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1094 lines (938 loc) · 30 KB
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/*-------------------------------------------------------------*/
/*--- Block sorting machinery ---*/
/*--- blocksort.c ---*/
/*-------------------------------------------------------------*/
/* ------------------------------------------------------------------
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 <jseward@bzip.org>
Please read the WARNING, DISCLAIMER and PATENTS sections in the
README file.
This program is released under the terms of the license contained
in the file LICENSE.
------------------------------------------------------------------ */
#include "bzlib_private.h"
/*---------------------------------------------*/
/*--- Fallback O(N log(N)^2) sorting ---*/
/*--- algorithm, for repetitive blocks ---*/
/*---------------------------------------------*/
/*---------------------------------------------*/
static
__inline__
void fallbackSimpleSort ( UInt32* fmap,
UInt32* eclass,
Int32 lo,
Int32 hi )
{
Int32 i, j, tmp;
UInt32 ec_tmp;
if (lo == hi) return;
if (hi - lo > 3) {
for ( i = hi-4; i >= lo; i-- ) {
tmp = fmap[i];
ec_tmp = eclass[tmp];
for ( j = i+4; j <= hi && ec_tmp > eclass[fmap[j]]; j += 4 )
fmap[j-4] = fmap[j];
fmap[j-4] = tmp;
}
}
for ( i = hi-1; i >= lo; i-- ) {
tmp = fmap[i];
ec_tmp = eclass[tmp];
for ( j = i+1; j <= hi && ec_tmp > eclass[fmap[j]]; j++ )
fmap[j-1] = fmap[j];
fmap[j-1] = tmp;
}
}
/*---------------------------------------------*/
#define fswap(zz1, zz2) \
{ Int32 zztmp = zz1; zz1 = zz2; zz2 = zztmp; }
#define fvswap(zzp1, zzp2, zzn) \
{ \
Int32 yyp1 = (zzp1); \
Int32 yyp2 = (zzp2); \
Int32 yyn = (zzn); \
while (yyn > 0) { \
fswap(fmap[yyp1], fmap[yyp2]); \
yyp1++; yyp2++; yyn--; \
} \
}
#define fmin(a,b) ((a) < (b)) ? (a) : (b)
#define fpush(lz,hz) { stackLo[sp] = lz; \
stackHi[sp] = hz; \
sp++; }
#define fpop(lz,hz) { sp--; \
lz = stackLo[sp]; \
hz = stackHi[sp]; }
#define FALLBACK_QSORT_SMALL_THRESH 10
#define FALLBACK_QSORT_STACK_SIZE 100
static
void fallbackQSort3 ( UInt32* fmap,
UInt32* eclass,
Int32 loSt,
Int32 hiSt )
{
Int32 unLo, unHi, ltLo, gtHi, n, m;
Int32 sp, lo, hi;
UInt32 med, r, r3;
Int32 stackLo[FALLBACK_QSORT_STACK_SIZE];
Int32 stackHi[FALLBACK_QSORT_STACK_SIZE];
r = 0;
sp = 0;
fpush ( loSt, hiSt );
while (sp > 0) {
AssertH ( sp < FALLBACK_QSORT_STACK_SIZE - 1, 1004 );
fpop ( lo, hi );
if (hi - lo < FALLBACK_QSORT_SMALL_THRESH) {
fallbackSimpleSort ( fmap, eclass, lo, hi );
continue;
}
/* Random partitioning. Median of 3 sometimes fails to
avoid bad cases. Median of 9 seems to help but
looks rather expensive. This too seems to work but
is cheaper. Guidance for the magic constants
7621 and 32768 is taken from Sedgewick's algorithms
book, chapter 35.
