
549 while (incs[hp] < bigN) hp++;
552 for (; hp >= 0; hp--) {
563 ptr[j-h]+d, v+d, block, quadrant, nblock, budget
567 if (j <= (lo + h - 1)) break;
577 ptr[j-h]+d, v+d, block, quadrant, nblock, budget
581 if (j <= (lo + h - 1)) break;
591 ptr[j-h]+d, v+d, block, quadrant, nblock, budget
595 if (j <= (lo + h - 1)) break;
600 if (*budget < 0) return;
606 /*---------------------------------------------*/
608 The following is an implementation of
609 an elegant 3-way quicksort for strings,
610 described in a paper "Fast Algorithms for
611 Sorting and Searching Strings", by Robert
612 Sedgewick and Jon L. Bentley.
615 #define mswap(zz1, zz2) \
616 { Int32 zztmp = zz1; zz1 = zz2; zz2 = zztmp; }
618 #define mvswap(zzp1, zzp2, zzn) \
620 Int32 yyp1 = (zzp1); \
621 Int32 yyp2 = (zzp2); \
624 mswap(ptr[yyp1], ptr[yyp2]); \
625 yyp1++; yyp2++; yyn--; \
631 UChar mmed3 ( UChar a, UChar b, UChar c )
634 if (a > b) { t = a; a = b; b = t; };
642 #define mmin(a,b) ((a) < (b)) ? (a) : (b)
644 #define mpush(lz,hz,dz) { stackLo[sp] = lz; \
649 #define mpop(lz,hz,dz) { sp--; \
655 #define mnextsize(az) (nextHi[az]-nextLo[az])
657 #define mnextswap(az,bz) \
659 tz = nextLo[az]; nextLo[az] = nextLo[bz]; nextLo[bz] = tz; \
660 tz = nextHi[az]; nextHi[az] = nextHi[bz]; nextHi[bz] = tz; \
661 tz = nextD [az]; nextD [az] = nextD [bz]; nextD [bz] = tz; }
664 #define MAIN_QSORT_SMALL_THRESH 20
665 #define MAIN_QSORT_DEPTH_THRESH (BZ_N_RADIX + BZ_N_QSORT)
666 #define MAIN_QSORT_STACK_SIZE 100
669 void mainQSort3 ( UInt32* ptr,
678 Int32 unLo, unHi, ltLo, gtHi, n, m, med;
681 Int32 stackLo[MAIN_QSORT_STACK_SIZE];
682 Int32 stackHi[MAIN_QSORT_STACK_SIZE];
683 Int32 stackD [MAIN_QSORT_STACK_SIZE];
690 mpush ( loSt, hiSt, dSt );
694 AssertH ( sp < MAIN_QSORT_STACK_SIZE, 1001 );
697 if (hi - lo < MAIN_QSORT_SMALL_THRESH ||
698 d > MAIN_QSORT_DEPTH_THRESH) {
699 mainSimpleSort ( ptr, block, quadrant, nblock, lo, hi, d, budget );
700 if (*budget < 0) return;
705 mmed3 ( block[ptr[ lo ]+d],
707 block[ptr[ (lo+hi)>>1 ]+d] );
714 if (unLo > unHi) break;
715 n = ((Int32)block[ptr[unLo]+d]) - med;
717 mswap(ptr[unLo], ptr[ltLo]);
718 ltLo++; unLo++; continue;
724 if (unLo > unHi) break;
725 n = ((Int32)block[ptr[unHi]+d]) - med;
727 mswap(ptr[unHi], ptr[gtHi]);
728 gtHi--; unHi--; continue;
733 if (unLo > unHi) break;
734 mswap(ptr[unLo], ptr[unHi]); unLo++; unHi--;
737 AssertD ( unHi == unLo-1, "mainQSort3(2)" );
744 n = mmin(ltLo-lo, unLo-ltLo); mvswap(lo, unLo-n, n);
745 m = mmin(hi-gtHi, gtHi-unHi); mvswap(unLo, hi-m+1, m);
747 n = lo + unLo - ltLo - 1;
748 m = hi - (gtHi - unHi) + 1;
750 nextLo[0] = lo; nextHi[0] = n; nextD[0] = d;
751 nextLo[1] = m; nextHi[1] = hi; nextD[1] = d;
752 nextLo[2] = n+1; nextHi[2] = m-1; nextD[2] = d+1;
754 if (mnextsize(0) < mnextsize(1)) mnextswap(0,1);
755 if (mnextsize(1) < mnextsize(2)) mnextswap(1,2);
756 if (mnextsize(0) < mnextsize(1)) mnextswap(0,1);
758 AssertD (mnextsize(0) >= mnextsize(1), "mainQSort3(8)" );
759 AssertD (mnextsize(1) >= mnextsize(2), "mainQSort3(9)" );
761 mpush (nextLo[0], nextHi[0], nextD[0]);
762 mpush (nextLo[1], nextHi[1], nextD[1]);
763 mpush (nextLo[2], nextHi[2], nextD[2]);
774 #undef MAIN_QSORT_SMALL_THRESH
775 #undef MAIN_QSORT_DEPTH_THRESH
