1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1992, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #if defined(LIBC_SCCS) && !defined(lint) 33 static char sccsid[] = "@(#)qsort.c 8.1 (Berkeley) 6/4/93"; 34 #endif /* LIBC_SCCS and not lint */ 35 #include <sys/cdefs.h> 36 __FBSDID("$FreeBSD$"); 37 38 #include <stdlib.h> 39 40 #ifdef I_AM_QSORT_R 41 typedef int cmp_t(void *, const void *, const void *); 42 #else 43 typedef int cmp_t(const void *, const void *); 44 #endif 45 static inline char *med3(char *, char *, char *, cmp_t *, void *); 46 47 #define MIN(a, b) ((a) < (b) ? a : b) 48 49 /* 50 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". 51 */ 52 53 static inline void 54 swapfunc(char *a, char *b, size_t es) 55 { 56 char t; 57 58 do { 59 t = *a; 60 *a++ = *b; 61 *b++ = t; 62 } while (--es > 0); 63 } 64 65 #define vecswap(a, b, n) \ 66 if ((n) > 0) swapfunc(a, b, n) 67 68 #ifdef I_AM_QSORT_R 69 #define CMP(t, x, y) (cmp((t), (x), (y))) 70 #else 71 #define CMP(t, x, y) (cmp((x), (y))) 72 #endif 73 74 static inline char * 75 med3(char *a, char *b, char *c, cmp_t *cmp, void *thunk 76 #ifndef I_AM_QSORT_R 77 __unused 78 #endif 79 ) 80 { 81 return CMP(thunk, a, b) < 0 ? 82 (CMP(thunk, b, c) < 0 ? b : (CMP(thunk, a, c) < 0 ? c : a )) 83 :(CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c )); 84 } 85 86 #ifdef I_AM_QSORT_R 87 void 88 qsort_r(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp) 89 #else 90 #define thunk NULL 91 void 92 qsort(void *a, size_t n, size_t es, cmp_t *cmp) 93 #endif 94 { 95 char *pa, *pb, *pc, *pd, *pl, *pm, *pn; 96 size_t d1, d2; 97 int cmp_result; 98 int swap_cnt; 99 100 loop: 101 swap_cnt = 0; 102 if (n < 7) { 103 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 104 for (pl = pm; 105 pl > (char *)a && CMP(thunk, pl - es, pl) > 0; 106 pl -= es) 107 swapfunc(pl, pl - es, es); 108 return; 109 } 110 pm = (char *)a + (n / 2) * es; 111 if (n > 7) { 112 pl = a; 113 pn = (char *)a + (n - 1) * es; 114 if (n > 40) { 115 size_t d = (n / 8) * es; 116 117 pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk); 118 pm = med3(pm - d, pm, pm + d, cmp, thunk); 119 pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk); 120 } 121 pm = med3(pl, pm, pn, cmp, thunk); 122 } 123 swapfunc(a, pm, es); 124 pa = pb = (char *)a + es; 125 126 pc = pd = (char *)a + (n - 1) * es; 127 for (;;) { 128 while (pb <= pc && (cmp_result = CMP(thunk, pb, a)) <= 0) { 129 if (cmp_result == 0) { 130 swap_cnt = 1; 131 swapfunc(pa, pb, es); 132 pa += es; 133 } 134 pb += es; 135 } 136 while (pb <= pc && (cmp_result = CMP(thunk, pc, a)) >= 0) { 137 if (cmp_result == 0) { 138 swap_cnt = 1; 139 swapfunc(pc, pd, es); 140 pd -= es; 141 } 142 pc -= es; 143 } 144 if (pb > pc) 145 break; 146 swapfunc(pb, pc, es); 147 swap_cnt = 1; 148 pb += es; 149 pc -= es; 150 } 151 if (swap_cnt == 0) { /* Switch to insertion sort */ 152 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 153 for (pl = pm; 154 pl > (char *)a && CMP(thunk, pl - es, pl) > 0; 155 pl -= es) 156 swapfunc(pl, pl - es, es); 157 return; 158 } 159 160 pn = (char *)a + n * es; 161 d1 = MIN(pa - (char *)a, pb - pa); 162 vecswap(a, pb - d1, d1); 163 d1 = MIN(pd - pc, pn - pd - es); 164 vecswap(pb, pn - d1, d1); 165 166 d1 = pb - pa; 167 d2 = pd - pc; 168 if (d1 <= d2) { 169 /* Recurse on left partition, then iterate on right partition */ 170 if (d1 > es) { 171 #ifdef I_AM_QSORT_R 172 qsort_r(a, d1 / es, es, thunk, cmp); 173 #else 174 qsort(a, d1 / es, es, cmp); 175 #endif 176 } 177 if (d2 > es) { 178 /* Iterate rather than recurse to save stack space */ 179 /* qsort(pn - d2, d2 / es, es, cmp); */ 180 a = pn - d2; 181 n = d2 / es; 182 goto loop; 183 } 184 } else { 185 /* Recurse on right partition, then iterate on left partition */ 186 if (d2 > es) { 187 #ifdef I_AM_QSORT_R 188 qsort_r(pn - d2, d2 / es, es, thunk, cmp); 189 #else 190 qsort(pn - d2, d2 / es, es, cmp); 191 #endif 192 } 193 if (d1 > es) { 194 /* Iterate rather than recurse to save stack space */ 195 /* qsort(a, d1 / es, es, cmp); */ 196 n = d1 / es; 197 goto loop; 198 } 199 } 200 } 201