*/
r = ((r * 7621) + 1) % 32768;
r3 = r % 3;
if (r3 == 0) med = eclass[fmap[lo]]; else
if (r3 == 1) med = eclass[fmap[(lo+hi)>>1]]; else
med = eclass[fmap[hi]];
unLo = ltLo = lo;
unHi = gtHi = hi;
while (1) {
while (1) {
if (unLo > unHi) break;
n = (Int32)eclass[fmap[unLo]] - (Int32)med;
if (n == 0) {
fswap(fmap[unLo], fmap[ltLo]);
ltLo++; unLo++;
continue;
};
if (n > 0) break;
unLo++;
}
while (1) {
if (unLo > unHi) break;
n = (Int32)eclass[fmap[unHi]] - (Int32)med;
if (n == 0) {
fswap(fmap[unHi], fmap[gtHi]);
gtHi--; unHi--;
continue;
};
if (n < 0) break;
unHi--;
}
if (unLo > unHi) break;
fswap(fmap[unLo], fmap[unHi]); unLo++; unHi--;
}
AssertD ( unHi == unLo-1, "fallbackQSort3(2)" );
if (gtHi < ltLo) continue;
n = fmin(ltLo-lo, unLo-ltLo); fvswap(lo, unLo-n, n);
m = fmin(hi-gtHi, gtHi-unHi); fvswap(unLo, hi-m+1, m);
n = lo + unLo - ltLo - 1;
m = hi - (gtHi - unHi) + 1;
if (n - lo > hi - m) {
fpush ( lo, n );
fpush ( m, hi );
} else {
fpush ( m, hi );
fpush ( lo, n );
}
}
}
#undef fmin
#undef fpush
#undef fpop
#undef fswap
#undef fvswap
#undef FALLBACK_QSORT_SMALL_THRESH
#undef FALLBACK_QSORT_STACK_SIZE
/*---------------------------------------------*/
/* Pre:
nblock > 0
eclass exists for [0 .. nblock-1]
((UChar*)eclass) [0 .. nblock-1] holds block
ptr exists for [0 .. nblock-1]
Post:
((UChar*)eclass) [0 .. nblock-1] holds block
All other areas of eclass destroyed
fmap [0 .. nblock-1] holds sorted order
bhtab [ 0 .. 2+(nblock/32) ] destroyed
*/
#define SET_BH(zz) bhtab[(zz) >> 5] |= (1 << ((zz) & 31))
#define CLEAR_BH(zz) bhtab[(zz) >> 5] &= ~(1 << ((zz) & 31))
#define ISSET_BH(zz) (bhtab[(zz) >> 5] & (1 << ((zz) & 31)))
#define WORD_BH(zz) bhtab[(zz) >> 5]
#define UNALIGNED_BH(zz) ((zz) & 0x01f)
static
void fallbackSort ( UInt32* fmap,
UInt32* eclass,
UInt32* bhtab,
Int32 nblock,
Int32 verb )
{
Int32 ftab[257];
Int32 ftabCopy[256];
Int32 H, i, j, k, l, r, cc, cc1;
Int32 nNotDone;
Int32 nBhtab;
UChar* eclass8 = (UChar*)eclass;
/*--
Initial 1-char radix sort to generate
initial fmap and initial BH bits.
--*/
if (verb >= 4)
VPrintf0 ( " bucket sorting ...\n" );
for (i = 0; i < 257; i++) ftab[i] = 0;
for (i = 0; i < nblock; i++) ftab[eclass8[i]]++;
for (i = 0; i < 256; i++) ftabCopy[i] = ftab[i];
for (i = 1; i < 257; i++) ftab[i] += ftab[i-1];
for (i = 0; i < nblock; i++) {
j = eclass8[i];
k = ftab[j] - 1;
ftab[j] = k;
fmap[k] = i;
}
nBhtab = 2 + (nblock / 32);
for (i = 0; i < nBhtab; i++) bhtab[i] = 0;
for (i = 0; i < 256; i++) SET_BH(ftab[i]);
/*--
Inductively refine the buckets. Kind-of an
"exponential radix sort" (!), inspired by the
Manber-Myers suffix array construction algorithm.
