[U-Boot] [PATCH v2 02/11] lib: charset: add u16_strncmp()

[AKASHI Takahiro <takahiro.akashi@linaro.org>]

u16_strncmp() works like u16_strcmp() but only at most n characters
(in u16) are compared.
This function will be used in a later patch.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
---
 include/charset.h |  5 +++++
 lib/charset.c     | 13 +++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/include/charset.h b/include/charset.h
index 747a9b376c03..49842a88bc8b 100644
--- a/include/charset.h
+++ b/include/charset.h
@@ -171,6 +171,11 @@ s32 utf_to_upper(const s32 code);
  */
 int u16_strcmp(const u16 *s1, const u16 *s2);
 
+/*
+ * u16_strncmp() - strncmp() for u16 strings
+ */
+int u16_strncmp(const u16 *s1, const u16 *s2, size_t n);
+
 /**
  * u16_strlen - count non-zero words
  *
diff --git a/lib/charset.c b/lib/charset.c
index 4a25ac0bdb9c..85f08db68fe2 100644
--- a/lib/charset.c
+++ b/lib/charset.c
@@ -345,6 +345,19 @@ int u16_strcmp(const u16 *s1, const u16 *s2)
 	return (*(uint16_t *)s1 - *(uint16_t *)s2);
 }
 
+int u16_strncmp(const u16 *s1, const u16 *s2, size_t n)
+{
+	while ((n-- > 0) && (*s1 == *s2++)) {
+		if (*s1++ == 0)
+			return 0;
+		if (!n)
+			return 0;
+	}
+	--s2;
+
+	return (*(uint16_t *)s1 - *(uint16_t *)s2);
+}
+
 size_t u16_strlen(const u16 *in)
 {
 	size_t i;
-- 
2.20.1