1 /* $NetBSD: qsort.c,v 1.12 1999/09/20 04:39:40 lukem Exp $ */ 2 3 /*- 4 * Copyright (c) 1992, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by the University of 18 * California, Berkeley and its contributors. 19 * 4. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36 #include <sys/cdefs.h> 37 #if defined(LIBC_SCCS) && !defined(lint) 38 #if 0 39 static char sccsid[] = "@(#)qsort.c 8.1 (Berkeley) 6/4/93"; 40 #else 41 __RCSID("$NetBSD: qsort.c,v 1.12 1999/09/20 04:39:40 lukem Exp $"); 42 #endif 43 #endif /* LIBC_SCCS and not lint */ 44 45 #include <sys/types.h> 46 47 #include <assert.h> 48 #include <errno.h> 49 #include <stdlib.h> 50 51 static __inline char *med3 __P((char *, char *, char *, 52 int (*)(const void *, const void *))); 53 static __inline void swapfunc __P((char *, char *, size_t, int)); 54 55 #define min(a, b) (a) < (b) ? a : b 56 57 /* 58 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". 59 */ 60 #define swapcode(TYPE, parmi, parmj, n) { \ 61 size_t i = (n) / sizeof (TYPE); \ 62 TYPE *pi = (TYPE *)(void *)(parmi); \ 63 TYPE *pj = (TYPE *)(void *)(parmj); \ 64 do { \ 65 TYPE t = *pi; \ 66 *pi++ = *pj; \ 67 *pj++ = t; \ 68 } while (--i > 0); \ 69 } 70 71 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \ 72 es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1; 73 74 static __inline void 75 swapfunc(a, b, n, swaptype) 76 char *a, *b; 77 size_t n; 78 int swaptype; 79 { 80 if (swaptype <= 1) 81 swapcode(long, a, b, n) 82 else 83 swapcode(char, a, b, n) 84 } 85 86 #define swap(a, b) \ 87 if (swaptype == 0) { \ 88 long t = *(long *)(void *)(a); \ 89 *(long *)(void *)(a) = *(long *)(void *)(b); \ 90 *(long *)(void *)(b) = t; \ 91 } else \ 92 swapfunc(a, b, es, swaptype) 93 94 #define vecswap(a, b, n) if ((n) > 0) swapfunc((a), (b), (size_t)(n), swaptype) 95 96 static __inline char * 97 med3(a, b, c, cmp) 98 char *a, *b, *c; 99 int (*cmp) __P((const void *, const void *)); 100 { 101 return cmp(a, b) < 0 ? 102 (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a )) 103 :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c )); 104 } 105 106 void 107 qsort(a, n, es, cmp) 108 void *a; 109 size_t n, es; 110 int (*cmp) __P((const void *, const void *)); 111 { 112 char *pa, *pb, *pc, *pd, *pl, *pm, *pn; 113 int d, r, swaptype, swap_cnt; 114 115 _DIAGASSERT(a != NULL); 116 _DIAGASSERT(cmp != NULL); 117 118 loop: SWAPINIT(a, es); 119 swap_cnt = 0; 120 if (n < 7) { 121 for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es) 122 for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; 123 pl -= es) 124 swap(pl, pl - es); 125 return; 126 } 127 pm = (char *) a + (n / 2) * es; 128 if (n > 7) { 129 pl = (char *) a; 130 pn = (char *) a + (n - 1) * es; 131 if (n > 40) { 132 d = (n / 8) * es; 133 pl = med3(pl, pl + d, pl + 2 * d, cmp); 134 pm = med3(pm - d, pm, pm + d, cmp); 135 pn = med3(pn - 2 * d, pn - d, pn, cmp); 136 } 137 pm = med3(pl, pm, pn, cmp); 138 } 139 swap(a, pm); 140 pa = pb = (char *) a + es; 141 142 pc = pd = (char *) a + (n - 1) * es; 143 for (;;) { 144 while (pb <= pc && (r = cmp(pb, a)) <= 0) { 145 if (r == 0) { 146 swap_cnt = 1; 147 swap(pa, pb); 148 pa += es; 149 } 150 pb += es; 151 } 152 while (pb <= pc && (r = cmp(pc, a)) >= 0) { 153 if (r == 0) { 154 swap_cnt = 1; 155 swap(pc, pd); 156 pd -= es; 157 } 158 pc -= es; 159 } 160 if (pb > pc) 161 break; 162 swap(pb, pc); 163 swap_cnt = 1; 164 pb += es; 165 pc -= es; 166 } 167 if (swap_cnt == 0) { /* Switch to insertion sort */ 168 for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es) 169 for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; 170 pl -= es) 171 swap(pl, pl - es); 172 return; 173 } 174 175 pn = (char *) a + n * es; 176 r = min(pa - (char *) a, pb - pa); 177 vecswap(a, pb - r, r); 178 r = min(pd - pc, pn - pd - es); 179 vecswap(pb, pn - r, r); 180 if ((r = pb - pa) > es) 181 qsort(a, r / es, es, cmp); 182 if ((r = pd - pc) > es) { 183 /* Iterate rather than recurse to save stack space */ 184 a = pn - r; 185 n = r / es; 186 goto loop; 187 } 188 /* qsort(pn - r, r / es, es, cmp);*/ 189 } 190