--*/
/*-- set sentinel bits for block-end detection --*/
for (i = 0; i < 32; i++) {
SET_BH(nblock + 2*i);
CLEAR_BH(nblock + 2*i + 1);
}
/*-- the log(N) loop --*/
H = 1;
while (1) {
if (verb >= 4)
VPrintf1 ( " depth %6d has ", H );
j = 0;
for (i = 0; i < nblock; i++) {
if (ISSET_BH(i)) j = i;
k = fmap[i] - H; if (k < 0) k += nblock;
eclass[k] = j;
}
nNotDone = 0;
r = -1;
while (1) {
/*-- find the next non-singleton bucket --*/
k = r + 1;
while (ISSET_BH(k) && UNALIGNED_BH(k)) k++;
if (ISSET_BH(k)) {
while (WORD_BH(k) == 0xffffffff) k += 32;
while (ISSET_BH(k)) k++;
}
l = k - 1;
if (l >= nblock) break;
while (!ISSET_BH(k) && UNALIGNED_BH(k)) k++;
if (!ISSET_BH(k)) {
while (WORD_BH(k) == 0x00000000) k += 32;
while (!ISSET_BH(k)) k++;
}
r = k - 1;
if (r >= nblock) break;
/*-- now [l, r] bracket current bucket --*/
if (r > l) {
nNotDone += (r - l + 1);
fallbackQSort3 ( fmap, eclass, l, r );
/*-- scan bucket and generate header bits-- */
cc = -1;
for (i = l; i <= r; i++) {
cc1 = eclass[fmap[i]];
if (cc != cc1) { SET_BH(i); cc = cc1; };
}
}
}
if (verb >= 4)
VPrintf1 ( "%6d unresolved strings\n", nNotDone );
H *= 2;
if (H > nblock || nNotDone == 0) break;
}
/*--
Reconstruct the original block in
eclass8 [0 .. nblock-1], since the
previous phase destroyed it.
--*/
if (verb >= 4)
VPrintf0 ( " reconstructing block ...\n" );
j = 0;
for (i = 0; i < nblock; i++) {
while (ftabCopy[j] == 0) j++;
ftabCopy[j]--;
eclass8[fmap[i]] = (UChar)j;
}
AssertH ( j < 256, 1005 );
}
#undef SET_BH
#undef CLEAR_BH
#undef ISSET_BH
#undef WORD_BH
#undef UNALIGNED_BH
/*---------------------------------------------*/
/*--- The main, O(N^2 log(N)) sorting ---*/
/*--- algorithm. Faster for "normal" ---*/
/*--- non-repetitive blocks. ---*/
/*---------------------------------------------*/
/*---------------------------------------------*/
static
__inline__
Bool mainGtU ( UInt32 i1,
UInt32 i2,
UChar* block,
UInt16* quadrant,
UInt32 nblock,
Int32* budget )
{
Int32 k;
UChar c1, c2;
UInt16 s1, s2;
AssertD ( i1 != i2, "mainGtU" );
/* 1 */
c1 = block[i1]; c2 = block[i2];
if (c1 != c2) return (c1 > c2);
i1++; i2++;
/* 2 */
c1 = block[i1]; c2 = block[i2];
if (c1 != c2) return (c1 > c2);
i1++; i2++;
/* 3 */
c1 = block[i1]; c2 = block[i2];
if (c1 != c2) return (c1 > c2);
i1++; i2++;
/* 4 */
c1 = block[i1]; c2 = block[i2];
