code: /*
   * Copyright 2014-2016 the libsecp256k1 contributors
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *    http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package org.bitcoin;
  
  /**
   * This class holds the context reference used in native methods 
   * to handle ECDSA operations.
   */
  public class Secp256k1Context {
    private static final boolean enabled; //true if the library is loaded
    private static final long context; //ref to pointer to context obj
  
    static { //static initializer
        boolean isEnabled = true;
        long contextRef = -1;
        try {
            System.loadLibrary("secp256k1");
            contextRef = secp256k1_init_context();
        } catch (UnsatisfiedLinkError e) {
            System.out.println("UnsatisfiedLinkError: " + e.toString());
            isEnabled = false;
        }
        enabled = isEnabled;
        context = contextRef;
    }
  
    public static boolean isEnabled() {
       return enabled;
    }
  
    public static long getContext() {
       if(!enabled) return -1; //sanity check
       return context;
    }
  
    private static native long secp256k1_init_context();
  }
  