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/* msort -- an alternative to qsort, with an identical interface.
Copyright (C) 1992, 1995 Free Software Foundation, Inc.
Written by Mike Haertel, September 1988.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA. */
#include <ansidecl.h>
#include <stdlib.h>
#include <string.h>
#include <memcopy.h>
static void
DEFUN(msort_with_tmp, (b, n, s, cmp, t),
PTR b AND size_t n AND size_t s AND __compar_fn_t cmp AND char *t)
{
char *tmp;
char *b1, *b2;
size_t n1, n2;
if (n <= 1)
return;
n1 = n / 2;
n2 = n - n1;
b1 = b;
b2 = (char *) b + (n1 * s);
msort_with_tmp (b1, n1, s, cmp, t);
msort_with_tmp (b2, n2, s, cmp, t);
tmp = t;
if (s == OPSIZ && (b1 - (char *) 0) % OPSIZ == 0)
/* We are operating on aligned words. Use direct word stores. */
while (n1 > 0 && n2 > 0)
{
if ((*cmp) (b1, b2) <= 0)
{
--n1;
*((op_t *) tmp)++ = *((op_t *) b1)++;
}
else
{
--n2;
*((op_t *) tmp)++ = *((op_t *) b2)++;
}
}
else
while (n1 > 0 && n2 > 0)
{
if ((*cmp) (b1, b2) <= 0)
{
memcpy (tmp, b1, s);
b1 += s;
--n1;
}
else
{
memcpy (tmp, b2, s);
b2 += s;
--n2;
}
tmp += s;
}
if (n1 > 0)
memcpy (tmp, b1, n1 * s);
memcpy (b, t, (n - n2) * s);
}
void
DEFUN(qsort, (b, n, s, cmp),
PTR b AND size_t n AND size_t s AND __compar_fn_t cmp)
{
CONST size_t size = n * s;
if (size < 1024)
/* The temporary array is small, so put it on the stack. */
msort_with_tmp (b, n, s, cmp, __alloca (size));
else
{
/* It's somewhat large, so malloc it. */
int save = errno;
char *tmp = malloc (size);
if (tmp == NULL)
{
/* Couldn't get space, so use the slower algorithm
that doesn't need a temporary array. */
extern void EXFUN(_quicksort, (PTR __base,
size_t __nmemb, size_t __size,
__compar_fn_t __compar));
_quicksort (b, n, s, cmp);
}
else
{
msort_with_tmp (b, n, s, cmp, tmp);
free (tmp);
}
errno = save;
}
}
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