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 * @(#)qsort.c 8.1 (Berkeley) 6/4/93 30 * $FreeBSD: src/lib/libc/stdlib/qsort.c,v 1.15 2008/01/14 09:21:34 das Exp $ 31 * $DragonFly: src/lib/libc/stdlib/qsort.c,v 1.5 2005/11/20 12:37:49 swildner Exp $ 32 */ 33 34 #include <stdlib.h> 35 36 #ifdef I_AM_QSORT_R 37 typedef int cmp_t(void *, const void *, const void *); 38 #else 39 typedef int cmp_t(const void *, const void *); 40 #endif 41 static inline char *med3(char *, char *, char *, cmp_t *, void *); 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 TYPE *pi = (TYPE *) (parmi); \ 52 TYPE *pj = (TYPE *) (parmj); \ 53 do { \ 54 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(char *a, char *b, int n, int 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 82 #ifdef I_AM_QSORT_R 83 #define CMP(t, x, y) (cmp((t), (x), (y))) 84 #else 85 #define CMP(t, x, y) (cmp((x), (y))) 86 #endif 87 88 static inline char * 89 med3(char *a, char *b, char *c, cmp_t *cmp, void *thunk 90 #ifndef I_AM_QSORT_R 91 __unused 92 #endif 93 ) 94 { 95 return CMP(thunk, a, b) < 0 ? 96 (CMP(thunk, b, c) < 0 ? b : (CMP(thunk, a, c) < 0 ? c : a )) 97 :(CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c )); 98 } 99 100 #ifdef I_AM_QSORT_R 101 void 102 qsort_r(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp) 103 #else 104 #define thunk NULL 105 void 106 qsort(void *a, size_t n, size_t es, cmp_t *cmp) 107 #endif 108 { 109 char *pa, *pb, *pc, *pd, *pl, *pm, *pn; 110 size_t d, r; 111 int cmp_result; 112 int swaptype, swap_cnt; 113 114 loop: SWAPINIT(a, es); 115 swap_cnt = 0; 116 if (n < 7) { 117 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 118 for (pl = pm; 119 pl > (char *)a && CMP(thunk, pl - es, pl) > 0; 120 pl -= es) 121 swap(pl, pl - es); 122 return; 123 } 124 pm = (char *)a + (n / 2) * es; 125 if (n > 7) { 126 pl = a; 127 pn = (char *)a + (n - 1) * es; 128 if (n > 40) { 129 d = (n / 8) * es; 130 pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk); 131 pm = med3(pm - d, pm, pm + d, cmp, thunk); 132 pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk); 133 } 134 pm = med3(pl, pm, pn, cmp, thunk); 135 } 136 swap(a, pm); 137 pa = pb = (char *)a + es; 138 139 pc = pd = (char *)a + (n - 1) * es; 140 for (;;) { 141 while (pb <= pc && (cmp_result = CMP(thunk, pb, a)) <= 0) { 142 if (cmp_result == 0) { 143 swap_cnt = 1; 144 swap(pa, pb); 145 pa += es; 146 } 147 pb += es; 148 } 149 while (pb <= pc && (cmp_result = CMP(thunk, pc, a)) >= 0) { 150 if (cmp_result == 0) { 151 swap_cnt = 1; 152 swap(pc, pd); 153 pd -= es; 154 } 155 pc -= es; 156 } 157 if (pb > pc) 158 break; 159 swap(pb, pc); 160 swap_cnt = 1; 161 pb += es; 162 pc -= es; 163 } 164 if (swap_cnt == 0) { /* Switch to insertion sort */ 165 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 166 for (pl = pm; 167 pl > (char *)a && CMP(thunk, pl - es, pl) > 0; 168 pl -= es) 169 swap(pl, pl - es); 170 return; 171 } 172 173 pn = (char *)a + n * es; 174 r = min(pa - (char *)a, pb - pa); 175 vecswap(a, pb - r, r); 176 r = min(pd - pc, pn - pd - es); 177 vecswap(pb, pn - r, r); 178 if ((r = pb - pa) > es) 179 #ifdef I_AM_QSORT_R 180 qsort_r(a, r / es, es, thunk, cmp); 181 #else 182 qsort(a, r / es, es, cmp); 183 #endif 184 if ((r = pd - pc) > es) { 185 /* Iterate rather than recurse to save stack space */ 186 a = pn - r; 187 n = r / es; 188 goto loop; 189 } 190 /* qsort(pn - r, r / es, es, cmp);*/ 191 } 192