bsd/kern/qsort.c

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_OSREFERENCE_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
  10  * License may not be used to create, or enable the creation or
  11  * redistribution of, unlawful or unlicensed copies of an Apple operating
  12  * system, or to circumvent, violate, or enable the circumvention or
  13  * violation of, any terms of an Apple operating system software license
  14  * agreement.
  15  *
  16  * Please obtain a copy of the License at
  17  * http://www.opensource.apple.com/apsl/ and read it before using this
  18  * file.
  19  *
  20  * The Original Code and all software distributed under the License are
  21  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  22  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  23  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  24  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  25  * Please see the License for the specific language governing rights and
  26  * limitations under the License.
  27  *
  28  * @APPLE_LICENSE_OSREFERENCE_HEADER_END@
  29  */
  30 /*
  31  * Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved
  32  *
  33  * Copyright (c) 1992, 1993
  34  *      The Regents of the University of California.  All rights reserved.
  35  *
  36  * Redistribution and use in source and binary forms, with or without
  37  * modification, are permitted provided that the following conditions
  38  * are met:
  39  * 1. Redistributions of source code must retain the above copyright
  40  *    notice, this list of conditions and the following disclaimer.
  41  * 2. Redistributions in binary form must reproduce the above copyright
  42  *    notice, this list of conditions and the following disclaimer in the
  43  *    documentation and/or other materials provided with the distribution.
  44  * 3. All advertising materials mentioning features or use of this software
  45  *    must display the following acknowledgement:
  46  *      This product includes software developed by the University of
  47  *      California, Berkeley and its contributors.
  48  * 4. Neither the name of the University nor the names of its contributors
  49  *    may be used to endorse or promote products derived from this software
  50  *    without specific prior written permission.
  51  *
  52  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  53  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  54  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  55  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  56  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  57  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  58  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  59  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  60  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  61  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  62  * SUCH DAMAGE.
  63  *
  64  *      @(#)qsort.c     8.1 (Berkeley) 6/4/93
  65  */
  66
  67
  68 #include <sys/types.h>
  69 //#include <stdlib.h>
  70
  71 static inline char      *med3(char *, char *, char *, int (*)());
  72 static inline void       swapfunc(char *, char *, int, int);
  73
  74 #define min(a, b)       (a) < (b) ? a : b
  75
  76 /*
  77  * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
  78  */
  79 #define swapcode(TYPE, parmi, parmj, n) {               \
  80         long i = (n) / sizeof (TYPE);                   \
  81         register TYPE *pi = (TYPE *) (parmi);           \
  82         register TYPE *pj = (TYPE *) (parmj);           \
  83         do {                                            \
  84                 register TYPE   t = *pi;                \
  85                 *pi++ = *pj;                            \
  86                 *pj++ = t;                              \
  87         } while (--i > 0);                              \
  88 }
  89
  90 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
  91         es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
  92
  93 static inline void
  94 swapfunc(a, b, n, swaptype)
  95         char *a, *b;
  96         int n, 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(a, b, c, cmp)
 116         char *a, *b, *c;
 117         int (*cmp)();
 118 {
 119         return cmp(a, b) < 0 ?
 120                (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a ))
 121               :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c ));
 122 }
 123
 124 __private_extern__
 125 void
 126 qsort(a, n, es, cmp)
 127         void *a;
 128         size_t n, es;
 129         int (*cmp)();
 130 {
 131         char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
 132         int d, r, swaptype, swap_cnt;
 133
 134 loop:   SWAPINIT(a, es);
 135         swap_cnt = 0;
 136         if (n < 7) {
 137                 for (pm = (char *)a + es; pm < (char *) a + n * es; pm += es)
 138                         for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
 139                              pl -= es)
 140                                 swap(pl, pl - es);
 141                 return;
 142         }
 143         pm = (char *)a + (n / 2) * es;
 144         if (n > 7) {
 145                 pl = a;
 146                 pn = (char *)a + (n - 1) * es;
 147                 if (n > 40) {
 148                         d = (n / 8) * es;
 149                         pl = med3(pl, pl + d, pl + 2 * d, cmp);
 150                         pm = med3(pm - d, pm, pm + d, cmp);
 151                         pn = med3(pn - 2 * d, pn - d, pn, cmp);
 152                 }
 153                 pm = med3(pl, pm, pn, cmp);
 154         }
 155         swap(a, pm);
 156         pa = pb = (char *)a + es;
 157
 158         pc = pd = (char *)a + (n - 1) * es;
 159         for (;;) {
 160                 while (pb <= pc && (r = cmp(pb, a)) <= 0) {
 161                         if (r == 0) {
 162                                 swap_cnt = 1;
 163                                 swap(pa, pb);
 164                                 pa += es;
 165                         }
 166                         pb += es;
 167                 }
 168                 while (pb <= pc && (r = cmp(pc, a)) >= 0) {
 169                         if (r == 0) {
 170                                 swap_cnt = 1;
 171                                 swap(pc, pd);
 172                                 pd -= es;
 173                         }
 174                         pc -= es;
 175                 }
 176                 if (pb > pc)
 177                         break;
 178                 swap(pb, pc);
 179                 swap_cnt = 1;
 180                 pb += es;
 181                 pc -= es;
 182         }
 183         if (swap_cnt == 0) {  /* Switch to insertion sort */
 184                 for (pm = (char *)a + es; pm < (char *) a + n * es; pm += es)
 185                         for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
 186                              pl -= es)
 187                                 swap(pl, pl - es);
 188                 return;
 189         }
 190
 191         pn = (char *)a + n * es;
 192         r = min(pa - (char *)a, pb - pa);
 193         vecswap(a, pb - r, r);
 194         r = min(pd - pc, pn - pd - es);
 195         vecswap(pb, pn - r, r);
 196         if ((r = pb - pa) > es)
 197                 qsort(a, r / es, es, cmp);
 198         if ((r = pd - pc) > es) {
 199                 /* Iterate rather than recurse to save stack space */
 200                 a = pn - r;
 201                 n = r / es;
 202                 goto loop;
 203         }
 204 /*              qsort(pn - r, r / es, es, cmp);*/
 205 }