xpcom/ds/nsQuickSort.cpp
author Kris Maglione <maglione.k@gmail.com>
Thu, 10 May 2018 10:36:53 -0700
changeset 473641 1becc594554c1a273535ed175895e801667735e9
parent 377484 a3af628d69b3f4d4f029d5f9118dd44bf1fadbd3
child 505383 6f3709b3878117466168c40affa7bca0b60cf75b
permissions -rw-r--r--
Bug 1460600: Remove unsupported --enable-system-hunspell flag. r=glandium Our bundled Hunspell now significantly differs from upstream Hunspell. Most importantly, it supports loading dictionaries from jar: URIs, which is now a requirement for loading bundled and extension dictionaries. This means that system Hunspell libraries are no longer compatible with our spell checker code. We should remove the option to use them so that users don't fall into the trap of trying to use them. MozReview-Commit-ID: 2ihJe6YOnGf

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/*-
 * 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.
 */

/* We need this because Solaris' version of qsort is broken and
 * causes array bounds reads.
 */

#include <stdlib.h>
#include "nsAlgorithm.h"
#include "nsQuickSort.h"

extern "C" {

#if !defined(DEBUG) && (defined(__cplusplus) || defined(__gcc))
# ifndef INLINE
#  define INLINE inline
# endif
#else
# define INLINE
#endif

typedef int		 cmp_t(const void *, const void *, void *);
static INLINE char	*med3(char *, char *, char *, cmp_t *, void *);
static INLINE void	swapfunc(char *, char *, int, int);

/*
 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
 */
#define swapcode(TYPE, parmi, parmj, n) { 		\
	long i = (n) / sizeof (TYPE); 			\
	TYPE *pi = (TYPE *) (parmi); 			\
	TYPE *pj = (TYPE *) (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, 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((char *)a, (char*)b, (int)es, swaptype)

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

static INLINE char *
med3(char *a, char *b, char *c, cmp_t* cmp, void *data)
{
	return cmp(a, b, data) < 0 ?
	       (cmp(b, c, data) < 0 ? b : (cmp(a, c, data) < 0 ? c : a ))
              :(cmp(b, c, data) > 0 ? b : (cmp(a, c, data) < 0 ? a : c ));
}

void NS_QuickSort (
	void *a,
	unsigned int n,
    unsigned int es,
	cmp_t *cmp,
	void *data
    )
{
	char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
	int d, r, swaptype;

loop:	SWAPINIT(a, es);
	/* Use insertion sort when input is small */
	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, data) > 0;
			     pl -= es)
				swap(pl, pl - es);
		return;
	}
	/* Choose pivot */
	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, data);
			pm = med3(pm - d, pm, pm + d, cmp, data);
			pn = med3(pn - 2 * d, pn - d, pn, cmp, data);
		}
		pm = med3(pl, pm, pn, cmp, data);
	}
	swap(a, pm);
	pa = pb = (char *)a + es;

	pc = pd = (char *)a + (n - 1) * es;
	/* loop invariants:
	 * [a, pa) = pivot
	 * [pa, pb) < pivot
	 * [pb, pc + es) unprocessed
	 * [pc + es, pd + es) > pivot
	 * [pd + es, pn) = pivot
	 */
	for (;;) {
		while (pb <= pc && (r = cmp(pb, a, data)) <= 0) {
			if (r == 0) {
				swap(pa, pb);
				pa += es;
			}
			pb += es;
		}
		while (pb <= pc && (r = cmp(pc, a, data)) >= 0) {
			if (r == 0) {
				swap(pc, pd);
				pd -= es;
			}
			pc -= es;
		}
		if (pb > pc)
			break;
		swap(pb, pc);
		pb += es;
		pc -= es;
	}
	/* Move pivot values */
	pn = (char *)a + n * es;
	r = XPCOM_MIN(pa - (char *)a, pb - pa);
	vecswap(a, pb - r, r);
	r = XPCOM_MIN<size_t>(pd - pc, pn - pd - es);
	vecswap(pb, pn - r, r);
	/* Recursively process partitioned items */
	if ((r = pb - pa) > (int)es)
        NS_QuickSort(a, r / es, es, cmp, data);
	if ((r = pd - pc) > (int)es) {
		/* Iterate rather than recurse to save stack space */
		a = pn - r;
		n = r / es;
		goto loop;
	}
/*		NS_QuickSort(pn - r, r / es, es, cmp, data);*/
}

}

#undef INLINE
#undef swapcode
#undef SWAPINIT
#undef swap
#undef vecswap