1 files changed, 31 insertions, 0 deletions
diff --git a/src/ctype/isupper.c b/src/ctype/isupper.c
new file mode 100644
index 00000000..84247c28
--- /dev/null
+++ b/src/ctype/isupper.c
@@ -0,0 +1,31 @@
+#include <ctype.h>
+#include "limits.h"
+#include "nonstd/assert.h"
+#include "nonstd/ctype.h"
+#include "nonstd/internal.h"
+
+/** test whether a character is an uppercase letter **/
+int isupper(int c)
+{
+	unsigned int *map = __libc(CTYPE);
+
+	ASSERT_REPRESENTABLE(c, 0, UCHAR_MAX, unsigned char, EOF);
+	/*
+	RETURN(NONZERO, ARGUMENT(c) is an uppercase letter);
+	RETURN(0, ARGUMENT(c) is not an uppercase letter);
+	*/
+
+	return map[c] & UPPER;
+}
+
+/***
+tests whether ARGUMENT(c) is a character in the class CHARACTER_CLASS(upper)
+in the current locale.
+***/
+
+/*
+LC_CTYPE
+C_LOCALE(`THIS() is true for the characters CHAR(A), CHAR(B), CHAR(C), CHAR(D), CHAR(E), CHAR(F), CHAR(G), CHAR(H), CHAR(I), CHAR(J), CHAR(K), CHAR(L), CHAR(M), CHAR(N), CHAR(O), CHAR(P), CHAR(Q), CHAR(S), CHAR(T), CHAR(U), CHAR(W), CHAR(X), CHAR(Y), and CHAR(Z)')
+OTHER_LOCALES(`THIS() is true for a set of characters for which none of FUNCTION(iscntrl), FUNCTION(isdigit), FUNCTION(ispunct), or FUNCTION(isspace) is true')
+STDC(1)
+*/