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 #ifndef __GNUC__
  43 #define inline
  44 #endif
  45
  46 /* FIXME: these types should be from the default includes */
  47
  48 typedef int (*  _pfunccmp_t) (const void *, const void *);
  49
  50 #define min(a,b) ((a)<(b)?(a):(b))
  51
  52 /*
  53  * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
  54  */
  55 #define swapcode(TYPE, parmi, parmj, n) {               \
  56         long i = (n) / sizeof (TYPE);                   \
  57         register TYPE *pi = (TYPE *) (parmi);           \
  58         register TYPE *pj = (TYPE *) (parmj);           \
  59         do {                                            \
  60                 register TYPE   t = *pi;                \
  61                 *pi++ = *pj;                            \
  62                 *pj++ = t;                              \
  63         } while (--i > 0);                              \
  64 }
  65
  66 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
  67         es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
  68
  69 static inline void
  70 swapfunc (
  71         char    * a,
  72         char    * b,
  73         int     n,
  74         int     swaptype
  75         )
  76 {
  77         if(swaptype <= 1)
  78                 swapcode(long, a, b, n)
  79         else
  80                 swapcode(char, a, b, n)
  81 }
  82
  83 #define swap(a, b)                                      \
  84         if (swaptype == 0) {                            \
  85                 long t = *(long *)(a);                  \
  86                 *(long *)(a) = *(long *)(b);            \
  87                 *(long *)(b) = t;                       \
  88         } else                                          \
  89                 swapfunc(a, b, es, swaptype)
  90
  91 #define vecswap(a, b, n)        if ((n) > 0) swapfunc(a, b, n, swaptype)
  92
  93 static inline char *
  94 med3 (
  95         char            * a,
  96         char            * b,
  97         char            * c,
  98         _pfunccmp_t     cmp
  99         )
 100 {
 101         return cmp(a, b) < 0 ?
 102                (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a ))
 103               :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c ));
 104 }
 105
 106
 107 /* EXPORTED */
 108 void
 109 qsort (
 110         void            * a,
 111         size_t          n,
 112         size_t          es,
 113         _pfunccmp_t     cmp
 114         )
 115 {
 116         char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
 117         int d, r, swaptype, swap_cnt;
 118
 119 loop:   SWAPINIT(a, es);
 120         swap_cnt = 0;
 121         if (n < 7)
 122         {
 123                 for (   pm = (char *) a + es;
 124                         pm < (char *) a + n * es;
 125                         pm += es
 126                         )
 127                 {
 128                         for (   pl = pm;
 129                                 pl > (char *) a && cmp(pl - es, pl) > 0;
 130                                 pl -= es
 131                                 )
 132                         {
 133                                 swap(pl, pl - es);
 134                         }
 135                 }
 136                 return;
 137         }
 138         pm = (char *) a + (n / 2) * es;
 139         if (n > 7)
 140         {
 141                 pl = (char *) a;
 142                 pn = (char *) a + (n - 1) * es;
 143                 if (n > 40)
 144                 {
 145                         d = (n / 8) * es;
 146                         pl = med3(pl, pl + d, pl + 2 * d, cmp);
 147                         pm = med3(pm - d, pm, pm + d, cmp);
 148                         pn = med3(pn - 2 * d, pn - d, pn, cmp);
 149                 }
 150                 pm = med3(pl, pm, pn, cmp);
 151         }
 152         swap(a, pm);
 153         pa = pb = (char *) a + es;
 154
 155         pc = pd = (char *) a + (n - 1) * es;
 156         for (;;)
 157         {
 158                 while (pb <= pc && (r = cmp(pb, a)) <= 0)
 159                 {
 160                         if (r == 0)
 161                         {
 162                                 swap_cnt = 1;
 163                                 swap(pa, pb);
 164                                 pa += es;
 165                         }
 166                         pb += es;
 167                 }
 168                 while (pb <= pc && (r = cmp(pc, a)) >= 0)
 169                 {
 170                         if (r == 0)
 171                         {
 172                                 swap_cnt = 1;
 173                                 swap(pc, pd);
 174                                 pd -= es;
 175                         }
 176                         pc -= es;
 177                 }
 178                 if (pb > pc)
 179                 {
 180                         break;
 181                 }
 182                 swap(pb, pc);
 183                 swap_cnt = 1;
 184                 pb += es;
 185                 pc -= es;
 186         }
 187         if (swap_cnt == 0)  /* Switch to insertion sort */
 188         {
 189                 for (   pm = (char *) a + es;
 190                         pm < (char *) a + n * es;
 191                         pm += es
 192                         )
 193                 {
 194                         for (   pl = pm;
 195                                 pl > (char *) a && cmp(pl - es, pl) > 0;
 196                                 pl -= es
 197                                 )
 198                         {
 199                                 swap(pl, pl - es);
 200                         }
 201                 }
 202                 return;
 203         }
 204
 205         pn = (char *) a + n * es;
 206         r = min(pa - (char *)a, pb - pa);
 207         vecswap(a, pb - r, r);
 208         r = min(pd - pc, pn - pd - es);
 209         vecswap(pb, pn - r, r);
 210         if ((r = pb - pa) > es)
 211         {
 212                 qsort(a, r / es, es, cmp);
 213         }
 214         if ((r = pd - pc) > es)
 215         {
 216                 /* Iterate rather than recurse to save stack space */
 217                 a = pn - r;
 218                 n = r / es;
 219                 goto loop;
 220         }
 221 /*              qsort(pn - r, r / es, es, cmp);*/
 222 }
 223
 224
 225 /* EOF */