// (c) Alex McLean 2005
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.

class Envelope {
  private float[] values;
  private int count, step;
  
  Envelope (float[] values) {
    this.values = values;
    count = values.length - 1;
    step = 1 / count;
  }
  
  float value (float percentage) {
    float result, diff, point;
    point = count * percentage;
    int a, b;
    a = int(point);
    b = int(point + 1);
    if (a < 0)  {
      a = 0;
    }
    if (b > (count - 1)) {
      b = count - 1;
    }
    diff = values[b] - values[a];
    result = values[a] + (diff * (point - a));
    return(result);
  }
}