add libc building to agbcc.

1 files changed, 44 insertions, 0 deletions

diff --git a/libc/ctype/isalpha.c b/libc/ctype/isalpha.c
new file mode 100644
index 0000000..35f14d3
--- /dev/null
+++ b/libc/ctype/isalpha.c
@@ -0,0 +1,44 @@
+/*
+FUNCTION
+	<<isalpha>>---alphabetic character predicate
+
+INDEX
+	isalpha
+
+ANSI_SYNOPSIS
+	#include <ctype.h>
+	int isalpha(int <[c]>);
+
+TRAD_SYNOPSIS
+	#include <ctype.h>
+	int isalpha(<[c]>);
+
+DESCRIPTION
+<<isalpha>> is a macro which classifies ASCII integer values by table
+lookup.  It is a predicate returning non-zero when <[c]> represents an
+alphabetic ASCII character, and 0 otherwise.  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 isalpha>>'.
+
+RETURNS
+<<isalpha>> returns non-zero if <[c]> is a letter (<<A>>--<<Z>> or
+<<a>>--<<z>>). 
+
+PORTABILITY
+<<isalpha>> is ANSI C.
+
+No supporting OS subroutines are required.
+*/
+
+#include <_ansi.h>
+#include <ctype.h>
+
+#undef isalpha
+int
+_DEFUN(isalpha,(c),int c)
+{
+	return((_ctype_ + 1)[c] & (_U|_L));
+}
+