// multi.h file
#ifndef __MULTI__
#define __MULTI__

#include <ap_int.h>

extern "C" {
  void ffn(ap_fixed<18,4,AP_TRN,AP_SAT> x_in_1, 
           ap_fixed<18,4,AP_TRN,AP_SAT> x_in_2, 
           ap_fixed<18,4,AP_TRN,AP_SAT> x_in_3,
           ap_fixed<18,4,AP_TRN,AP_SAT> x_in_4,
           ap_fixed<18,4,AP_TRN,AP_SAT> & y_out);
}

#endif


// multi.cpp file
#include "multi.h"

void multi(
  ap_fixed<18, 4, AP_TRN, AP_SAT> x_in_1,
  ap_fixed<18, 4, AP_TRN, AP_SAT> x_in_2,
  ap_fixed<18, 4, AP_TRN, AP_SAT> x_in_3,
  ap_fixed<18, 4, AP_TRN, AP_SAT> x_in_4,
  ap_fixed<18, 4, AP_TRN, AP_SAT> & y_out
) {
  //#pragma HLS pipeline II=1
  y_out = x_in_1 * x_in_2 * x_in_3 * x_in_4;

}