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 defined(LIBC_SCCS) && !defined(lint) 31 static char *rcsid = "$OpenBSD: qsort.c,v 1.9 2005/03/30 18:51:49 pat Exp $"; 32 #endif /* LIBC_SCCS and not lint */ 33 34 #include <sys/types.h> 35 #include <stdlib.h> 36 37 static __inline char *med3(char *, char *, char *, int (*)(const void *, const void *)); 38 static __inline void swapfunc(char *, char *, int, int); 39 40 #define min(a, b) (a) < (b) ? a : b 41 42 /* 43 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". 44 */ 45 #define swapcode(TYPE, parmi, parmj, n) { \ 46 long i = (n) / sizeof (TYPE); \ 47 TYPE *pi = (TYPE *) (parmi); \ 48 TYPE *pj = (TYPE *) (parmj); \ 49 do { \ 50 TYPE t = *pi; \ 51 *pi++ = *pj; \ 52 *pj++ = t; \ 53 } while (--i > 0); \ 54 } 55 56 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \ 57 es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1; 58 59 static __inline void 60 swapfunc(char *a, char *b, int n, int swaptype) 61 { 62 if (swaptype <= 1) 63 swapcode(long, a, b, n) 64 else 65 swapcode(char, a, b, n) 66 } 67 68 #define swap(a, b) \ 69 if (swaptype == 0) { \ 70 long t = *(long *)(a); \ 71 *(long *)(a) = *(long *)(b); \ 72 *(long *)(b) = t; \ 73 } else \ 74 swapfunc(a, b, es, swaptype) 75 76 #define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype) 77 78 static __inline char * 79 med3(char *a, char *b, char *c, int (*cmp)(const void *, const void *)) 80 { 81 return cmp(a, b) < 0 ? 82 (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a )) 83 :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c )); 84 } 85 86 void 87 qsort(void *aa, size_t n, size_t es, int (*cmp)(const void *, const void *)) 88 { 89 char *pa, *pb, *pc, *pd, *pl, *pm, *pn; 90 int d, r, swaptype, swap_cnt; 91 char *a = aa; 92 93 loop: SWAPINIT(a, es); 94 swap_cnt = 0; 95 if (n < 7) { 96 for (pm = (char *)a + es; pm < (char *) a + n * es; pm += es) 97 for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; 98 pl -= es) 99 swap(pl, pl - es); 100 return; 101 } 102 pm = (char *)a + (n / 2) * es; 103 if (n > 7) { 104 pl = (char *)a; 105 pn = (char *)a + (n - 1) * es; 106 if (n > 40) { 107 d = (n / 8) * es; 108 pl = med3(pl, pl + d, pl + 2 * d, cmp); 109 pm = med3(pm - d, pm, pm + d, cmp); 110 pn = med3(pn - 2 * d, pn - d, pn, cmp); 111 } 112 pm = med3(pl, pm, pn, cmp); 113 } 114 swap(a, pm); 115 pa = pb = (char *)a + es; 116 117 pc = pd = (char *)a + (n - 1) * es; 118 for (;;) { 119 while (pb <= pc && (r = cmp(pb, a)) <= 0) { 120 if (r == 0) { 121 swap_cnt = 1; 122 swap(pa, pb); 123 pa += es; 124 } 125 pb += es; 126 } 127 while (pb <= pc && (r = cmp(pc, a)) >= 0) { 128 if (r == 0) { 129 swap_cnt = 1; 130 swap(pc, pd); 131 pd -= es; 132 } 133 pc -= es; 134 } 135 if (pb > pc) 136 break; 137 swap(pb, pc); 138 swap_cnt = 1; 139 pb += es; 140 pc -= es; 141 } 142 if (swap_cnt == 0) { /* Switch to insertion sort */ 143 for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es) 144 for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; 145 pl -= es) 146 swap(pl, pl - es); 147 return; 148 } 149 150 pn = (char *)a + n * es; 151 r = min(pa - (char *)a, pb - pa); 152 vecswap(a, pb - r, r); 153 r = min(pd - pc, pn - pd - es); 154 vecswap(pb, pn - r, r); 155 if ((r = pb - pa) > es) 156 qsort(a, r / es, es, cmp); 157 if ((r = pd - pc) > es) { 158 /* Iterate rather than recurse to save stack space */ 159 a = pn - r; 160 n = r / es; 161 goto loop; 162 } 163 /* qsort(pn - r, r / es, es, cmp);*/ 164 } 165