bsd/kern/qsort.c

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23  * Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved
  24  *
  25  * Copyright (c) 1992, 1993
  26  *      The Regents of the University of California.  All rights reserved.
  27  *
  28  * Redistribution and use in source and binary forms, with or without
  29  * modification, are permitted provided that the following conditions
  30  * are met:
  31  * 1. Redistributions of source code must retain the above copyright
  32  *    notice, this list of conditions and the following disclaimer.
  33  * 2. Redistributions in binary form must reproduce the above copyright
  34  *    notice, this list of conditions and the following disclaimer in the
  35  *    documentation and/or other materials provided with the distribution.
  36  * 3. All advertising materials mentioning features or use of this software
  37  *    must display the following acknowledgement:
  38  *      This product includes software developed by the University of
  39  *      California, Berkeley and its contributors.
  40  * 4. Neither the name of the University nor the names of its contributors
  41  *    may be used to endorse or promote products derived from this software
  42  *    without specific prior written permission.
  43  *
  44  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  45  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  46  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  47  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  48  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  49  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  50  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  51  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  52  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  53  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  54  * SUCH DAMAGE.
  55  *
  56  *      @(#)qsort.c     8.1 (Berkeley) 6/4/93
  57  */
  58
  59
  60 #include <sys/types.h>
  61 #include <stdlib.h>
  62
  63 static inline char      *med3 __P((char *, char *, char *, int (*)()));
  64 static inline void       swapfunc __P((char *, char *, int, int));
  65
  66 #define min(a, b)       (a) < (b) ? a : b
  67
  68 /*
  69  * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
  70  */
  71 #define swapcode(TYPE, parmi, parmj, n) {               \
  72         long i = (n) / sizeof (TYPE);                   \
  73         register TYPE *pi = (TYPE *) (parmi);           \
  74         register TYPE *pj = (TYPE *) (parmj);           \
  75         do {                                            \
  76                 register TYPE   t = *pi;                \
  77                 *pi++ = *pj;                            \
  78                 *pj++ = t;                              \
  79         } while (--i > 0);                              \
  80 }
  81
  82 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
  83         es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
  84
  85 static inline void
  86 swapfunc(a, b, n, swaptype)
  87         char *a, *b;
  88         int n, swaptype;
  89 {
  90         if(swaptype <= 1)
  91                 swapcode(long, a, b, n)
  92         else
  93                 swapcode(char, a, b, n)
  94 }
  95
  96 #define swap(a, b)                                      \
  97         if (swaptype == 0) {                            \
  98                 long t = *(long *)(a);                  \
  99                 *(long *)(a) = *(long *)(b);            \
 100                 *(long *)(b) = t;                       \
 101         } else                                          \
 102                 swapfunc(a, b, es, swaptype)
 103
 104 #define vecswap(a, b, n)        if ((n) > 0) swapfunc(a, b, n, swaptype)
 105
 106 static inline char *
 107 med3(a, b, c, cmp)
 108         char *a, *b, *c;
 109         int (*cmp)();
 110 {
 111         return cmp(a, b) < 0 ?
 112                (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a ))
 113               :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c ));
 114 }
 115
 116 void
 117 qsort(a, n, es, cmp)
 118         void *a;
 119         size_t n, es;
 120         int (*cmp)();
 121 {
 122         char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
 123         int d, r, swaptype, swap_cnt;
 124
 125 loop:   SWAPINIT(a, es);
 126         swap_cnt = 0;
 127         if (n < 7) {
 128                 for (pm = a + es; pm < (char *) a + n * es; pm += es)
 129                         for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
 130                              pl -= es)
 131                                 swap(pl, pl - es);
 132                 return;
 133         }
 134         pm = a + (n / 2) * es;
 135         if (n > 7) {
 136                 pl = a;
 137                 pn = a + (n - 1) * es;
 138                 if (n > 40) {
 139                         d = (n / 8) * es;
 140                         pl = med3(pl, pl + d, pl + 2 * d, cmp);
 141                         pm = med3(pm - d, pm, pm + d, cmp);
 142                         pn = med3(pn - 2 * d, pn - d, pn, cmp);
 143                 }
 144                 pm = med3(pl, pm, pn, cmp);
 145         }
 146         swap(a, pm);
 147         pa = pb = a + es;
 148
 149         pc = pd = a + (n - 1) * es;
 150         for (;;) {
 151                 while (pb <= pc && (r = cmp(pb, a)) <= 0) {
 152                         if (r == 0) {
 153                                 swap_cnt = 1;
 154                                 swap(pa, pb);
 155                                 pa += es;
 156                         }
 157                         pb += es;
 158                 }
 159                 while (pb <= pc && (r = cmp(pc, a)) >= 0) {
 160                         if (r == 0) {
 161                                 swap_cnt = 1;
 162                                 swap(pc, pd);
 163                                 pd -= es;
 164                         }
 165                         pc -= es;
 166                 }
 167                 if (pb > pc)
 168                         break;
 169                 swap(pb, pc);
 170                 swap_cnt = 1;
 171                 pb += es;
 172                 pc -= es;
 173         }
 174         if (swap_cnt == 0) {  /* Switch to insertion sort */
 175                 for (pm = a + es; pm < (char *) a + n * es; pm += es)
 176                         for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
 177                              pl -= es)
 178                                 swap(pl, pl - es);
 179                 return;
 180         }
 181
 182         pn = a + n * es;
 183         r = min(pa - (char *)a, pb - pa);
 184         vecswap(a, pb - r, r);
 185         r = min(pd - pc, pn - pd - es);
 186         vecswap(pb, pn - r, r);
 187         if ((r = pb - pa) > es)
 188                 qsort(a, r / es, es, cmp);
 189         if ((r = pd - pc) > es) {
 190                 /* Iterate rather than recurse to save stack space */
 191                 a = pn - r;
 192                 n = r / es;
 193                 goto loop;
 194         }
 195 /*              qsort(pn - r, r / es, es, cmp);*/
 196 }