usr/lib/libc/stdlib/qsort.c

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This source file includes following definitions.
swapfunc
med3
qsort
   1 /*-
   2  * Copyright (c) 1992, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  */
  29 
  30 #include <sys/cdefs.h>
  31 #include <sys/types.h>
  32 
  33 #include <assert.h>
  34 #include <errno.h>
  35 #include <stdlib.h>
  36 
  37 static __inline char    *med3(char *, char *, char *,
  38     int (*)(const void *, const void *));
  39 static __inline void     swapfunc(char *, char *, size_t, int);
  40 
  41 #define min(a, b)       (a) < (b) ? a : b
  42 
  43 /*
  44  * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
  45  */
  46 #define swapcode(TYPE, parmi, parmj, n) {               \
  47         size_t i = (n) / sizeof (TYPE);                 \
  48         TYPE *pi = (TYPE *)(void *)(parmi);             \
  49         TYPE *pj = (TYPE *)(void *)(parmj);             \
  50         do {                                            \
  51                 TYPE    t = *pi;                        \
  52                 *pi++ = *pj;                            \
  53                 *pj++ = t;                              \
  54         } while (--i > 0);                              \
  55 }
  56 
  57 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
  58         es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
  59 
  60 static __inline void
  61 swapfunc(a, b, n, swaptype)
  62         char *a, *b;
  63         size_t n;
  64         int swaptype;
  65 {
  66         if (swaptype <= 1)
  67                 swapcode(long, a, b, n)
  68         else
  69                 swapcode(char, a, b, n)
  70 }
  71 
  72 #define swap(a, b)                                              \
  73         if (swaptype == 0) {                                    \
  74                 long t = *(long *)(void *)(a);                  \
  75                 *(long *)(void *)(a) = *(long *)(void *)(b);    \
  76                 *(long *)(void *)(b) = t;                       \
  77         } else                                                  \
  78                 swapfunc(a, b, es, swaptype)
  79 
  80 #define vecswap(a, b, n) if ((n) > 0) swapfunc((a), (b), (size_t)(n), swaptype)
  81 
  82 static __inline char *
  83 med3(a, b, c, cmp)
  84         char *a, *b, *c;
  85         int (*cmp)(const void *, const void *);
  86 {
  87         return cmp(a, b) < 0 ?
  88                (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a ))
  89               :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c ));
  90 }
  91 
  92 void
  93 qsort(a, n, es, cmp)
  94         void *a;
  95         size_t n, es;
  96         int (*cmp)(const void *, const void *);
  97 {
  98         char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
  99         int d, r, swaptype, swap_cnt;
 100 
 101 loop:   SWAPINIT(a, es);
 102         swap_cnt = 0;
 103         if (n < 7) {
 104                 for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es)
 105                         for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
 106                              pl -= es)
 107                                 swap(pl, pl - es);
 108                 return;
 109         }
 110         pm = (char *) a + (n / 2) * es;
 111         if (n > 7) {
 112                 pl = (char *) a;
 113                 pn = (char *) a + (n - 1) * es;
 114                 if (n > 40) {
 115                         d = (n / 8) * es;
 116                         pl = med3(pl, pl + d, pl + 2 * d, cmp);
 117                         pm = med3(pm - d, pm, pm + d, cmp);
 118                         pn = med3(pn - 2 * d, pn - d, pn, cmp);
 119                 }
 120                 pm = med3(pl, pm, pn, cmp);
 121         }
 122         swap(a, pm);
 123         pa = pb = (char *) a + es;
 124 
 125         pc = pd = (char *) a + (n - 1) * es;
 126         for (;;) {
 127                 while (pb <= pc && (r = cmp(pb, a)) <= 0) {
 128                         if (r == 0) {
 129                                 swap_cnt = 1;
 130                                 swap(pa, pb);
 131                                 pa += es;
 132                         }
 133                         pb += es;
 134                 }
 135                 while (pb <= pc && (r = cmp(pc, a)) >= 0) {
 136                         if (r == 0) {
 137                                 swap_cnt = 1;
 138                                 swap(pc, pd);
 139                                 pd -= es;
 140                         }
 141                         pc -= es;
 142                 }
 143                 if (pb > pc)
 144                         break;
 145                 swap(pb, pc);
 146                 swap_cnt = 1;
 147                 pb += es;
 148                 pc -= es;
 149         }
 150         if (swap_cnt == 0) {  /* Switch to insertion sort */
 151                 for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es)
 152                         for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
 153                              pl -= es)
 154                                 swap(pl, pl - es);
 155                 return;
 156         }
 157         pn = (char *) a + n * es;
 158         r = min(pa - (char *) a, pb - pa);
 159         vecswap(a, pb - r, r);
 160         r = min(pd - pc, pn - pd - es);
 161         vecswap(pb, pn - r, r);
 162         if ((r = pb - pa) > es)
 163                 qsort(a, r / es, es, cmp);
 164         if ((r = pd - pc) > es) {
 165                 /* Iterate rather than recurse to save stack space */
 166                 a = pn - r;
 167                 n = r / es;
 168                 goto loop;
 169         }
 170 /*              qsort(pn - r, r / es, es, cmp);*/
 171 }
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root/usr/lib/libc/stdlib/qsort.c

DEFINITIONS
