reactos/lib/rtl/qsort.c

   1 /*
   2  * COPYRIGHT:
   3  *-
   4  * Copyright (c) 1992, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. All advertising materials mentioning features or use of this software
  16  *    must display the following acknowledgement:
  17  *      This product includes software developed by the University of
  18  *      California, Berkeley and its contributors.
  19  * 4. Neither the name of the University nor the names of its contributors
  20  *    may be used to endorse or promote products derived from this software
  21  *    without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  *
  35  * PROJECT:           ReactOS system libraries
  36  * PURPOSE:           Unicode Conversion Routines
  37  * FILE:              lib/rtl/qsort.c
  38  * PROGRAMMER:        Adapted from CygWin newlib 2000-03-12.
  39  */
  40 #include <rtl.h>
  41
  42 /* FIXME: these types should be from the default includes */
  43
  44 typedef int (*  _pfunccmp_t) (const void *, const void *);
  45
  46 #define min(a,b) ((a)<(b)?(a):(b))
  47
  48 /*
  49  * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
  50  */
  51 #define swapcode(TYPE, parmi, parmj, n) {               \
  52         long i = (n) / sizeof (TYPE);                   \
  53         register TYPE *pi = (TYPE *) (parmi);           \
  54         register TYPE *pj = (TYPE *) (parmj);           \
  55         do {                                            \
  56                 register TYPE   t = *pi;                \
  57                 *pi++ = *pj;                            \
  58                 *pj++ = t;                              \
  59         } while (--i > 0);                              \
  60 }
  61
  62 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
  63         es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
  64
  65 static __inline void
  66 swapfunc (
  67         char    * a,
  68         char    * b,
  69         int     n,
  70         int     swaptype
  71         )
  72 {
  73         if(swaptype <= 1)
  74                 swapcode(long, a, b, n)
  75         else
  76                 swapcode(char, a, b, n)
  77 }
  78
  79 #define swap(a, b)                                      \
  80         if (swaptype == 0) {                            \
  81                 long t = *(long *)(a);                  \
  82                 *(long *)(a) = *(long *)(b);            \
  83                 *(long *)(b) = t;                       \
  84         } else                                          \
  85                 swapfunc(a, b, es, swaptype)
  86
  87 #define vecswap(a, b, n)        if ((n) > 0) swapfunc(a, b, n, swaptype)
  88
  89 static __inline char *
  90 med3 (
  91         char            * a,
  92         char            * b,
  93         char            * c,
  94         _pfunccmp_t     cmp
  95         )
  96 {
  97         return cmp(a, b) < 0 ?
  98                (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a ))
  99               :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c ));
 100 }
 101
 102
 103 /* EXPORTED */
 104 void
 105 qsort (
 106         void            * a,
 107         size_t          n,
 108         size_t          es,
 109         _pfunccmp_t     cmp
 110         )
 111 {
 112         char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
 113         int d, r, swaptype, swap_cnt;
 114
 115 loop:   SWAPINIT(a, es);
 116         swap_cnt = 0;
 117         if (n < 7)
 118         {
 119                 for (   pm = (char *) a + es;
 120                         pm < (char *) a + n * es;
 121                         pm += es
 122                         )
 123                 {
 124                         for (   pl = pm;
 125                                 pl > (char *) a && cmp(pl - es, pl) > 0;
 126                                 pl -= es
 127                                 )
 128                         {
 129                                 swap(pl, pl - es);
 130                         }
 131                 }
 132                 return;
 133         }
 134         pm = (char *) a + (n / 2) * es;
 135         if (n > 7)
 136         {
 137                 pl = (char *) a;
 138                 pn = (char *) a + (n - 1) * es;
 139                 if (n > 40)
 140                 {
 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         {
 154                 while (pb <= pc && (r = cmp(pb, a)) <= 0)
 155                 {
 156                         if (r == 0)
 157                         {
 158                                 swap_cnt = 1;
 159                                 swap(pa, pb);
 160                                 pa += es;
 161                         }
 162                         pb += es;
 163                 }
 164                 while (pb <= pc && (r = cmp(pc, a)) >= 0)
 165                 {
 166                         if (r == 0)
 167                         {
 168                                 swap_cnt = 1;
 169                                 swap(pc, pd);
 170                                 pd -= es;
 171                         }
 172                         pc -= es;
 173                 }
 174                 if (pb > pc)
 175                 {
 176                         break;
 177                 }
 178                 swap(pb, pc);
 179                 swap_cnt = 1;
 180                 pb += es;
 181                 pc -= es;
 182         }
 183         if (swap_cnt == 0)  /* Switch to insertion sort */
 184         {
 185                 for (   pm = (char *) a + es;
 186                         pm < (char *) a + n * es;
 187                         pm += es
 188                         )
 189                 {
 190                         for (   pl = pm;
 191                                 pl > (char *) a && cmp(pl - es, pl) > 0;
 192                                 pl -= es
 193                                 )
 194                         {
 195                                 swap(pl, pl - es);
 196                         }
 197                 }
 198                 return;
 199         }
 200
 201         pn = (char *) a + n * es;
 202         r = min(pa - (char *)a, pb - pa);
 203         vecswap(a, pb - r, r);
 204         r = min(pd - pc, pn - pd - es);
 205         vecswap(pb, pn - r, r);
 206         if ((r = pb - pa) > es)
 207         {
 208                 qsort(a, r / es, es, cmp);
 209         }
 210         if ((r = pd - pc) > es)
 211         {
 212                 /* Iterate rather than recurse to save stack space */
 213                 a = pn - r;
 214                 n = r / es;
 215                 goto loop;
 216         }
 217 /*              qsort(pn - r, r / es, es, cmp);*/
 218 }
 219
 220
 221 /* EOF */