1 /* $OpenBSD: qsort.c,v 1.10 2005/08/08 08:05:37 espie 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/types.h> 32 #include <stdlib.h> 33 34 static __inline char *med3(char *, char *, char *, int (*)(const void *, const void *)); 35 static __inline void swapfunc(char *, char *, int, int); 36 37 #define min(a, b) (a) < (b) ? a : b 38 39 /* 40 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". 41 */ 42 #define swapcode(TYPE, parmi, parmj, n) { \ 43 long i = (n) / sizeof (TYPE); \ 44 TYPE *pi = (TYPE *) (parmi); \ 45 TYPE *pj = (TYPE *) (parmj); \ 46 do { \ 47 TYPE t = *pi; \ 48 *pi++ = *pj; \ 49 *pj++ = t; \ 50 } while (--i > 0); \ 51 } 52 53 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \ 54 es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1; 55 56 static __inline void 57 swapfunc(char *a, char *b, int n, int swaptype) 58 { 59 if (swaptype <= 1) 60 swapcode(long, a, b, n) 61 else 62 swapcode(char, a, b, n) 63 } 64 65 #define swap(a, b) \ 66 if (swaptype == 0) { \ 67 long t = *(long *)(a); \ 68 *(long *)(a) = *(long *)(b); \ 69 *(long *)(b) = t; \ 70 } else \ 71 swapfunc(a, b, es, swaptype) 72 73 #define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype) 74 75 static __inline char * 76 med3(char *a, char *b, char *c, int (*cmp)(const void *, const void *)) 77 { 78 return cmp(a, b) < 0 ? 79 (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a )) 80 :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c )); 81 } 82 83 void 84 qsort(void *aa, size_t n, size_t es, int (*cmp)(const void *, const void *)) 85 { 86 char *pa, *pb, *pc, *pd, *pl, *pm, *pn; 87 int d, r, swaptype, swap_cnt; 88 char *a = aa; 89 90 loop: SWAPINIT(a, es); 91 swap_cnt = 0; 92 if (n < 7) { 93 for (pm = (char *)a + es; pm < (char *) a + n * es; pm += es) 94 for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; 95 pl -= es) 96 swap(pl, pl - es); 97 return; 98 } 99 pm = (char *)a + (n / 2) * es; 100 if (n > 7) { 101 pl = (char *)a; 102 pn = (char *)a + (n - 1) * es; 103 if (n > 40) { 104 d = (n / 8) * es; 105 pl = med3(pl, pl + d, pl + 2 * d, cmp); 106 pm = med3(pm - d, pm, pm + d, cmp); 107 pn = med3(pn - 2 * d, pn - d, pn, cmp); 108 } 109 pm = med3(pl, pm, pn, cmp); 110 } 111 swap(a, pm); 112 pa = pb = (char *)a + es; 113 114 pc = pd = (char *)a + (n - 1) * es; 115 for (;;) { 116 while (pb <= pc && (r = cmp(pb, a)) <= 0) { 117 if (r == 0) { 118 swap_cnt = 1; 119 swap(pa, pb); 120 pa += es; 121 } 122 pb += es; 123 } 124 while (pb <= pc && (r = cmp(pc, a)) >= 0) { 125 if (r == 0) { 126 swap_cnt = 1; 127 swap(pc, pd); 128 pd -= es; 129 } 130 pc -= es; 131 } 132 if (pb > pc) 133 break; 134 swap(pb, pc); 135 swap_cnt = 1; 136 pb += es; 137 pc -= es; 138 } 139 if (swap_cnt == 0) { /* Switch to insertion sort */ 140 for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es) 141 for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; 142 pl -= es) 143 swap(pl, pl - es); 144 return; 145 } 146 147 pn = (char *)a + n * es; 148 r = min(pa - (char *)a, pb - pa); 149 vecswap(a, pb - r, r); 150 r = min(pd - pc, pn - pd - (int)es); 151 vecswap(pb, pn - r, r); 152 if ((r = pb - pa) > (int)es) 153 qsort(a, r / es, es, cmp); 154 if ((r = pd - pc) > (int)es) { 155 /* Iterate rather than recurse to save stack space */ 156 a = pn - r; 157 n = r / es; 158 goto loop; 159 } 160 /* qsort(pn - r, r / es, es, cmp); */ 161 } 162
