qsort.c revision 302408
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) 31static char sccsid[] = "@(#)qsort.c 8.1 (Berkeley) 6/4/93"; 32#endif /* LIBC_SCCS and not lint */ 33#include <sys/cdefs.h> 34__FBSDID("$FreeBSD: stable/11/lib/libc/stdlib/qsort.c 288030 2015-09-20 20:24:28Z rodrigc $"); 35 36#include <stdlib.h> 37 38#ifdef I_AM_QSORT_R 39typedef int cmp_t(void *, const void *, const void *); 40#else 41typedef int cmp_t(const void *, const void *); 42#endif 43static inline char *med3(char *, char *, char *, cmp_t *, void *); 44static inline void swapfunc(char *, char *, int, int, int); 45 46#define MIN(a, b) ((a) < (b) ? a : b) 47 48/* 49 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". 50 */ 51#define swapcode(TYPE, parmi, parmj, n) { \ 52 long i = (n) / sizeof (TYPE); \ 53 TYPE *pi = (TYPE *) (parmi); \ 54 TYPE *pj = (TYPE *) (parmj); \ 55 do { \ 56 TYPE t = *pi; \ 57 *pi++ = *pj; \ 58 *pj++ = t; \ 59 } while (--i > 0); \ 60} 61 62#define SWAPINIT(TYPE, a, es) swaptype_ ## TYPE = \ 63 ((char *)a - (char *)0) % sizeof(TYPE) || \ 64 es % sizeof(TYPE) ? 2 : es == sizeof(TYPE) ? 0 : 1; 65 66static inline void 67swapfunc( char *a, char *b, int n, int swaptype_long, int swaptype_int) 68{ 69 if (swaptype_long <= 1) 70 swapcode(long, a, b, n) 71 else if (swaptype_int <= 1) 72 swapcode(int, a, b, n) 73 else 74 swapcode(char, a, b, n) 75} 76 77#define swap(a, b) \ 78 if (swaptype_long == 0) { \ 79 long t = *(long *)(a); \ 80 *(long *)(a) = *(long *)(b); \ 81 *(long *)(b) = t; \ 82 } else if (swaptype_int == 0) { \ 83 int t = *(int *)(a); \ 84 *(int *)(a) = *(int *)(b); \ 85 *(int *)(b) = t; \ 86 } else \ 87 swapfunc(a, b, es, swaptype_long, swaptype_int) 88 89#define vecswap(a, b, n) \ 90 if ((n) > 0) swapfunc(a, b, n, swaptype_long, swaptype_int) 91 92#ifdef I_AM_QSORT_R 93#define CMP(t, x, y) (cmp((t), (x), (y))) 94#else 95#define CMP(t, x, y) (cmp((x), (y))) 96#endif 97 98static inline char * 99med3(char *a, char *b, char *c, cmp_t *cmp, void *thunk 100#ifndef I_AM_QSORT_R 101__unused 102#endif 103) 104{ 105 return CMP(thunk, a, b) < 0 ? 106 (CMP(thunk, b, c) < 0 ? b : (CMP(thunk, a, c) < 0 ? c : a )) 107 :(CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c )); 108} 109 110#ifdef I_AM_QSORT_R 111void 112qsort_r(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp) 113#else 114#define thunk NULL 115void 116qsort(void *a, size_t n, size_t es, cmp_t *cmp) 117#endif 118{ 119 char *pa, *pb, *pc, *pd, *pl, *pm, *pn; 120 size_t d, r; 121 int cmp_result; 122 int swaptype_long, swaptype_int, swap_cnt; 123 124loop: SWAPINIT(long, a, es); 125 SWAPINIT(int, a, es); 126 swap_cnt = 0; 127 if (n < 7) { 128 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 129 for (pl = pm; 130 pl > (char *)a && CMP(thunk, pl - es, pl) > 0; 131 pl -= es) 132 swap(pl, pl - es); 133 return; 134 } 135 pm = (char *)a + (n / 2) * es; 136 if (n > 7) { 137 pl = a; 138 pn = (char *)a + (n - 1) * es; 139 if (n > 40) { 140 d = (n / 8) * es; 141 pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk); 142 pm = med3(pm - d, pm, pm + d, cmp, thunk); 143 pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk); 144 } 145 pm = med3(pl, pm, pn, cmp, thunk); 146 } 147 swap(a, pm); 148 pa = pb = (char *)a + es; 149 150 pc = pd = (char *)a + (n - 1) * es; 151 for (;;) { 152 while (pb <= pc && (cmp_result = CMP(thunk, pb, a)) <= 0) { 153 if (cmp_result == 0) { 154 swap_cnt = 1; 155 swap(pa, pb); 156 pa += es; 157 } 158 pb += es; 159 } 160 while (pb <= pc && (cmp_result = CMP(thunk, pc, a)) >= 0) { 161 if (cmp_result == 0) { 162 swap_cnt = 1; 163 swap(pc, pd); 164 pd -= es; 165 } 166 pc -= es; 167 } 168 if (pb > pc) 169 break; 170 swap(pb, pc); 171 swap_cnt = 1; 172 pb += es; 173 pc -= es; 174 } 175 if (swap_cnt == 0) { /* Switch to insertion sort */ 176 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 177 for (pl = pm; 178 pl > (char *)a && CMP(thunk, pl - es, pl) > 0; 179 pl -= es) 180 swap(pl, pl - es); 181 return; 182 } 183 184 pn = (char *)a + n * es; 185 r = MIN(pa - (char *)a, pb - pa); 186 vecswap(a, pb - r, r); 187 r = MIN(pd - pc, pn - pd - es); 188 vecswap(pb, pn - r, r); 189 if ((r = pb - pa) > es) 190#ifdef I_AM_QSORT_R 191 qsort_r(a, r / es, es, thunk, cmp); 192#else 193 qsort(a, r / es, es, cmp); 194#endif 195 if ((r = pd - pc) > es) { 196 /* Iterate rather than recurse to save stack space */ 197 a = pn - r; 198 n = r / es; 199 goto loop; 200 } 201/* qsort(pn - r, r / es, es, cmp);*/ 202} 203