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 * 4. 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 */
29
30#if defined(LIBC_SCCS) && !defined(lint)
31static char sccsid[] = "@(#)qsort.c	8.1 (Berkeley) 6/4/93";
32#endif /* LIBC_SCCS and not lint */
33#include <sys/cdefs.h>
34__FBSDID("$FreeBSD: src/lib/libc/stdlib/qsort.c,v 1.15 2008/01/14 09:21:34 das Exp $");
35
36#include <stdlib.h>
37#include <string.h>
38
39#ifdef I_AM_QSORT_R
40typedef int		 cmp_t(void *, const void *, const void *);
41#else
42typedef int		 cmp_t(const void *, const void *);
43#endif
44#ifdef I_AM_QSORT_B
45static inline char	*med3(char *, char *, char *, cmp_t ^, void *) __attribute__((always_inline));
46#else
47static inline char	*med3(char *, char *, char *, cmp_t *, void *) __attribute__((always_inline));
48#endif
49static inline void	 swapfunc(char *, char *, int, int) __attribute__((always_inline));
50
51#define min(a, b)	(a) < (b) ? a : b
52
53/*
54 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
55 */
56#define swapcode(TYPE, parmi, parmj, n) { 		\
57	long i = (n) / sizeof (TYPE); 			\
58	TYPE *pi = (TYPE *) (parmi); 		\
59	TYPE *pj = (TYPE *) (parmj); 		\
60	do { 						\
61		TYPE	t = *pi;		\
62		*pi++ = *pj;				\
63		*pj++ = t;				\
64        } while (--i > 0);				\
65}
66
67#define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
68	es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
69
70static inline void
71swapfunc(a, b, n, swaptype)
72	char *a, *b;
73	int n, swaptype;
74{
75	if(swaptype <= 1)
76		swapcode(long, a, b, n)
77	else
78		swapcode(char, a, b, n)
79}
80
81#define swap(a, b)					\
82	if (swaptype == 0) {				\
83		long t = *(long *)(a);			\
84		*(long *)(a) = *(long *)(b);		\
85		*(long *)(b) = t;			\
86	} else						\
87		swapfunc(a, b, es, swaptype)
88
89#define vecswap(a, b, n) 	if ((n) > 0) swapfunc(a, b, n, swaptype)
90
91#ifdef I_AM_QSORT_R
92#define	CMP(t, x, y) (cmp((t), (x), (y)))
93#else
94#define	CMP(t, x, y) (cmp((x), (y)))
95#endif
96
97static inline char *
98med3(char *a, char *b, char *c,
99#ifdef I_AM_QSORT_B
100cmp_t ^cmp,
101#else
102cmp_t *cmp,
103#endif
104void *thunk
105#ifndef I_AM_QSORT_R
106__unused
107#endif
108)
109{
110	return CMP(thunk, a, b) < 0 ?
111	       (CMP(thunk, b, c) < 0 ? b : (CMP(thunk, a, c) < 0 ? c : a ))
112              :(CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c ));
113}
114
115#ifdef __LP64__
116#define DEPTH(x)	(2 * (flsl((long)(x)) - 1))
117#else /* !__LP64__ */
118#define DEPTH(x)	(2 * (fls((int)(x)) - 1))
119#endif /* __LP64__ */
120
121#ifdef I_AM_QSORT_R
122int __heapsort_r(void *, size_t, size_t, void *, int (*)(void *, const void *, const void *));
123#endif
124
125static void
126_qsort(void *a, size_t n, size_t es,
127#ifdef I_AM_QSORT_R
128void *thunk,
129#else
130#define thunk	NULL
131#endif
132#ifdef I_AM_QSORT_B
133cmp_t ^cmp,
134#else
135cmp_t *cmp,
136#endif
137int depth_limit)
138{
139	char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
140	size_t d, r;
141	int cmp_result;
142	int swaptype, swap_cnt;
143
144loop:
145	if (depth_limit-- <= 0) {
146#ifdef I_AM_QSORT_B
147		heapsort_b(a, n, es, cmp);
148#elif defined(I_AM_QSORT_R)
149		__heapsort_r(a, n, es, thunk, cmp);
150#else
151		heapsort(a, n, es, cmp);
152#endif
153		return;
154	}
155	SWAPINIT(a, es);
156	swap_cnt = 0;
157	if (n < 7) {
158		for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
159			for (pl = pm;
160			     pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
161			     pl -= es)
162				swap(pl, pl - es);
163		return;
164	}
165	pm = (char *)a + (n / 2) * es;
166	if (n > 7) {
167		pl = a;
168		pn = (char *)a + (n - 1) * es;
169		if (n > 40) {
170			d = (n / 8) * es;
171			pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk);
172			pm = med3(pm - d, pm, pm + d, cmp, thunk);
173			pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk);
174		}
175		pm = med3(pl, pm, pn, cmp, thunk);
176	}
177	swap(a, pm);
178	pa = pb = (char *)a + es;
179
180	pc = pd = (char *)a + (n - 1) * es;
181	for (;;) {
182		while (pb <= pc && (cmp_result = CMP(thunk, pb, a)) <= 0) {
183			if (cmp_result == 0) {
184				swap_cnt = 1;
185				swap(pa, pb);
186				pa += es;
187			}
188			pb += es;
189		}
190		while (pb <= pc && (cmp_result = CMP(thunk, pc, a)) >= 0) {
191			if (cmp_result == 0) {
192				swap_cnt = 1;
193				swap(pc, pd);
194				pd -= es;
195			}
196			pc -= es;
197		}
198		if (pb > pc)
199			break;
200		swap(pb, pc);
201		swap_cnt = 1;
202		pb += es;
203		pc -= es;
204	}
205
206	pn = (char *)a + n * es;
207	r = min(pa - (char *)a, pb - pa);
208	vecswap(a, pb - r, r);
209	r = min(pd - pc, pn - pd - es);
210	vecswap(pb, pn - r, r);
211
212	if (swap_cnt == 0) {  /* Switch to insertion sort */
213		r = 1 + n / 4; /* n >= 7, so r >= 2 */
214		for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
215			for (pl = pm;
216			     pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
217			     pl -= es) {
218				swap(pl, pl - es);
219				if (++swap_cnt > r) goto nevermind;
220			}
221		return;
222	}
223
224nevermind:
225	if ((r = pb - pa) > es)
226#ifdef I_AM_QSORT_R
227		_qsort(a, r / es, es, thunk, cmp, depth_limit);
228#else
229		_qsort(a, r / es, es, cmp, depth_limit);
230#endif
231	if ((r = pd - pc) > es) {
232		/* Iterate rather than recurse to save stack space */
233		a = pn - r;
234		n = r / es;
235		goto loop;
236	}
237/*		qsort(pn - r, r / es, es, cmp);*/
238}
239
240void
241#ifdef I_AM_QSORT_R
242qsort_r(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp)
243#elif defined(I_AM_QSORT_B)
244qsort_b(void *a, size_t n, size_t es, cmp_t ^cmp)
245#else
246qsort(void *a, size_t n, size_t es, cmp_t *cmp)
247#endif
248{
249	_qsort(a, n, es,
250#ifdef I_AM_QSORT_R
251		thunk,
252#endif
253		cmp, DEPTH(n));
254}
255