utf8_strlen: Improve performance

Use utf8_charlen() rather than utf8_tounicode()
Note that utf8_charlen() now returns 1 instead of -1 for an invalid
utf-8 start byte.

Reported-by: dbohdan <dbohdan@dbohdan.com>
Signed-off-by: Steve Bennett <steveb@workware.net.au>

1 files changed, 2 insertions, 3 deletions

diff --git a/utf8.h b/utf8.h
index 40fc95f..9970683 100644
--- a/utf8.h
+++ b/utf8.h
@@ -49,9 +49,8 @@ int utf8_fromunicode(char *p, unsigned uc);
 /**
  * Returns the length of the utf-8 sequence starting with 'c'.
  *
- * Returns 1-4, or -1 if this is not a valid start byte.
- *
- * Note that charlen=4 is not supported by the rest of the API.
+ * Returns 1-4.
+ * If 'c' is not a valid start byte, returns 1.
  */
 int utf8_charlen(int c);