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>
diff --git a/include/lib/libc/string.h b/include/lib/libc/string.h
index ee6eeac..de20f61 100644
--- a/include/lib/libc/string.h
+++ b/include/lib/libc/string.h
@@ -4,7 +4,7 @@
* SPDX-License-Identifier: BSD-3-Clause
*/
/*
- * Portions copyright (c) 2018, ARM Limited and Contributors.
+ * Portions copyright (c) 2018-2019, ARM Limited and Contributors.
* All rights reserved.
*/
@@ -23,6 +23,7 @@
int strcmp(const char *s1, const char *s2);
int strncmp(const char *s1, const char *s2, size_t n);
void *memchr(const void *src, int c, size_t len);
+void *memrchr(const void *src, int c, size_t len);
char *strchr(const char *s, int c);
void *memset(void *dst, int val, size_t count);
size_t strlen(const char *s);
diff --git a/lib/libc/libc.mk b/lib/libc/libc.mk
index e1b5560..93d30d0 100644
--- a/lib/libc/libc.mk
+++ b/lib/libc/libc.mk
@@ -12,6 +12,7 @@
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 0000000..01caef3
--- /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;
+}