xref: /freebsd/sys/libkern/qsort.c (revision da31cbbca0f3ce0826f8c0d1f71224b3a0264f37)
1d89a1b60SPoul-Henning Kamp /*-
2d89a1b60SPoul-Henning Kamp  * Copyright (c) 1992, 1993
3d89a1b60SPoul-Henning Kamp  *	The Regents of the University of California.  All rights reserved.
4d89a1b60SPoul-Henning Kamp  *
5d89a1b60SPoul-Henning Kamp  * Redistribution and use in source and binary forms, with or without
6d89a1b60SPoul-Henning Kamp  * modification, are permitted provided that the following conditions
7d89a1b60SPoul-Henning Kamp  * are met:
8d89a1b60SPoul-Henning Kamp  * 1. Redistributions of source code must retain the above copyright
9d89a1b60SPoul-Henning Kamp  *    notice, this list of conditions and the following disclaimer.
10d89a1b60SPoul-Henning Kamp  * 2. Redistributions in binary form must reproduce the above copyright
11d89a1b60SPoul-Henning Kamp  *    notice, this list of conditions and the following disclaimer in the
12d89a1b60SPoul-Henning Kamp  *    documentation and/or other materials provided with the distribution.
13fbbd9655SWarner Losh  * 3. Neither the name of the University nor the names of its contributors
14d89a1b60SPoul-Henning Kamp  *    may be used to endorse or promote products derived from this software
15d89a1b60SPoul-Henning Kamp  *    without specific prior written permission.
16d89a1b60SPoul-Henning Kamp  *
17d89a1b60SPoul-Henning Kamp  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18d89a1b60SPoul-Henning Kamp  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19d89a1b60SPoul-Henning Kamp  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20d89a1b60SPoul-Henning Kamp  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21d89a1b60SPoul-Henning Kamp  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22d89a1b60SPoul-Henning Kamp  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23d89a1b60SPoul-Henning Kamp  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24d89a1b60SPoul-Henning Kamp  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25d89a1b60SPoul-Henning Kamp  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26d89a1b60SPoul-Henning Kamp  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27d89a1b60SPoul-Henning Kamp  * SUCH DAMAGE.
28d89a1b60SPoul-Henning Kamp  */
29d89a1b60SPoul-Henning Kamp 
30ab0de15bSDavid E. O'Brien #include <sys/cdefs.h>
31ab0de15bSDavid E. O'Brien __FBSDID("$FreeBSD$");
32ab0de15bSDavid E. O'Brien 
33b1e34c44SGleb Smirnoff #include <sys/param.h>
3453592f43SPoul-Henning Kamp #include <sys/libkern.h>
35d89a1b60SPoul-Henning Kamp 
36b1e34c44SGleb Smirnoff #ifdef I_AM_QSORT_R
37b1e34c44SGleb Smirnoff typedef int		 cmp_t(void *, const void *, const void *);
38b1e34c44SGleb Smirnoff #else
398febc6baSAlfred Perlstein typedef int		 cmp_t(const void *, const void *);
40b1e34c44SGleb Smirnoff #endif
41*da31cbbcSXin LI static inline char	*med3(char *, char *, char *, cmp_t *, void *);
