java/src/liba/lpf.java

   1 package liba;
   2
   3 import java.nio.ByteBuffer;
   4
   5 /** Low Pass Filter */
   6 public class lpf {
   7     ByteBuffer ctx;
   8     static {
   9         System.loadLibrary("a");
  10         clinit();
  11     }
  12
  13     static final native void clinit();
  14
  15     final native void init(double fc, double ts);
  16
  17     /**
  18      * construct a new {@link lpf} object
  19      *
  20      * @param fc cut-off frequency unit(hz)
  21      * @param ts sampling time unit(s)
  22      */
  23     public lpf(double fc, double ts) {
  24         init(fc, ts);
  25     }
  26
  27     /**
  28      * get coefficient for Low Pass Filter
  29      *
  30      * @return filter coefficient [0,1]
  31      */
  32     public final native double alpha();
  33
  34     /**
  35      * get output for Low Pass Filter
  36      *
  37      * @return filter output
  38      */
  39     public final native double output();
  40
  41     /**
  42      * generate for Low Pass Filter
  43      *
  44      * @param fc cut-off frequency unit(hz)
  45      * @param ts sampling time unit(s)
  46      * @return {@link lpf}
  47      */
  48     public final native lpf gen(double fc, double ts);
  49
  50     /**
  51      * calculate for Low Pass Filter
  52      *
  53      * @param x input value
  54      * @return output value
  55      */
  56     public final native double iter(double x);
  57
  58     /**
  59      * zeroing for Low Pass Filter
  60      *
  61      * @return {@link lpf}
  62      */
  63     public final native lpf zero();
  64 }