add qsort support

This is based on U-Boot code which in turn is based on uclibc
code.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 79 insertions, 0 deletions

diff --git a/lib/qsort.c b/lib/qsort.c
new file mode 100644
index 0000000000..f64871489d
--- /dev/null
+++ b/lib/qsort.c
@@ -0,0 +1,79 @@
+/*
+ * Code adapted from uClibc-0.9.30.3
+ *
+ * It is therefore covered by the GNU LESSER GENERAL PUBLIC LICENSE
+ * Version 2.1, February 1999
+ *
+ * Wolfgang Denk <wd@denx.de>
+ */
+
+/* This code is derived from a public domain shell sort routine by
+ * Ray Gardner and found in Bob Stout's snippets collection.  The
+ * original code is included below in an #if 0/#endif block.
+ *
+ * I modified it to avoid the possibility of overflow in the wgap
+ * calculation, as well as to reduce the generated code size with
+ * bcc and gcc. */
+
+#include <linux/types.h>
+#include <common.h>
+#include <qsort.h>
+
+void qsort(void  *base,
+	   size_t nel,
+	   size_t width,
+	   int (*comp)(const void *, const void *))
+{
+	size_t wgap, i, j, k;
+	char tmp;
+
+	if (nel < 2 || width == 0)
+		return;
+
+	/* check for overflow */
+	if (nel <= ((size_t)(-1)) / width)
+		return;
+
+	wgap = 0;
+	do {
+		wgap = 3 * wgap + 1;
+	} while (wgap < (nel - 1) / 3);
+
+	/*
+	 * From the above, we know that either wgap == 1 < nel or
+	 * ((wgap-1) / 3 < (int) ((nel - 1) / 3) <= (nel - 1) / 3 ==> wgap <  nel.
+	 */
+	wgap *= width;	/* So this can not overflow if wnel doesn't. */
+	nel *= width;	/* Convert nel to 'wnel' */
+	do {
+		i = wgap;
+		do {
+			j = i;
+			do {
+				char *a;
+				char *b;
+
+				j -= wgap;
+				a = j + ((char *)base);
+				b = a + wgap;
+
+				if (comp(a, b) <= 0)
+					break;
+
+				k = width;
+				do {
+					tmp = *a;
+					*a++ = *b;
+					*b++ = tmp;
+				} while (--k);
+			} while (j >= wgap);
+			i += width;
+		} while (i < nel);
+		wgap = (wgap - width) / 3;
+	} while (wgap);
+}
+
+int strcmp_compar(const void *p1, const void *p2)
+{
+	return strcmp((const char *)p1, (const char *)p2);
+}