1 /* $NetBSD: qsort.c,v 1.5 1995/12/28 08:52:36 thorpej 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 #if defined(LIBC_SCCS) && !defined(lint) 37 #if 0 38 static char sccsid[] = "from: @(#)qsort.c 8.1 (Berkeley) 6/4/93"; 39 #else 40 static char *rcsid = "$NetBSD: qsort.c,v 1.5 1995/12/28 08:52:36 thorpej Exp $"; 41 #endif 42 #endif /* LIBC_SCCS and not lint */ 43 44 #include <sys/types.h> 45 #include <stdlib.h> 46 47 static inline char *med3 __P((char *, char *, char *, int (*)())); 48 static inline void swapfunc __P((char *, char *, int, int)); 49 50 #define min(a, b) (a) < (b) ? a : b 51 52 /* 53 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". 54 */ 55 #define swapcode(TYPE, parmi, parmj, n) { \ 56 long i = (n) / sizeof (TYPE); \ 57 register TYPE *pi = (TYPE *) (parmi); \ 58 register TYPE *pj = (TYPE *) (parmj); \ 59 do { \ 60 register TYPE t = *pi; \ 61 *pi++ = *pj; \ 62 *pj++ = t; \ 63 } while (--i > 0); \ 64 } 65 66 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \ 67 es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1; 68 69 static inline void 70 swapfunc(a, b, n, swaptype) 71 char *a, *b; 72 int n, swaptype; 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 *)(a); \ 83 *(long *)(a) = *(long *)(b); \ 84 *(long *)(b) = t; \ 85 } else \ 86 swapfunc(a, b, es, swaptype) 87 88 #define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype) 89 90 static inline char * 91 med3(a, b, c, cmp) 92 char *a, *b, *c; 93 int (*cmp)(); 94 { 95 return cmp(a, b) < 0 ? 96 (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a )) 97 :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c )); 98 } 99 100 void 101 qsort(a, n, es, cmp) 102 void *a; 103 size_t n, es; 104 int (*cmp)(); 105 { 106 char *pa, *pb, *pc, *pd, *pl, *pm, *pn; 107 int d, r, swaptype, swap_cnt; 108 109 loop: SWAPINIT(a, es); 110 swap_cnt = 0; 111 if (n < 7) { 112 for (pm = a + es; pm < (char *) a + n * es; pm += es) 113 for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; 114 pl -= es) 115 swap(pl, pl - es); 116 return; 117 } 118 pm = a + (n / 2) * es; 119 if (n > 7) { 120 pl = a; 121 pn = a + (n - 1) * es; 122 if (n > 40) { 123 d = (n / 8) * es; 124 pl = med3(pl, pl + d, pl + 2 * d, cmp); 125 pm = med3(pm - d, pm, pm + d, cmp); 126 pn = med3(pn - 2 * d, pn - d, pn, cmp); 127 } 128 pm = med3(pl, pm, pn, cmp); 129 } 130 swap(a, pm); 131 pa = pb = a + es; 132 133 pc = pd = a + (n - 1) * es; 134 for (;;) { 135 while (pb <= pc && (r = cmp(pb, a)) <= 0) { 136 if (r == 0) { 137 swap_cnt = 1; 138 swap(pa, pb); 139 pa += es; 140 } 141 pb += es; 142 } 143 while (pb <= pc && (r = cmp(pc, a)) >= 0) { 144 if (r == 0) { 145 swap_cnt = 1; 146 swap(pc, pd); 147 pd -= es; 148 } 149 pc -= es; 150 } 151 if (pb > pc) 152 break; 153 swap(pb, pc); 154 swap_cnt = 1; 155 pb += es; 156 pc -= es; 157 } 158 if (swap_cnt == 0) { /* Switch to insertion sort */ 159 for (pm = a + es; pm < (char *) a + n * es; pm += es) 160 for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; 161 pl -= es) 162 swap(pl, pl - es); 163 return; 164 } 165 166 pn = a + n * es; 167 r = min(pa - (char *)a, pb - pa); 168 vecswap(a, pb - r, r); 169 r = min(pd - pc, pn - pd - es); 170 vecswap(pb, pn - r, r); 171 if ((r = pb - pa) > es) 172 qsort(a, r / es, es, cmp); 173 if ((r = pd - pc) > es) { 174 /* Iterate rather than recurse to save stack space */ 175 a = pn - r; 176 n = r / es; 177 goto loop; 178 } 179 /* qsort(pn - r, r / es, es, cmp);*/ 180 } 181