payloads/libpayload/libc/qsort.c

   1 /*      $OpenBSD: qsort.c,v 1.11 2010/02/08 11:04:07 otto Exp $ */
   2 /*-
   3  * Copyright (c) 1992, 1993
   4  *      The Regents of the University of California.  All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  * 3. Neither the name of the University nor the names of its contributors
  15  *    may be used to endorse or promote products derived from this software
  16  *    without specific prior written permission.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  28  * SUCH DAMAGE.
  29  */
  30
  31 #include <sys/types.h>
  32 #include <stdlib.h>
  33
  34 static __inline char    *med3(char *, char *, char *, int (*)(const void *, const void *));
  35 static __inline void     swapfunc(char *, char *, size_t, int);
  36
  37 #define min(a, b)       (a) < (b) ? a : b
  38
  39 /*
  40  * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
  41  */
  42 #define swapcode(TYPE, parmi, parmj, n) {               \
  43         size_t i = (n) / sizeof (TYPE);                 \
  44         TYPE *pi = (TYPE *) (parmi);                    \
  45         TYPE *pj = (TYPE *) (parmj);                    \
  46         do {                                            \
  47                 TYPE    t = *pi;                        \
  48                 *pi++ = *pj;                            \
  49                 *pj++ = t;                              \
  50         } while (--i > 0);                              \
  51 }
  52
  53 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
  54         es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
  55
  56 static __inline void
  57 swapfunc(char *a, char *b, size_t n, int swaptype)
  58 {
  59         if (swaptype <= 1)
  60                 swapcode(long, a, b, n)
  61         else
  62                 swapcode(char, a, b, n)
  63 }
  64
  65 #define swap(a, b)                                      \
  66         if (swaptype == 0) {                            \
  67                 long t = *(long *)(a);                  \
  68                 *(long *)(a) = *(long *)(b);            \
  69                 *(long *)(b) = t;                       \
  70         } else                                          \
  71                 swapfunc(a, b, es, swaptype)
  72
  73 #define vecswap(a, b, n)        if ((n) > 0) swapfunc(a, b, n, swaptype)
  74
  75 static __inline char *
  76 med3(char *a, char *b, char *c, int (*cmp)(const void *, const void *))
  77 {
  78         return cmp(a, b) < 0 ?
  79                (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a ))
  80               :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c ));
  81 }
  82
  83 void
  84 qsort(void *aa, size_t n, size_t es, int (*cmp)(const void *, const void *))
  85 {
  86         char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
  87         int cmp_result, swaptype, swap_cnt;
  88         size_t d, r;
  89         char *a = aa;
  90
  91 loop:   SWAPINIT(a, es);
  92         swap_cnt = 0;
  93         if (n < 7) {
  94                 for (pm = (char *)a + es; pm < (char *) a + n * es; pm += es)
  95                         for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
  96                              pl -= es)
  97                                 swap(pl, pl - es);
  98                 return;
  99         }
 100         pm = (char *)a + (n / 2) * es;
 101         if (n > 7) {
 102                 pl = (char *)a;
 103                 pn = (char *)a + (n - 1) * es;
 104                 if (n > 40) {
 105                         d = (n / 8) * es;
 106                         pl = med3(pl, pl + d, pl + 2 * d, cmp);
 107                         pm = med3(pm - d, pm, pm + d, cmp);
 108                         pn = med3(pn - 2 * d, pn - d, pn, cmp);
 109                 }
 110                 pm = med3(pl, pm, pn, cmp);
 111         }
 112         swap(a, pm);
 113         pa = pb = (char *)a + es;
 114
 115         pc = pd = (char *)a + (n - 1) * es;
 116         for (;;) {
 117                 while (pb <= pc && (cmp_result = cmp(pb, a)) <= 0) {
 118                         if (cmp_result == 0) {
 119                                 swap_cnt = 1;
 120                                 swap(pa, pb);
 121                                 pa += es;
 122                         }
 123                         pb += es;
 124                 }
 125                 while (pb <= pc && (cmp_result = cmp(pc, a)) >= 0) {
 126                         if (cmp_result == 0) {
 127                                 swap_cnt = 1;
 128                                 swap(pc, pd);
 129                                 pd -= es;
 130                         }
 131                         pc -= es;
 132                 }
 133                 if (pb > pc)
 134                         break;
 135                 swap(pb, pc);
 136                 swap_cnt = 1;
 137                 pb += es;
 138                 pc -= es;
 139         }
 140         if (swap_cnt == 0) {  /* Switch to insertion sort */
 141                 for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es)
 142                         for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
 143                              pl -= es)
 144                                 swap(pl, pl - es);
 145                 return;
 146         }
 147
 148         pn = (char *)a + n * es;
 149         r = min(pa - (char *)a, pb - pa);
 150         vecswap(a, pb - r, r);
 151         r = min(pd - pc, pn - pd - es);
 152         vecswap(pb, pn - r, r);
 153         if ((r = pb - pa) > es)
 154                 qsort(a, r / es, es, cmp);
 155         if ((r = pd - pc) > es) {
 156                 /* Iterate rather than recurse to save stack space */
 157                 a = pn - r;
 158                 n = r / es;
 159                 goto loop;
 160         }
 161 /*              qsort(pn - r, r / es, es, cmp);*/
 162 }