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busybox/archival/libarchive/bz/blocksort.c
Denys Vlasenko 0e60a36c92 bzip2: move runningOrder[] back to stack - 256 bytes is not much 
function                                             old     new   delta
mainSort                                            1119    1108     -11

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-02-03 22:52:55 +01:00

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/*
* bzip2 is written by Julian Seward <jseward@bzip.org>.
* Adapted for busybox by Denys Vlasenko <vda.linux@googlemail.com>.
* See README and LICENSE files in this directory for more information.
*/
/*-------------------------------------------------------------*/
/*--- 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 1.0.4 of 20 December 2006
Copyright (C) 1996-2006 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" */
#define mswap(zz1, zz2) \
{ \
int32_t zztmp = zz1; \
zz1 = zz2; \
zz2 = zztmp; \
}
static
/* No measurable speed gain with inlining */
/* ALWAYS_INLINE */
void mvswap(uint32_t* ptr, int32_t zzp1, int32_t zzp2, int32_t zzn)
{
while (zzn > 0) {
mswap(ptr[zzp1], ptr[zzp2]);
zzp1++;
zzp2++;
zzn--;
}
}
static
ALWAYS_INLINE
int32_t mmin(int32_t a, int32_t b)
{
return (a < b) ? a : b;
}
/*---------------------------------------------*/
/*--- Fallback O(N log(N)^2) sorting ---*/
/*--- algorithm, for repetitive blocks ---*/
/*---------------------------------------------*/
/*---------------------------------------------*/
static
inline
void fallbackSimpleSort(uint32_t* fmap,
uint32_t* eclass,
int32_t lo,
int32_t hi)
{
int32_t i, j, tmp;
uint32_t 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 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_t* fmap,
uint32_t* eclass,
int32_t loSt,
int32_t hiSt)
{
int32_t sp;
uint32_t r;
int32_t stackLo[FALLBACK_QSORT_STACK_SIZE];
int32_t stackHi[FALLBACK_QSORT_STACK_SIZE];
r = 0;
sp = 0;
fpush(loSt, hiSt);
while (sp > 0) {
int32_t unLo, unHi, ltLo, gtHi, n, m;
int32_t lo, hi;
uint32_t med;
uint32_t r3;
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_t)eclass[fmap[unLo]] - (int32_t)med;
if (n == 0) {
mswap(fmap[unLo], fmap[ltLo]);
ltLo++;
unLo++;
continue;
}
if (n > 0) break;
unLo++;
}
while (1) {
if (unLo > unHi) break;
n = (int32_t)eclass[fmap[unHi]] - (int32_t)med;
if (n == 0) {
mswap(fmap[unHi], fmap[gtHi]);
gtHi--; unHi--;
continue;
}
if (n < 0) break;
unHi--;
}
if (unLo > unHi) break;
mswap(fmap[unLo], fmap[unHi]); unLo++; unHi--;
}
AssertD(unHi == unLo-1, "fallbackQSort3(2)");
if (gtHi < ltLo) continue;
n = mmin(ltLo-lo, unLo-ltLo); mvswap(fmap, lo, unLo-n, n);
m = mmin(hi-gtHi, gtHi-unHi); mvswap(fmap, 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 fpush
#undef fpop
#undef FALLBACK_QSORT_SMALL_THRESH
#undef FALLBACK_QSORT_STACK_SIZE
/*---------------------------------------------*/
/* Pre:
* nblock > 0
* eclass exists for [0 .. nblock-1]
* ((uint8_t*)eclass) [0 .. nblock-1] holds block
* ptr exists for [0 .. nblock-1]
*
* Post:
* ((uint8_t*)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(EState* state)
{
int32_t ftab[257];
int32_t ftabCopy[256];
int32_t H, i, j, k, l, r, cc, cc1;
int32_t nNotDone;
int32_t nBhtab;
/* params */
uint32_t *const fmap = state->arr1;
uint32_t *const eclass = state->arr2;
#define eclass8 ((uint8_t*)eclass)
uint32_t *const bhtab = state->ftab;
const int32_t nblock = state->nblock;
/*
* Initial 1-char radix sort to generate
* initial fmap and initial BH bits.
