mes/lib/stdlib/qsort.c

81 lines
2.2 KiB
C

/* -*-comment-start: "//";comment-end:""-*-
* GNU Mes --- Maxwell Equations of Software
* Copyright © 2017,2018 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
* Copyright © 2021 Paul Dersey <pdersey@gmail.com>
*
* 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 *pa = a;
char *pb = b;
do
{
char tmp = *pa;
*pa++ = *pb;
*pb++ = tmp;
} while (--size > 0);
}
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)
{
#if 1 //__x86_64__
qswap (base + i * size, base + j * size, size);
#else
int p1 = base + i * size;
int p2 = base + j * size;
qswap (p1, p2, size);
#endif
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);
#if 1 //__x86_64__
qsort (base + p * size, count - p, size, compare);
#else
int p1 = base + p * size;
int p2 = count - p;
qsort (p1, p2, size, compare);
#endif
}
}