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. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * @(#)qsort.c 8.1 (Berkeley) 6/4/93 34 * $FreeBSD: src/lib/libc/stdlib/qsort.c,v 1.8 1999/08/28 00:01:35 peter Exp $ 35 * $DragonFly: src/lib/libc/stdlib/qsort.c,v 1.2 2003/06/17 04:26:46 dillon Exp $ 36 */ 37 38 #include <stdlib.h> 39 40 typedef int cmp_t __P((const void *, const void *)); 41 static inline char *med3 __P((char *, char *, char *, cmp_t *)); 42 static inline void swapfunc __P((char *, char *, int, int)); 43 44 #define min(a, b) (a) < (b) ? a : b 45 46 /* 47 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". 48 */ 49 #define swapcode(TYPE, parmi, parmj, n) { \ 50 long i = (n) / sizeof (TYPE); \ 51 register TYPE *pi = (TYPE *) (parmi); \ 52 register TYPE *pj = (TYPE *) (parmj); \ 53 do { \ 54 register TYPE t = *pi; \ 55 *pi++ = *pj; \ 56 *pj++ = t; \ 57 } while (--i > 0); \ 58 } 59 60 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \ 61 es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1; 62 63 static inline void 64 swapfunc(a, b, n, swaptype) 65 char *a, *b; 66 int n, swaptype; 67 { 68 if(swaptype <= 1) 69 swapcode(long, a, b, n) 70 else 71 swapcode(char, a, b, n) 72 } 73 74 #define swap(a, b) \ 75 if (swaptype == 0) { \ 76 long t = *(long *)(a); \ 77 *(long *)(a) = *(long *)(b); \ 78 *(long *)(b) = t; \ 79 } else \ 80 swapfunc(a, b, es, swaptype) 81 82 #define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype) 83 84 static inline char * 85 med3(a, b, c, cmp) 86 char *a, *b, *c; 87 cmp_t *cmp; 88 { 89 return cmp(a, b) < 0 ? 90 (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a )) 91 :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c )); 92 } 93 94 void 95 qsort(a, n, es, cmp) 96 void *a; 97 size_t n, es; 98 cmp_t *cmp; 99 { 100 char *pa, *pb, *pc, *pd, *pl, *pm, *pn; 101 int d, r, swaptype, swap_cnt; 102 103 loop: SWAPINIT(a, es); 104 swap_cnt = 0; 105 if (n < 7) { 106 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 107 for (pl = pm; pl > (char *)a && cmp(pl - es, pl) > 0; 108 pl -= es) 109 swap(pl, pl - es); 110 return; 111 } 112 pm = (char *)a + (n / 2) * es; 113 if (n > 7) { 114 pl = a; 115 pn = (char *)a + (n - 1) * es; 116 if (n > 40) { 117 d = (n / 8) * es; 118 pl = med3(pl, pl + d, pl + 2 * d, cmp); 119 pm = med3(pm - d, pm, pm + d, cmp); 120 pn = med3(pn - 2 * d, pn - d, pn, cmp); 121 } 122 pm = med3(pl, pm, pn, cmp); 123 } 124 swap(a, pm); 125 pa = pb = (char *)a + es; 126 127 pc = pd = (char *)a + (n - 1) * es; 128 for (;;) { 129 while (pb <= pc && (r = cmp(pb, a)) <= 0) { 130 if (r == 0) { 131 swap_cnt = 1; 132 swap(pa, pb); 133 pa += es; 134 } 135 pb += es; 136 } 137 while (pb <= pc && (r = cmp(pc, a)) >= 0) { 138 if (r == 0) { 139 swap_cnt = 1; 140 swap(pc, pd); 141 pd -= es; 142 } 143 pc -= es; 144 } 145 if (pb > pc) 146 break; 147 swap(pb, pc); 148 swap_cnt = 1; 149 pb += es; 150 pc -= es; 151 } 152 if (swap_cnt == 0) { /* Switch to insertion sort */ 153 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 154 for (pl = pm; pl > (char *)a && cmp(pl - es, pl) > 0; 155 pl -= es) 156 swap(pl, pl - es); 157 return; 158 } 159 160 pn = (char *)a + n * es; 161 r = min(pa - (char *)a, pb - pa); 162 vecswap(a, pb - r, r); 163 r = min(pd - pc, pn - pd - es); 164 vecswap(pb, pn - r, r); 165 if ((r = pb - pa) > es) 166 qsort(a, r / es, es, cmp); 167 if ((r = pd - pc) > es) { 168 /* Iterate rather than recurse to save stack space */ 169 a = pn - r; 170 n = r / es; 171 goto loop; 172 } 173 /* qsort(pn - r, r / es, es, cmp);*/ 174 } 175