1 /* $NetBSD: qsort.c,v 1.8 1997/07/13 20:16:51 christos Exp $ */ 2 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. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by the University of 18 * California, Berkeley and its contributors. 19 * 4. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36 #include <sys/cdefs.h> 37 #if defined(LIBC_SCCS) && !defined(lint) 38 #if 0 39 static char sccsid[] = "@(#)qsort.c 8.1 (Berkeley) 6/4/93"; 40 #else 41 __RCSID("$NetBSD: qsort.c,v 1.8 1997/07/13 20:16:51 christos Exp $"); 42 #endif 43 #endif /* LIBC_SCCS and not lint */ 44 45 #include <sys/types.h> 46 #include <stdlib.h> 47 48 static __inline char *med3 __P((char *, char *, char *, 49 int (*)(const void *, const void *))); 50 static __inline void swapfunc __P((char *, char *, int, int)); 51 52 #define min(a, b) (a) < (b) ? a : b 53 54 /* 55 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". 56 */ 57 #define swapcode(TYPE, parmi, parmj, n) { \ 58 long i = (n) / sizeof (TYPE); \ 59 register TYPE *pi = (TYPE *) (parmi); \ 60 register TYPE *pj = (TYPE *) (parmj); \ 61 do { \ 62 register TYPE t = *pi; \ 63 *pi++ = *pj; \ 64 *pj++ = t; \ 65 } while (--i > 0); \ 66 } 67 68 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \ 69 es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1; 70 71 static __inline void 72 swapfunc(a, b, n, swaptype) 73 char *a, *b; 74 int n, swaptype; 75 { 76 if (swaptype <= 1) 77 swapcode(long, a, b, n) 78 else 79 swapcode(char, a, b, n) 80 } 81 82 #define swap(a, b) \ 83 if (swaptype == 0) { \ 84 long t = *(long *)(a); \ 85 *(long *)(a) = *(long *)(b); \ 86 *(long *)(b) = t; \ 87 } else \ 88 swapfunc(a, b, es, swaptype) 89 90 #define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype) 91 92 static __inline char * 93 med3(a, b, c, cmp) 94 char *a, *b, *c; 95 int (*cmp) __P((const void *, const void *)); 96 { 97 return cmp(a, b) < 0 ? 98 (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a )) 99 :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c )); 100 } 101 102 void 103 qsort(a, n, es, cmp) 104 void *a; 105 size_t n, es; 106 int (*cmp) __P((const void *, const void *)); 107 { 108 char *pa, *pb, *pc, *pd, *pl, *pm, *pn; 109 int d, r, swaptype, swap_cnt; 110 111 loop: SWAPINIT(a, es); 112 swap_cnt = 0; 113 if (n < 7) { 114 for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es) 115 for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 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); 127 pm = med3(pm - d, pm, pm + d, cmp); 128 pn = med3(pn - 2 * d, pn - d, pn, cmp); 129 } 130 pm = med3(pl, pm, pn, cmp); 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 && (r = cmp(pb, a)) <= 0) { 138 if (r == 0) { 139 swap_cnt = 1; 140 swap(pa, pb); 141 pa += es; 142 } 143 pb += es; 144 } 145 while (pb <= pc && (r = cmp(pc, a)) >= 0) { 146 if (r == 0) { 147 swap_cnt = 1; 148 swap(pc, pd); 149 pd -= es; 150 } 151 pc -= es; 152 } 153 if (pb > pc) 154 break; 155 swap(pb, pc); 156 swap_cnt = 1; 157 pb += es; 158 pc -= es; 159 } 160 if (swap_cnt == 0) { /* Switch to insertion sort */ 161 for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es) 162 for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; 163 pl -= es) 164 swap(pl, pl - es); 165 return; 166 } 167 168 pn = (char *) a + n * es; 169 r = min(pa - (char *) a, pb - pa); 170 vecswap(a, pb - r, r); 171 r = min(pd - pc, pn - pd - es); 172 vecswap(pb, pn - r, r); 173 if ((r = pb - pa) > es) 174 qsort(a, r / es, es, cmp); 175 if ((r = pd - pc) > es) { 176 /* Iterate rather than recurse to save stack space */ 177 a = pn - r; 178 n = r / es; 179 goto loop; 180 } 181 /* qsort(pn - r, r / es, es, cmp);*/ 182 } 183