add bytestorune and stringtorune to sys.

SVN=126321

src/cmd/gc/sys.go

@@ -45,6 +45,8 @@ func	mapassign1(hmap *map[any]any, key any, val any);
 func	mapassign2(hmap *map[any]any, key any, val any, pres bool);
 
 func	readfile(string) (string, bool);	// read file into string; boolean status
+func	bytestorune(*byte, int32, int32) (int32, int32);	// convert bytes to runes	
+func	stringtorune(string, int32, int32) (int32, int32);	// convert bytes to runes	
 
 func	exit(int32);
 
@@ -94,6 +96,10 @@ export
 	// files
 	readfile
 
+	// runes and utf-8
+	bytestorune
+	stringtorune
+
 	// system calls
 	exit
 	;

src/runtime/rune.c

@@ -222,3 +222,22 @@ runetochar(byte *str, int32 rune)  /* note: in original, arg2 was pointer */
 	str[3] = Tx | (c & Maskx);
 	return 4;
 }
+
+/*
+ * Wrappers for calling from go
+ */
+void
+sys·bytestorune(byte *str, int32 off, int32 length, int32 outrune, int32 outcount)
+{
+	outcount = charntorune(&outrune, str + off, length);
+	FLUSH(&outrune);
+	FLUSH(&outcount);
+}
+
+void
+sys·stringtorune(string str, int32 off, int32 length, int32 outrune, int32 outcount)
+{
+	outcount = charntorune(&outrune, str->str + off, length);
+	FLUSH(&outrune);
+	FLUSH(&outcount);
+}

src/runtime/runtime.h

@@ -142,4 +142,10 @@ void	sys·intstring(int64, string);
 void	sys·ifaces2i(Sigi*, Sigs*, Map*, void*);
 void	sys·ifacei2i(Sigi*, Map*, void*);
 void	sys·ifacei2s(Sigs*, Map*, void*);
+
+/*
+ * User go-called
+ */
 void	sys·readfile(string, string, bool);
+void	sys·bytestorune(byte*, int32, int32, int32, int32);
+void	sys·stringtorune(string, int32, int32, int32, int32);