42*da31cbbcSXin LI static inline void	 swapfunc(char *, char *, size_t, int, int);
43d89a1b60SPoul-Henning Kamp 
44d89a1b60SPoul-Henning Kamp /*
45d89a1b60SPoul-Henning Kamp  * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
46d89a1b60SPoul-Henning Kamp  */
47d89a1b60SPoul-Henning Kamp #define	swapcode(TYPE, parmi, parmj, n) {		\
48*da31cbbcSXin LI 	size_t i = (n) / sizeof (TYPE);			\
49484820d4SConrad Meyer 	TYPE *pi = (TYPE *) (parmi);		\
50484820d4SConrad Meyer 	TYPE *pj = (TYPE *) (parmj);		\
51d89a1b60SPoul-Henning Kamp 	do { 						\
52484820d4SConrad Meyer 		TYPE	t = *pi;		\
53d89a1b60SPoul-Henning Kamp 		*pi++ = *pj;				\
54d89a1b60SPoul-Henning Kamp 		*pj++ = t;				\
55d89a1b60SPoul-Henning Kamp 	} while (--i > 0);				\
56d89a1b60SPoul-Henning Kamp }
57d89a1b60SPoul-Henning Kamp 
58*da31cbbcSXin LI #define	SWAPINIT(TYPE, a, es) swaptype_ ## TYPE =	\
59*da31cbbcSXin LI 	((char *)a - (char *)0) % sizeof(TYPE) ||	\
60*da31cbbcSXin LI 	es % sizeof(TYPE) ? 2 : es == sizeof(TYPE) ? 0 : 1;
61d89a1b60SPoul-Henning Kamp 
62*da31cbbcSXin LI static inline void
63*da31cbbcSXin LI swapfunc(char *a, char *b, size_t n, int swaptype_long, int swaptype_int)
64d89a1b60SPoul-Henning Kamp {
65*da31cbbcSXin LI 	if (swaptype_long <= 1)
66d89a1b60SPoul-Henning Kamp 		swapcode(long, a, b, n)
67*da31cbbcSXin LI 	else if (swaptype_int <= 1)
68*da31cbbcSXin LI 		swapcode(int, a, b, n)
69d89a1b60SPoul-Henning Kamp 	else
70d89a1b60SPoul-Henning Kamp 		swapcode(char, a, b, n)
71d89a1b60SPoul-Henning Kamp }
72d89a1b60SPoul-Henning Kamp 
73d89a1b60SPoul-Henning Kamp #define	swap(a, b)					\
74*da31cbbcSXin LI 	if (swaptype_long == 0) {			\
75d89a1b60SPoul-Henning Kamp 		long t = *(long *)(a);			\
76d89a1b60SPoul-Henning Kamp 		*(long *)(a) = *(long *)(b);		\
77d89a1b60SPoul-Henning Kamp 		*(long *)(b) = t;			\
78*da31cbbcSXin LI 	} else if (swaptype_int == 0) {			\
79*da31cbbcSXin LI 		int t = *(int *)(a);			\
80*da31cbbcSXin LI 		*(int *)(a) = *(int *)(b);		\
81*da31cbbcSXin LI 		*(int *)(b) = t;			\
82d89a1b60SPoul-Henning Kamp 	} else						\
83*da31cbbcSXin LI 		swapfunc(a, b, es, swaptype_long, swaptype_int)
84d89a1b60SPoul-Henning Kamp 
85*da31cbbcSXin LI #define	vecswap(a, b, n)				\
86*da31cbbcSXin LI 	if ((n) > 0) swapfunc(a, b, n, swaptype_long, swaptype_int)
87d89a1b60SPoul-Henning Kamp 
88b1e34c44SGleb Smirnoff #ifdef I_AM_QSORT_R
89b1e34c44SGleb Smirnoff #define	CMP(t, x, y) (cmp((t), (x), (y)))
90b1e34c44SGleb Smirnoff #else
91b1e34c44SGleb Smirnoff #define	CMP(t, x, y) (cmp((x), (y)))
92b1e34c44SGleb Smirnoff #endif
93b1e34c44SGleb Smirnoff 
94*da31cbbcSXin LI static inline char *
95b1e34c44SGleb Smirnoff med3(char *a, char *b, char *c, cmp_t *cmp, void *thunk
96b1e34c44SGleb Smirnoff #ifndef I_AM_QSORT_R
97b1e34c44SGleb Smirnoff __unused
98b1e34c44SGleb Smirnoff #endif
99b1e34c44SGleb Smirnoff )
100d89a1b60SPoul-Henning Kamp {
101b1e34c44SGleb Smirnoff 	return CMP(thunk, a, b) < 0 ?
