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 1.5 2005/11/20 12:37:49 swildner Exp $ 36 */ 37 38 #include <stdlib.h> 39 40 typedef int cmp_t (const void *, const void *); 41 static inline char *med3 (char *, char *, char *, cmp_t *); 42 static inline void swapfunc (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 TYPE *pi = (TYPE *) (parmi); \ 52 TYPE *pj = (TYPE *) (parmj); \ 53 do { \ 54 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(char *a, char *b, int n, int swaptype) 65 { 66 if(swaptype <= 1) 67 swapcode(long, a, b, n) 68 else 69 swapcode(char, a, b, n) 70 } 71 72 #define swap(a, b) \ 73 if (swaptype == 0) { \ 74 long t = *(long *)(a); \ 75 *(long *)(a) = *(long *)(b); \ 76 *(long *)(b) = t; \ 77 } else \ 78 swapfunc(a, b, es, swaptype) 79 80 #define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype) 81 82 static inline char * 83 med3(char *a, char *b, char *c, cmp_t *cmp) 84 { 85 return cmp(a, b) < 0 ? 86 (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a )) 87 :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c )); 88 } 89 90 void 91 qsort(void *a, size_t n, size_t es, cmp_t *cmp) 92 { 93 char *pa, *pb, *pc, *pd, *pl, *pm, *pn; 94 int d, r, swaptype, swap_cnt; 95 96 loop: SWAPINIT(a, es); 97 swap_cnt = 0; 98 if (n < 7) { 99 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 100 for (pl = pm; pl > (char *)a && cmp(pl - es, pl) > 0; 101 pl -= es) 102 swap(pl, pl - es); 103 return; 104 } 105 pm = (char *)a + (n / 2) * es; 106 if (n > 7) { 107 pl = a; 108 pn = (char *)a + (n - 1) * es; 109 if (n > 40) { 110 d = (n / 8) * es; 111 pl = med3(pl, pl + d, pl + 2 * d, cmp); 112 pm = med3(pm - d, pm, pm + d, cmp); 113 pn = med3(pn - 2 * d, pn - d, pn, cmp); 114 } 115 pm = med3(pl, pm, pn, cmp); 116 } 117 swap(a, pm); 118 pa = pb = (char *)a + es; 119 120 pc = pd = (char *)a + (n - 1) * es; 121 for (;;) { 122 while (pb <= pc && (r = cmp(pb, a)) <= 0) { 123 if (r == 0) { 124 swap_cnt = 1; 125 swap(pa, pb); 126 pa += es; 127 } 128 pb += es; 129 } 130 while (pb <= pc && (r = cmp(pc, a)) >= 0) { 131 if (r == 0) { 132 swap_cnt = 1; 133 swap(pc, pd); 134 pd -= es; 135 } 136 pc -= es; 137 } 138 if (pb > pc) 139 break; 140 swap(pb, pc); 141 swap_cnt = 1; 142 pb += es; 143 pc -= es; 144 } 145 if (swap_cnt == 0) { /* Switch to insertion sort */ 146 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 147 for (pl = pm; pl > (char *)a && cmp(pl - es, pl) > 0; 148 pl -= es) 149 swap(pl, pl - es); 150 return; 151 } 152 153 pn = (char *)a + n * es; 154 r = min(pa - (char *)a, pb - pa); 155 vecswap(a, pb - r, r); 156 r = min(pd - pc, pn - pd - es); 157 vecswap(pb, pn - r, r); 158 if ((r = pb - pa) > es) 159 qsort(a, r / es, es, cmp); 160 if ((r = pd - pc) > es) { 161 /* Iterate rather than recurse to save stack space */ 162 a = pn - r; 163 n = r / es; 164 goto loop; 165 } 166 /* qsort(pn - r, r / es, es, cmp);*/ 167 } 168