*/
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];
j = ftab[0]; /* bbox: optimized */
for (i = 1; i < 257; i++) {
j += ftab[i];
ftab[i] = j;
}
for (i = 0; i < nblock; i++) {
j = eclass8[i];
k = ftab[j] - 1;
ftab[j] = k;
fmap[k] = i;
}
nBhtab = 2 + ((uint32_t)nblock / 32); /* bbox: unsigned div is easier */
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) {
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;
}
}
}
}
H *= 2;
if (H > nblock || nNotDone == 0)
break;
}
/*
* Reconstruct the original block in
* eclass8 [0 .. nblock-1], since the
* previous phase destroyed it.
*/
j = 0;
for (i = 0; i < nblock; i++) {
while (ftabCopy[j] == 0)
j++;
ftabCopy[j]--;
eclass8[fmap[i]] = (uint8_t)j;
}
AssertH(j < 256, 1005);
#undef eclass8
}
#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
NOINLINE
int mainGtU(EState* state,
uint32_t i1,
uint32_t i2)
{
int32_t k;
uint8_t c1, c2;
uint16_t s1, s2;
uint8_t *const block = state->block;
uint16_t *const quadrant = state->quadrant;
const int32_t nblock = state->nblock;
/* Loop unrolling here is actually very useful
* (generated code is much simpler),
* code size increase is only 270 bytes (i386)
* but speeds up compression 10% overall
*/
#if CONFIG_BZIP2_FAST >= 1
#define TIMES_8(code) \
code; code; code; code; \
code; code; code; code;
#define TIMES_12(code) \
code; code; code; code; \
code; code; code; code; \
code; code; code; code;
#else
#define TIMES_8(code) \
{ \
int nn = 8; \
do { \
code; \
} while (--nn); \
}
#define TIMES_12(code) \
{ \
int nn = 12; \
do { \
code; \
} while (--nn); \
}
#endif
AssertD(i1 != i2, "mainGtU");
TIMES_12(
c1 = block[i1]; c2 = block[i2];
if (c1 != c2) return (c1 > c2);
i1++; i2++;
)
k = nblock + 8;
do {
TIMES_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;
state->budget--;
k -= 8;
} while (k >= 0);
return False;
}
#undef TIMES_8
#undef TIMES_12
/*---------------------------------------------*/
/*
* 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
const uint32_t incs[14] = {
1, 4, 13, 40, 121, 364, 1093, 3280,
9841, 29524, 88573, 265720,
797161, 2391484
};
static
void mainSimpleSort(EState* state,
int32_t lo,
int32_t hi,
int32_t d)
{
uint32_t *const ptr = state->ptr;
/* At which increment to start? */
int hp = 0;
{
int bigN = hi - lo;
if (bigN <= 0)
return;
while (incs[hp] <= bigN)
hp++;
hp--;
}
for (; hp >= 0; hp--) {
int32_t i;
unsigned h;
h = incs[hp];
i = lo + h;
while (1) {
unsigned j;
unsigned v;
if (i > hi) break;
v = ptr[i];
j = i;
while (mainGtU(state, ptr[j-h]+d, v+d)) {
ptr[j] = ptr[j-h];
j = j - h;
if (j <= (lo + h - 1)) break;
}
ptr[j] = v;
i++;
/* 1.5% overall speedup, +290 bytes */
#if CONFIG_BZIP2_FAST >= 3
/*-- copy 2 --*/
if (i > hi) break;
v = ptr[i];
j = i;
while (mainGtU(state, ptr[j-h]+d, v+d)) {
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(state, ptr[j-h]+d, v+d)) {
ptr[j] = ptr[j-h];
j = j - h;
if (j <= (lo + h - 1)) break;
}
ptr[j] = v;
i++;
#endif
if (state->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.
