x48 is a very old program but it works fault free also on new
Linux systems (as of 2003 ;-). You need however to patch the file timer.c
and add the line "#include <time.h>":
--- timer.c.orig
+++ timer.c
@@ -44,6 +44,7 @@
#include <stdio.h>
#include <unistd.h>
#include <sys/time.h>
+#include <time.h>
#include "timer.h"
#include "debugger.h"