|
|
/* $OpenBSD: qsort.c,v 1.17 2017/05/24 21:18:25 millert Exp $ */
|
|
|
/*-
|
|
|
* Copyright (c) 1992, 1993
|
|
|
* The Regents of the University of California. 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. Redistributions in binary form must reproduce the above copyright
|
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
|
* documentation and/or other materials provided with the distribution.
|
|
|
* 3. Neither the name of the University nor the names of its contributors
|
|
|
* may be used to endorse or promote products derived from this software
|
|
|
* without specific prior written permission.
|
|
|
*
|
|
|
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
|
|
|
*/
|
|
|
|
|
|
#include <sys/types.h>
|
|
|
#include <stdlib.h>
|
|
|
|
|
|
static __inline char *med3(char *, char *, char *, int (*)(const void *, const void *));
|
|
|
static __inline void swapfunc(char *, char *, size_t, int);
|
|
|
|
|
|
#define min(a, b) (a) < (b) ? a : b
|
|
|
|
|
|
/*
|
|
|
* Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
|
|
|
*
|
|
|
* This version differs from Bentley & McIlroy in the following ways:
|
|
|
* 1. The partition value is swapped into a[0] instead of being
|
|
|
* stored out of line.
|
|
|
*
|
|
|
* 2. The swap function can swap 32-bit aligned elements on 64-bit
|
|
|
* platforms instead of swapping them as byte-aligned.
|
|
|
*
|
|
|
* 3. It uses David Musser's introsort algorithm to fall back to
|
|
|
* heapsort(3) when the recursion depth reaches 2*lg(n + 1).
|
|
|
* This avoids quicksort's quadratic behavior for pathological
|
|
|
* input without appreciably changing the average run time.
|
|
|
*
|
|
|
* 4. Tail recursion is eliminated when sorting the larger of two
|
|
|
* subpartitions to save stack space.
|
|
|
*/
|
|
|
#define SWAPTYPE_BYTEV 1
|
|
|
#define SWAPTYPE_INTV 2
|
|
|
#define SWAPTYPE_LONGV 3
|
|
|
#define SWAPTYPE_INT 4
|
|
|
#define SWAPTYPE_LONG 5
|
|
|
|
|
|
#define TYPE_ALIGNED(TYPE, a, es) \
|
|
|
(((char *)a - (char *)0) % sizeof(TYPE) == 0 && es % sizeof(TYPE) == 0)
|
|
|
|
|
|
#define swapcode(TYPE, parmi, parmj, n) { \
|
|
|
size_t i = (n) / sizeof (TYPE); \
|
|
|
TYPE *pi = (TYPE *) (parmi); \
|
|
|
TYPE *pj = (TYPE *) (parmj); \
|
|
|
do { \
|
|
|
TYPE t = *pi; \
|
|
|
*pi++ = *pj; \
|
|
|
*pj++ = t; \
|
|
|
} while (--i > 0); \
|
|
|
}
|
|
|
|
|
|
static __inline void
|
|
|
swapfunc(char *a, char *b, size_t n, int swaptype)
|
|
|
{
|
|
|
switch (swaptype) {
|
|
|
case SWAPTYPE_INT:
|
|
|
case SWAPTYPE_INTV:
|
|
|
swapcode(int, a, b, n);
|
|
|
break;
|
|
|
case SWAPTYPE_LONG:
|
|
|
case SWAPTYPE_LONGV:
|
|
|
swapcode(long, a, b, n);
|
|
|
break;
|
|
|
default:
|
|
|
swapcode(char, a, b, n);
|
|
|
break;
|
|
|
}
|
|
|
}
|
|
|
|
|
|
#define swap(a, b) do { \
|
|
|
switch (swaptype) { \
|
|
|
case SWAPTYPE_INT: { \
|
|
|
int t = *(int *)(a); \
|
|
|
*(int *)(a) = *(int *)(b); \
|
|
|
*(int *)(b) = t; \
|
|
|
break; \
|
|
|
} \
|
|
|
case SWAPTYPE_LONG: { \
|
|
|
long t = *(long *)(a); \
|
|
|
*(long *)(a) = *(long *)(b); \
|
|
|
*(long *)(b) = t; \
|
|
|
break; \
|
|
|
} \
|
|
|
default: \
|
|
|
swapfunc(a, b, es, swaptype); \
|
|
|
} \
|
|
|
} while (0)
|
|
|
|
|
|
#define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype)
|
|
|
|
|
|
static __inline char *
|
|
|
med3(char *a, char *b, char *c, int (*cmp)(const void *, const void *))
|
|
|
{
|
|
|
return cmp(a, b) < 0 ?