102b1e34c44SGleb Smirnoff 	       (CMP(thunk, b, c) < 0 ? b : (CMP(thunk, a, c) < 0 ? c : a ))
103b1e34c44SGleb Smirnoff 	      :(CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c ));
104d89a1b60SPoul-Henning Kamp }
105d89a1b60SPoul-Henning Kamp 
106b1e34c44SGleb Smirnoff #ifdef I_AM_QSORT_R
107d89a1b60SPoul-Henning Kamp void
108b1e34c44SGleb Smirnoff qsort_r(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp)
109b1e34c44SGleb Smirnoff #else
110b1e34c44SGleb Smirnoff #define	thunk NULL
111b1e34c44SGleb Smirnoff void
112b1e34c44SGleb Smirnoff qsort(void *a, size_t n, size_t es, cmp_t *cmp)
113b1e34c44SGleb Smirnoff #endif
114d89a1b60SPoul-Henning Kamp {
115d89a1b60SPoul-Henning Kamp 	char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
116*da31cbbcSXin LI 	size_t d1, d2;
117*da31cbbcSXin LI 	int cmp_result;
118*da31cbbcSXin LI 	int swaptype_long, swaptype_int, swap_cnt;
119d89a1b60SPoul-Henning Kamp 
120*da31cbbcSXin LI loop:	SWAPINIT(long, a, es);
121*da31cbbcSXin LI 	SWAPINIT(int, a, es);
122d89a1b60SPoul-Henning Kamp 	swap_cnt = 0;
123d89a1b60SPoul-Henning Kamp 	if (n < 7) {
12409a8dfa2SBruce Evans 		for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
125*da31cbbcSXin LI 			for (pl = pm;
126*da31cbbcSXin LI 			     pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
127d89a1b60SPoul-Henning Kamp 			     pl -= es)
128d89a1b60SPoul-Henning Kamp 				swap(pl, pl - es);
129d89a1b60SPoul-Henning Kamp 		return;
130d89a1b60SPoul-Henning Kamp 	}
13109a8dfa2SBruce Evans 	pm = (char *)a + (n / 2) * es;
132d89a1b60SPoul-Henning Kamp 	if (n > 7) {
133d89a1b60SPoul-Henning Kamp 		pl = a;
13409a8dfa2SBruce Evans 		pn = (char *)a + (n - 1) * es;
135d89a1b60SPoul-Henning Kamp 		if (n > 40) {
136*da31cbbcSXin LI 			size_t d = (n / 8) * es;
137*da31cbbcSXin LI 
138b1e34c44SGleb Smirnoff 			pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk);
139b1e34c44SGleb Smirnoff 			pm = med3(pm - d, pm, pm + d, cmp, thunk);
140b1e34c44SGleb Smirnoff 			pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk);
141d89a1b60SPoul-Henning Kamp 		}
142b1e34c44SGleb Smirnoff 		pm = med3(pl, pm, pn, cmp, thunk);
143d89a1b60SPoul-Henning Kamp 	}
144d89a1b60SPoul-Henning Kamp 	swap(a, pm);
14509a8dfa2SBruce Evans 	pa = pb = (char *)a + es;
146d89a1b60SPoul-Henning Kamp 
14709a8dfa2SBruce Evans 	pc = pd = (char *)a + (n - 1) * es;
148d89a1b60SPoul-Henning Kamp 	for (;;) {
149*da31cbbcSXin LI 		while (pb <= pc && (cmp_result = CMP(thunk, pb, a)) <= 0) {
150*da31cbbcSXin LI 			if (cmp_result == 0) {
151d89a1b60SPoul-Henning Kamp 				swap_cnt = 1;
152d89a1b60SPoul-Henning Kamp 				swap(pa, pb);
153d89a1b60SPoul-Henning Kamp 				pa += es;
154d89a1b60SPoul-Henning Kamp 			}
155d89a1b60SPoul-Henning Kamp 			pb += es;
156d89a1b60SPoul-Henning Kamp 		}
157*da31cbbcSXin LI 		while (pb <= pc && (cmp_result = CMP(thunk, pc, a)) >= 0) {
