Add ARM assembly of strlcat which is implemented using (the ARM optimized)

strnlen and strlcpy.

common/lib/libc/arch/arm/string/strlcat_arm.S

@@ -0,0 +1,52 @@
+/*-
+ * Copyright (c) 2013 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to The NetBSD Foundation
+ * by Matt Thomas of 3am Software Foundry.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <machine/asm.h>
+
+RCSID("$NetBSD: strlcat_arm.S,v 1.1 2013/01/23 07:02:45 matt Exp $")
+
+/* LINTSTUB: size_t strlcat(char *, const char *, size_t) */
+ENTRY(strlcat)
+	push	{r4-r6, lr}
+	mov	r4, r0			/* save dst */
+	mov	r5, r1			/* save src */
+	mov	r6, r2			/* save siz */
+        
+	mov	r1, r6			/* get siz */
+	bl	PLT_SYM(strnlen)	/* find length of dst (up to siz) */
+
+	sub	r2, r6, r0		/* get remaining space in dst */
+	mov	r1, r5			/* restore src */
+	mov	r5, r0			/* save remaining space */
+	add	r0, r0, r4		/* set start to end of dst */
+	bl	PLT_SYM(strlcpy)	/* attempt to copy src */
+	add	r0, r0, r5		/* add remaining to strlcpy return */
+	pop	{r4-r6, lr}		/* restore registers */
+	RET				/* return */
+END(strlcat)