[U-Boot] [RFC 01/15] lib: charset: add u16_strcmp()

AKASHI Takahiro
2019-09-18T01:26:29Z

u16 version of strcmp(): u16_strncmp() works like u16_strcmp() but only
at most n characters (in u16) are compared.
This function will be used in my UEFI secure boot patch.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
---
include/charset.h | 15 +++++++++++++++
lib/charset.c | 25 +++++++++++++++++++++++++
2 files changed, 40 insertions(+)

diff --git a/include/charset.h b/include/charset.h
index 020f8a90df07..fde6bddbc2fb 100644
--- a/include/charset.h
+++ b/include/charset.h
@@ -168,6 +168,21 @@ s32 utf_to_lower(const s32 code);
*/
s32 utf_to_upper(const s32 code);

+/*
+ * u16_strncmp() - compare two u16 string
+ *
+ * @s1: first string to compare
+ * @s2: second string to compare
+ * @n: maximum number of u16 to compare
+ * Return: 0 if the first n u16 are the same in s1 and s2
+ * < 0 if the first different u16 in s1 is less than the
+ * corresponding u16 in s2
+ * > 0 if the first different u16 in s1 is greater than the
+ * corresponding u16 in s2
+ */
+int u16_strncmp(const u16 *s1, const u16 *s2, size_t n);
+#define u16_strcmp(s1, s2) u16_strncmp((s1), (s2), SIZE_MAX)
+
/**
* u16_strlen - count non-zero words
*
diff --git a/lib/charset.c b/lib/charset.c
index 72d745da4f4e..1c6a7f693de4 100644
--- a/lib/charset.c
+++ b/lib/charset.c
@@ -335,6 +335,31 @@ s32 utf_to_upper(const s32 code)
return ret;
}

+/*
+ * u16_strncmp() - compare two u16 string
+ *
+ * @s1: first string to compare
+ * @s2: second string to compare
+ * @n: maximum number of u16 to compare
+ * Return: 0 if the first n u16 are the same in s1 and s2
+ * < 0 if the first different u16 in s1 is less than the
+ * corresponding u16 in s2
+ * > 0 if the first different u16 in s1 is greater than the
+ * corresponding u16 in s2
+ */
+int u16_strncmp(const u16 *s1, const u16 *s2, size_t n)
+{
+ int ret = 0;
+
+ for (; n; --n, ++s1, ++s2) {
+ ret = *s1 - *s2;
+ if (ret || !*s1)
+ break;
+ }
+
+ return ret;
+}
+
size_t u16_strlen(const void *in)
{
const char *pos = in;
--
2.21.0