|
|
|
(cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a ))
|
|
|
:(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c ));
|
|
|
}
|
|
|
|
|
|
static void
|
|
|
introsort(char *a, size_t n, size_t es, size_t maxdepth, int swaptype,
|
|
|
int (*cmp)(const void *, const void *))
|
|
|
{
|
|
|
char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
|
|
|
int cmp_result;
|
|
|
size_t r, s;
|
|
|
|
|
|
loop: if (maxdepth == 0) {
|
|
|
if (heapsort(a, n, es, cmp) == 0)
|
|
|
return;
|
|
|
}
|
|
|
maxdepth--;
|
|
|
if (n < 7) {
|
|
|
for (pm = a + es; pm < a + n * es; pm += es)
|
|
|
for (pl = pm; pl > a && cmp(pl - es, pl) > 0;
|
|
|
pl -= es)
|
|
|
swap(pl, pl - es);
|
|
|
return;
|
|
|
}
|
|
|
pm = a + (n / 2) * es;
|
|
|
if (n > 7) {
|
|
|
pl = a;
|
|
|
pn = a + (n - 1) * es;
|
|
|
if (n > 40) {
|
|
|
s = (n / 8) * es;
|
|
|
pl = med3(pl, pl + s, pl + 2 * s, cmp);
|
|
|
pm = med3(pm - s, pm, pm + s, cmp);
|
|
|
pn = med3(pn - 2 * s, pn - s, pn, cmp);
|
|
|
}
|
|
|
pm = med3(pl, pm, pn, cmp);
|
|
|
}
|
|
|
swap(a, pm);
|
|
|
pa = pb = a + es;
|
|
|
pc = pd = a + (n - 1) * es;
|
|
|
for (;;) {
|
|
|
while (pb <= pc && (cmp_result = cmp(pb, a)) <= 0) {
|
|
|
if (cmp_result == 0) {
|
|
|
swap(pa, pb);
|
|
|
pa += es;
|
|
|
}
|
|
|
pb += es;
|
|
|
}
|
|
|
while (pb <= pc && (cmp_result = cmp(pc, a)) >= 0) {
|
|
|
if (cmp_result == 0) {
|
|
|
swap(pc, pd);
|
|
|
pd -= es;
|
|
|
}
|
|
|
pc -= es;
|
|
|
}
|
|
|
if (pb > pc)
|
|
|
break;
|
|
|
swap(pb, pc);
|
|
|
pb += es;
|
|
|
pc -= es;
|
|
|
}
|
|
|
|
|
|
pn = a + n * es;
|
|
|
r = min(pa - a, pb - pa);
|
|
|
vecswap(a, pb - r, r);
|
|
|
r = min(pd - pc, pn - pd - es);
|
|
|
vecswap(pb, pn - r, r);
|
|
|
/*
|
|
|
* To save stack space we sort the smaller side of the partition first
|
|
|
* using recursion and eliminate tail recursion for the larger side.
|
|
|
*/
|
|
|
r = pb - pa;
|
|
|
s = pd - pc;
|
|
|
if (r < s) {
|
|
|
/* Recurse for 1st side, iterate for 2nd side. */
|
|
|
if (s > es) {
|
|
|
if (r > es) {
|
|
|
introsort(a, r / es, es, maxdepth,
|
|
|
swaptype, cmp);
|
|
|
}
|
|
|
a = pn - s;
|
|
|
n = s / es;
|
|
|
goto loop;
|
|
|
}
|
|
|
} else {
|
|
|
/* Recurse for 2nd side, iterate for 1st side. */
|
|
|
if (r > es) {
|
|
|
if (s > es) {
|
|
|
introsort(pn - s, s / es, es, maxdepth,
|
|
|
swaptype, cmp);
|
|
|
}
|
|
|
n = r / es;
|
|
|
goto loop;
|
|
|
}
|
|
|
}
|
|
|
}
|
|
|
|
|
|
void
|
|
|
qsort(void *a, size_t n, size_t es, int (*cmp)(const void *, const void *))
|
|
|
{
|
|
|
size_t i, maxdepth = 0;
|
|
|
int swaptype;
|
|
|
|
|
|
/* Approximate 2*ceil(lg(n + 1)) */
|
|
|
for (i = n; i > 0; i >>= 1)
|
|
|
maxdepth++;
|
|
|
maxdepth *= 2;
|
|
|
|
|
|
if (TYPE_ALIGNED(long, a, es))
|
|
|
swaptype = es == sizeof(long) ? SWAPTYPE_LONG : SWAPTYPE_LONGV;
|
|
|
else if (sizeof(int) != sizeof(long) && TYPE_ALIGNED(int, a, es))
|
|
|
swaptype = es == sizeof(int) ? SWAPTYPE_INT : SWAPTYPE_INTV;
|
|
|
else
|
|
|
swaptype = SWAPTYPE_BYTEV;
|
|
|
|
|
|
introsort(a, n, es, maxdepth, swaptype, cmp);
|
|
|
|
|
|
}
|
|
|
|
|
|
DEF_STRONG(qsort);
|