1 files changed, 45 insertions, 0 deletions
diff --git a/libc/ctype/isxdigit.c b/libc/ctype/isxdigit.c
new file mode 100644
index 0000000..f8a035f
--- /dev/null
+++ b/libc/ctype/isxdigit.c
@@ -0,0 +1,45 @@
+
+/*
+FUNCTION
+<<isxdigit>>---hexadecimal digit predicate
+
+INDEX
+isxdigit
+
+ANSI_SYNOPSIS
+#include <ctype.h>
+int isxdigit(int <[c]>);
+
+TRAD_SYNOPSIS
+#include <ctype.h>
+int isxdigit(int <[c]>);
+
+DESCRIPTION
+<<isxdigit>> is a macro which classifies ASCII integer values by table
+lookup.  It is a predicate returning non-zero for hexadecimal digits,
+and <<0>> for other characters.  It is defined only when
+<<isascii>>(<[c]>) is true or <[c]> is EOF.
+
+You can use a compiled subroutine instead of the macro definition by
+undefining the macro using `<<#undef isxdigit>>'.
+
+RETURNS
+<<isxdigit>> returns non-zero if <[c]> is a hexadecimal digit
+(<<0>>--<<9>>, <<a>>--<<f>>, or <<A>>--<<F>>).
+
+PORTABILITY
+<<isxdigit>> is ANSI C.
+
+No supporting OS subroutines are required.
+*/
+#include <_ansi.h>
+#include <ctype.h>
+
+
+#undef isxdigit
+int
+_DEFUN(isxdigit,(c),int c)
+{
+	return((_ctype_ + 1)[c] & ((_X)|(_N)));
+}
+