--- a/simtool/hexread.c	Tue Jan 26 00:51:59 2021 +0000
+++ b/simtool/hexread.c	Tue Jan 26 01:27:58 2021 +0000
@@ -65,3 +65,33 @@
 	}
 	return(count);
 }
+
+decode_hex_data_from_string(arg, databuf)
+	char *arg;
+	u_char *databuf;
+{
+	unsigned count;
+
+	for (count = 0; ; count++) {
+		while (isspace(*arg))
+			arg++;
+		if (!*arg)
+			break;
+		if (!isxdigit(arg[0]) || !isxdigit(arg[1])) {
+			fprintf(stderr, "error: invalid hex string input\n");
+			return(-1);
+		}
+		if (count >= 255) {
+			fprintf(stderr, "error: hex input data is too long\n");
+			return(-1);
+		}
+		databuf[count] = (decode_hex_digit(arg[0]) << 4) |
+				 decode_hex_digit(arg[1]);
+		arg += 2;
+	}
+	if (!count) {
+		fprintf(stderr, "error: empty hex string argument\n");
+		return(-1);
+	}
+	return(count);
+}