776 #undef MAIN_QSORT_STACK_SIZE
779 /*---------------------------------------------*/
782 block32 exists for [0 .. nblock-1 +N_OVERSHOOT]
783 ((UChar*)block32) [0 .. nblock-1] holds block
784 ptr exists for [0 .. nblock-1]
787 ((UChar*)block32) [0 .. nblock-1] holds block
788 All other areas of block32 destroyed
789 ftab [0 .. 65536 ] destroyed
790 ptr [0 .. nblock-1] holds sorted order
791 if (*budget < 0), sorting was abandoned
794 #define BIGFREQ(b) (ftab[((b)+1) << 8] - ftab[(b) << 8])
795 #define SETMASK (1 << 21)
796 #define CLEARMASK (~(SETMASK))
799 void mainSort ( UInt32* ptr,
807 Int32 i, j, k, ss, sb;
808 Int32 runningOrder[256];
810 Int32 copyStart[256];
815 if (verb >= 4) VPrintf0 ( " main sort initialise ...\n" );
817 /*-- set up the 2-byte frequency table --*/
818 for (i = 65536; i >= 0; i--) ftab[i] = 0;
822 for (; i >= 3; i -= 4) {
824 j = (j >> 8) | ( ((UInt16)block[i]) << 8);
827 j = (j >> 8) | ( ((UInt16)block[i-1]) << 8);
830 j = (j >> 8) | ( ((UInt16)block[i-2]) << 8);
833 j = (j >> 8) | ( ((UInt16)block[i-3]) << 8);
836 for (; i >= 0; i--) {
838 j = (j >> 8) | ( ((UInt16)block[i]) << 8);
842 /*-- (emphasises close relationship of block & quadrant) --*/
843 for (i = 0; i < BZ_N_OVERSHOOT; i++) {
844 block [nblock+i] = block[i];
845 quadrant[nblock+i] = 0;
848 if (verb >= 4) VPrintf0 ( " bucket sorting ...\n" );
850 /*-- Complete the initial radix sort --*/
851 for (i = 1; i <= 65536; i++) ftab[i] += ftab[i-1];
855 for (; i >= 3; i -= 4) {
856 s = (s >> 8) | (block[i] << 8);
860 s = (s >> 8) | (block[i-1] << 8);
864 s = (s >> 8) | (block[i-2] << 8);
868 s = (s >> 8) | (block[i-3] << 8);
873 for (; i >= 0; i--) {
874 s = (s >> 8) | (block[i] << 8);
881 Now ftab contains the first loc of every small bucket.
882 Calculate the running order, from smallest to largest
885 for (i = 0; i <= 255; i++) {
893 do h = 3 * h + 1; while (h <= 256);
896 for (i = h; i <= 255; i++) {
897 vv = runningOrder[i];
899 while ( BIGFREQ(runningOrder[j-h]) > BIGFREQ(vv) ) {
900 runningOrder[j] = runningOrder[j-h];
902 if (j <= (h - 1)) goto zero;
905 runningOrder[j] = vv;
911 The main sorting loop.
916 for (i = 0; i <= 255; i++) {
919 Process big buckets, starting with the least full.
920 Basically this is a 3-step process in which we call
921 mainQSort3 to sort the small buckets [ss, j], but
922 also make a big effort to avoid the calls if we can.
924 ss = runningOrder[i];
928 Complete the big bucket [ss] by quicksorting
929 any unsorted small buckets [ss, j], for j != ss.
930 Hopefully previous pointer-scanning phases have already
931 completed many of the small buckets [ss, j], so
932 we don't have to sort them at all.
934 for (j = 0; j <= 255; j++) {
937 if ( ! (ftab[sb] & SETMASK) ) {
938 Int32 lo = ftab[sb] & CLEARMASK;
939 Int32 hi = (ftab[sb+1] & CLEARMASK) - 1;
942 VPrintf4 ( " qsort [0x%x, 0x%x] "
944 ss, j, numQSorted, hi - lo + 1 );
946 ptr, block, quadrant, nblock,
947 lo, hi, BZ_N_RADIX, budget
949 numQSorted += (hi - lo + 1);
950 if (*budget < 0) return;
957 AssertH ( !bigDone[ss], 1006 );
961 Now scan this big bucket [ss] so as to synthesise the
962 sorted order for small buckets [t, ss] for all t,
963 including, magically, the bucket [ss,ss] too.
