stdlib/FreeBSD/qsort.c

   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  * 4. 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 #if defined(LIBC_SCCS) && !defined(lint)
  31 static char sccsid[] = "@(#)qsort.c     8.1 (Berkeley) 6/4/93";
  32 #endif /* LIBC_SCCS and not lint */
  33 #include <sys/cdefs.h>
  34 __FBSDID("$FreeBSD: src/lib/libc/stdlib/qsort.c,v 1.15 2008/01/14 09:21:34 das Exp $");
  35
  36 #include <stdlib.h>
  37 #include <string.h>
  38
  39 #ifdef I_AM_QSORT_R
  40 typedef int              cmp_t(void *, const void *, const void *);
  41 #else
  42 typedef int              cmp_t(const void *, const void *);
  43 #endif
  44 #ifdef I_AM_QSORT_B
  45 static inline char      *med3(char *, char *, char *, cmp_t ^, void *) __attribute__((always_inline));
  46 #else
  47 static inline char      *med3(char *, char *, char *, cmp_t *, void *) __attribute__((always_inline));
  48 #endif
  49 static inline void       swapfunc(char *, char *, int, int) __attribute__((always_inline));
  50
  51 #define min(a, b)       (a) < (b) ? a : b
  52
  53 /*
  54  * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
  55  */
  56 #define swapcode(TYPE, parmi, parmj, n) {               \
  57         long i = (n) / sizeof (TYPE);                   \
  58         TYPE *pi = (TYPE *) (parmi);            \
  59         TYPE *pj = (TYPE *) (parmj);            \
  60         do {                                            \
  61                 TYPE    t = *pi;                \
  62                 *pi++ = *pj;                            \
  63                 *pj++ = t;                              \
  64         } while (--i > 0);                              \
  65 }
  66
  67 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
  68         es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
  69
  70 static inline void
  71 swapfunc(a, b, n, swaptype)
  72         char *a, *b;
  73         int n, swaptype;
  74 {
  75         if(swaptype <= 1)
  76                 swapcode(long, a, b, n)
  77         else
  78                 swapcode(char, a, b, n)
  79 }
  80
  81 #define swap(a, b)                                      \
  82         if (swaptype == 0) {                            \
  83                 long t = *(long *)(a);                  \
  84                 *(long *)(a) = *(long *)(b);            \
  85                 *(long *)(b) = t;                       \
  86         } else                                          \
  87                 swapfunc(a, b, es, swaptype)
  88
  89 #define vecswap(a, b, n)        if ((n) > 0) swapfunc(a, b, n, swaptype)
  90
  91 #ifdef I_AM_QSORT_R
  92 #define CMP(t, x, y) (cmp((t), (x), (y)))
  93 #else
  94 #define CMP(t, x, y) (cmp((x), (y)))
  95 #endif
  96
  97 static inline char *
  98 med3(char *a, char *b, char *c,
  99 #ifdef I_AM_QSORT_B
 100 cmp_t ^cmp,
 101 #else
 102 cmp_t *cmp,
 103 #endif
 104 void *thunk
 105 #ifndef I_AM_QSORT_R
 106 __unused
 107 #endif
 108 )
 109 {
 110         return CMP(thunk, a, b) < 0 ?
