NetBSD/lib/libc/stdlib/qsort.c

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/* $NetBSD: qsort.c,v 1.12 1999/09/20 04:39:40 lukem Exp $ */
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/*-
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* Copyright (c) 1992, 1993
* The Regents of the University of California. All rights reserved.
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*
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. 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>
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#if defined(LIBC_SCCS) && !defined(lint)
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#if 0
static char sccsid[] = "@(#)qsort.c 8.1 (Berkeley) 6/4/93";
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#else
__RCSID("$NetBSD: qsort.c,v 1.12 1999/09/20 04:39:40 lukem Exp $");
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#endif
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#endif /* LIBC_SCCS and not lint */
#include <sys/types.h>
#include <assert.h>
#include <errno.h>
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#include <stdlib.h>
static __inline char *med3 __P((char *, char *, char *,
int (*)(const void *, const void *)));
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static __inline void swapfunc __P((char *, char *, size_t, int));
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#define min(a, b) (a) < (b) ? a : b
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/*
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* Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
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*/
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#define swapcode(TYPE, parmi, parmj, n) { \
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size_t i = (n) / sizeof (TYPE); \
TYPE *pi = (TYPE *)(void *)(parmi); \
TYPE *pj = (TYPE *)(void *)(parmj); \
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do { \
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TYPE t = *pi; \
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*pi++ = *pj; \
*pj++ = t; \
} while (--i > 0); \
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}
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#define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
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static __inline void
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swapfunc(a, b, n, swaptype)
char *a, *b;
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size_t n;
int swaptype;
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{
if (swaptype <= 1)
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swapcode(long, a, b, n)
else
swapcode(char, a, b, n)
}
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#define swap(a, b) \
if (swaptype == 0) { \
long t = *(long *)(void *)(a); \
*(long *)(void *)(a) = *(long *)(void *)(b); \
*(long *)(void *)(b) = t; \
} else \
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swapfunc(a, b, es, swaptype)
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#define vecswap(a, b, n) if ((n) > 0) swapfunc((a), (b), (size_t)(n), swaptype)
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static __inline char *
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med3(a, b, c, cmp)
char *a, *b, *c;
int (*cmp) __P((const void *, const void *));
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{
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 ));
}
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void
qsort(a, n, es, cmp)
void *a;
size_t n, es;
int (*cmp) __P((const void *, const void *));
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{
char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
int d, r, swaptype, swap_cnt;
_DIAGASSERT(a != NULL);
_DIAGASSERT(cmp != NULL);
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loop: SWAPINIT(a, es);
swap_cnt = 0;
if (n < 7) {
for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es)
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for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
pl -= es)
swap(pl, pl - es);
return;
}
pm = (char *) a + (n / 2) * es;
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if (n > 7) {
pl = (char *) a;
pn = (char *) a + (n - 1) * es;
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if (n > 40) {
d = (n / 8) * es;
pl = med3(pl, pl + d, pl + 2 * d, cmp);
pm = med3(pm - d, pm, pm + d, cmp);
pn = med3(pn - 2 * d, pn - d, pn, cmp);
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}
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pm = med3(pl, pm, pn, cmp);
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}
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swap(a, pm);
pa = pb = (char *) a + es;
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pc = pd = (char *) a + (n - 1) * es;
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for (;;) {
while (pb <= pc && (r = cmp(pb, a)) <= 0) {
if (r == 0) {
swap_cnt = 1;
swap(pa, pb);
pa += es;
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}
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pb += es;
}
while (pb <= pc && (r = cmp(pc, a)) >= 0) {
if (r == 0) {
swap_cnt = 1;
swap(pc, pd);
pd -= es;
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}
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pc -= es;
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}
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if (pb > pc)
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break;
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swap(pb, pc);
swap_cnt = 1;
pb += es;
pc -= es;
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}
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if (swap_cnt == 0) { /* Switch to insertion sort */
for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es)
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for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
pl -= es)
swap(pl, pl - es);
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return;
}
pn = (char *) a + n * es;
r = min(pa - (char *) a, pb - pa);
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vecswap(a, pb - r, r);
r = min(pd - pc, pn - pd - es);
vecswap(pb, pn - r, r);
if ((r = pb - pa) > es)
qsort(a, r / es, es, cmp);
if ((r = pd - pc) > es) {
/* Iterate rather than recurse to save stack space */
a = pn - r;
n = r / es;
goto loop;
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}
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/* qsort(pn - r, r / es, es, cmp);*/
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}