+#include <glib.h>
+#include "libsigrok.h"
+#include "libsigrok-internal.h"
+
+/* Message logging helpers with subsystem-specific prefix string. */
+#define LOG_PREFIX "filter: "
+#define sr_log(l, s, args...) sr_log(l, LOG_PREFIX s, ## args)
+#define sr_spew(s, args...) sr_spew(LOG_PREFIX s, ## args)
+#define sr_dbg(s, args...) sr_dbg(LOG_PREFIX s, ## args)
+#define sr_info(s, args...) sr_info(LOG_PREFIX s, ## args)
+#define sr_warn(s, args...) sr_warn(LOG_PREFIX s, ## args)
+#define sr_err(s, args...) sr_err(LOG_PREFIX s, ## args)
+
+/**
+ * @file
+ *
+ * Helper functions to filter out unused probes from samples.
+ */
+
+/**
+ * @defgroup grp_filter Probe filter
+ *
+ * Helper functions to filter out unused probes from samples.
+ *
+ * @{
+ */