if (c1 != c2) return (c1 > c2);
i1++; i2++;
/* 5 */
c1 = block[i1]; c2 = block[i2];
if (c1 != c2) return (c1 > c2);
i1++; i2++;
/* 6 */
c1 = block[i1]; c2 = block[i2];
if (c1 != c2) return (c1 > c2);
i1++; i2++;
/* 7 */
c1 = block[i1]; c2 = block[i2];
if (c1 != c2) return (c1 > c2);
i1++; i2++;
/* 8 */
c1 = block[i1]; c2 = block[i2];
if (c1 != c2) return (c1 > c2);
i1++; i2++;
/* 9 */
c1 = block[i1]; c2 = block[i2];
if (c1 != c2) return (c1 > c2);
i1++; i2++;
/* 10 */
c1 = block[i1]; c2 = block[i2];
if (c1 != c2) return (c1 > c2);
i1++; i2++;
/* 11 */
c1 = block[i1]; c2 = block[i2];
if (c1 != c2) return (c1 > c2);
i1++; i2++;
/* 12 */
c1 = block[i1]; c2 = block[i2];
if (c1 != c2) return (c1 > c2);
i1++; i2++;
k = nblock + 8;
do {
/* 1 */
c1 = block[i1]; c2 = block[i2];
if (c1 != c2) return (c1 > c2);
s1 = quadrant[i1]; s2 = quadrant[i2];
if (s1 != s2) return (s1 > s2);
i1++; i2++;
/* 2 */
c1 = block[i1]; c2 = block[i2];
if (c1 != c2) return (c1 > c2);
s1 = quadrant[i1]; s2 = quadrant[i2];
if (s1 != s2) return (s1 > s2);
i1++; i2++;
/* 3 */
c1 = block[i1]; c2 = block[i2];
if (c1 != c2) return (c1 > c2);
s1 = quadrant[i1]; s2 = quadrant[i2];
if (s1 != s2) return (s1 > s2);
i1++; i2++;
/* 4 */
c1 = block[i1]; c2 = block[i2];
if (c1 != c2) return (c1 > c2);
s1 = quadrant[i1]; s2 = quadrant[i2];
if (s1 != s2) return (s1 > s2);
i1++; i2++;
/* 5 */
c1 = block[i1]; c2 = block[i2];
if (c1 != c2) return (c1 > c2);
s1 = quadrant[i1]; s2 = quadrant[i2];
if (s1 != s2) return (s1 > s2);
i1++; i2++;
/* 6 */
c1 = block[i1]; c2 = block[i2];
if (c1 != c2) return (c1 > c2);
s1 = quadrant[i1]; s2 = quadrant[i2];
if (s1 != s2) return (s1 > s2);
i1++; i2++;
/* 7 */
c1 = block[i1]; c2 = block[i2];
if (c1 != c2) return (c1 > c2);
s1 = quadrant[i1]; s2 = quadrant[i2];
if (s1 != s2) return (s1 > s2);
i1++; i2++;
/* 8 */
c1 = block[i1]; c2 = block[i2];
if (c1 != c2) return (c1 > c2);
s1 = quadrant[i1]; s2 = quadrant[i2];
if (s1 != s2) return (s1 > s2);
i1++; i2++;
if (i1 >= nblock) i1 -= nblock;
if (i2 >= nblock) i2 -= nblock;
k -= 8;
(*budget)--;
}
while (k >= 0);
return False;
}
/*---------------------------------------------*/
/*--
Knuth's increments seem to work better
than Incerpi-Sedgewick here. Possibly
because the number of elems to sort is
usually small, typically <= 20.
