}
void
-qsort (void *base, size_t nmemb, size_t size, int (*compar)(void const *, void const *))
+qswap (void *a, void *b, size_t size)
{
- eputs ("qsort stub\n");
+ 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++)
+ {
+ if (compare (base+j*size, p) < 0)
+ {
+ qswap (base+i*size, base+j*size, size);
+ 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);
+ }
}
int
--- /dev/null
+/* -*-comment-start: "//";comment-end:""-*-
+ * Mes --- Maxwell Equations of Software
+ * Copyright © 2017 Jan Nieuwenhuizen <janneke@gnu.org>
+ *
+ * This file is part of Mes.
+ *
+ * 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.
+ *
+ * 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 Mes. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "30-test.i"
+#include <string.h>
+
+
+int
+compare_int (void *a, void *b)
+{
+ eputs ("compare: "); eputs (itoa (*(int*)a)); eputs (" <? "); eputs (itoa (*(int*)b));
+ eputs (" => "); eputs (itoa (*(int*)a - *(int*)b)); eputs ("\n");
+ return *(int*)a - *(int*)b;
+}
+
+int
+test ()
+{
+ int lst[6] = {0, 5, 4, 3, 2, -1};
+ qsort (lst, 6, sizeof (int), compare_int);
+ for (int i = 0; i < 6; i++)
+ {
+ eputs (itoa (i)); eputs (":"); eputs (itoa (lst[i])); eputs ("\n");
+ }
+ if (lst[0] != -1) return 1;
+ if (lst[5] != 5) return 2;
+ return 0;
+}