[PATCH 1/3] lib: add function u16_strcasecmp()

[Heinrich Schuchardt]

Provide a function for comparing UTF-16 strings in a case insensitive
manner.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
---
 include/charset.h | 13 +++++++++++++
 lib/charset.c     | 26 ++++++++++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/include/charset.h b/include/charset.h
index e900fd789a..6e79d7152e 100644
--- a/include/charset.h
+++ b/include/charset.h
@@ -173,6 +173,19 @@ s32 utf_to_lower(const s32 code);
  */
 s32 utf_to_upper(const s32 code);
 
+/**
+ * u16_strcasecmp() - compare two u16 strings case insensitively
+ *
+ * @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
+ */
+int u16_strcasecmp(const u16 *s1, const u16 *s2);
+
 /**
  * u16_strncmp() - compare two u16 string
  *
diff --git a/lib/charset.c b/lib/charset.c
index bece4985bf..b1842755eb 100644
--- a/lib/charset.c
+++ b/lib/charset.c
@@ -350,6 +350,32 @@ s32 utf_to_upper(const s32 code)
 	return ret;
 }
 
+/*
+ * u16_strcasecmp() - compare two u16 strings case insensitively
+ *
+ * @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
+ */
+int u16_strcasecmp(const u16 *s1, const u16 *s2)
+{
+	int ret = 0;
+	s32 c1, c2;
+
+	for (;;) {
+		c1 = utf_to_upper(utf16_get(&s1));
+		c2 = utf_to_upper(utf16_get(&s2));
+		ret = c1 - c2;
+		if (ret || !c1 || c1 == -1 || c2 == -1)
+			break;
+	}
+	return ret;
+}
+
 /*
  * u16_strncmp() - compare two u16 string
  *
-- 
2.37.2