Move utf16 functions to kernel core and rename

We want to be able to use the utf16 functions that are currently present
in the EFI variables code in platform-specific code as well. Move them to
the kernel core, and in the process rename them to accurately describe what
they do - they don't handle UTF16, only UCS2.

Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

lib/ucs2_string.c

@@ -0,0 +1,51 @@
+#include <linux/ucs2_string.h>
+#include <linux/module.h>
+
+/* Return the number of unicode characters in data */
+unsigned long
+ucs2_strnlen(const ucs2_char_t *s, size_t maxlength)
+{
+        unsigned long length = 0;
+
+        while (*s++ != 0 && length < maxlength)
+                length++;
+        return length;
+}
+EXPORT_SYMBOL(ucs2_strnlen);
+
+unsigned long
+ucs2_strlen(const ucs2_char_t *s)
+{
+        return ucs2_strnlen(s, ~0UL);
+}
+EXPORT_SYMBOL(ucs2_strlen);
+
+/*
+ * Return the number of bytes is the length of this string
+ * Note: this is NOT the same as the number of unicode characters
+ */
+unsigned long
+ucs2_strsize(const ucs2_char_t *data, unsigned long maxlength)
+{
+        return ucs2_strnlen(data, maxlength/sizeof(ucs2_char_t)) * sizeof(ucs2_char_t);
+}
+EXPORT_SYMBOL(ucs2_strsize);
+
+int
+ucs2_strncmp(const ucs2_char_t *a, const ucs2_char_t *b, size_t len)
+{
+        while (1) {
+                if (len == 0)
+                        return 0;
+                if (*a < *b)
+                        return -1;
+                if (*a > *b)
+                        return 1;
+                if (*a == 0) /* implies *b == 0 */
+                        return 0;
+                a++;
+                b++;
+                len--;
+        }
+}
+EXPORT_SYMBOL(ucs2_strncmp);