 111                (CMP(thunk, b, c) < 0 ? b : (CMP(thunk, a, c) < 0 ? c : a ))
 112               :(CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c ));
 113 }
 114
 115 #ifdef __LP64__
 116 #define DEPTH(x)        (2 * (flsl((long)(x)) - 1))
 117 #else /* !__LP64__ */
 118 #define DEPTH(x)        (2 * (fls((int)(x)) - 1))
 119 #endif /* __LP64__ */
 120
 121 #ifdef I_AM_QSORT_R
 122 int __heapsort_r(void *, size_t, size_t, void *, int (*)(void *, const void *, const void *));
 123 #endif
 124
 125 static void
 126 _qsort(void *a, size_t n, size_t es,
 127 #ifdef I_AM_QSORT_R
 128 void *thunk,
 129 #else
 130 #define thunk   NULL
 131 #endif
 132 #ifdef I_AM_QSORT_B
 133 cmp_t ^cmp,
 134 #else
 135 cmp_t *cmp,
 136 #endif
 137 int depth_limit)
 138 {
 139         char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
 140         size_t d, r;
 141         int cmp_result;
 142         int swaptype, swap_cnt;
 143
 144 loop:
 145         if (depth_limit-- <= 0) {
 146 #ifdef I_AM_QSORT_B
 147                 heapsort_b(a, n, es, cmp);
 148 #elif defined(I_AM_QSORT_R)
 149                 __heapsort_r(a, n, es, thunk, cmp);
 150 #else
 151                 heapsort(a, n, es, cmp);
 152 #endif
 153                 return;
 154         }
 155         SWAPINIT(a, es);
 156         swap_cnt = 0;
 157         if (n < 7) {
 158                 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
 159                         for (pl = pm;
 160                              pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
 161                              pl -= es)
 162                                 swap(pl, pl - es);
 163                 return;
 164         }
 165         pm = (char *)a + (n / 2) * es;
 166         if (n > 7) {
 167                 pl = a;
 168                 pn = (char *)a + (n - 1) * es;
 169                 if (n > 40) {
 170                         d = (n / 8) * es;
 171                         pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk);
 172                         pm = med3(pm - d, pm, pm + d, cmp, thunk);
 173                         pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk);
 174                 }
 175                 pm = med3(pl, pm, pn, cmp, thunk);
 176         }
 177         swap(a, pm);
 178         pa = pb = (char *)a + es;
 179
 180         pc = pd = (char *)a + (n - 1) * es;
 181         for (;;) {
 182                 while (pb <= pc && (cmp_result = CMP(thunk, pb, a)) <= 0) {
 183                         if (cmp_result == 0) {
 184                                 swap_cnt = 1;
 185                                 swap(pa, pb);
 186                                 pa += es;
 187                         }
 188                         pb += es;
 189                 }
 190                 while (pb <= pc && (cmp_result = CMP(thunk, pc, a)) >= 0) {
 191                         if (cmp_result == 0) {
 192                                 swap_cnt = 1;
 193                                 swap(pc, pd);
 194                                 pd -= es;
 195                         }
 196                         pc -= es;
 197                 }
 198                 if (pb > pc)
 199                         break;
 200                 swap(pb, pc);
 201                 swap_cnt = 1;
 202                 pb += es;
 203                 pc -= es;
 204         }
 205
 206         pn = (char *)a + n * es;
 207         r = min(pa - (char *)a, pb - pa);
 208         vecswap(a, pb - r, r);
 209         r = min(pd - pc, pn - pd - es);
 210         vecswap(pb, pn - r, r);
 211
 212         if (swap_cnt == 0) {  /* Switch to insertion sort */
 213                 r = 1 + n / 4; /* n >= 7, so r >= 2 */
 214                 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
 215                         for (pl = pm;
 216                              pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
 217                              pl -= es) {
 218                                 swap(pl, pl - es);
 219                                 if (++swap_cnt > r) goto nevermind;
 220                         }
 221                 return;
 222         }
 223
 224 nevermind:
 225         if ((r = pb - pa) > es)
 226 #ifdef I_AM_QSORT_R
 227                 _qsort(a, r / es, es, thunk, cmp, depth_limit);
 228 #else
 229                 _qsort(a, r / es, es, cmp, depth_limit);
 230 #endif
 231         if ((r = pd - pc) > es) {
 232                 /* Iterate rather than recurse to save stack space */
 233                 a = pn - r;
 234                 n = r / es;
 235                 goto loop;
 236         }
 237 /*              qsort(pn - r, r / es, es, cmp);*/
 238 }
 239
 240 void
 241 #ifdef I_AM_QSORT_R
 242 qsort_r(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp)
 243 #elif defined(I_AM_QSORT_B)
 244 qsort_b(void *a, size_t n, size_t es, cmp_t ^cmp)
 245 #else
 246 qsort(void *a, size_t n, size_t es, cmp_t *cmp)
 247 #endif
 248 {
 249         _qsort(a, n, es,
 250 #ifdef I_AM_QSORT_R
 251                 thunk,
 252 #endif
 253                 cmp, DEPTH(n));
 254 }