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/* msort -- an alternative to qsort, with an identical interface.
This file is part of the GNU C Library.
Copyright (C) 1992, 1995, 1996, 1997 Free Software Foundation, Inc.
Written by Mike Haertel, September 1988.
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., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include <stdlib.h>
#include <string.h>
#include <memcopy.h>
#include <errno.h>
static void msort_with_tmp __P ((void *b, size_t n, size_t s,
__compar_fn_t cmp, char *t));
static void
msort_with_tmp (b, n, s, cmp, t)
void *b;
size_t n;
size_t s;
__compar_fn_t cmp;
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
qsort (b, n, s, cmp)
void *b;
size_t n;
size_t s;
__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 _quicksort __P ((void *__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);
}
__set_errno (save);
}
}
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