*/
static
ALWAYS_INLINE
uint8_t mmed3(uint8_t a, uint8_t b, uint8_t c)
{
uint8_t t;
if (a > b) {
t = a;
a = b;
b = t;
}
/* here b >= a */
if (b > c) {
b = c;
if (a > b)
b = a;
}
return 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_t 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 NOINLINE
void mainQSort3(EState* state,
int32_t loSt,
int32_t hiSt
/*int32_t dSt*/)
{
enum { dSt = BZ_N_RADIX };
int32_t unLo, unHi, ltLo, gtHi, n, m, med;
int32_t sp, lo, hi, d;
int32_t stackLo[MAIN_QSORT_STACK_SIZE];
int32_t stackHi[MAIN_QSORT_STACK_SIZE];
int32_t stackD [MAIN_QSORT_STACK_SIZE];
int32_t nextLo[3];
int32_t nextHi[3];
int32_t nextD [3];
uint32_t *const ptr = state->ptr;
uint8_t *const block = state->block;
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(state, lo, hi, d);
if (state->budget < 0)
return;
continue;
}
med = (int32_t) mmed3(block[ptr[lo ] + d],
block[ptr[hi ] + d],
block[ptr[(lo+hi) >> 1] + d]);
unLo = ltLo = lo;
unHi = gtHi = hi;
while (1) {
while (1) {
if (unLo > unHi)
break;
n = ((int32_t)block[ptr[unLo]+d]) - med;
if (n == 0) {
mswap(ptr[unLo], ptr[ltLo]);
ltLo++;
unLo++;
continue;
}
if (n > 0) break;
unLo++;
}
while (1) {
if (unLo > unHi)
break;
n = ((int32_t)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(ptr, lo, unLo-n, n);
m = mmin(hi-gtHi, gtHi-unHi); mvswap(ptr, 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 mpush
#undef mpop
#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]
* ((uint8_t*)block32) [0 .. nblock-1] holds block
* ptr exists for [0 .. nblock-1]
*
* Post:
* ((uint8_t*)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 NOINLINE
void mainSort(EState* state)
{
int32_t i, j;
Bool bigDone[256];
uint8_t runningOrder[256];
/* bbox: moved to EState to save stack
int32_t copyStart[256];
int32_t copyEnd [256];
*/
#define copyStart (state->mainSort__copyStart)
#define copyEnd (state->mainSort__copyEnd)
uint32_t *const ptr = state->ptr;
uint8_t *const block = state->block;
uint32_t *const ftab = state->ftab;
const int32_t nblock = state->nblock;
uint16_t *const quadrant = state->quadrant;
/*-- set up the 2-byte frequency table --*/
/* was: for (i = 65536; i >= 0; i--) ftab[i] = 0; */
memset(ftab, 0, 65537 * sizeof(ftab[0]));
j = block[0] << 8;
i = nblock - 1;
/* 3%, +300 bytes */
#if CONFIG_BZIP2_FAST >= 2
for (; i >= 3; i -= 4) {
quadrant[i] = 0;
j = (j >> 8) | (((unsigned)block[i]) << 8);
ftab[j]++;
quadrant[i-1] = 0;
j = (j >> 8) | (((unsigned)block[i-1]) << 8);
ftab[j]++;
quadrant[i-2] = 0;
j = (j >> 8) | (((unsigned)block[i-2]) << 8);
ftab[j]++;
quadrant[i-3] = 0;
j = (j >> 8) | (((unsigned)block[i-3]) << 8);
ftab[j]++;
}
#endif
for (; i >= 0; i--) {
quadrant[i] = 0;
j = (j >> 8) | (((unsigned)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;
}
/*-- Complete the initial radix sort --*/
j = ftab[0]; /* bbox: optimized */
for (i = 1; i <= 65536; i++) {
j += ftab[i];
ftab[i] = j;
}
{
unsigned s;
s = block[0] << 8;
i = nblock - 1;
#if CONFIG_BZIP2_FAST >= 2
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;
}
#endif
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;
}
{
/* bbox: was: int32_t h = 1; */
/* do h = 3 * h + 1; while (h <= 256); */
unsigned h = 364;
do {
/*h = h / 3;*/
h = (h * 171) >> 9; /* bbox: fast h/3 */
for (i = h; i <= 255; i++) {
unsigned vv, jh;
vv = runningOrder[i]; /* uint8[] */
j = i;
while (jh = j - h, BIGFREQ(runningOrder[jh]) > BIGFREQ(vv)) {
runningOrder[j] = runningOrder[jh];
j = jh;
if (j < h)
break;
}
runningOrder[j] = vv;
}
} while (h != 1);
}
/*
* The main sorting loop.
