i386/libsa/qsort.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
   7  * Reserved.  This file contains Original Code and/or Modifications of
   8  * Original Code as defined in and that are subject to the Apple Public
   9  * Source License Version 1.1 (the "License").  You may not use this file
  10  * except in compliance with the License.  Please obtain a copy of the
  11  * License at http://www.apple.com/publicsource and read it before using
  12  * this file.
  13  *
  14  * The Original Code and all software distributed under the License are
  15  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  16  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  17  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE OR NON- INFRINGEMENT.  Please see the
  19  * License for the specific language governing rights and limitations
  20  * under the License.
  21  *
  22  * @APPLE_LICENSE_HEADER_END@
  23  */
  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
  57
  58 #include <sys/types.h>
  59 #include <stdlib.h>
  60
  61 static inline char      *med3 __P((char *, char *, char *, int (*)()));
  62 static inline void       swapfunc __P((char *, char *, int, int));
  63
  64 #define min(a, b)       (a) < (b) ? a : b
  65
  66 /*
  67  * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
  68  */
  69 #define swapcode(TYPE, parmi, parmj, n) {               \
  70         long i = (n) / sizeof (TYPE);                   \
  71         register TYPE *pi = (TYPE *) (parmi);           \
  72         register TYPE *pj = (TYPE *) (parmj);           \
  73         do {                                            \
  74                 register TYPE   t = *pi;                \
  75                 *pi++ = *pj;                            \
  76                 *pj++ = t;                              \
  77         } while (--i > 0);                              \
  78 }
  79
  80 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
  81         es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
  82
  83 static inline void
  84 swapfunc(a, b, n, swaptype)
  85         char *a, *b;
  86         int n, swaptype;
  87 {
  88         if(swaptype <= 1)
  89                 swapcode(long, a, b, n)
  90         else
  91                 swapcode(char, a, b, n)
  92 }
  93
  94 #define swap(a, b)                                      \
  95         if (swaptype == 0) {                            \
  96                 long t = *(long *)(a);                  \
  97                 *(long *)(a) = *(long *)(b);            \
  98                 *(long *)(b) = t;                       \
  99         } else                                          \
 100                 swapfunc(a, b, es, swaptype)
 101
 102 #define vecswap(a, b, n)        if ((n) > 0) swapfunc(a, b, n, swaptype)
 103
 104 static inline char *
 105 med3(a, b, c, cmp)
 106         char *a, *b, *c;
 107         int (*cmp)();
 108 {
 109         return cmp(a, b) < 0 ?
 110                (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a ))
 111               :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c ));
 112 }
 113
 114 void
 115 qsort(a, n, es, cmp)
 116         void *a;
 117         size_t n, es;
 118         int (*cmp)();
 119 {
 120         char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
 121         int d, r, swaptype, swap_cnt;
 122
 123 loop:   SWAPINIT(a, es);
 124         swap_cnt = 0;
 125         if (n < 7) {
 126                 for (pm = a + es; pm < (char *) a + n * es; pm += es)
 127                         for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
 128                              pl -= es)
 129                                 swap(pl, pl - es);
 130                 return;
 131         }
 132         pm = a + (n / 2) * es;
 133         if (n > 7) {
 134                 pl = a;
 135                 pn = a + (n - 1) * es;
 136                 if (n > 40) {
 137                         d = (n / 8) * es;
 138                         pl = med3(pl, pl + d, pl + 2 * d, cmp);
 139                         pm = med3(pm - d, pm, pm + d, cmp);
 140                         pn = med3(pn - 2 * d, pn - d, pn, cmp);
 141                 }
 142                 pm = med3(pl, pm, pn, cmp);
 143         }
 144         swap(a, pm);
 145         pa = pb = a + es;
 146
 147         pc = pd = a + (n - 1) * es;
 148         for (;;) {
 149                 while (pb <= pc && (r = cmp(pb, a)) <= 0) {
 150                         if (r == 0) {
 151                                 swap_cnt = 1;
 152                                 swap(pa, pb);
 153                                 pa += es;
 154                         }
 155                         pb += es;
 156                 }
 157                 while (pb <= pc && (r = cmp(pc, a)) >= 0) {
 158                         if (r == 0) {
 159                                 swap_cnt = 1;
 160                                 swap(pc, pd);
 161                                 pd -= es;
 162                         }
 163                         pc -= es;
 164                 }
 165                 if (pb > pc)
 166                         break;
 167                 swap(pb, pc);
 168                 swap_cnt = 1;
 169                 pb += es;
 170                 pc -= es;
 171         }
 172         if (swap_cnt == 0) {  /* Switch to insertion sort */
 173                 for (pm = a + es; pm < (char *) a + n * es; pm += es)
 174                         for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
 175                              pl -= es)
 176                                 swap(pl, pl - es);
 177                 return;
 178         }
 179
 180         pn = a + n * es;
 181         r = min(pa - (char *)a, pb - pa);
 182         vecswap(a, pb - r, r);
 183         r = min(pd - pc, pn - pd - es);
 184         vecswap(pb, pn - r, r);
 185         if ((r = pb - pa) > es)
 186                 qsort(a, r / es, es, cmp);
 187         if ((r = pd - pc) > es) {
 188                 /* Iterate rather than recurse to save stack space */
 189                 a = pn - r;
 190                 n = r / es;
 191                 goto loop;
 192         }
 193 /*              qsort(pn - r, r / es, es, cmp);*/
 194 }