From ebff1072681c5ed09bb70d9c4f617476822db757 Mon Sep 17 00:00:00 2001
From: Ambroise Vincent <ambroise.vincent@arm.com>
Date: Wed, 19 Jun 2019 17:14:09 +0100
Subject: libc: add memrchr

This function scans a string backwards from the end for the first
instance of a character.

Change-Id: I46b21573ed25a0ff222eac340e1e1fb93b040763
Signed-off-by: Ambroise Vincent <ambroise.vincent@arm.com>
---
 lib/libc/libc.mk   |  1 +
 lib/libc/memrchr.c | 24 ++++++++++++++++++++++++
 2 files changed, 25 insertions(+)
 create mode 100644 lib/libc/memrchr.c

(limited to 'lib')

diff --git a/lib/libc/libc.mk b/lib/libc/libc.mk
index e1b5560f8..93d30d035 100644
--- a/lib/libc/libc.mk
+++ b/lib/libc/libc.mk
@@ -12,6 +12,7 @@ LIBC_SRCS	:=	$(addprefix lib/libc/,		\
 			memcmp.c			\
 			memcpy.c			\
 			memmove.c			\
+			memrchr.c			\
 			memset.c			\
 			printf.c			\
 			putchar.c			\
diff --git a/lib/libc/memrchr.c b/lib/libc/memrchr.c
new file mode 100644
index 000000000..01caef3ae
--- /dev/null
+++ b/lib/libc/memrchr.c
@@ -0,0 +1,24 @@
+/*
+ * Copyright (c) 2019, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <string.h>
+
+#undef memrchr
+
+void *memrchr(const void *src, int c, size_t len)
+{
+	const unsigned char *s = src + (len - 1);
+
+	while (len--) {
+		if (*s == (unsigned char)c) {
+			return (void*) s;
+		}
+
+		s--;
+	}
+
+	return NULL;
+}
-- 
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