bsd/kern/qsort.c

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*
  26  * Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved
  27  *
  28  * Copyright (c) 1992, 1993
  29  *      The Regents of the University of California.  All rights reserved.
  30  *
  31  * Redistribution and use in source and binary forms, with or without
  32  * modification, are permitted provided that the following conditions
  33  * are met:
  34  * 1. Redistributions of source code must retain the above copyright
  35  *    notice, this list of conditions and the following disclaimer.
  36  * 2. Redistributions in binary form must reproduce the above copyright
  37  *    notice, this list of conditions and the following disclaimer in the
  38  *    documentation and/or other materials provided with the distribution.
  39  * 3. All advertising materials mentioning features or use of this software
  40  *    must display the following acknowledgement:
  41  *      This product includes software developed by the University of
  42  *      California, Berkeley and its contributors.
  43  * 4. Neither the name of the University nor the names of its contributors
  44  *    may be used to endorse or promote products derived from this software
  45  *    without specific prior written permission.
  46  *
  47  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  48  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  49  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  50  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  51  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  52  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  53  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  54  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  55  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  56  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  57  * SUCH DAMAGE.
  58  *
  59  *      @(#)qsort.c     8.1 (Berkeley) 6/4/93
  60  */
  61
  62
  63 #include <sys/types.h>
  64 //#include <stdlib.h>
  65
  66 static inline char      *med3 __P((char *, char *, char *, int (*)()));
  67 static inline void       swapfunc __P((char *, char *, int, int));
  68
  69 #define min(a, b)       (a) < (b) ? a : b
  70
  71 /*
  72  * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
  73  */
  74 #define swapcode(TYPE, parmi, parmj, n) {               \
  75         long i = (n) / sizeof (TYPE);                   \
  76         register TYPE *pi = (TYPE *) (parmi);           \
  77         register TYPE *pj = (TYPE *) (parmj);           \
  78         do {                                            \
  79                 register TYPE   t = *pi;                \
  80                 *pi++ = *pj;                            \
  81                 *pj++ = t;                              \
  82         } while (--i > 0);                              \
  83 }
  84
  85 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
  86         es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
  87
  88 static inline void
  89 swapfunc(a, b, n, swaptype)
  90         char *a, *b;
  91         int n, swaptype;
  92 {
  93         if(swaptype <= 1)
  94                 swapcode(long, a, b, n)
  95         else
  96                 swapcode(char, a, b, n)
  97 }
  98
  99 #define swap(a, b)                                      \
 100         if (swaptype == 0) {                            \
 101                 long t = *(long *)(a);                  \
 102                 *(long *)(a) = *(long *)(b);            \
 103                 *(long *)(b) = t;                       \
 104         } else                                          \
 105                 swapfunc(a, b, es, swaptype)
 106
 107 #define vecswap(a, b, n)        if ((n) > 0) swapfunc(a, b, n, swaptype)
 108
 109 static inline char *
 110 med3(a, b, c, cmp)
 111         char *a, *b, *c;
 112         int (*cmp)();
 113 {
 114         return cmp(a, b) < 0 ?
 115                (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a ))
 116               :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c ));
 117 }
 118
 119 __private_extern__
 120 void
 121 qsort(a, n, es, cmp)
 122         void *a;
 123         size_t n, es;
 124         int (*cmp)();
 125 {
 126         char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
 127         int d, r, swaptype, swap_cnt;
 128
 129 loop:   SWAPINIT(a, es);
 130         swap_cnt = 0;
 131         if (n < 7) {
 132                 for (pm = (char *)a + es; pm < (char *) a + n * es; pm += es)
 133                         for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
 134                              pl -= es)
 135                                 swap(pl, pl - es);
 136                 return;
 137         }
 138         pm = (char *)a + (n / 2) * es;
 139         if (n > 7) {
 140                 pl = a;
 141                 pn = (char *)a + (n - 1) * es;
 142                 if (n > 40) {
 143                         d = (n / 8) * es;
 144                         pl = med3(pl, pl + d, pl + 2 * d, cmp);
 145                         pm = med3(pm - d, pm, pm + d, cmp);
 146                         pn = med3(pn - 2 * d, pn - d, pn, cmp);
 147                 }
 148                 pm = med3(pl, pm, pn, cmp);
 149         }
 150         swap(a, pm);
 151         pa = pb = (char *)a + es;
 152
 153         pc = pd = (char *)a + (n - 1) * es;
 154         for (;;) {
 155                 while (pb <= pc && (r = cmp(pb, a)) <= 0) {
 156                         if (r == 0) {
 157                                 swap_cnt = 1;
 158                                 swap(pa, pb);
 159                                 pa += es;
 160                         }
 161                         pb += es;
 162                 }
 163                 while (pb <= pc && (r = cmp(pc, a)) >= 0) {
 164                         if (r == 0) {
 165                                 swap_cnt = 1;
 166                                 swap(pc, pd);
 167                                 pd -= es;
 168                         }
 169                         pc -= es;
 170                 }
 171                 if (pb > pc)
 172                         break;
 173                 swap(pb, pc);
 174                 swap_cnt = 1;
 175                 pb += es;
 176                 pc -= es;
 177         }
 178         if (swap_cnt == 0) {  /* Switch to insertion sort */
 179                 for (pm = (char *)a + es; pm < (char *) a + n * es; pm += es)
 180                         for (pl = pm; pl > (char *) a && cmp(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                 qsort(a, r / es, es, cmp);
 193         if ((r = pd - pc) > es) {
 194                 /* Iterate rather than recurse to save stack space */
 195                 a = pn - r;
 196                 n = r / es;
 197                 goto loop;
 198         }
 199 /*              qsort(pn - r, r / es, es, cmp);*/
 200 }