1 // SPDX-License-Identifier: BSD-3-Clause 2 /* $OpenBSD: qsort.c,v 1.10 2005/08/08 08:05:37 espie Exp $ */ 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 #include <sys/types.h> 32 #include <stdlib.h> 33 static __inline char 34 *med3(char *, char *, char *, int (*)(const void *, const void *)); 35 static __inline void swapfunc(char *, char *, int, int); 36 #define min(a, b) (a) < (b) ? a : b 37 /* 38 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". 39 */ 40 #define swapcode(TYPE, parmi, parmj, n) { \ 41 long i = (n) / sizeof (TYPE); \ 42 TYPE *pi = (TYPE *) (parmi); \ 43 TYPE *pj = (TYPE *) (parmj); \ 44 do { \ 45 TYPE t = *pi; \ 46 *pi++ = *pj; \ 47 *pj++ = t; \ 48 } while (--i > 0); \ 49 } 50 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \ 51 es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1; 52 static __inline void 53 swapfunc(char *a, char *b, int n, int swaptype) 54 { 55 if (swaptype <= 1) 56 swapcode(long, a, b, n) 57 else 58 swapcode(char, a, b, n) 59 } 60 #define swap(a, b) \ 61 if (swaptype == 0) { \ 62 long t = *(long *)(a); \ 63 *(long *)(a) = *(long *)(b); \ 64 *(long *)(b) = t; \ 65 } else \ 66 swapfunc(a, b, es, swaptype) 67 #define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype) 68 static __inline char * 69 med3(char *a, char *b, char *c, int (*cmp)(const void *, const void *)) 70 { 71 return cmp(a, b) < 0 ? 72 (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a )) 73 :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c )); 74 } 75 void 76 qsort(void *aa, size_t n, size_t es, int (*cmp)(const void *, const void *)) 77 { 78 char *pa, *pb, *pc, *pd, *pl, *pm, *pn; 79 int d, r, swaptype, swap_cnt; 80 char *a = aa; 81 loop: SWAPINIT(a, es); 82 swap_cnt = 0; 83 if (n < 7) { 84 for (pm = (char *)a + es; pm < (char *) a + n * es; pm += es) 85 for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; 86 pl -= es) 87 swap(pl, pl - es); 88 return; 89 } 90 pm = (char *)a + (n / 2) * es; 91 if (n > 7) { 92 pl = (char *)a; 93 pn = (char *)a + (n - 1) * es; 94 if (n > 40) { 95 d = (n / 8) * es; 96 pl = med3(pl, pl + d, pl + 2 * d, cmp); 97 pm = med3(pm - d, pm, pm + d, cmp); 98 pn = med3(pn - 2 * d, pn - d, pn, cmp); 99 } 100 pm = med3(pl, pm, pn, cmp); 101 } 102 swap(a, pm); 103 pa = pb = (char *)a + es; 104 105 pc = pd = (char *)a + (n - 1) * es; 106 for (;;) { 107 while (pb <= pc && (r = cmp(pb, a)) <= 0) { 108 if (r == 0) { 109 swap_cnt = 1; 110 swap(pa, pb); 111 pa += es; 112 } 113 pb += es; 114 } 115 while (pb <= pc && (r = cmp(pc, a)) >= 0) { 116 if (r == 0) { 117 swap_cnt = 1; 118 swap(pc, pd); 119 pd -= es; 120 } 121 pc -= es; 122 } 123 if (pb > pc) 124 break; 125 swap(pb, pc); 126 swap_cnt = 1; 127 pb += es; 128 pc -= es; 129 } 130 if (swap_cnt == 0) { /* Switch to insertion sort */ 131 for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es) 132 for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; 133 pl -= es) 134 swap(pl, pl - es); 135 return; 136 } 137 pn = (char *)a + n * es; 138 r = min(pa - (char *)a, pb - pa); 139 vecswap(a, pb - r, r); 140 r = min(pd - pc, pn - pd - (int)es); 141 vecswap(pb, pn - r, r); 142 if ((r = pb - pa) > (int)es) 143 qsort(a, r / es, es, cmp); 144 if ((r = pd - pc) > (int)es) { 145 /* Iterate rather than recurse to save stack space */ 146 a = pn - r; 147 n = r / es; 148 goto loop; 149 } 150 /* qsort(pn - r, r / es, es, cmp);*/ 151 } 152