--- a/sw/mcsi-rxtx/tx_func.c	Mon Oct 28 06:34:42 2024 +0000
+++ b/sw/mcsi-rxtx/tx_func.c	Mon Oct 28 06:52:33 2024 +0000
@@ -4,6 +4,7 @@
  */
 
 #include <sys/types.h>
+#include <ctype.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ -46,3 +47,26 @@
 	do_idle_fill(tx_samples);
 	emit_uart_output(tx_samples);
 }
+
+void
+cmd_pcm_fill(argc, argv)
+	char **argv;
+{
+	u_long val;
+	char *endp;
+
+	if (argc < 2) {
+		printf("%04x\n", pcm_fill_word);
+		return;
+	}
+	if (!isxdigit(argv[1][0])) {
+inv:		printf("error: pcm-fill argument is not a valid hex word\n");
+		return;
+	}
+	val = strtoul(argv[1], &endp, 16);
+	if (*endp)
+		goto inv;
+	if (val > 0xFFFF)
+		goto inv;
+	pcm_fill_word = val;
+}