1 /* $NetBSD: qsort.c,v 1.22 2012/05/26 21:47:05 christos 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. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 #if defined(LIBC_SCCS) && !defined(lint) 34 #if 0 35 static char sccsid[] = "@(#)qsort.c 8.1 (Berkeley) 6/4/93"; 36 #else 37 __RCSID("$NetBSD: qsort.c,v 1.22 2012/05/26 21:47:05 christos Exp $"); 38 #endif 39 #endif /* LIBC_SCCS and not lint */ 40 41 #include <sys/types.h> 42 43 #include <assert.h> 44 #include <errno.h> 45 #include <stdlib.h> 46 47 static inline char *med3(char *, char *, char *, 48 int (*)(const void *, const void *)); 49 static inline void swapfunc(char *, char *, size_t, int); 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 size_t i = (n) / sizeof (TYPE); \ 58 TYPE *pi = (TYPE *)(void *)(parmi); \ 59 TYPE *pj = (TYPE *)(void *)(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 70 static inline void 71 swapfunc(char *a, char *b, size_t n, int swaptype) 72 { 73 74 if (swaptype <= 1) 75 swapcode(long, a, b, n) 76 else 77 swapcode(char, a, b, n) 78 } 79 80 #define swap(a, b) \ 81 if (swaptype == 0) { \ 82 long t = *(long *)(void *)(a); \ 83 *(long *)(void *)(a) = *(long *)(void *)(b); \ 84 *(long *)(void *)(b) = t; \ 85 } else \ 86 swapfunc(a, b, es, swaptype) 87 88 #define vecswap(a, b, n) if ((n) > 0) swapfunc((a), (b), (size_t)(n), swaptype) 89 90 static inline char * 91 med3(char *a, char *b, char *c, 92 int (*cmp)(const void *, const void *)) 93 { 94 95 return cmp(a, b) < 0 ? 96 (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a )) 97 :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c )); 98 } 99 100 void 101 qsort(void *a, size_t n, size_t es, 102 int (*cmp)(const void *, const void *)) 103 { 104 char *pa, *pb, *pc, *pd, *pl, *pm, *pn; 105 size_t d, r; 106 int swaptype, cmp_result; 107 108 _DIAGASSERT(a != NULL || n == 0 || es == 0); 109 _DIAGASSERT(cmp != NULL); 110 111 loop: SWAPINIT(a, es); 112 if (n < 7) { 113 for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es) 114 for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; 115 pl -= es) 116 swap(pl, pl - es); 117 return; 118 } 119 pm = (char *) a + (n / 2) * es; 120 if (n > 7) { 121 pl = (char *) a; 122 pn = (char *) a + (n - 1) * es; 123 if (n > 40) { 124 d = (n / 8) * es; 125 pl = med3(pl, pl + d, pl + 2 * d, cmp); 126 pm = med3(pm - d, pm, pm + d, cmp); 127 pn = med3(pn - 2 * d, pn - d, pn, cmp); 128 } 129 pm = med3(pl, pm, pn, cmp); 130 } 131 swap(a, pm); 132 pa = pb = (char *) a + es; 133 134 pc = pd = (char *) a + (n - 1) * es; 135 for (;;) { 136 while (pb <= pc && (cmp_result = cmp(pb, a)) <= 0) { 137 if (cmp_result == 0) { 138 swap(pa, pb); 139 pa += es; 140 } 141 pb += es; 142 } 143 while (pb <= pc && (cmp_result = cmp(pc, a)) >= 0) { 144 if (cmp_result == 0) { 145 swap(pc, pd); 146 pd -= es; 147 } 148 pc -= es; 149 } 150 if (pb > pc) 151 break; 152 swap(pb, pc); 153 pb += es; 154 pc -= es; 155 } 156 157 pn = (char *) a + n * es; 158 r = min(pa - (char *) a, pb - pa); 159 vecswap(a, pb - r, r); 160 r = min((size_t)(pd - pc), pn - pd - es); 161 vecswap(pb, pn - r, r); 162 if ((r = pb - pa) > es) 163 qsort(a, r / es, es, cmp); 164 if ((r = pd - pc) > es) { 165 /* Iterate rather than recurse to save stack space */ 166 a = pn - r; 167 n = r / es; 168 goto loop; 169 } 170 /* qsort(pn - r, r / es, es, cmp);*/ 171 } 172