xpcom/glue/nsQuickSort.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2
   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. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  */
  31
  32 /* We need this because Solaris' version of qsort is broken and
  33  * causes array bounds reads.
  34  */
  35
  36 #include <stdlib.h>
  37 #include "prtypes.h"
  38 #include "nsQuickSort.h"
  39
  40 PR_BEGIN_EXTERN_C
  41
  42 #if !defined(DEBUG) && (defined(__cplusplus) || defined(__gcc))
  43 # ifndef INLINE
  44 #  define INLINE inline
  45 # endif
  46 #else
  47 # define INLINE
  48 #endif
  49
  50 typedef int              cmp_t(const void *, const void *, void *);
  51 static INLINE char      *med3(char *, char *, char *, cmp_t *, void *);
  52 static INLINE void      swapfunc(char *, char *, int, int);
  53
  54 /*
  55  * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
  56  */
  57 #define swapcode(TYPE, parmi, parmj, n) {               \
  58         long i = (n) / sizeof (TYPE);                   \
  59         register TYPE *pi = (TYPE *) (parmi);           \
  60         register TYPE *pj = (TYPE *) (parmj);           \
  61         do {                                            \
  62                 register TYPE   t = *pi;                \
  63                 *pi++ = *pj;                            \
  64                 *pj++ = t;                              \
  65         } while (--i > 0);                              \
  66 }
  67
  68 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
  69         es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
  70
  71 static INLINE void
  72 swapfunc(char *a, char *b, int n, int swaptype)
  73 {
  74         if(swaptype <= 1)
  75                 swapcode(long, a, b, n)
  76         else
  77                 swapcode(char, a, b, n)
  78 }
  79
  80 #define swap(a, b)                                      \
  81         if (swaptype == 0) {                            \
  82                 long t = *(long *)(a);                  \
  83                 *(long *)(a) = *(long *)(b);            \
  84                 *(long *)(b) = t;                       \
  85         } else                                          \
  86                 swapfunc((char *)a, (char*)b, (int)es, swaptype)
  87
  88 #define vecswap(a, b, n)        if ((n) > 0) swapfunc((char *)a, (char *)b, (int)n, swaptype)
  89
  90 static INLINE char *
  91 med3(char *a, char *b, char *c, cmp_t* cmp, void *data)
  92 {
  93         return cmp(a, b, data) < 0 ?
  94                (cmp(b, c, data) < 0 ? b : (cmp(a, c, data) < 0 ? c : a ))
  95               :(cmp(b, c, data) > 0 ? b : (cmp(a, c, data) < 0 ? a : c ));
  96 }
  97
  98 void NS_QuickSort (
  99         void *a,
 100         unsigned int n,
 101     unsigned int es,
 102         cmp_t *cmp,
 103         void *data
 104     )
 105 {
 106         char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
 107         int d, r, swaptype, swap_cnt;
 108
 109 loop:   SWAPINIT(a, es);
 110         swap_cnt = 0;
 111         if (n < 7) {
 112                 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
 113                         for (pl = pm; pl > (char *)a && cmp(pl - es, pl, data) > 0;
 114                              pl -= es)
 115                                 swap(pl, pl - es);
 116                 return;
 117         }
 118         pm = (char *)a + (n / 2) * es;
 119         if (n > 7) {
 120                 pl = (char *)a;
 121                 pn = (char *)a + (n - 1) * es;
 122                 if (n > 40) {
 123                         d = (n / 8) * es;
 124                         pl = med3(pl, pl + d, pl + 2 * d, cmp, data);
 125                         pm = med3(pm - d, pm, pm + d, cmp, data);
 126                         pn = med3(pn - 2 * d, pn - d, pn, cmp, data);
 127                 }
 128                 pm = med3(pl, pm, pn, cmp, data);
 129         }
 130         swap(a, pm);
 131         pa = pb = (char *)a + es;
 132
 133         pc = pd = (char *)a + (n - 1) * es;
 134         for (;;) {
 135                 while (pb <= pc && (r = cmp(pb, a, data)) <= 0) {
 136                         if (r == 0) {
 137                                 swap_cnt = 1;
 138                                 swap(pa, pb);
 139                                 pa += es;
 140                         }
 141                         pb += es;
 142                 }
 143                 while (pb <= pc && (r = cmp(pc, a, data)) >= 0) {
 144                         if (r == 0) {
 145                                 swap_cnt = 1;
 146                                 swap(pc, pd);
 147                                 pd -= es;
 148                         }
 149                         pc -= es;
 150                 }
 151                 if (pb > pc)
 152                         break;
 153                 swap(pb, pc);
 154                 swap_cnt = 1;
 155                 pb += es;
 156                 pc -= es;
 157         }
 158         if (swap_cnt == 0) {  /* Switch to insertion sort */
 159                 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
 160                         for (pl = pm; pl > (char *)a && cmp(pl - es, pl, data) > 0;
 161                              pl -= es)
 162                                 swap(pl, pl - es);
 163                 return;
 164         }
 165
 166         pn = (char *)a + n * es;
 167         r = PR_MIN(pa - (char *)a, pb - pa);
 168         vecswap(a, pb - r, r);
 169         r = PR_MIN(pd - pc, (int)(pn - pd - es));
 170         vecswap(pb, pn - r, r);
 171         if ((r = pb - pa) > (int)es)
 172         NS_QuickSort(a, r / es, es, cmp, data);
 173         if ((r = pd - pc) > (int)es) {
 174                 /* Iterate rather than recurse to save stack space */
 175                 a = pn - r;
 176                 n = r / es;
 177                 goto loop;
 178         }
 179 /*              NS_QuickSort(pn - r, r / es, es, cmp, data);*/
 180 }
 181
 182 PR_END_EXTERN_C