GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: lib/libc/stdlib/qsort.c Lines: 0 72 0.0 %
Date: 2017-11-13 Branches: 0 88 0.0 %

Line Branch Exec Source
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/*	$OpenBSD: qsort.c,v 1.18 2017/05/30 14:54:09 millert Exp $ */
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/*-
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 * Copyright (c) 1992, 1993
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 *	The Regents of the University of California.  All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 * 1. Redistributions of source code must retain the above copyright
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 *    notice, this list of conditions and the following disclaimer.
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 * 2. Redistributions in binary form must reproduce the above copyright
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 *    notice, this list of conditions and the following disclaimer in the
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 *    documentation and/or other materials provided with the distribution.
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 * 3. Neither the name of the University nor the names of its contributors
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 *    may be used to endorse or promote products derived from this software
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 *    without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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 * SUCH DAMAGE.
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 */
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#include <sys/types.h>
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#include <stdlib.h>
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static __inline char	*med3(char *, char *, char *, int (*)(const void *, const void *));
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static __inline void	 swapfunc(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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 * This version differs from Bentley & McIlroy in the following ways:
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 *   1. The partition value is swapped into a[0] instead of being
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 *	stored out of line.
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 *
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 *   2. The swap function can swap 32-bit aligned elements on 64-bit
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 *	platforms instead of swapping them as byte-aligned.
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 *
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 *   3. It uses David Musser's introsort algorithm to fall back to
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 *	heapsort(3) when the recursion depth reaches 2*lg(n + 1).
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 *	This avoids quicksort's quadratic behavior for pathological
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 *	input without appreciably changing the average run time.
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 *
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 *   4. Tail recursion is eliminated when sorting the larger of two
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 *	subpartitions to save stack space.
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 */
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#define SWAPTYPE_BYTEV	1
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#define SWAPTYPE_INTV	2
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#define SWAPTYPE_LONGV	3
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#define SWAPTYPE_INT	4
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#define SWAPTYPE_LONG	5
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#define TYPE_ALIGNED(TYPE, a, es)			\
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	(((char *)a - (char *)0) % sizeof(TYPE) == 0 && es % sizeof(TYPE) == 0)
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#define swapcode(TYPE, parmi, parmj, n) { 		\
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	size_t i = (n) / sizeof (TYPE); 		\
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	TYPE *pi = (TYPE *) (parmi); 			\
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	TYPE *pj = (TYPE *) (parmj); 			\
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	do { 						\
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		TYPE	t = *pi;			\
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		*pi++ = *pj;				\
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		*pj++ = t;				\
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        } while (--i > 0);				\
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}
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static __inline void
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swapfunc(char *a, char *b, size_t n, int swaptype)
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{
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	switch (swaptype) {
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	case SWAPTYPE_INT:
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	case SWAPTYPE_INTV:
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		swapcode(int, a, b, n);
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		break;
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	case SWAPTYPE_LONG:
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	case SWAPTYPE_LONGV:
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		swapcode(long, a, b, n);
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		break;
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	default:
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		swapcode(char, a, b, n);
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		break;
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	}
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}
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#define swap(a, b)	do {				\
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	switch (swaptype) {				\
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	case SWAPTYPE_INT: {				\
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		int t = *(int *)(a);			\
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		*(int *)(a) = *(int *)(b);		\
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		*(int *)(b) = t;			\
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		break;					\
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	    }						\
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	case SWAPTYPE_LONG: {				\
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		long t = *(long *)(a);			\
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		*(long *)(a) = *(long *)(b);		\
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		*(long *)(b) = t;			\
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		break;					\
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	    }						\
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	default:					\
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		swapfunc(a, b, es, swaptype);		\
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	}						\
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} while (0)
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#define vecswap(a, b, n) 	if ((n) > 0) swapfunc(a, b, n, swaptype)
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static __inline char *
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med3(char *a, char *b, char *c, int (*cmp)(const void *, const void *))
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{
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	return cmp(a, b) < 0 ?
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	       (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a ))
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              :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c ));
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}
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static void
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introsort(char *a, size_t n, size_t es, size_t maxdepth, int swaptype,
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    int (*cmp)(const void *, const void *))
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{
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	char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
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	int cmp_result;
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	size_t r, s;
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loop:	if (n < 7) {
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		for (pm = a + es; pm < a + n * es; pm += es)
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			for (pl = pm; pl > a && cmp(pl - es, pl) > 0;
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			     pl -= es)
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				swap(pl, pl - es);
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		return;
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	}
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	if (maxdepth == 0) {
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		if (heapsort(a, n, es, cmp) == 0)
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			return;
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	}
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	maxdepth--;
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	pm = a + (n / 2) * es;
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	if (n > 7) {
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		pl = a;
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		pn = a + (n - 1) * es;
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		if (n > 40) {
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			s = (n / 8) * es;
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			pl = med3(pl, pl + s, pl + 2 * s, cmp);
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			pm = med3(pm - s, pm, pm + s, cmp);
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			pn = med3(pn - 2 * s, pn - s, 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);
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	pa = pb = a + es;
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	pc = pd = a + (n - 1) * es;
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	for (;;) {
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		while (pb <= pc && (cmp_result = cmp(pb, a)) <= 0) {
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			if (cmp_result == 0) {
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				swap(pa, pb);
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				pa += es;
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			}
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			pb += es;
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		}
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		while (pb <= pc && (cmp_result = cmp(pc, a)) >= 0) {
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			if (cmp_result == 0) {
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				swap(pc, pd);
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				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);
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		pb += es;
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		pc -= es;
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	}
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	pn = a + n * es;
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	r = min(pa - a, pb - pa);
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	vecswap(a, pb - r, r);
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	r = min(pd - pc, pn - pd - es);
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	vecswap(pb, pn - r, r);
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	/*
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	 * To save stack space we sort the smaller side of the partition first
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	 * using recursion and eliminate tail recursion for the larger side.
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	 */
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	r = pb - pa;
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	s = pd - pc;
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	if (r < s) {
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		/* Recurse for 1st side, iterate for 2nd side. */
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		if (s > es) {
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			if (r > es) {
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				introsort(a, r / es, es, maxdepth,
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				    swaptype, cmp);
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			}
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			a = pn - s;
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			n = s / es;
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			goto loop;
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		}
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	} else {
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		/* Recurse for 2nd side, iterate for 1st side. */
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		if (r > es) {
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			if (s > es) {
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				introsort(pn - s, s / es, es, maxdepth,
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				    swaptype, cmp);
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			}
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			n = r / es;
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			goto loop;
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		}
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	}
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}
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void
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qsort(void *a, size_t n, size_t es, int (*cmp)(const void *, const void *))
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{
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	size_t i, maxdepth = 0;
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	int swaptype;
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	/* Approximate 2*ceil(lg(n + 1)) */
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	for (i = n; i > 0; i >>= 1)
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		maxdepth++;
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	maxdepth *= 2;
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	if (TYPE_ALIGNED(long, a, es))
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		swaptype = es == sizeof(long) ? SWAPTYPE_LONG : SWAPTYPE_LONGV;
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	else if (sizeof(int) != sizeof(long) && TYPE_ALIGNED(int, a, es))
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		swaptype = es == sizeof(int) ? SWAPTYPE_INT : SWAPTYPE_INTV;
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	else
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		swaptype = SWAPTYPE_BYTEV;
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	introsort(a, n, es, maxdepth, swaptype, cmp);
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}
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DEF_STRONG(qsort);