feat(ctype): classification and case-mapping tables

src/ctype/toascii.c

@@ -0,0 +1,15 @@
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <ctype.h>
+
+/*
+ * Clear every bit above the low 7 of c. Pure bit arithmetic: defined for
+ * every int value, EOF included (toascii(-1) is 0x7f).
+ */
+int
+toascii(int c)
+{
+    return c & 0x7f;
+}