qsort.c revision 279663
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) 31static char sccsid[] = "@(#)qsort.c 8.1 (Berkeley) 6/4/93"; 32#endif /* LIBC_SCCS and not lint */ 33#include <sys/cdefs.h> 34__FBSDID("$FreeBSD: head/lib/libc/stdlib/qsort.c 279663 2015-03-05 17:00:39Z pfg $"); 35 36#include <stdlib.h> 37 38#ifdef I_AM_QSORT_R 39typedef int cmp_t(void *, const void *, const void *); 40#else 41typedef int cmp_t(const void *, const void *); 42#endif 43static inline char *med3(char *, char *, char *, cmp_t *, void *); 44static inline void swapfunc(char *, char *, int, int, int); 45 46#define min(a, b) (a) < (b) ? a : b 47 48/* 49 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". 50 */ 51#define swapcode(TYPE, parmi, parmj, n) { \ 52 long i = (n) / sizeof (TYPE); \ 53 TYPE *pi = (TYPE *) (parmi); \ 54 TYPE *pj = (TYPE *) (parmj); \ 55 do { \ 56 TYPE t = *pi; \ 57 *pi++ = *pj; \ 58 *pj++ = t; \ 59 } while (--i > 0); \ 60} 61 62#define SWAPINIT(TYPE, a, es) swaptype_ ## TYPE = \ 63 ((char *)a - (char *)0) % sizeof(TYPE) || \ 64 es % sizeof(TYPE) ? 2 : es == sizeof(TYPE) ? 0 : 1; 65 66static inline void 67swapfunc(a, b, n, swaptype_long, swaptype_int) 68 char *a, *b; 69 int n, swaptype_long, swaptype_int; 70{ 71 if (swaptype_long <= 1) 72 swapcode(long, a, b, n) 73 else if (swaptype_int <= 1) 74 swapcode(int, a, b, n) 75 else 76 swapcode(char, a, b, n) 77} 78 79#define swap(a, b) \ 80 if (swaptype_long == 0) { \ 81 long t = *(long *)(a); \ 82 *(long *)(a) = *(long *)(b); \ 83 *(long *)(b) = t; \ 84 } else if (swaptype_int == 0) { \ 85 int t = *(int *)(a); \ 86 *(int *)(a) = *(int *)(b); \ 87 *(int *)(b) = t; \ 88 } else \ 89 swapfunc(a, b, es, swaptype_long, swaptype_int) 90 91#define vecswap(a, b, n) \ 92 if ((n) > 0) swapfunc(a, b, n, swaptype_long, swaptype_int) 93 94#ifdef I_AM_QSORT_R 95#define CMP(t, x, y) (cmp((t), (x), (y))) 96#else 97#define CMP(t, x, y) (cmp((x), (y))) 98#endif 99 100static inline char * 101med3(char *a, char *b, char *c, cmp_t *cmp, void *thunk 102#ifndef I_AM_QSORT_R 103__unused 104#endif 105) 106{ 107 return CMP(thunk, a, b) < 0 ? 108 (CMP(thunk, b, c) < 0 ? b : (CMP(thunk, a, c) < 0 ? c : a )) 109 :(CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c )); 110} 111 112#ifdef I_AM_QSORT_R 113void 114qsort_r(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp) 115#else 116#define thunk NULL 117void 118qsort(void *a, size_t n, size_t es, cmp_t *cmp) 119#endif 120{ 121 char *pa, *pb, *pc, *pd, *pl, *pm, *pn; 122 size_t d, r; 123 int cmp_result; 124 int swaptype_long, swaptype_int, swap_cnt; 125 126loop: SWAPINIT(long, a, es); 127 SWAPINIT(int, a, es); 128 swap_cnt = 0; 129 if (n < 7) { 130 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 131 for (pl = pm; 132 pl > (char *)a && CMP(thunk, pl - es, pl) > 0; 133 pl -= es) 134 swap(pl, pl - es); 135 return; 136 } 137 pm = (char *)a + (n / 2) * es; 138 if (n > 7) { 139 pl = a; 140 pn = (char *)a + (n - 1) * es; 141 if (n > 40) { 142 d = (n / 8) * es; 143 pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk); 144 pm = med3(pm - d, pm, pm + d, cmp, thunk); 145 pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk); 146 } 147 pm = med3(pl, pm, pn, cmp, thunk); 148 } 149 swap(a, pm); 150 pa = pb = (char *)a + es; 151 152 pc = pd = (char *)a + (n - 1) * es; 153 for (;;) { 154 while (pb <= pc && (cmp_result = CMP(thunk, pb, a)) <= 0) { 155 if (cmp_result == 0) { 156 swap_cnt = 1; 157 swap(pa, pb); 158 pa += es; 159 } 160 pb += es; 161 } 162 while (pb <= pc && (cmp_result = CMP(thunk, pc, a)) >= 0) { 163 if (cmp_result == 0) { 164 swap_cnt = 1; 165 swap(pc, pd); 166 pd -= es; 167 } 168 pc -= es; 169 } 170 if (pb > pc) 171 break; 172 swap(pb, pc); 173 swap_cnt = 1; 174 pb += es; 175 pc -= es; 176 } 177 if (swap_cnt == 0) { /* Switch to insertion sort */ 178 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 179 for (pl = pm; 180 pl > (char *)a && CMP(thunk, pl - es, pl) > 0; 181 pl -= es) 182 swap(pl, pl - es); 183 return; 184 } 185 186 pn = (char *)a + n * es; 187 r = min(pa - (char *)a, pb - pa); 188 vecswap(a, pb - r, r); 189 r = min(pd - pc, pn - pd - es); 190 vecswap(pb, pn - r, r); 191 if ((r = pb - pa) > es) 192#ifdef I_AM_QSORT_R 193 qsort_r(a, r / es, es, thunk, cmp); 194#else 195 qsort(a, r / es, es, cmp); 196#endif 197 if ((r = pd - pc) > es) { 198 /* Iterate rather than recurse to save stack space */ 199 a = pn - r; 200 n = r / es; 201 goto loop; 202 } 203/* qsort(pn - r, r / es, es, cmp);*/ 204} 205