158*da31cbbcSXin LI 			if (cmp_result == 0) {
159d89a1b60SPoul-Henning Kamp 				swap_cnt = 1;
160d89a1b60SPoul-Henning Kamp 				swap(pc, pd);
161d89a1b60SPoul-Henning Kamp 				pd -= es;
162d89a1b60SPoul-Henning Kamp 			}
163d89a1b60SPoul-Henning Kamp 			pc -= es;
164d89a1b60SPoul-Henning Kamp 		}
165d89a1b60SPoul-Henning Kamp 		if (pb > pc)
166d89a1b60SPoul-Henning Kamp 			break;
167d89a1b60SPoul-Henning Kamp 		swap(pb, pc);
168d89a1b60SPoul-Henning Kamp 		swap_cnt = 1;
169d89a1b60SPoul-Henning Kamp 		pb += es;
170d89a1b60SPoul-Henning Kamp 		pc -= es;
171d89a1b60SPoul-Henning Kamp 	}
172d89a1b60SPoul-Henning Kamp 	if (swap_cnt == 0) {  /* Switch to insertion sort */
17309a8dfa2SBruce Evans 		for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
174*da31cbbcSXin LI 			for (pl = pm;
175*da31cbbcSXin LI 			     pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
176d89a1b60SPoul-Henning Kamp 			     pl -= es)
177d89a1b60SPoul-Henning Kamp 				swap(pl, pl - es);
178d89a1b60SPoul-Henning Kamp 		return;
179d89a1b60SPoul-Henning Kamp 	}
180d89a1b60SPoul-Henning Kamp 
18109a8dfa2SBruce Evans 	pn = (char *)a + n * es;
182*da31cbbcSXin LI 	d1 = MIN(pa - (char *)a, pb - pa);
183*da31cbbcSXin LI 	vecswap(a, pb - d1, d1);
184*da31cbbcSXin LI 	d1 = MIN(pd - pc, pn - pd - es);
185*da31cbbcSXin LI 	vecswap(pb, pn - d1, d1);
186*da31cbbcSXin LI 
187*da31cbbcSXin LI 	d1 = pb - pa;
188*da31cbbcSXin LI 	d2 = pd - pc;
189*da31cbbcSXin LI 	if (d1 <= d2) {
190*da31cbbcSXin LI 		/* Recurse on left partition, then iterate on right partition */
191*da31cbbcSXin LI 		if (d1 > es) {
192b1e34c44SGleb Smirnoff #ifdef I_AM_QSORT_R
193*da31cbbcSXin LI 			qsort_r(a, d1 / es, es, thunk, cmp);
194b1e34c44SGleb Smirnoff #else
195*da31cbbcSXin LI 			qsort(a, d1 / es, es, cmp);
196b1e34c44SGleb Smirnoff #endif
197*da31cbbcSXin LI 		}
198*da31cbbcSXin LI 		if (d2 > es) {
199d89a1b60SPoul-Henning Kamp 			/* Iterate rather than recurse to save stack space */
200*da31cbbcSXin LI 			/* qsort(pn - d2, d2 / es, es, cmp); */
201*da31cbbcSXin LI 			a = pn - d2;
202*da31cbbcSXin LI 			n = d2 / es;
203d89a1b60SPoul-Henning Kamp 			goto loop;
204d89a1b60SPoul-Henning Kamp 		}
205*da31cbbcSXin LI 	} else {
206*da31cbbcSXin LI 		/* Recurse on right partition, then iterate on left partition */
207*da31cbbcSXin LI 		if (d2 > es) {
208*da31cbbcSXin LI #ifdef I_AM_QSORT_R
209*da31cbbcSXin LI 			qsort_r(pn - d2, d2 / es, es, thunk, cmp);
210*da31cbbcSXin LI #else
211*da31cbbcSXin LI 			qsort(pn - d2, d2 / es, es, cmp);
212*da31cbbcSXin LI #endif
213*da31cbbcSXin LI 		}
214*da31cbbcSXin LI 		if (d1 > es) {
215*da31cbbcSXin LI 			/* Iterate rather than recurse to save stack space */
216*da31cbbcSXin LI 			/* qsort(a, d1 / es, es, cmp); */
217*da31cbbcSXin LI 			n = d1 / es;
218*da31cbbcSXin LI 			goto loop;
219*da31cbbcSXin LI 		}
220*da31cbbcSXin LI 	}
221d89a1b60SPoul-Henning Kamp }
222