bsd/kern/qsort.c

   1 /*
   2  * Copyright (c) 2000-2006 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 /*
  29  * Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved
  30  *
  31  * Copyright (c) 1992, 1993
  32  *      The Regents of the University of California.  All rights reserved.
  33  *
  34  * Redistribution and use in source and binary forms, with or without
  35  * modification, are permitted provided that the following conditions
  36  * are met:
  37  * 1. Redistributions of source code must retain the above copyright
  38  *    notice, this list of conditions and the following disclaimer.
  39  * 2. Redistributions in binary form must reproduce the above copyright
  40  *    notice, this list of conditions and the following disclaimer in the
  41  *    documentation and/or other materials provided with the distribution.
  42  * 3. All advertising materials mentioning features or use of this software
  43  *    must display the following acknowledgement:
  44  *      This product includes software developed by the University of
  45  *      California, Berkeley and its contributors.
  46  * 4. Neither the name of the University nor the names of its contributors
  47  *    may be used to endorse or promote products derived from this software
  48  *    without specific prior written permission.
  49  *
  50  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  51  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  52  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  53  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  54  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  55  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  56  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  57  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  58  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  59  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  60  * SUCH DAMAGE.
  61  *
  62  *      @(#)qsort.c     8.1 (Berkeley) 6/4/93
  63  */
  64
  65
  66 #include <sys/types.h>
  67 //#include <stdlib.h>
  68
  69 __private_extern__
  70 void
  71 qsort(void *a, size_t n, size_t es, int (*cmp)(const void *, const void *));
  72
  73 static inline char      *med3(char *, char *, char *, int (*)(const void *, const void *));
  74 static inline void       swapfunc(char *, char *, int, int);
  75
  76 #define min(a, b)       (a) < (b) ? a : b
  77
  78 /*
  79  * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
  80  */
  81 #define swapcode(TYPE, parmi, parmj, n) {               \
  82         long i = (n) / sizeof (TYPE);                   \
  83         TYPE *pi = (TYPE *) (parmi);                    \
  84         TYPE *pj = (TYPE *) (parmj);                    \
  85         do {                                            \
  86                 TYPE    t = *pi;                        \
  87                 *pi++ = *pj;                            \
  88                 *pj++ = t;                              \
  89         } while (--i > 0);                              \
  90 }
  91
  92 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
  93         es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
  94
  95 static inline void
  96 swapfunc(char *a, char *b, int n, int swaptype)
  97 {
  98         if(swaptype <= 1)
  99                 swapcode(long, a, b, n)
 100         else
 101                 swapcode(char, a, b, n)
 102 }
 103
 104 #define swap(a, b)                                      \
 105         if (swaptype == 0) {                            \
 106                 long t = *(long *)(a);                  \
 107                 *(long *)(a) = *(long *)(b);            \
 108                 *(long *)(b) = t;                       \
 109         } else                                          \
 110                 swapfunc(a, b, es, swaptype)
 111
 112 #define vecswap(a, b, n)        if ((n) > 0) swapfunc(a, b, n, swaptype)
 113
 114 static inline char *
 115 med3(char *a, char *b, char *c, int (*cmp)(const void *, const void *))
 116 {
 117         return cmp(a, b) < 0 ?
 118                (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a ))
 119               :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c ));
 120 }
 121
 122 __private_extern__
 123 void
 124 qsort(void *a, size_t n, size_t es, int (*cmp)(const void *, const void *))
 125 {
 126         char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
 127         int d, swaptype, swap_cnt;
 128         int r;
 129
 130 loop:   SWAPINIT(a, es);
 131         swap_cnt = 0;
 132         if (n < 7) {
 133                 for (pm = (char *)a + es; pm < (char *) a + n * es; pm += es)
 134                         for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
 135                              pl -= es)
 136                                 swap(pl, pl - es);
 137                 return;
 138         }
 139         pm = (char *)a + (n / 2) * es;
 140         if (n > 7) {
 141                 pl = a;
 142                 pn = (char *)a + (n - 1) * es;
 143                 if (n > 40) {
 144                         d = (n / 8) * es;
 145                         pl = med3(pl, pl + d, pl + 2 * d, cmp);
 146                         pm = med3(pm - d, pm, pm + d, cmp);
 147                         pn = med3(pn - 2 * d, pn - d, pn, cmp);
 148                 }
 149                 pm = med3(pl, pm, pn, cmp);
 150         }
 151         swap(a, pm);
 152         pa = pb = (char *)a + es;
 153
 154         pc = pd = (char *)a + (n - 1) * es;
 155         for (;;) {
 156                 while (pb <= pc && (r = cmp(pb, a)) <= 0) {
 157                         if (r == 0) {
 158                                 swap_cnt = 1;
 159                                 swap(pa, pb);
 160                                 pa += es;
 161                         }
 162                         pb += es;
 163                 }
 164                 while (pb <= pc && (r = cmp(pc, a)) >= 0) {
 165                         if (r == 0) {
 166                                 swap_cnt = 1;
 167                                 swap(pc, pd);
 168                                 pd -= es;
 169                         }
 170                         pc -= es;
 171                 }
 172                 if (pb > pc)
 173                         break;
 174                 swap(pb, pc);
 175                 swap_cnt = 1;
 176                 pb += es;
 177                 pc -= es;
 178         }
 179         if (swap_cnt == 0) {  /* Switch to insertion sort */
 180                 for (pm = (char *)a + es; pm < (char *) a + n * es; pm += es)
 181                         for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
 182                              pl -= es)
 183                                 swap(pl, pl - es);
 184                 return;
 185         }
 186
 187         pn = (char *)a + n * es;
 188         r = min(pa - (char *)a, pb - pa);
 189         vecswap(a, pb - r, r);
 190         r = min((size_t)(pd - pc), pn - pd - es);
 191         vecswap(pb, pn - r, r);
 192         if ((size_t)(r = pb - pa) > es)
 193                 qsort(a, r / es, es, cmp);
 194         if ((size_t)(r = pd - pc) > es) {
 195                 /* Iterate rather than recurse to save stack space */
 196                 a = pn - r;
 197                 n = r / es;
 198                 goto loop;
 199         }
 200 /*              qsort(pn - r, r / es, es, cmp);*/
 201 }