mes/lib/stdlib/qsort.c
Jan Nieuwenhuizen f22cc0c173
mescc: Mes C Library: Fix qsort to support duplicate entries.
* lib/stdlib/qsort.c (qpart): Handle dupes.
* scaffold/tests/81-qsort-dupes.c: New file.
* build-aux/check-mescc.sh (tests): Run it.
2018-08-27 22:37:12 +02:00

64 lines
1.7 KiB
C

/* -*-comment-start: "//";comment-end:""-*-
* GNU Mes --- Maxwell Equations of Software
* Copyright © 2017,2018 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
*
* This file is part of GNU Mes.
*
* GNU Mes is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or (at
* your option) any later version.
*
* GNU Mes 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GNU Mes. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdlib.h>
#include <string.h>
void
qswap (void *a, void *b, size_t size)
{
char *buf[8];
memcpy (buf, a, size);
memcpy (a, b, size);
memcpy (b, buf, size);
}
size_t
qpart (void *base, size_t count, size_t size, int (*compare)(void const *, void const *))
{
void* p = base + count*size;
size_t i = 0;
for (size_t j = 0; j < count; j++)
{
int c = compare (base+j*size, p);
if (c < 0)
{
qswap (base+i*size, base+j*size, size);
i++;
}
else if (c == 0)
i++;
}
if (compare (base+count*size, base+i*size) < 0)
qswap (base+i*size, base+count*size, size);
return i;
}
void
qsort (void *base, size_t count, size_t size, int (*compare)(void const *, void const *))
{
if (count > 1)
{
int p = qpart (base, count-1, size, compare);
qsort (base, p, size, compare);
qsort (base+p*size, count-p, size, compare);
}
}