1 /*- 2 * Copyright (c) 1992, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 #if defined(LIBC_SCCS) && !defined(lint) 35 static char *rcsid = "$OpenBSD: qsort.c,v 1.7 2002/02/17 19:42:24 millert Exp $"; 36 #endif /* LIBC_SCCS and not lint */ 37 38 #include <sys/types.h> 39 #include <stdlib.h> 40 41 static __inline char *med3(char *, char *, char *, int (*)()); 42 static __inline void swapfunc(char *, char *, int, int); 43 44 #define min(a, b) (a) < (b) ? a : b 45 46 /* 47 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". 48 */ 49 #define swapcode(TYPE, parmi, parmj, n) { \ 50 long i = (n) / sizeof (TYPE); \ 51 register TYPE *pi = (TYPE *) (parmi); \ 52 register TYPE *pj = (TYPE *) (parmj); \ 53 do { \ 54 register TYPE t = *pi; \ 55 *pi++ = *pj; \ 56 *pj++ = t; \ 57 } while (--i > 0); \ 58 } 59 60 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \ 61 es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1; 62 63 static __inline void 64 swapfunc(a, b, n, swaptype) 65 char *a, *b; 66 int n, swaptype; 67 { 68 if (swaptype <= 1) 69 swapcode(long, a, b, n) 70 else 71 swapcode(char, a, b, n) 72 } 73 74 #define swap(a, b) \ 75 if (swaptype == 0) { \ 76 long t = *(long *)(a); \ 77 *(long *)(a) = *(long *)(b); \ 78 *(long *)(b) = t; \ 79 } else \ 80 swapfunc(a, b, es, swaptype) 81 82 #define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype) 83 84 static __inline char * 85 med3(a, b, c, cmp) 86 char *a, *b, *c; 87 int (*cmp)(); 88 { 89 return cmp(a, b) < 0 ? 90 (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a )) 91 :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c )); 92 } 93 94 void 95 qsort(aa, n, es, cmp) 96 void *aa; 97 size_t n, es; 98 int (*cmp)(); 99 { 100 char *pa, *pb, *pc, *pd, *pl, *pm, *pn; 101 int d, r, swaptype, swap_cnt; 102 register char *a = aa; 103 104 loop: SWAPINIT(a, es); 105 swap_cnt = 0; 106 if (n < 7) { 107 for (pm = (char *)a + es; pm < (char *) a + n * es; pm += es) 108 for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; 109 pl -= es) 110 swap(pl, pl - es); 111 return; 112 } 113 pm = (char *)a + (n / 2) * es; 114 if (n > 7) { 115 pl = (char *)a; 116 pn = (char *)a + (n - 1) * es; 117 if (n > 40) { 118 d = (n / 8) * es; 119 pl = med3(pl, pl + d, pl + 2 * d, cmp); 120 pm = med3(pm - d, pm, pm + d, cmp); 121 pn = med3(pn - 2 * d, pn - d, pn, cmp); 122 } 123 pm = med3(pl, pm, pn, cmp); 124 } 125 swap(a, pm); 126 pa = pb = (char *)a + es; 127 128 pc = pd = (char *)a + (n - 1) * es; 129 for (;;) { 130 while (pb <= pc && (r = cmp(pb, a)) <= 0) { 131 if (r == 0) { 132 swap_cnt = 1; 133 swap(pa, pb); 134 pa += es; 135 } 136 pb += es; 137 } 138 while (pb <= pc && (r = cmp(pc, a)) >= 0) { 139 if (r == 0) { 140 swap_cnt = 1; 141 swap(pc, pd); 142 pd -= es; 143 } 144 pc -= es; 145 } 146 if (pb > pc) 147 break; 148 swap(pb, pc); 149 swap_cnt = 1; 150 pb += es; 151 pc -= es; 152 } 153 if (swap_cnt == 0) { /* Switch to insertion sort */ 154 for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es) 155 for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; 156 pl -= es) 157 swap(pl, pl - es); 158 return; 159 } 160 161 pn = (char *)a + n * es; 162 r = min(pa - (char *)a, pb - pa); 163 vecswap(a, pb - r, r); 164 r = min(pd - pc, pn - pd - es); 165 vecswap(pb, pn - r, r); 166 if ((r = pb - pa) > es) 167 qsort(a, r / es, es, cmp); 168 if ((r = pd - pc) > es) { 169 /* Iterate rather than recurse to save stack space */ 170 a = pn - r; 171 n = r / es; 172 goto loop; 173 } 174 /* qsort(pn - r, r / es, es, cmp);*/ 175 } 176