Initial commit

libs/c/src/qsort.c

@@ -0,0 +1,40 @@
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static
+void swap(void *base, size_t i, size_t j, size_t size)
+{
+	void *tmp = malloc(size);
+
+	assert(tmp);
+
+	memcpy(tmp, (char*) base + i * size, size);
+	memmove((char*) base + i * size, (char*) base + j * size, size);
+	memcpy((char*) base + j * size, tmp, size);
+	free(tmp);
+}
+
+/* qsort: sort v[left]...v[right] into increasing order */
+void
+qsort(void *base, size_t nmemb, size_t size, 
+      int(*compar)(const void *, const void *))
+{
+	int i, last;
+
+	if (nmemb <= 1)
+		return;
+
+	swap(base, 0, nmemb / 2, size);
+
+	last = 0;
+	for (i = 1; i < nmemb; i++)
+		if (compar((char*) base + (i * size), base) < 0)
+			swap(base, i, ++last, size);
+
+	swap(base, 0, last, size);
+
+	qsort(base, last, size, compar);
+	qsort((char*) base + (last + 1) * size, nmemb - last - 1, size, compar);
+}