bsd/kern/qsort.c

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