1 /* $NetBSD: qsort.c,v 1.24 2025/03/02 16:35:41 riastradh Exp $ */ 2 /*- 3 * Copyright (c) 1992, 1993 4 * The Regents of the University of California. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. Neither the name of the University nor the names of its contributors 15 * may be used to endorse or promote products derived from this software 16 * without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 */ 30 31 #include <sys/cdefs.h> 32 #if defined(LIBC_SCCS) && !defined(lint) 33 #if 0 34 static char sccsid[] = "@(#)qsort.c 8.1 (Berkeley) 6/4/93"; 35 #else 36 __RCSID("$NetBSD: qsort.c,v 1.24 2025/03/02 16:35:41 riastradh Exp $"); 37 #endif 38 #endif /* LIBC_SCCS and not lint */ 39 40 #include <sys/types.h> 41 42 #include <assert.h> 43 #include <errno.h> 44 #include <stdlib.h> 45 46 static inline char *med3(char *, char *, char *, 47 int (*)(const void *, const void *, void *), 48 void *); 49 static inline void swapfunc(char *, char *, size_t, int); 50 51 #define min(a, b) (a) < (b) ? a : b 52 53 /* 54 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". 55 */ 56 #define swapcode(TYPE, parmi, parmj, n) { \ 57 size_t i = (n) / sizeof (TYPE); \ 58 TYPE *pi = (TYPE *)(void *)(parmi); \ 59 TYPE *pj = (TYPE *)(void *)(parmj); \ 60 do { \ 61 TYPE t = *pi; \ 62 *pi++ = *pj; \ 63 *pj++ = t; \ 64 } while (--i > 0); \ 65 } 66 67 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \ 68 es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1; 69 70 static inline void 71 swapfunc(char *a, char *b, size_t n, int swaptype) 72 { 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 *)(void *)(a); \ 83 *(long *)(void *)(a) = *(long *)(void *)(b); \ 84 *(long *)(void *)(b) = t; \ 85 } else \ 86 swapfunc(a, b, es, swaptype) 87 88 #define vecswap(a, b, n) if ((n) > 0) swapfunc((a), (b), (size_t)(n), swaptype) 89 90 static inline char * 91 med3(char *a, char *b, char *c, 92 int (*cmp)(const void *, const void *, void *), void *cookie) 93 { 94 95 return cmp(a, b, cookie) < 0 ? 96 (cmp(b, c, cookie) < 0 ? b : (cmp(a, c, cookie) < 0 ? c : a )) 97 :(cmp(b, c, cookie) > 0 ? b : (cmp(a, c, cookie) < 0 ? a : c )); 98 } 99 100 void 101 qsort_r(void *a, size_t n, size_t es, 102 int (*cmp)(const void *, const void *, void *), void *cookie) 103 { 104 char *pa, *pb, *pc, *pd, *pl, *pm, *pn; 105 size_t d, r, s; 106 int swaptype, cmp_result; 107 108 _DIAGASSERT(a != NULL || n == 0 || es == 0); 109 _DIAGASSERT(cmp != NULL); 110 111 loop: SWAPINIT(a, es); 112 if (n < 7) { 113 for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es) 114 for (pl = pm; 115 pl > (char *) a && cmp(pl - es, pl, cookie) > 0; 116 pl -= es) 117 swap(pl, pl - es); 118 return; 119 } 120 pm = (char *) a + (n / 2) * es; 121 if (n > 7) { 122 pl = (char *) a; 123 pn = (char *) a + (n - 1) * es; 124 if (n > 40) { 125 d = (n / 8) * es; 126 pl = med3(pl, pl + d, pl + 2 * d, cmp, cookie); 127 pm = med3(pm - d, pm, pm + d, cmp, cookie); 128 pn = med3(pn - 2 * d, pn - d, pn, cmp, cookie); 129 } 130 pm = med3(pl, pm, pn, cmp, cookie); 131 } 132 swap(a, pm); 133 pa = pb = (char *) a + es; 134 135 pc = pd = (char *) a + (n - 1) * es; 136 for (;;) { 137 while (pb <= pc && (cmp_result = cmp(pb, a, cookie)) <= 0) { 138 if (cmp_result == 0) { 139 swap(pa, pb); 140 pa += es; 141 } 142 pb += es; 143 } 144 while (pb <= pc && (cmp_result = cmp(pc, a, cookie)) >= 0) { 145 if (cmp_result == 0) { 146 swap(pc, pd); 147 pd -= es; 148 } 149 pc -= es; 150 } 151 if (pb > pc) 152 break; 153 swap(pb, pc); 154 pb += es; 155 pc -= es; 156 } 157 158 pn = (char *) a + n * es; 159 r = min(pa - (char *) a, pb - pa); 160 vecswap(a, pb - r, r); 161 r = min((size_t)(pd - pc), pn - pd - es); 162 vecswap(pb, pn - r, r); 163 /* 164 * To save stack space we sort the smaller side of the partition first 165 * using recursion and eliminate tail recursion for the larger side. 166 */ 167 r = pb - pa; 168 s = pd - pc; 169 if (r < s) { 170 /* Recurse for 1st side, iterate for 2nd side. */ 171 if (s > es) { 172 if (r > es) 173 qsort_r(a, r / es, es, cmp, cookie); 174 a = pn - s; 175 n = s / es; 176 goto loop; 177 } 178 } else { 179 /* Recurse for 2nd side, iterate for 1st side. */ 180 if (r > es) { 181 if (s > es) 182 qsort_r(pn - s, s / es, es, cmp, cookie); 183 n = r / es; 184 goto loop; 185 } 186 } 187 } 188 189 static int 190 cmpnocookie(const void *a, const void *b, void *cookie) 191 { 192 int (*cmp)(const void *, const void *) = cookie; 193 194 return cmp(a, b); 195 } 196 197 void 198 qsort(void *a, size_t n, size_t es, 199 int (*cmp)(const void *, const void *)) 200 { 201 202 qsort_r(a, n, es, cmpnocookie, cmp); 203 } 204
Indexes created Sat Sep 20 22:09:52 GMT 2025