qsort.c revision 37289
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 * $Id: qsort.c,v 1.8 1998/04/15 17:46:34 bde Exp $ 34 */ 35 36#include <sys/libkern.h> 37 38typedef int cmp_t __P((const void *, const void *)); 39static __inline char *med3 __P((char *, char *, char *, cmp_t *)); 40static __inline void swapfunc __P((char *, char *, int, int)); 41 42#define min(a, b) (a) < (b) ? a : b 43 44/* 45 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". 46 */ 47#define swapcode(TYPE, parmi, parmj, n) { \ 48 long i = (n) / sizeof (TYPE); \ 49 register TYPE *pi = (TYPE *) (parmi); \ 50 register TYPE *pj = (TYPE *) (parmj); \ 51 do { \ 52 register TYPE t = *pi; \ 53 *pi++ = *pj; \ 54 *pj++ = t; \ 55 } while (--i > 0); \ 56} 57 58#define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \ 59 es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1; 60 61static __inline void 62swapfunc(a, b, n, swaptype) 63 char *a, *b; 64 int n, swaptype; 65{ 66 if(swaptype <= 1) 67 swapcode(long, a, b, n) 68 else 69 swapcode(char, a, b, n) 70} 71 72#define swap(a, b) \ 73 if (swaptype == 0) { \ 74 long t = *(long *)(a); \ 75 *(long *)(a) = *(long *)(b); \ 76 *(long *)(b) = t; \ 77 } else \ 78 swapfunc(a, b, es, swaptype) 79 80#define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype) 81 82static __inline char * 83med3(a, b, c, cmp) 84 char *a, *b, *c; 85 cmp_t *cmp; 86{ 87 return cmp(a, b) < 0 ? 88 (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a )) 89 :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c )); 90} 91 92void 93qsort(a, n, es, cmp) 94 void *a; 95 size_t n, es; 96 cmp_t *cmp; 97{ 98 char *pa, *pb, *pc, *pd, *pl, *pm, *pn; 99 int d, r, swaptype, swap_cnt; 100 101loop: SWAPINIT(a, es); 102 swap_cnt = 0; 103 if (n < 7) { 104 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 105 for (pl = pm; pl > (char *)a && cmp(pl - es, pl) > 0; 106 pl -= es) 107 swap(pl, pl - es); 108 return; 109 } 110 pm = (char *)a + (n / 2) * es; 111 if (n > 7) { 112 pl = a; 113 pn = (char *)a + (n - 1) * es; 114 if (n > 40) { 115 d = (n / 8) * es; 116 pl = med3(pl, pl + d, pl + 2 * d, cmp); 117 pm = med3(pm - d, pm, pm + d, cmp); 118 pn = med3(pn - 2 * d, pn - d, pn, cmp); 119 } 120 pm = med3(pl, pm, pn, cmp); 121 } 122 swap(a, pm); 123 pa = pb = (char *)a + es; 124 125 pc = pd = (char *)a + (n - 1) * es; 126 for (;;) { 127 while (pb <= pc && (r = cmp(pb, a)) <= 0) { 128 if (r == 0) { 129 swap_cnt = 1; 130 swap(pa, pb); 131 pa += es; 132 } 133 pb += es; 134 } 135 while (pb <= pc && (r = cmp(pc, a)) >= 0) { 136 if (r == 0) { 137 swap_cnt = 1; 138 swap(pc, pd); 139 pd -= es; 140 } 141 pc -= es; 142 } 143 if (pb > pc) 144 break; 145 swap(pb, pc); 146 swap_cnt = 1; 147 pb += es; 148 pc -= es; 149 } 150 if (swap_cnt == 0) { /* Switch to insertion sort */ 151 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 152 for (pl = pm; pl > (char *)a && cmp(pl - es, pl) > 0; 153 pl -= es) 154 swap(pl, pl - es); 155 return; 156 } 157 158 pn = (char *)a + n * es; 159 r = min(pa - (char *)a, pb - pa); 160 vecswap(a, pb - r, r); 161 r = min(pd - pc, pn - pd - es); 162 vecswap(pb, pn - r, r); 163 if ((r = pb - pa) > es) 164 qsort(a, r / es, es, cmp); 165 if ((r = pd - pc) > es) { 166 /* Iterate rather than recurse to save stack space */ 167 a = pn - r; 168 n = r / es; 169 goto loop; 170 } 171/* qsort(pn - r, r / es, es, cmp);*/ 172} 173