New modules 'unistr/u8-mblen', 'unistr/u16-mblen', 'unistr/u32-mblen'.

[gnulib.git] / lib / unistr / u8-mblen.c

diff --git a/lib/unistr/u8-mblen.c b/lib/unistr/u8-mblen.c
new file mode 100644 (file)
index 0000000..12ecd83
--- /dev/null
+++ b/lib/unistr/u8-mblen.c
@@ -0,0 +1,100 @@
+/* Look at first character in UTF-8 string.
+   Copyright (C) 1999-2000, 2002, 2006-2007 Free Software Foundation, Inc.
+   Written by Bruno Haible <bruno@clisp.org>, 2002.
+
+   This program is free software; you can redistribute it and/or modify it
+   under the terms of the GNU Library General Public License as published
+   by the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
+   USA.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include "unistr.h"
+
+int
+u8_mblen (const uint8_t *s, size_t n)
+{
+  if (n > 0)
+    {
+      /* Keep in sync with utf8-ucs4.h and utf8-ucs4.c.  */
+      uint8_t c = *s;
+
+      if (c < 0x80)
+       return (c != 0 ? 1 : 0);
+      if (c >= 0xc2)
+       {
+         if (c < 0xe0)
+           {
+             if (n >= 2
+#if CONFIG_UNICODE_SAFETY
+                 && (s[1] ^ 0x80) < 0x40
+#endif
+                )
+               return 2;
+           }
+         else if (c < 0xf0)
+           {
+             if (n >= 3
+#if CONFIG_UNICODE_SAFETY
+                 && (s[1] ^ 0x80) < 0x40 && (s[2] ^ 0x80) < 0x40
+                 && (c >= 0xe1 || s[1] >= 0xa0)
+                 && (c != 0xed || s[1] < 0xa0)
+#endif
+                )
+               return 3;
+           }
+         else if (c < 0xf8)
+           {
+             if (n >= 4
+#if CONFIG_UNICODE_SAFETY
+                 && (s[1] ^ 0x80) < 0x40 && (s[2] ^ 0x80) < 0x40
+                 && (s[3] ^ 0x80) < 0x40
+                 && (c >= 0xf1 || s[1] >= 0x90)
+#if 1
+                 && (c < 0xf4 || (c == 0xf4 && s[1] < 0x90))
+#endif
+#endif
+                )
+               return 4;
+           }
+#if 0
+         else if (c < 0xfc)
+           {
+             if (n >= 5
+#if CONFIG_UNICODE_SAFETY
+                 && (s[1] ^ 0x80) < 0x40 && (s[2] ^ 0x80) < 0x40
+                 && (s[3] ^ 0x80) < 0x40 && (s[4] ^ 0x80) < 0x40
+                 && (c >= 0xf9 || s[1] >= 0x88)
+#endif
+                )
+               return 5;
+           }
+         else if (c < 0xfe)
+           {
+             if (n >= 6
+#if CONFIG_UNICODE_SAFETY
+                 && (s[1] ^ 0x80) < 0x40 && (s[2] ^ 0x80) < 0x40
+                 && (s[3] ^ 0x80) < 0x40 && (s[4] ^ 0x80) < 0x40
+                 && (s[5] ^ 0x80) < 0x40
+                 && (c >= 0xfd || s[1] >= 0x84)
+#endif
+                )
+               return 6;
+           }
+#endif
+       }
+    }
+  /* invalid or incomplete multibyte character */
+  return -1;
+}