[deliverable/linux.git] / fs / xfs / support / qsort.c

/*
 * 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 <linux/kernel.h>
#include <linux/string.h>

/*
 * 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, int (*cmp)(const void *, const void *))
{
	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 ));
}

void
qsort(void *aa, size_t n, size_t es, int (*cmp)(const void *, const void *))
{
	char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
	int d, r, swaptype, swap_cnt;
	register char *a = aa;

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((long)(pd - pc), (long)(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);*/
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Copyright (c) 1992, 1993
	3	* The Regents of the University of California. All rights reserved.
	4	*
	5	* Redistribution and use in source and binary forms, with or without
	6	* modification, are permitted provided that the following conditions
	7	* are met:
	8	* 1. Redistributions of source code must retain the above copyright
	9	* notice, this list of conditions and the following disclaimer.
	10	* 2. Redistributions in binary form must reproduce the above copyright
	11	* notice, this list of conditions and the following disclaimer in the
	12	* documentation and/or other materials provided with the distribution.
	13	* 3. Neither the name of the University nor the names of its contributors
	14	* may be used to endorse or promote products derived from this software
	15	* without specific prior written permission.
	16	*
	17	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	18	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	19	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	20	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	21	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	22	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	23	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	24	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	25	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	26	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	27	* SUCH DAMAGE.
	28	*/
1da177e4 LT	29	#include <linux/kernel.h>
	30	#include <linux/string.h>
	31
	32	/*
	33	* Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
	34	*/
	35	#define swapcode(TYPE, parmi, parmj, n) { \
	36	long i = (n) / sizeof (TYPE); \
	37	register TYPE pi = (TYPE ) (parmi); \
	38	register TYPE pj = (TYPE ) (parmj); \
	39	do { \
	40	register TYPE t = *pi; \
	41	pi++ = pj; \
	42	*pj++ = t; \
	43	} while (--i > 0); \
	44	}
	45
	46	#define SWAPINIT(a, es) swaptype = ((char )a - (char )0) % sizeof(long) \|\| \
	47	es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
	48
	49	static __inline void
	50	swapfunc(char a, char b, int n, int swaptype)
	51	{
	52	if (swaptype <= 1)
	53	swapcode(long, a, b, n)
	54	else
	55	swapcode(char, a, b, n)
	56	}
	57
	58	#define swap(a, b) \
	59	if (swaptype == 0) { \
	60	long t = (long )(a); \
	61	(long )(a) = (long )(b); \
	62	(long )(b) = t; \
	63	} else \
	64	swapfunc(a, b, es, swaptype)
	65
	66	#define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype)
	67
	68	static __inline char *
	69	med3(char a, char b, char c, int (cmp)(const void , const void ))
	70	{
	71	return cmp(a, b) < 0 ?
	72	(cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a ))
	73	:(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c ));
	74	}
	75
	76	void
	77	qsort(void aa, size_t n, size_t es, int (cmp)(const void , const void ))
	78	{
	79	char pa, pb, pc, pd, pl, pm, *pn;
	80	int d, r, swaptype, swap_cnt;
	81	register char *a = aa;
	82
	83	loop: SWAPINIT(a, es);
	84	swap_cnt = 0;
	85	if (n < 7) {
	86	for (pm = (char )a + es; pm < (char ) a + n * es; pm += es)
	87	for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
	88	pl -= es)
	89	swap(pl, pl - es);
	90	return;
	91	}
	92	pm = (char )a + (n / 2) es;
93	if (n > 7) {
94	pl = (char *)a;
95	pn = (char )a + (n - 1) es;
96	if (n > 40) {
97	d = (n / 8) * es;
98	pl = med3(pl, pl + d, pl + 2 * d, cmp);
99	pm = med3(pm - d, pm, pm + d, cmp);
100	pn = med3(pn - 2 * d, pn - d, pn, cmp);
101	}
102	pm = med3(pl, pm, pn, cmp);
103	}
104	swap(a, pm);
105	pa = pb = (char *)a + es;
106
107	pc = pd = (char )a + (n - 1) es;
108	for (;;) {
109	while (pb <= pc && (r = cmp(pb, a)) <= 0) {
110	if (r == 0) {
111	swap_cnt = 1;
112	swap(pa, pb);
113	pa += es;
114	}
115	pb += es;
116	}
117	while (pb <= pc && (r = cmp(pc, a)) >= 0) {
118	if (r == 0) {
119	swap_cnt = 1;
120	swap(pc, pd);
121	pd -= es;
122	}
123	pc -= es;
124	}
125	if (pb > pc)
126	break;
127	swap(pb, pc);
128	swap_cnt = 1;
129	pb += es;
130	pc -= es;
131	}
132	if (swap_cnt == 0) { /* Switch to insertion sort */
133	for (pm = (char ) a + es; pm < (char ) a + n * es; pm += es)
134	for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
135	pl -= es)
136	swap(pl, pl - es);
137	return;
138	}
139
140	pn = (char )a + n es;
141	r = min(pa - (char *)a, pb - pa);
142	vecswap(a, pb - r, r);
143	r = min((long)(pd - pc), (long)(pn - pd - es));
144	vecswap(pb, pn - r, r);
145	if ((r = pb - pa) > es)
146	qsort(a, r / es, es, cmp);
147	if ((r = pd - pc) > es) {
148	/* Iterate rather than recurse to save stack space */
149	a = pn - r;
150	n = r / es;
151	goto loop;
152	}
153	/* qsort(pn - r, r / es, es, cmp);*/
154	}