qsort.c revision 103165
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) 35static char sccsid[] = "@(#)qsort.c 8.1 (Berkeley) 6/4/93"; 36#endif /* LIBC_SCCS and not lint */ 37#include <sys/cdefs.h> 38__FBSDID("$FreeBSD: head/lib/libc/stdlib/qsort.c 103165 2002-09-10 02:04:49Z wollman $"); 39 40#include <stdlib.h> 41 42#ifdef I_AM_QSORT_R 43typedef int cmp_t(void *, const void *, const void *); 44#else 45typedef int cmp_t(const void *, const void *); 46#endif 47static inline char *med3(char *, char *, char *, cmp_t *, void *); 48static inline void swapfunc(char *, char *, int, int); 49 50#define min(a, b) (a) < (b) ? a : b 51 52/* 53 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". 54 */ 55#define swapcode(TYPE, parmi, parmj, n) { \ 56 long i = (n) / sizeof (TYPE); \ 57 TYPE *pi = (TYPE *) (parmi); \ 58 TYPE *pj = (TYPE *) (parmj); \ 59 do { \ 60 TYPE t = *pi; \ 61 *pi++ = *pj; \ 62 *pj++ = t; \ 63 } while (--i > 0); \ 64} 65 66#define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \ 67 es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1; 68 69static inline void 70swapfunc(a, b, n, swaptype) 71 char *a, *b; 72 int n, swaptype; 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 *)(a); \ 83 *(long *)(a) = *(long *)(b); \ 84 *(long *)(b) = t; \ 85 } else \ 86 swapfunc(a, b, es, swaptype) 87 88#define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype) 89 90#ifdef I_AM_QSORT_R 91#define CMP(t, x, y) (cmp((t), (x), (y))) 92#else 93#define CMP(t, x, y) (cmp((x), (y))) 94#endif 95 96static inline char * 97med3(char *a, char *b, char *c, cmp_t *cmp, void *thunk 98#ifndef I_AM_QSORT_R 99__unused 100#endif 101) 102{ 103 return CMP(thunk, a, b) < 0 ? 104 (CMP(thunk, b, c) < 0 ? b : (CMP(thunk, a, c) < 0 ? c : a )) 105 :(CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c )); 106} 107 108#ifdef I_AM_QSORT_R 109void 110qsort_r(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp) 111#else 112#define thunk NULL 113void 114qsort(void *a, size_t n, size_t es, cmp_t *cmp) 115#endif 116{ 117 char *pa, *pb, *pc, *pd, *pl, *pm, *pn; 118 int d, r, swaptype, swap_cnt; 119 120loop: SWAPINIT(a, es); 121 swap_cnt = 0; 122 if (n < 7) { 123 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 124 for (pl = pm; 125 pl > (char *)a && CMP(thunk, pl - es, pl) > 0; 126 pl -= es) 127 swap(pl, pl - es); 128 return; 129 } 130 pm = (char *)a + (n / 2) * es; 131 if (n > 7) { 132 pl = a; 133 pn = (char *)a + (n - 1) * es; 134 if (n > 40) { 135 d = (n / 8) * es; 136 pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk); 137 pm = med3(pm - d, pm, pm + d, cmp, thunk); 138 pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk); 139 } 140 pm = med3(pl, pm, pn, cmp, thunk); 141 } 142 swap(a, pm); 143 pa = pb = (char *)a + es; 144 145 pc = pd = (char *)a + (n - 1) * es; 146 for (;;) { 147 while (pb <= pc && (r = CMP(thunk, pb, a)) <= 0) { 148 if (r == 0) { 149 swap_cnt = 1; 150 swap(pa, pb); 151 pa += es; 152 } 153 pb += es; 154 } 155 while (pb <= pc && (r = CMP(thunk, pc, a)) >= 0) { 156 if (r == 0) { 157 swap_cnt = 1; 158 swap(pc, pd); 159 pd -= es; 160 } 161 pc -= es; 162 } 163 if (pb > pc) 164 break; 165 swap(pb, pc); 166 swap_cnt = 1; 167 pb += es; 168 pc -= es; 169 } 170 if (swap_cnt == 0) { /* Switch to insertion sort */ 171 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 172 for (pl = pm; 173 pl > (char *)a && CMP(thunk, pl - es, pl) > 0; 174 pl -= es) 175 swap(pl, pl - es); 176 return; 177 } 178 179 pn = (char *)a + n * es; 180 r = min(pa - (char *)a, pb - pa); 181 vecswap(a, pb - r, r); 182 r = min(pd - pc, pn - pd - es); 183 vecswap(pb, pn - r, r); 184 if ((r = pb - pa) > es) 185#ifdef I_AM_QSORT_R 186 qsort_r(a, r / es, es, thunk, cmp); 187#else 188 qsort(a, r / es, es, cmp); 189#endif 190 if ((r = pd - pc) > es) { 191 /* Iterate rather than recurse to save stack space */ 192 a = pn - r; 193 n = r / es; 194 goto loop; 195 } 196/* qsort(pn - r, r / es, es, cmp);*/ 197} 198