reactos/lib/rtl/qsort.c

/*
 * COPYRIGHT:
 *-
 * 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. 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.
 *
 * PROJECT:           ReactOS system libraries
 * PURPOSE:           Unicode Conversion Routines
 * FILE:              lib/rtl/qsort.c
 * PROGRAMMER:        Adapted from CygWin newlib 2000-03-12.
 */
#include <rtl.h>

/* FIXME: these types should be from the default includes */

typedef int (__cdecl* 	_pfunccmp_t) (const void *, const void *);

/*
 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
 */
#define swapcode(TYPE, parmi, parmj, n) { 		\
	long i = (n) / sizeof (TYPE); 			\
	register TYPE *pi = (TYPE *) (parmi); 		\
	register TYPE *pj = (TYPE *) (parmj); 		\
	do { 						\
		register 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,
	int	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 *)(a);			\
		*(long *)(a) = *(long *)(b);		\
		*(long *)(b) = t;			\
	} else						\
		swapfunc(a, b, es, swaptype)

#define vecswap(a, b, n) 	if ((n) > 0) swapfunc(a, b, n, swaptype)

static __inline char *
med3 (
	char		* a,
	char		* b,
	char		* c,
	_pfunccmp_t	cmp
	)
{
	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 ));
}


/* EXPORTED */
void
__cdecl
qsort (
	void		* a,
	size_t		n,
	size_t		es,
	_pfunccmp_t	cmp
	)
{
	char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
	int d, r, swaptype, swap_cnt;

loop:	SWAPINIT(a, es);
	swap_cnt = 0;
	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) > 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);
			pm = med3(pm - d, pm, pm + d, cmp);
			pn = med3(pn - 2 * d, pn - d, pn, cmp);
		}
		pm = med3(pl, pm, pn, cmp);
	}
	swap(a, pm);
	pa = pb = (char *) a + es;

	pc = pd = (char *) a + (n - 1) * es;
	for (;;)
	{
		while (pb <= pc && (r = cmp(pb, a)) <= 0)
		{
			if (r == 0)
			{
				swap_cnt = 1;
				swap(pa, pb);
				pa += es;
			}
			pb += es;
		}
		while (pb <= pc && (r = cmp(pc, a)) >= 0)
		{
			if (r == 0)
			{
				swap_cnt = 1;
				swap(pc, pd);
				pd -= es;
			}
			pc -= es;
		}
		if (pb > pc)
		{
			break;
		}
		swap(pb, pc);
		swap_cnt = 1;
		pb += es;
		pc -= es;
	}
	if (swap_cnt == 0)  /* Switch to insertion sort */
	{
		for (	pm = (char *) a + es;
			pm < (char *) a + n * es;
			pm += es
			)
		{
			for (	pl = pm;
				pl > (char *) a && cmp(pl - es, pl) > 0;
				pl -= es
				)
			{
				swap(pl, pl - es);
			}
		}
		return;
	}

	pn = (char *) a + n * es;
	r = min(pa - (char *)a, pb - pa);
	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;
	}
/*		qsort(pn - r, r / es, es, cmp);*/
}


/* EOF */