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 335603 2018-06-24 13:26:31Z kib $"); 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 *); 44 45#define MIN(a, b) ((a) < (b) ? a : b) 46 47/* 48 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". 49 */ 50 51static inline void 52swapfunc(char *a, char *b, size_t es) 53{ 54 char t; 55 56 do { 57 t = *a; 58 *a++ = *b; 59 *b++ = t; 60 } while (--es > 0); 61} 62 63#define vecswap(a, b, n) \ 64 if ((n) > 0) swapfunc(a, b, n) 65 66#ifdef I_AM_QSORT_R 67#define CMP(t, x, y) (cmp((t), (x), (y))) 68#else 69#define CMP(t, x, y) (cmp((x), (y))) 70#endif 71 72static inline char * 73med3(char *a, char *b, char *c, cmp_t *cmp, void *thunk 74#ifndef I_AM_QSORT_R 75__unused 76#endif 77) 78{ 79 return CMP(thunk, a, b) < 0 ? 80 (CMP(thunk, b, c) < 0 ? b : (CMP(thunk, a, c) < 0 ? c : a )) 81 :(CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c )); 82} 83 84#ifdef I_AM_QSORT_R 85void 86qsort_r(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp) 87#else 88#define thunk NULL 89void 90qsort(void *a, size_t n, size_t es, cmp_t *cmp) 91#endif 92{ 93 char *pa, *pb, *pc, *pd, *pl, *pm, *pn; 94 size_t d1, d2; 95 int cmp_result; 96 int swap_cnt; 97 98loop: 99 swap_cnt = 0; 100 if (n < 7) { 101 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 102 for (pl = pm; 103 pl > (char *)a && CMP(thunk, pl - es, pl) > 0; 104 pl -= es) 105 swapfunc(pl, pl - es, es); 106 return; 107 } 108 pm = (char *)a + (n / 2) * es; 109 if (n > 7) { 110 pl = a; 111 pn = (char *)a + (n - 1) * es; 112 if (n > 40) { 113 size_t d = (n / 8) * es; 114 115 pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk); 116 pm = med3(pm - d, pm, pm + d, cmp, thunk); 117 pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk); 118 } 119 pm = med3(pl, pm, pn, cmp, thunk); 120 } 121 swapfunc(a, pm, es); 122 pa = pb = (char *)a + es; 123 124 pc = pd = (char *)a + (n - 1) * es; 125 for (;;) { 126 while (pb <= pc && (cmp_result = CMP(thunk, pb, a)) <= 0) { 127 if (cmp_result == 0) { 128 swap_cnt = 1; 129 swapfunc(pa, pb, es); 130 pa += es; 131 } 132 pb += es; 133 } 134 while (pb <= pc && (cmp_result = CMP(thunk, pc, a)) >= 0) { 135 if (cmp_result == 0) { 136 swap_cnt = 1; 137 swapfunc(pc, pd, es); 138 pd -= es; 139 } 140 pc -= es; 141 } 142 if (pb > pc) 143 break; 144 swapfunc(pb, pc, es); 145 swap_cnt = 1; 146 pb += es; 147 pc -= es; 148 } 149 if (swap_cnt == 0) { /* Switch to insertion sort */ 150 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 151 for (pl = pm; 152 pl > (char *)a && CMP(thunk, pl - es, pl) > 0; 153 pl -= es) 154 swapfunc(pl, pl - es, es); 155 return; 156 } 157 158 pn = (char *)a + n * es; 159 d1 = MIN(pa - (char *)a, pb - pa); 160 vecswap(a, pb - d1, d1); 161 d1 = MIN(pd - pc, pn - pd - es); 162 vecswap(pb, pn - d1, d1); 163 164 d1 = pb - pa; 165 d2 = pd - pc; 166 if (d1 <= d2) { 167 /* Recurse on left partition, then iterate on right partition */ 168 if (d1 > es) { 169#ifdef I_AM_QSORT_R 170 qsort_r(a, d1 / es, es, thunk, cmp); 171#else 172 qsort(a, d1 / es, es, cmp); 173#endif 174 } 175 if (d2 > es) { 176 /* Iterate rather than recurse to save stack space */ 177 /* qsort(pn - d2, d2 / es, es, cmp); */ 178 a = pn - d2; 179 n = d2 / es; 180 goto loop; 181 } 182 } else { 183 /* Recurse on right partition, then iterate on left partition */ 184 if (d2 > es) { 185#ifdef I_AM_QSORT_R 186 qsort_r(pn - d2, d2 / es, es, thunk, cmp); 187#else 188 qsort(pn - d2, d2 / es, es, cmp); 189#endif 190 } 191 if (d1 > es) { 192 /* Iterate rather than recurse to save stack space */ 193 /* qsort(a, d1 / es, es, cmp); */ 194 n = d1 / es; 195 goto loop; 196 } 197 } 198} 199