--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libcoding/check_high_bit.c	Sat Aug 05 16:55:24 2023 +0000
@@ -0,0 +1,20 @@
+/*
+ * The function implemented in this module is intended for validating inputs
+ * that are expected to be in the form of GSM7 characters carried in an octet
+ * string, where the high bit of every octet is expected to be cleared.
+ */
+
+#include <sys/types.h>
+
+check_high_bit(buf, len)
+	u_char *buf;
+	unsigned len;
+{
+	unsigned n;
+
+	for (n = 0; n < len; n++) {
+		if (buf[n] & 0x80)
+			return(-1);
+	}
+	return(0);
+}