*/
for (i = 0; /*i <= 255*/; i++) {
unsigned ss;
/*
* 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) {
unsigned sb;
sb = (ss << 8) + j;
if (!(ftab[sb] & SETMASK)) {
int32_t lo = ftab[sb] /*& CLEARMASK (redundant)*/;
int32_t hi = (ftab[sb+1] & CLEARMASK) - 1;
if (hi > lo) {
mainQSort3(state, lo, hi /*,BZ_N_RADIX*/);
if (state->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++) {
unsigned c1;
int32_t k;
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--) {
unsigned c1;
int32_t k;
k = ptr[j]-1;
if (k < 0)
k += nblock;
c1 = block[k];
if (!bigDone[c1])
ptr[copyEnd[c1]--] = k;
}
}
/* 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. */
AssertH((copyStart[ss]-1 == copyEnd[ss]) \
|| (copyStart[ss] == 0 && copyEnd[ss] == nblock-1), 1007);
for (j = 0; j <= 255; j++)
ftab[(j << 8) + ss] |= SETMASK;
if (i == 255)
break;
/*
* 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;
{
unsigned bbStart = ftab[ss << 8] & CLEARMASK;
unsigned bbSize = (ftab[(ss+1) << 8] & CLEARMASK) - bbStart;
unsigned shifts = 0;
while ((bbSize >> shifts) > 65534) shifts++;
for (j = bbSize-1; j >= 0; j--) {
unsigned a2update = ptr[bbStart + j]; /* uint32[] */
uint16_t qVal = (uint16_t)(j >> shifts);
quadrant[a2update] = qVal;
if (a2update < BZ_N_OVERSHOOT)
quadrant[a2update + nblock] = qVal;
}
AssertH(((bbSize-1) >> shifts) <= 65535, 1002);
}
}
#undef runningOrder
#undef copyStart
#undef copyEnd
}
#undef BIGFREQ
#undef SETMASK
#undef CLEARMASK
/*---------------------------------------------*/
/* Pre:
* nblock > 0
* arr2 exists for [0 .. nblock-1 +N_OVERSHOOT]
* ((uint8_t*)arr2)[0 .. nblock-1] holds block
* arr1 exists for [0 .. nblock-1]
*
* Post:
* ((uint8_t*)arr2) [0 .. nblock-1] holds block
* All other areas of block destroyed
* ftab[0 .. 65536] destroyed
* arr1[0 .. nblock-1] holds sorted order
*/
static NOINLINE
int32_t BZ2_blockSort(EState* state)
{
/* In original bzip2 1.0.4, it's a parameter, but 30
* (which was the default) should work ok. */
enum { wfact = 30 };
unsigned i;
int32_t origPtr = origPtr;
if (state->nblock >= 10000) {
/* 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 = state->nblock + BZ_N_OVERSHOOT;
if (i & 1)
i++;
state->quadrant = (uint16_t*) &(state->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.
*/
state->budget = state->nblock * ((wfact-1) / 3);
mainSort(state);
if (state->budget >= 0)
goto good;
}
fallbackSort(state);
good:
#if BZ_LIGHT_DEBUG
origPtr = -1;
#endif
for (i = 0; i < state->nblock; i++) {
if (state->ptr[i] == 0) {
origPtr = i;
break;
}
}
AssertH(origPtr != -1, 1003);
return origPtr;
}
/*-------------------------------------------------------------*/
/*--- end blocksort.c ---*/
/*-------------------------------------------------------------*/
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