#define isupper(c) ((__ismask(c)&(_U)) != 0)
#define isxdigit(c) ((__ismask(c)&(_D|_X)) != 0)
+/*
+ * Rather than doubling the size of the _ctype lookup table to hold a 'blank'
+ * flag, just check for space or tab.
+ */
+#define isblank(c) (c == ' ' || c == '\t')
+
#define isascii(c) (((unsigned char)(c))<=0x7f)
#define toascii(c) (((unsigned char)(c))&0x7f)