1 files changed, 77 insertions, 0 deletions
diff --git a/libgo/runtime/go-rune.c b/libgo/runtime/go-rune.c
new file mode 100644
index 000000000..7e31eb8d6
--- /dev/null
+++ b/libgo/runtime/go-rune.c
@@ -0,0 +1,77 @@
+/* go-rune.c -- rune functions for Go.
+
+   Copyright 2009, 2010 The Go Authors. All rights reserved.
+   Use of this source code is governed by a BSD-style
+   license that can be found in the LICENSE file.  */
+
+#include <stddef.h>
+
+#include "go-string.h"
+
+/* Get a character from the UTF-8 string STR, of length LEN.  Store
+   the Unicode character, if any, in *RUNE.  Return the number of
+   characters used from STR.  */
+
+int
+__go_get_rune (const unsigned char *str, size_t len, int *rune)
+{
+  int c, c1, c2, c3;
+
+  /* Default to the "replacement character".  */
+  *rune = 0xfffd;
+
+  if (len <= 0)
+    return 1;
+
+  c = *str;
+  if (c <= 0x7f)
+    {
+      *rune = c;
+      return 1;
+    }
+
+  if (len <= 1)
+    return 1;
+
+  c1 = str[1];
+  if ((c & 0xe0) == 0xc0
+      && (c1 & 0xc0) == 0x80)
+    {
+      *rune = (((c & 0x1f) << 6)
+	       + (c1 & 0x3f));
+      return 2;
+    }
+
+  if (len <= 2)
+    return 1;
+
+  c2 = str[2];
+  if ((c & 0xf0) == 0xe0
+      && (c1 & 0xc0) == 0x80
+      && (c2 & 0xc0) == 0x80)
+    {
+      *rune = (((c & 0xf) << 12)
+	       + ((c1 & 0x3f) << 6)
+	       + (c2 & 0x3f));
+      return 3;
+    }
+
+  if (len <= 3)
+    return 1;
+
+  c3 = str[3];
+  if ((c & 0xf8) == 0xf0
+      && (c1 & 0xc0) == 0x80
+      && (c2 & 0xc0) == 0x80
+      && (c3 & 0xc0) == 0x80)
+    {
+      *rune = (((c & 0x7) << 18)
+	       + ((c1 & 0x3f) << 12)
+	       + ((c2 & 0x3f) << 6)
+	       + (c3 & 0x3f));
+      return 4;
+    }
+
+  /* Invalid encoding.  Return 1 so that we advance.  */
+  return 1;
+}