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/* |
FUNCTION |
<<qsort>>---sort an array |
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INDEX |
qsort |
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ANSI_SYNOPSIS |
#include <stdlib.h> |
void qsort(void *<[base]>, size_t <[nmemb]>, size_t <[size]>, |
int (*<[compar]>)(const void *, const void *) ); |
|
TRAD_SYNOPSIS |
#include <stdlib.h> |
qsort(<[base]>, <[nmemb]>, <[size]>, <[compar]> ) |
char *<[base]>; |
size_t <[nmemb]>; |
size_t <[size]>; |
int (*<[compar]>)(); |
|
DESCRIPTION |
<<qsort>> sorts an array (beginning at <[base]>) of <[nmemb]> objects. |
<[size]> describes the size of each element of the array. |
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You must supply a pointer to a comparison function, using the argument |
shown as <[compar]>. (This permits sorting objects of unknown |
properties.) Define the comparison function to accept two arguments, |
each a pointer to an element of the array starting at <[base]>. The |
result of <<(*<[compar]>)>> must be negative if the first argument is |
less than the second, zero if the two arguments match, and positive if |
the first argument is greater than the second (where ``less than'' and |
``greater than'' refer to whatever arbitrary ordering is appropriate). |
|
The array is sorted in place; that is, when <<qsort>> returns, the |
array elements beginning at <[base]> have been reordered. |
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RETURNS |
<<qsort>> does not return a result. |
|
PORTABILITY |
<<qsort>> is required by ANSI (without specifying the sorting algorithm). |
*/ |
|
/*- |
* Copyright (c) 1992, 1993 |
* The Regents of the University of California. All rights reserved. |
* |
* Redistribution and use in source and binary forms, with or without |
* modification, are permitted provided that the following conditions |
* are met: |
* 1. Redistributions of source code must retain the above copyright |
* notice, this list of conditions and the following disclaimer. |
* 2. Redistributions in binary form must reproduce the above copyright |
* notice, this list of conditions and the following disclaimer in the |
* documentation and/or other materials provided with the distribution. |
* 3. All advertising materials mentioning features or use of this software |
* must display the following acknowledgement: |
* This product includes software developed by the University of |
* California, Berkeley and its contributors. |
* 4. Neither the name of the University nor the names of its contributors |
* may be used to endorse or promote products derived from this software |
* without specific prior written permission. |
* |
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
* SUCH DAMAGE. |
*/ |
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#include <_ansi.h> |
#include <stdlib.h> |
|
#ifndef __GNUC__ |
#define inline |
#endif |
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static inline char *med3 _PARAMS((char *, char *, char *, int (*)())); |
static inline void swapfunc _PARAMS((char *, char *, int, int)); |
|
#define min(a, b) (a) < (b) ? a : b |
|
/* |
* Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". |
*/ |
#define swapcode(TYPE, parmi, parmj, n) { \ |
long i = (n) / sizeof (TYPE); \ |
register TYPE *pi = (TYPE *) (parmi); \ |
register TYPE *pj = (TYPE *) (parmj); \ |
do { \ |
register TYPE t = *pi; \ |
*pi++ = *pj; \ |
*pj++ = t; \ |
} while (--i > 0); \ |
} |
|
#define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \ |
es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1; |
|
static inline void |
_DEFUN(swapfunc, (a, b, n, swaptype), |
char *a _AND |
char *b _AND |
int n _AND |
int swaptype) |
{ |
if(swaptype <= 1) |
swapcode(long, a, b, n) |
else |
swapcode(char, a, b, n) |
} |
|
#define swap(a, b) \ |
if (swaptype == 0) { \ |
long t = *(long *)(a); \ |
*(long *)(a) = *(long *)(b); \ |
*(long *)(b) = t; \ |
} else \ |
swapfunc(a, b, es, swaptype) |
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#define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype) |
|
static inline char * |
_DEFUN(med3, (a, b, c, cmp), |
char *a _AND |
char *b _AND |
char *c _AND |
int (*cmp)()) |
{ |
return cmp(a, b) < 0 ? |
(cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a )) |
:(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c )); |
} |
|
void |
_DEFUN(qsort, (a, n, es, cmp), |
void *a _AND |
size_t n _AND |
size_t es _AND |
int (*cmp)()) |
{ |
char *pa, *pb, *pc, *pd, *pl, *pm, *pn; |
int d, r, swaptype, swap_cnt; |
|
loop: SWAPINIT(a, es); |
swap_cnt = 0; |
if (n < 7) { |
for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es) |
for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; |
pl -= es) |
swap(pl, pl - es); |
return; |
} |
pm = (char *) a + (n / 2) * es; |
if (n > 7) { |
pl = a; |
pn = (char *) a + (n - 1) * es; |
if (n > 40) { |
d = (n / 8) * es; |
pl = med3(pl, pl + d, pl + 2 * d, cmp); |
pm = med3(pm - d, pm, pm + d, cmp); |
pn = med3(pn - 2 * d, pn - d, pn, cmp); |
} |
pm = med3(pl, pm, pn, cmp); |
} |
swap(a, pm); |
pa = pb = (char *) a + es; |
|
pc = pd = (char *) a + (n - 1) * es; |
for (;;) { |
while (pb <= pc && (r = cmp(pb, a)) <= 0) { |
if (r == 0) { |
swap_cnt = 1; |
swap(pa, pb); |
pa += es; |
} |
pb += es; |
} |
while (pb <= pc && (r = cmp(pc, a)) >= 0) { |
if (r == 0) { |
swap_cnt = 1; |
swap(pc, pd); |
pd -= es; |
} |
pc -= es; |
} |
if (pb > pc) |
break; |
swap(pb, pc); |
swap_cnt = 1; |
pb += es; |
pc -= es; |
} |
if (swap_cnt == 0) { /* Switch to insertion sort */ |
for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es) |
for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; |
pl -= es) |
swap(pl, pl - es); |
return; |
} |
|
pn = (char *) a + n * es; |
r = min(pa - (char *)a, pb - pa); |
vecswap(a, pb - r, r); |
r = min(pd - pc, pn - pd - es); |
vecswap(pb, pn - r, r); |
if ((r = pb - pa) > es) |
qsort(a, r / es, es, cmp); |
if ((r = pd - pc) > es) { |
/* Iterate rather than recurse to save stack space */ |
a = pn - r; |
n = r / es; |
goto loop; |
} |
/* qsort(pn - r, r / es, es, cmp);*/ |
} |