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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *   http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  
18  package org.apache.bcel;
19  
20  public class NanoTimer {
21  
22      private long timeNanos;
23  
24      public void reset() {
25          timeNanos = 0;
26      }
27  
28      public NanoTimer start() {
29          timeNanos -= System.nanoTime();
30          return this;
31      }
32  
33      public void stop() {
34          timeNanos += System.nanoTime();
35      }
36  
37      public void subtract(final NanoTimer o) {
38          timeNanos -= o.timeNanos;
39      }
40  
41      /**
42       * May ony be called after stop has been called as many times as start.
43       */
44      @Override
45      public String toString() {
46          return (double) timeNanos / 1000000000 + " s";
47      }
48  
49  }