--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/frbl/test/hexdecode.c	Thu Mar 05 22:05:01 2020 +0000
@@ -0,0 +1,30 @@
+/*
+ * This module contains the decode_hex_byte() function,
+ * which is used by the SREC file reader and will likely be used
+ * by other code as well, such as the dump-to-file function
+ * of loadtool.
+ */
+
+#include <ctype.h>
+
+decode_hex_byte(s)
+	char *s;
+{
+	register int u, l;
+
+	if (!isxdigit(s[0]) || !isxdigit(s[1]))
+		return(-1);
+	if (isdigit(s[0]))
+		u = s[0] - '0';
+	else if (isupper(s[0]))
+		u = s[0] - 'A' + 10;
+	else
+		u = s[0] - 'a' + 10;
+	if (isdigit(s[1]))
+		l = s[1] - '0';
+	else if (isupper(s[1]))
+		l = s[1] - 'A' + 10;
+	else
+		l = s[1] - 'a' + 10;
+	return((u << 4) | l);
+}