xref: /freebsd/crypto/heimdal/lib/roken/qsort.c (revision 0957b409)
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  */
29 
30 #if 0
31 #if defined(LIBC_SCCS) && !defined(lint)
32 static char sccsid[] = "@(#)qsort.c	8.1 (Berkeley) 6/4/93";
33 #endif /* LIBC_SCCS and not lint */
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
36 #endif
37 
38 #include <config.h>
39 
40 #ifdef NEED_QSORT
41 
42 #include "roken.h"
43 
44 #include <stdlib.h>
45 
46 #ifdef I_AM_QSORT_R
47 typedef int		 cmp_t(void *, const void *, const void *);
48 #else
49 typedef int		 cmp_t(const void *, const void *);
50 #endif
51 static inline char	*med3(char *, char *, char *, cmp_t *, void *);
52 static inline void	 swapfunc(char *, char *, int, int);
53 
54 /*
55  * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
56  */
57 #define swapcode(TYPE, parmi, parmj, n) { 		\
58 	long i = (n) / sizeof (TYPE); 			\
59 	TYPE *pi = (TYPE *) (parmi); 		\
60 	TYPE *pj = (TYPE *) (parmj); 		\
61 	do { 						\
62 		TYPE	t = *pi;		\
63 		*pi++ = *pj;				\
64 		*pj++ = t;				\
65         } while (--i > 0);				\
66 }
67 
68 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
69 	es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
70 
71 static inline void
72 swapfunc(a, b, n, swaptype)
73 	char *a, *b;
74 	int n, swaptype;
75 {
76 	if(swaptype <= 1)
77 		swapcode(long, a, b, n)
78 	else
79 		swapcode(char, a, b, n)
80 }
81 
82 #define swap(a, b)					\
83 	if (swaptype == 0) {				\
84 		long t = *(long *)(a);			\
85 		*(long *)(a) = *(long *)(b);		\
86 		*(long *)(b) = t;			\
87 	} else						\
88 		swapfunc(a, b, es, swaptype)
89 
90 #define vecswap(a, b, n) 	if ((n) > 0) swapfunc(a, b, n, swaptype)
91 
92 #ifdef I_AM_QSORT_R
93 #define	CMP(t, x, y) (cmp((t), (x), (y)))
94 #else
95 #define	CMP(t, x, y) (cmp((x), (y)))
96 #endif
97 
98 static inline char *
99 med3(char *a, char *b, char *c, cmp_t *cmp, void *thunk
100 #ifndef I_AM_QSORT_R
101 /* __unused */
102 #endif
103 )
104 {
105 	return CMP(thunk, a, b) < 0 ?
106 	       (CMP(thunk, b, c) < 0 ? b : (CMP(thunk, a, c) < 0 ? c : a ))
107               :(CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c ));
108 }
109 
110 #ifdef I_AM_QSORT_R
111 void
112 rk_qsort_r(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp)
113 #else
114 #define thunk NULL
115 void
116 rk_qsort(void *a, size_t n, size_t es, cmp_t *cmp)
117 #endif
118 {
119 	char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
120 	size_t d, r;
121 	int cmp_result;
122 	int swaptype, swap_cnt;
123 
124 loop:	SWAPINIT(a, es);
125 	swap_cnt = 0;
126 	if (n < 7) {
127 		for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
128 			for (pl = pm;
129 			     pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
130 			     pl -= es)
131 				swap(pl, pl - es);
132 		return;
133 	}
134 	pm = (char *)a + (n / 2) * es;
135 	if (n > 7) {
136 		pl = a;
137 		pn = (char *)a + (n - 1) * es;
138 		if (n > 40) {
139 			d = (n / 8) * es;
140 			pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk);
141 			pm = med3(pm - d, pm, pm + d, cmp, thunk);
142 			pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk);
143 		}
144 		pm = med3(pl, pm, pn, cmp, thunk);
145 	}
146 	swap(a, pm);
147 	pa = pb = (char *)a + es;
148 
149 	pc = pd = (char *)a + (n - 1) * es;
150 	for (;;) {
151 		while (pb <= pc && (cmp_result = CMP(thunk, pb, a)) <= 0) {
152 			if (cmp_result == 0) {
153 				swap_cnt = 1;
154 				swap(pa, pb);
155 				pa += es;
156 			}
157 			pb += es;
158 		}
159 		while (pb <= pc && (cmp_result = CMP(thunk, pc, a)) >= 0) {
160 			if (cmp_result == 0) {
161 				swap_cnt = 1;
162 				swap(pc, pd);
163 				pd -= es;
164 			}
165 			pc -= es;
166 		}
167 		if (pb > pc)
168 			break;
169 		swap(pb, pc);
170 		swap_cnt = 1;
171 		pb += es;
172 		pc -= es;
173 	}
174 	if (swap_cnt == 0) {  /* Switch to insertion sort */
175 		for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
176 			for (pl = pm;
177 			     pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
178 			     pl -= es)
179 				swap(pl, pl - es);
180 		return;
181 	}
182 
183 	pn = (char *)a + n * es;
184 	r = min(pa - (char *)a, pb - pa);
185 	vecswap(a, pb - r, r);
186 	r = min(pd - pc, pn - pd - es);
187 	vecswap(pb, pn - r, r);
188 	if ((r = pb - pa) > es)
189 #ifdef I_AM_QSORT_R
190 		rk_qsort_r(a, r / es, es, thunk, cmp);
191 #else
192 		rk_qsort(a, r / es, es, cmp);
193 #endif
194 	if ((r = pd - pc) > es) {
195 		/* Iterate rather than recurse to save stack space */
196 		a = pn - r;
197 		n = r / es;
198 		goto loop;
199 	}
200 /*		rk_qsort(pn - r, r / es, es, cmp);*/
201 }
202 
203 #endif /* NEED_QSORT */
204