--*/
static
Int32 incs[14] = { 1, 4, 13, 40, 121, 364, 1093, 3280,
9841, 29524, 88573, 265720,
797161, 2391484 };
static
void mainSimpleSort ( UInt32* ptr,
UChar* block,
UInt16* quadrant,
Int32 nblock,
Int32 lo,
Int32 hi,
Int32 d,
Int32* budget )
{
Int32 i, j, h, bigN, hp;
UInt32 v;
bigN = hi - lo + 1;
if (bigN < 2) return;
hp = 0;
while (incs[hp] < bigN) hp++;
hp--;
for (; hp >= 0; hp--) {
h = incs[hp];
i = lo + h;
while (True) {
/*-- copy 1 --*/
if (i > hi) break;
v = ptr[i];
j = i;
while ( mainGtU (
ptr[j-h]+d, v+d, block, quadrant, nblock, budget
) ) {
ptr[j] = ptr[j-h];
j = j - h;
if (j <= (lo + h - 1)) break;
}
ptr[j] = v;
i++;
/*-- copy 2 --*/
if (i > hi) break;
v = ptr[i];
j = i;
while ( mainGtU (
ptr[j-h]+d, v+d, block, quadrant, nblock, budget
) ) {
ptr[j] = ptr[j-h];
j = j - h;
if (j <= (lo + h - 1)) break;
}
ptr[j] = v;
i++;
/*-- copy 3 --*/
if (i > hi) break;
v = ptr[i];
j = i;
while ( mainGtU (
ptr[j-h]+d, v+d, block, quadrant, nblock, budget
) ) {
ptr[j] = ptr[j-h];
j = j - h;
if (j <= (lo + h - 1)) break;
}
ptr[j] = v;
i++;
if (*budget < 0) return;
}
}
}
/*---------------------------------------------*/
/*--
The following is an implementation of
an elegant 3-way quicksort for strings,
described in a paper "Fast Algorithms for
Sorting and Searching Strings", by Robert
Sedgewick and Jon L. Bentley.
--*/
#define mswap(zz1, zz2) \
{ Int32 zztmp = zz1; zz1 = zz2; zz2 = zztmp; }
#define mvswap(zzp1, zzp2, zzn) \
{ \
Int32 yyp1 = (zzp1); \
Int32 yyp2 = (zzp2); \
Int32 yyn = (zzn); \
while (yyn > 0) { \
mswap(ptr[yyp1], ptr[yyp2]); \
yyp1++; yyp2++; yyn--; \
} \
}
static
__inline__
UChar mmed3 ( UChar a, UChar b, UChar c )
{
UChar t;
if (a > b) { t = a; a = b; b = t; };
if (b > c) {
b = c;
if (a > b) b = a;
}
return b;
}
#define mmin(a,b) ((a) < (b)) ? (a) : (b)
#define mpush(lz,hz,dz) { stackLo[sp] = lz; \
stackHi[sp] = hz; \
stackD [sp] = dz; \
sp++; }
#define mpop(lz,hz,dz) { sp--; \
lz = stackLo[sp]; \
hz = stackHi[sp]; \
dz = stackD [sp]; }
#define mnextsize(az) (nextHi[az]-nextLo[az])
#define mnextswap(az,bz) \
{ Int32 tz; \
tz = nextLo[az]; nextLo[az] = nextLo[bz]; nextLo[bz] = tz; \
tz = nextHi[az]; nextHi[az] = nextHi[bz]; nextHi[bz] = tz; \
tz = nextD [az]; nextD [az] = nextD [bz]; nextD [bz] = tz; }
#define MAIN_QSORT_SMALL_THRESH 20
#define MAIN_QSORT_DEPTH_THRESH (BZ_N_RADIX + BZ_N_QSORT)
#define MAIN_QSORT_STACK_SIZE 100
static
void mainQSort3 ( UInt32* ptr,
UChar* block,
UInt16* quadrant,
Int32 nblock,
Int32 loSt,
Int32 hiSt,
Int32 dSt,
Int32* budget )
{
Int32 unLo, unHi, ltLo, gtHi, n, m, med;
Int32 sp, lo, hi, d;
Int32 stackLo[MAIN_QSORT_STACK_SIZE];
Int32 stackHi[MAIN_QSORT_STACK_SIZE];
Int32 stackD [MAIN_QSORT_STACK_SIZE];
