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. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30 #if defined(LIBC_SCCS) && !defined(lint) 31 static char *rcsid = "$OpenBSD: qsort.c,v 1.8 2003/06/02 20:18:38 millert Exp $"; 32 #endif /* LIBC_SCCS and not lint */ 33 34 #include <sys/types.h> 35 #include <stdlib.h> 36 37 static __inline char *med3(char *, char *, char *, int (*)()); 38 static __inline void swapfunc(char *, char *, int, int); 39 40 #define min(a, b) (a) < (b) ? a : b 41 42 /* 43 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". 44 */ 45 #define swapcode(TYPE, parmi, parmj, n) { \ 46 long i = (n) / sizeof (TYPE); \ 47 register TYPE *pi = (TYPE *) (parmi); \ 48 register TYPE *pj = (TYPE *) (parmj); \ 49 do { \ 50 register TYPE t = *pi; \ 51 *pi++ = *pj; \ 52 *pj++ = t; \ 53 } while (--i > 0); \ 54 } 55 56 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \ 57 es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1; 58 59 static __inline void 60 swapfunc(a, b, n, swaptype) 61 char *a, *b; 62 int n, swaptype; 63 { 64 if (swaptype <= 1) 65 swapcode(long, a, b, n) 66 else 67 swapcode(char, a, b, n) 68 } 69 70 #define swap(a, b) \ 71 if (swaptype == 0) { \ 72 long t = *(long *)(a); \ 73 *(long *)(a) = *(long *)(b); \ 74 *(long *)(b) = t; \ 75 } else \ 76 swapfunc(a, b, es, swaptype) 77 78 #define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype) 79 80 static __inline char * 81 med3(a, b, c, cmp) 82 char *a, *b, *c; 83 int (*cmp)(); 84 { 85 return cmp(a, b) < 0 ? 86 (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a )) 87 :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c )); 88 } 89 90 void 91 qsort(aa, n, es, cmp) 92 void *aa; 93 size_t n, es; 94 int (*cmp)(); 95 { 96 char *pa, *pb, *pc, *pd, *pl, *pm, *pn; 97 int d, r, swaptype, swap_cnt; 98 register char *a = aa; 99 100 loop: SWAPINIT(a, es); 101 swap_cnt = 0; 102 if (n < 7) { 103 for (pm = (char *)a + es; pm < (char *) a + n * es; pm += es) 104 for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; 105 pl -= es) 106 swap(pl, pl - es); 107 return; 108 } 109 pm = (char *)a + (n / 2) * es; 110 if (n > 7) { 111 pl = (char *)a; 112 pn = (char *)a + (n - 1) * es; 113 if (n > 40) { 114 d = (n / 8) * es; 115 pl = med3(pl, pl + d, pl + 2 * d, cmp); 116 pm = med3(pm - d, pm, pm + d, cmp); 117 pn = med3(pn - 2 * d, pn - d, pn, cmp); 118 } 119 pm = med3(pl, pm, pn, cmp); 120 } 121 swap(a, pm); 122 pa = pb = (char *)a + es; 123 124 pc = pd = (char *)a + (n - 1) * es; 125 for (;;) { 126 while (pb <= pc && (r = cmp(pb, a)) <= 0) { 127 if (r == 0) { 128 swap_cnt = 1; 129 swap(pa, pb); 130 pa += es; 131 } 132 pb += es; 133 } 134 while (pb <= pc && (r = cmp(pc, a)) >= 0) { 135 if (r == 0) { 136 swap_cnt = 1; 137 swap(pc, pd); 138 pd -= es; 139 } 140 pc -= es; 141 } 142 if (pb > pc) 143 break; 144 swap(pb, pc); 145 swap_cnt = 1; 146 pb += es; 147 pc -= es; 148 } 149 if (swap_cnt == 0) { /* Switch to insertion sort */ 150 for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es) 151 for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; 152 pl -= es) 153 swap(pl, pl - es); 154 return; 155 } 156 157 pn = (char *)a + n * es; 158 r = min(pa - (char *)a, pb - pa); 159 vecswap(a, pb - r, r); 160 r = min(pd - pc, pn - pd - es); 161 vecswap(pb, pn - r, r); 162 if ((r = pb - pa) > es) 163 qsort(a, r / es, es, cmp); 164 if ((r = pd - pc) > es) { 165 /* Iterate rather than recurse to save stack space */ 166 a = pn - r; 167 n = r / es; 168 goto loop; 169 } 170 /* qsort(pn - r, r / es, es, cmp);*/ 171 } 172