firmware/libc/qsort.c

   1 /*
   2 FUNCTION
   3 <<qsort>>---sort an array
   4
   5 INDEX
   6         qsort
   7
   8 ANSI_SYNOPSIS
   9         #include <stdlib.h>
  10         void qsort(void *<[base]>, size_t <[nmemb]>, size_t <[size]>,
  11                    int (*<[compar]>)(const void *, const void *) );
  12
  13 TRAD_SYNOPSIS
  14         #include <stdlib.h>
  15         qsort(<[base]>, <[nmemb]>, <[size]>, <[compar]> )
  16         char *<[base]>;
  17         size_t <[nmemb]>;
  18         size_t <[size]>;
  19         int (*<[compar]>)();
  20
  21 DESCRIPTION
  22 <<qsort>> sorts an array (beginning at <[base]>) of <[nmemb]> objects.
  23 <[size]> describes the size of each element of the array.
  24
  25 You must supply a pointer to a comparison function, using the argument
  26 shown as <[compar]>.  (This permits sorting objects of unknown
  27 properties.)  Define the comparison function to accept two arguments,
  28 each a pointer to an element of the array starting at <[base]>.  The
  29 result of <<(*<[compar]>)>> must be negative if the first argument is
  30 less than the second, zero if the two arguments match, and positive if
  31 the first argument is greater than the second (where ``less than'' and
  32 ``greater than'' refer to whatever arbitrary ordering is appropriate).
  33
  34 The array is sorted in place; that is, when <<qsort>> returns, the
  35 array elements beginning at <[base]> have been reordered.
  36
  37 RETURNS
  38 <<qsort>> does not return a result.
  39
  40 PORTABILITY
  41 <<qsort>> is required by ANSI (without specifying the sorting algorithm).
  42 */
  43
  44 /*-
  45  * Copyright (c) 1992, 1993
  46  *      The Regents of the University of California.  All rights reserved.
  47  *
  48  * Redistribution and use in source and binary forms, with or without
  49  * modification, are permitted provided that the following conditions
  50  * are met:
  51  * 1. Redistributions of source code must retain the above copyright
  52  *    notice, this list of conditions and the following disclaimer.
  53  * 2. Redistributions in binary form must reproduce the above copyright
  54  *    notice, this list of conditions and the following disclaimer in the
  55  *    documentation and/or other materials provided with the distribution.
  56  * 3. All advertising materials mentioning features or use of this software
  57  *    must display the following acknowledgement:
  58  *      This product includes software developed by the University of
  59  *      California, Berkeley and its contributors.
  60  * 4. Neither the name of the University nor the names of its contributors
  61  *    may be used to endorse or promote products derived from this software
  62  *    without specific prior written permission.
  63  *
  64  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  65  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  66  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  67  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  68  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  69  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  70  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  71  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  72  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  73  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  74  * SUCH DAMAGE.