Int32 nextLo[3];
Int32 nextHi[3];
Int32 nextD [3];
sp = 0;
mpush ( loSt, hiSt, dSt );
while (sp > 0) {
AssertH ( sp < MAIN_QSORT_STACK_SIZE - 2, 1001 );
mpop ( lo, hi, d );
if (hi - lo < MAIN_QSORT_SMALL_THRESH ||
d > MAIN_QSORT_DEPTH_THRESH) {
mainSimpleSort ( ptr, block, quadrant, nblock, lo, hi, d, budget );
if (*budget < 0) return;
continue;
}
med = (Int32)
mmed3 ( block[ptr[ lo ]+d],
block[ptr[ hi ]+d],
block[ptr[ (lo+hi)>>1 ]+d] );
unLo = ltLo = lo;
unHi = gtHi = hi;
while (True) {
while (True) {
if (unLo > unHi) break;
n = ((Int32)block[ptr[unLo]+d]) - med;
if (n == 0) {
mswap(ptr[unLo], ptr[ltLo]);
ltLo++; unLo++; continue;
};
if (n > 0) break;
unLo++;
}
while (True) {
if (unLo > unHi) break;
n = ((Int32)block[ptr[unHi]+d]) - med;
if (n == 0) {
mswap(ptr[unHi], ptr[gtHi]);
gtHi--; unHi--; continue;
};
if (n < 0) break;
unHi--;
}
if (unLo > unHi) break;
mswap(ptr[unLo], ptr[unHi]); unLo++; unHi--;
}
AssertD ( unHi == unLo-1, "mainQSort3(2)" );
if (gtHi < ltLo) {
mpush(lo, hi, d+1 );
continue;
}
n = mmin(ltLo-lo, unLo-ltLo); mvswap(lo, unLo-n, n);
m = mmin(hi-gtHi, gtHi-unHi); mvswap(unLo, hi-m+1, m);
n = lo + unLo - ltLo - 1;
m = hi - (gtHi - unHi) + 1;
nextLo[0] = lo; nextHi[0] = n; nextD[0] = d;
nextLo[1] = m; nextHi[1] = hi; nextD[1] = d;
nextLo[2] = n+1; nextHi[2] = m-1; nextD[2] = d+1;
if (mnextsize(0) < mnextsize(1)) mnextswap(0,1);
if (mnextsize(1) < mnextsize(2)) mnextswap(1,2);
if (mnextsize(0) < mnextsize(1)) mnextswap(0,1);
AssertD (mnextsize(0) >= mnextsize(1), "mainQSort3(8)" );
AssertD (mnextsize(1) >= mnextsize(2), "mainQSort3(9)" );
mpush (nextLo[0], nextHi[0], nextD[0]);
mpush (nextLo[1], nextHi[1], nextD[1]);
mpush (nextLo[2], nextHi[2], nextD[2]);
}
}
#undef mswap
#undef mvswap
#undef mpush
#undef mpop
#undef mmin
#undef mnextsize
#undef mnextswap
#undef MAIN_QSORT_SMALL_THRESH
#undef MAIN_QSORT_DEPTH_THRESH
#undef MAIN_QSORT_STACK_SIZE
/*---------------------------------------------*/
/* Pre:
nblock > N_OVERSHOOT
block32 exists for [0 .. nblock-1 +N_OVERSHOOT]
((UChar*)block32) [0 .. nblock-1] holds block
ptr exists for [0 .. nblock-1]
Post:
((UChar*)block32) [0 .. nblock-1] holds block
All other areas of block32 destroyed
ftab [0 .. 65536 ] destroyed
ptr [0 .. nblock-1] holds sorted order
if (*budget < 0), sorting was abandoned
*/
#define BIGFREQ(b) (ftab[((b)+1) << 8] - ftab[(b) << 8])
#define SETMASK (1 << 21)
#define CLEARMASK (~(SETMASK))
static
void mainSort ( UInt32* ptr,
UChar* block,
UInt16* quadrant,
UInt32* ftab,
Int32 nblock,
Int32 verb,
Int32* budget )
{
Int32 i, j, k, ss, sb;
Int32 runningOrder[256];
Bool bigDone[256];
Int32 copyStart[256];
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)