/* $NetBSD: qsort.c,v 1.24 2025/03/02 16:35:41 riastradh 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/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char sccsid[] = "@(#)qsort.c 8.1 (Berkeley) 6/4/93";
#else
__RCSID("$NetBSD: qsort.c,v 1.24 2025/03/02 16:35:41 riastradh Exp $");
#endif
#endif /* LIBC_SCCS and not lint */
#include <sys/types.h>
#include <assert.h>
#include <errno.h>
#include <stdlib.h>
static inline char *med3(char *, char *, char *,
int (*)(const void *, const void *, void *),
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".
*/
#define swapcode(TYPE, parmi, parmj, n) { \
size_t i = (n) / sizeof (TYPE); \
TYPE *pi = (TYPE *)(void *)(parmi); \
TYPE *pj = (TYPE *)(void *)(parmj); \
do { \
TYPE t = *pi; \
*pi++ = *pj; \
*pj++ = t; \
} while (--i > 0); \
}
#define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
static inline void
swapfunc(char *a, char *b, size_t n, int swaptype)
{
if (swaptype <= 1)
swapcode(long, a, b, n)
else
swapcode(char, a, b, n)
}
#define swap(a, b) \
if (swaptype == 0) { \
long t = *(long *)(void *)(a); \
*(long *)(void *)(a) = *(long *)(void *)(b); \
*(long *)(void *)(b) = t; \
} else \
swapfunc(a, b, es, swaptype)
#define vecswap(a, b, n) if ((n) > 0) swapfunc((a), (b), (size_t)(n), swaptype)
static inline char *
med3(char *a, char *b, char *c,
int (*cmp)(const void *, const void *, void *), void *cookie)
{
return cmp(a, b, cookie) < 0 ?
(cmp(b, c, cookie) < 0 ? b : (cmp(a, c, cookie) < 0 ? c : a ))
:(cmp(b, c, cookie) > 0 ? b : (cmp(a, c, cookie) < 0 ? a : c ));
}
void
qsort_r(void *a, size_t n, size_t es,
int (*cmp)(const void *, const void *, void *), void *cookie)
{
char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
size_t d, r, s;
int swaptype, cmp_result;
_DIAGASSERT(a != NULL || n == 0 || es == 0);
_DIAGASSERT(cmp != NULL);
loop: SWAPINIT(a, es);
if (n < 7) {
for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es)
for (pl = pm;
pl > (char *) a && cmp(pl - es, pl, cookie) > 0;
pl -= es)
swap(pl, pl - es);
return;
}
pm = (char *) a + (n / 2) * es;
if (n > 7) {
pl = (char *) a;
pn = (char *) a + (n - 1) * es;
if (n > 40) {
d = (n / 8) * es;
pl = med3(pl, pl + d, pl + 2 * d, cmp, cookie);
pm = med3(pm - d, pm, pm + d, cmp, cookie);
pn = med3(pn - 2 * d, pn - d, pn, cmp, cookie);
}
pm = med3(pl, pm, pn, cmp, cookie);
}
swap(a, pm);
pa = pb = (char *) a + es;
pc = pd = (char *) a + (n - 1) * es;
for (;;) {
while (pb <= pc && (cmp_result = cmp(pb, a, cookie)) <= 0) {
if (cmp_result == 0) {
swap(pa, pb);
pa += es;
}
pb += es;
}
while (pb <= pc && (cmp_result = cmp(pc, a, cookie)) >= 0) {
if (cmp_result == 0) {
swap(pc, pd);
pd -= es;
}
pc -= es;
}
if (pb > pc)
break;
swap(pb, pc);
pb += es;
pc -= es;
}
pn = (char *) a + n * es;
r = min(pa - (char *) a, pb - pa);
vecswap(a, pb - r, r);
r = min((size_t)(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)
qsort_r(a, r / es, es, cmp, cookie);
a = pn - s;
n = s / es;
goto loop;
}
} else {
/* Recurse for 2nd side, iterate for 1st side. */
if (r > es) {
if (s > es)
qsort_r(pn - s, s / es, es, cmp, cookie);
n = r / es;
goto loop;
}
}
}
static int
cmpnocookie(const void *a, const void *b, void *cookie)
{
int (*cmp)(const void *, const void *) = cookie;
return cmp(a, b);
}
void
qsort(void *a, size_t n, size_t es,
int (*cmp)(const void *, const void *))
{
qsort_r(a, n, es, cmpnocookie, cmp);
}
