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 * 4. 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 * $FreeBSD: src/sys/libkern/qsort.c,v 1.10 1999/08/28 00:46:35 peter Exp $ 30 * $DragonFly: src/sys/libkern/qsort.c,v 1.6 2006/12/13 21:58:51 dillon Exp $ 31 */ 32 33 #include <sys/libkern.h> 34 35 typedef int cmp_t(const void *, const void *); 36 static __inline char *med3(char *, char *, char *, cmp_t *); 37 static __inline void swapfunc(char *, char *, int, int); 38 39 #define min(a, b) (a) < (b) ? a : b 40 41 /* 42 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". 43 */ 44 #define swapcode(TYPE, parmi, parmj, n) { \ 45 long i = (n) / sizeof (TYPE); \ 46 TYPE *pi = (TYPE *) (parmi); \ 47 TYPE *pj = (TYPE *) (parmj); \ 48 do { \ 49 TYPE t = *pi; \ 50 *pi++ = *pj; \ 51 *pj++ = t; \ 52 } while (--i > 0); \ 53 } 54 55 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \ 56 es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1; 57 58 static __inline void 59 swapfunc(char *a, char *b, int n, int swaptype) 60 { 61 if(swaptype <= 1) 62 swapcode(long, a, b, n) 63 else 64 swapcode(char, a, b, n) 65 } 66 67 #define swap(a, b) \ 68 if (swaptype == 0) { \ 69 long t = *(long *)(a); \ 70 *(long *)(a) = *(long *)(b); \ 71 *(long *)(b) = t; \ 72 } else \ 73 swapfunc(a, b, es, swaptype) 74 75 #define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype) 76 77 static __inline char * 78 med3(char *a, char *b, char *c, cmp_t *cmp) 79 { 80 return cmp(a, b) < 0 ? 81 (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a )) 82 :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c )); 83 } 84 85 void 86 kqsort(void *a, size_t n, size_t es, cmp_t *cmp) 87 { 88 char *pa, *pb, *pc, *pd, *pl, *pm, *pn; 89 int d, r, swaptype, swap_cnt; 90 91 loop: SWAPINIT(a, es); 92 swap_cnt = 0; 93 if (n < 7) { 94 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 95 for (pl = pm; pl > (char *)a && cmp(pl - es, pl) > 0; 96 pl -= es) 97 swap(pl, pl - es); 98 return; 99 } 100 pm = (char *)a + (n / 2) * es; 101 if (n > 7) { 102 pl = a; 103 pn = (char *)a + (n - 1) * es; 104 if (n > 40) { 105 d = (n / 8) * es; 106 pl = med3(pl, pl + d, pl + 2 * d, cmp); 107 pm = med3(pm - d, pm, pm + d, cmp); 108 pn = med3(pn - 2 * d, pn - d, pn, cmp); 109 } 110 pm = med3(pl, pm, pn, cmp); 111 } 112 swap(a, pm); 113 pa = pb = (char *)a + es; 114 115 pc = pd = (char *)a + (n - 1) * es; 116 for (;;) { 117 while (pb <= pc && (r = cmp(pb, a)) <= 0) { 118 if (r == 0) { 119 swap_cnt = 1; 120 swap(pa, pb); 121 pa += es; 122 } 123 pb += es; 124 } 125 while (pb <= pc && (r = cmp(pc, a)) >= 0) { 126 if (r == 0) { 127 swap_cnt = 1; 128 swap(pc, pd); 129 pd -= es; 130 } 131 pc -= es; 132 } 133 if (pb > pc) 134 break; 135 swap(pb, pc); 136 swap_cnt = 1; 137 pb += es; 138 pc -= es; 139 } 140 if (swap_cnt == 0) { /* Switch to insertion sort */ 141 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 142 for (pl = pm; pl > (char *)a && cmp(pl - es, pl) > 0; 143 pl -= es) 144 swap(pl, pl - es); 145 return; 146 } 147 148 pn = (char *)a + n * es; 149 r = min(pa - (char *)a, pb - pa); 150 vecswap(a, pb - r, r); 151 r = min(pd - pc, pn - pd - es); 152 vecswap(pb, pn - r, r); 153 if ((r = pb - pa) > es) 154 kqsort(a, r / es, es, cmp); 155 if ((r = pd - pc) > es) { 156 /* Iterate rather than recurse to save stack space */ 157 a = pn - r; 158 n = r / es; 159 goto loop; 160 } 161 /* kqsort(pn - r, r / es, es, cmp);*/ 162 } 163