--- a/libcommon/apducmd.c	Mon Mar 22 21:30:42 2021 +0000
+++ b/libcommon/apducmd.c	Mon Mar 22 23:58:11 2021 +0000
@@ -5,6 +5,7 @@
 
 #include <sys/types.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include "simresp.h"
 
 cmd_apdu(argc, argv)
@@ -24,3 +25,28 @@
 	printf("%04X\n", sim_resp_sw);
 	return(0);
 }
+
+cmd_apdu_checksw(argc, argv)
+	char **argv;
+{
+	u_char cmd[260];
+	int rc;
+	unsigned len, expect_sw;
+
+	rc = decode_hex_data_from_string(argv[1], cmd, 5, 260);
+	if (rc < 0)
+		return(rc);
+	len = rc;
+	expect_sw = strtoul(argv[2], 0, 16);
+	rc = apdu_exchange(cmd, len);
+	if (rc < 0)
+		return(rc);
+	if (sim_resp_sw == expect_sw)
+		return(0);
+	else {
+		fprintf(stderr,
+			"SW response mismatch: expected %04X, got %04X\n",
+			expect_sw, sim_resp_sw);
+		return(-1);
+	}
+}