  75  */
  76
  77 #include <_ansi.h>
  78 #include <stdlib.h>
  79
  80 #ifndef __GNUC__
  81 #define inline
  82 #endif
  83
  84 static inline char      *med3 _PARAMS((char *, char *, char *, int (*cmp)(const _PTR,const _PTR)));
  85 static inline void       swapfunc _PARAMS((char *, char *, int, int));
  86
  87 #define min(a, b)       (a) < (b) ? a : b
  88
  89 /*
  90  * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
  91  */
  92 #define swapcode(TYPE, parmi, parmj, n) {               \
  93         long i = (n) / sizeof (TYPE);                   \
  94         register TYPE *pi = (TYPE *) (parmi);           \
  95         register TYPE *pj = (TYPE *) (parmj);           \
  96         do {                                            \
  97                 register TYPE   t = *pi;                \
  98                 *pi++ = *pj;                            \
  99                 *pj++ = t;                              \
 100         } while (--i > 0);                              \
 101 }
 102
 103 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
 104         es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
 105
 106 static inline void
 107 _DEFUN(swapfunc, (a, b, n, swaptype),
 108         char *a _AND
 109         char *b _AND
 110         int n _AND
 111         int swaptype)
 112 {
 113         if(swaptype <= 1)
 114                 swapcode(long, a, b, n)
 115         else
 116                 swapcode(char, a, b, n)
 117 }
 118
 119 #define swap(a, b)                                      \
 120         if (swaptype == 0) {                            \
 121                 long t = *(long *)(a);                  \
 122                 *(long *)(a) = *(long *)(b);            \
 123                 *(long *)(b) = t;                       \
 124         } else                                          \
 125                 swapfunc(a, b, es, swaptype)
 126
 127 #define vecswap(a, b, n)        if ((n) > 0) swapfunc(a, b, n, swaptype)
 128
 129 static inline char *
 130 _DEFUN(med3, (a, b, c, cmp),
 131         char *a _AND
 132         char *b _AND
 133         char *c _AND
 134         int (*cmp)(const _PTR,const _PTR))
 135 {
 136         return cmp(a, b) < 0 ?
 137                (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a ))
 138               :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c ));
 139 }
 140
 141 void
 142 _DEFUN(qsort, (a, n, es, cmp),
 143         void *a _AND
 144         size_t n _AND
 145         size_t es _AND
 146         int (*cmp)(const _PTR,const _PTR))
 147 {
 148         char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
 149         int d, r, swaptype, swap_cnt;
 150
 151 loop:   SWAPINIT(a, es);
 152         swap_cnt = 0;
 153         if (n < 7) {
 154                 for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es)
 155                         for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
 156                              pl -= es)
 157                                 swap(pl, pl - es);
 158                 return;
 159         }
 160         pm = (char *) a + (n / 2) * es;
 161         if (n > 7) {
 162                 pl = a;
 163                 pn = (char *) a + (n - 1) * es;
 164                 if (n > 40) {
 165                         d = (n / 8) * es;
 166                         pl = med3(pl, pl + d, pl + 2 * d, cmp);
 167                         pm = med3(pm - d, pm, pm + d, cmp);
 168                         pn = med3(pn - 2 * d, pn - d, pn, cmp);
 169                 }
 170                 pm = med3(pl, pm, pn, cmp);
 171         }
 172         swap(a, pm);
 173         pa = pb = (char *) a + es;
 174
 175         pc = pd = (char *) a + (n - 1) * es;
 176         for (;;) {
 177                 while (pb <= pc && (r = cmp(pb, a)) <= 0) {
 178                         if (r == 0) {
 179                                 swap_cnt = 1;
 180                                 swap(pa, pb);
 181                                 pa += es;
 182                         }
 183                         pb += es;
 184                 }
 185                 while (pb <= pc && (r = cmp(pc, a)) >= 0) {
 186                         if (r == 0) {
 187                                 swap_cnt = 1;
 188                                 swap(pc, pd);
 189                                 pd -= es;
 190                         }
 191                         pc -= es;
 192                 }
 193                 if (pb > pc)
 194                         break;
 195                 swap(pb, pc);
 196                 swap_cnt = 1;
 197                 pb += es;
 198                 pc -= es;
 199         }
 200         if (swap_cnt == 0) {  /* Switch to insertion sort */
 201                 for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es)
 202                         for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
 203                              pl -= es)
 204                                 swap(pl, pl - es);
 205                 return;
 206         }
 207
 208         pn = (char *) a + n * es;
 209         r = min(pa - (char *)a, pb - pa);
 210         vecswap(a, pb - r, r);
 211         r = min((unsigned int)(pd - pc), pn - pd - es);
 212         vecswap(pb, pn - r, r);
 213         if ((unsigned int)(r = pb - pa) > es)
 214                 qsort(a, r / es, es, cmp);
 215         if ((unsigned int)(r = pd - pc) > es) {
 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 }