+#ifndef FILTER_H
+#define FILTER_H
+
+#include <dol.h>
+#include "global.h"
+
+#define PORT_INA "inA"
+#define PORT_INB "inB"
+#define PORT_OUTA "outA"
+#define PORT_OUTB "outB"
+
+typedef struct _local_states
+{
+ char id[10]; //will contain "filter_xx"
+ int first_invocation;
+ int process_index;
+ float inA, inB, out, filter_coefficient, zero;
+} Filter_State;
+
+void filter_init(DOLProcess *);
+int filter_fire(DOLProcess *);
+
+#endif