qsort.c revision 21673
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 34#if defined(LIBC_SCCS) && !defined(lint) 35#if 0 36static char sccsid[] = "@(#)qsort.c 8.1 (Berkeley) 6/4/93"; 37#endif 38static const char rcsid[] = 39 "$FreeBSD: head/lib/libc/stdlib/qsort.c 21673 1997-01-14 07:20:47Z jkh $"; 40#endif /* LIBC_SCCS and not lint */ 41 42#include <stdlib.h> 43 44typedef int cmp_t __P((const void *, const void *)); 45static inline char *med3 __P((char *, char *, char *, cmp_t *)); 46static inline void swapfunc __P((char *, char *, int, int)); 47 48#define min(a, b) (a) < (b) ? a : b 49 50/* 51 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". 52 */ 53#define swapcode(TYPE, parmi, parmj, n) { \ 54 long i = (n) / sizeof (TYPE); \ 55 register TYPE *pi = (TYPE *) (parmi); \ 56 register TYPE *pj = (TYPE *) (parmj); \ 57 do { \ 58 register TYPE t = *pi; \ 59 *pi++ = *pj; \ 60 *pj++ = t; \ 61 } while (--i > 0); \ 62} 63 64#define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \ 65 es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1; 66 67static inline void 68swapfunc(a, b, n, swaptype) 69 char *a, *b; 70 int n, swaptype; 71{ 72 if(swaptype <= 1) 73 swapcode(long, a, b, n) 74 else 75 swapcode(char, a, b, n) 76} 77 78#define swap(a, b) \ 79 if (swaptype == 0) { \ 80 long t = *(long *)(a); \ 81 *(long *)(a) = *(long *)(b); \ 82 *(long *)(b) = t; \ 83 } else \ 84 swapfunc(a, b, es, swaptype) 85 86#define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype) 87 88static inline char * 89med3(a, b, c, cmp) 90 char *a, *b, *c; 91 cmp_t *cmp; 92{ 93 return cmp(a, b) < 0 ? 94 (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a )) 95 :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c )); 96} 97 98void 99qsort(a, n, es, cmp) 100 void *a; 101 size_t n, es; 102 cmp_t *cmp; 103{ 104 char *pa, *pb, *pc, *pd, *pl, *pm, *pn; 105 int d, r, swaptype, swap_cnt; 106 107loop: SWAPINIT(a, es); 108 swap_cnt = 0; 109 if (n < 7) { 110 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 111 for (pl = pm; pl > (char *)a && cmp(pl - es, pl) > 0; 112 pl -= es) 113 swap(pl, pl - es); 114 return; 115 } 116 pm = (char *)a + (n / 2) * es; 117 if (n > 7) { 118 pl = a; 119 pn = (char *)a + (n - 1) * es; 120 if (n > 40) { 121 d = (n / 8) * es; 122 pl = med3(pl, pl + d, pl + 2 * d, cmp); 123 pm = med3(pm - d, pm, pm + d, cmp); 124 pn = med3(pn - 2 * d, pn - d, pn, cmp); 125 } 126 pm = med3(pl, pm, pn, cmp); 127 } 128 swap(a, pm); 129 pa = pb = (char *)a + es; 130 131 pc = pd = (char *)a + (n - 1) * es; 132 for (;;) { 133 while (pb <= pc && (r = cmp(pb, a)) <= 0) { 134 if (r == 0) { 135 swap_cnt = 1; 136 swap(pa, pb); 137 pa += es; 138 } 139 pb += es; 140 } 141 while (pb <= pc && (r = cmp(pc, a)) >= 0) { 142 if (r == 0) { 143 swap_cnt = 1; 144 swap(pc, pd); 145 pd -= es; 146 } 147 pc -= es; 148 } 149 if (pb > pc) 150 break; 151 swap(pb, pc); 152 swap_cnt = 1; 153 pb += es; 154 pc -= es; 155 } 156 if (swap_cnt == 0) { /* Switch to insertion sort */ 157 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 158 for (pl = pm; pl > (char *)a && cmp(pl - es, pl) > 0; 159 pl -= es) 160 swap(pl, pl - es); 161 return; 162 } 163 164 pn = (char *)a + n * es; 165 r = min(pa - (char *)a, pb - pa); 166 vecswap(a, pb - r, r); 167 r = min(pd - pc, pn - pd - es); 168 vecswap(pb, pn - r, r); 169 if ((r = pb - pa) > es) 170 qsort(a, r / es, es, cmp); 171 if ((r = pd - pc) > es) { 172 /* Iterate rather than recurse to save stack space */ 173 a = pn - r; 174 n = r / es; 175 goto loop; 176 } 177/* qsort(pn - r, r / es, es, cmp);*/ 178} 179