964 This will avoid doing Real Work in subsequent Step 1's.
967 for (j = 0; j <= 255; j++) {
968 copyStart[j] = ftab[(j << 8) + ss] & CLEARMASK;
969 copyEnd [j] = (ftab[(j << 8) + ss + 1] & CLEARMASK) - 1;
971 for (j = ftab[ss << 8] & CLEARMASK; j < copyStart[ss]; j++) {
972 k = ptr[j]-1; if (k < 0) k += nblock;
975 ptr[ copyStart[c1]++ ] = k;
977 for (j = (ftab[(ss+1) << 8] & CLEARMASK) - 1; j > copyEnd[ss]; j--) {
978 k = ptr[j]-1; if (k < 0) k += nblock;
981 ptr[ copyEnd[c1]-- ] = k;
985 AssertH ( copyStart[ss]-1 == copyEnd[ss], 1007 );
987 for (j = 0; j <= 255; j++) ftab[(j << 8) + ss] |= SETMASK;
991 The [ss] big bucket is now done. Record this fact,
992 and update the quadrant descriptors. Remember to
993 update quadrants in the overshoot area too, if
994 necessary. The "if (i < 255)" test merely skips
995 this updating for the last bucket processed, since
996 updating for the last bucket is pointless.
998 The quadrant array provides a way to incrementally
999 cache sort orderings, as they appear, so as to
1000 make subsequent comparisons in fullGtU() complete
1001 faster. For repetitive blocks this makes a big
1002 difference (but not big enough to be able to avoid
1003 the fallback sorting mechanism, exponential radix sort).
1005 The precise meaning is: at all times:
1007 for 0 <= i < nblock and 0 <= j <= nblock
1009 if block[i] != block[j],
1011 then the relative values of quadrant[i] and
1012 quadrant[j] are meaningless.
1015 if quadrant[i] < quadrant[j]
1016 then the string starting at i lexicographically
1017 precedes the string starting at j
1019 else if quadrant[i] > quadrant[j]
1020 then the string starting at j lexicographically
1021 precedes the string starting at i
1024 the relative ordering of the strings starting
1025 at i and j has not yet been determined.
1031 Int32 bbStart = ftab[ss << 8] & CLEARMASK;
1032 Int32 bbSize = (ftab[(ss+1) << 8] & CLEARMASK) - bbStart;
1035 while ((bbSize >> shifts) > 65534) shifts++;
1037 for (j = bbSize-1; j >= 0; j--) {
1038 Int32 a2update = ptr[bbStart + j];
1039 UInt16 qVal = (UInt16)(j >> shifts);
1040 quadrant[a2update] = qVal;
1041 if (a2update < BZ_N_OVERSHOOT)
1042 quadrant[a2update + nblock] = qVal;
1044 AssertH ( ((bbSize-1) >> shifts) <= 65535, 1002 );
1050 VPrintf3 ( " %d pointers, %d sorted, %d scanned\n",
1051 nblock, numQSorted, nblock - numQSorted );
1059 /*---------------------------------------------*/
1062 arr2 exists for [0 .. nblock-1 +N_OVERSHOOT]
1063 ((UChar*)arr2) [0 .. nblock-1] holds block
1064 arr1 exists for [0 .. nblock-1]
1067 ((UChar*)arr2) [0 .. nblock-1] holds block
1068 All other areas of block destroyed
1069 ftab [ 0 .. 65536 ] destroyed
1070 arr1 [0 .. nblock-1] holds sorted order
1072 void BZ2_blockSort ( EState* s )
1074 UInt32* ptr = s->ptr;
1075 UChar* block = s->block;
1076 UInt32* ftab = s->ftab;
1077 Int32 nblock = s->nblock;
1078 Int32 verb = s->verbosity;
1079 Int32 wfact = s->workFactor;
1085 if (nblock < 10000) {
1086 fallbackSort ( s->arr1, s->arr2, ftab, nblock, verb );
1088 /* Calculate the location for quadrant, remembering to get
1089 the alignment right. Assumes that &(block[0]) is at least
1090 2-byte aligned -- this should be ok since block is really
1091 the first section of arr2.
1093 i = nblock+BZ_N_OVERSHOOT;
1095 quadrant = (UInt16*)(&(block[i]));
1097 /* (wfact-1) / 3 puts the default-factor-30
1098 transition point at very roughly the same place as
1099 with v0.1 and v0.9.0.
1100 Not that it particularly matters any more, since the
1101 resulting compressed stream is now the same regardless
1102 of whether or not we use the main sort or fallback sort.
1104 if (wfact < 1 ) wfact = 1;
1105 if (wfact > 100) wfact = 100;
1106 budgetInit = nblock * ((wfact-1) / 3);
1107 budget = budgetInit;
1109 mainSort ( ptr, block, quadrant, ftab, nblock, verb, &budget );
1111 VPrintf3 ( " %d work, %d block, ratio %5.2f\n",
1112 budgetInit - budget,
1114 (float)(budgetInit - budget) /
1115 (float)(nblock==0 ? 1 : nblock) );
1118 VPrintf0 ( " too repetitive; using fallback"
1119 " sorting algorithm\n" );
1120 fallbackSort ( s->arr1, s->arr2, ftab, nblock, verb );
1125 for (i = 0; i < s->nblock; i++)
1127 { s->origPtr = i; break; };
1129 AssertH( s->origPtr != -1, 1003 );
1133 /*-------------------------------------------------------------*/
1134 /*--- end blocksort.c ---*/
1135 /*-------------------------------------------------------------*/