contract ERC20CompatibleToken is owned {
  using SafeMath for uint;

  // Public variables of the token
  string public name;
  string public symbol;
  uint8 public decimals = 18;
  uint256 public totalSupply;

  mapping(address => uint) balances; // List of user balances.

  event Transfer(address indexed from, address indexed to, uint value);
  event Approval(address indexed owner, address indexed spender, uint256 value);
  mapping (address => mapping (address => uint256)) internal allowed;
  mapping (address => bool) public frozenAccount;

  /**
   * Constrctor function
   *
   * Initializes contract with initial supply tokens to the creator of the contract
   */
  constructor(
      uint256 initialSupply,
      string memory tokenName,
      string memory tokenSymbol
  ) public {
      totalSupply = initialSupply * 10 ** uint256(decimals);  // Update total supply with the decimal amount
      balances[msg.sender] = totalSupply;                    // Give the creator all initial tokens
      name = tokenName;                                       // Set the name for display purposes
      symbol = tokenSymbol;                                   // Set the symbol for display purposes
  }

  /**
  * @dev Transfer tokens from one address to another
  * @param _from address The address which you want to send tokens from
  * @param _to address The address which you want to transfer to
  * @param _value uint256 the amount of tokens to be transferred
  */
  function transferFrom(address _from, address _to, uint256 _value) public returns (bool) {
    uint codeLength;
    bytes memory empty;

    require(_to != address(0));
    require(_value <= balances[_from]);
    require(_value <= allowed[_from][msg.sender]);

    require(!frozenAccount[_from]);                         // Check if sender is frozen
    require(!frozenAccount[_to]);                           // Check if recipient is frozen

    assembly {
      // Retrieve the size of the code on target address, this needs assembly .
      codeLength := extcodesize(_to)
    }
    if(codeLength>0) {
      ERC223ReceivingContract receiver = ERC223ReceivingContract(_to);
      receiver.tokenFallback(_from, _value, empty);
    }

    balances[_from] = balances[_from].sub(_value);
    balances[_to] = balances[_to].add(_value);
    allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
    emit Transfer(_from, _to, _value);
    return true;
  }

  /**
   * @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.
   *
   * @param _spender The address which will spend the funds.
   * @param _value The amount of tokens to be spent.
   */
  function approve(address _spender, uint256 _value) public returns (bool) {
    allowed[msg.sender][_spender] = _value;
    emit Approval(msg.sender, _spender, _value);
    return true;
  }

  /**
   * @dev Function to check the amount of tokens that an owner allowed to a spender.
   * @param _owner address The address which owns the funds.
   * @param _spender address The address which will spend the funds.
   * @return A uint256 specifying the amount of tokens still available for the spender.
   */
  function allowance(address _owner, address _spender) public view returns (uint256) {
    return allowed[_owner][_spender];
  }

  /**
   * approve should be called when allowed[_spender] == 0. To increment
   * allowed value is better to use this function to avoid 2 calls (and wait until
   * the first transaction is mined)
   * From MonolithDAO Token.sol
   */
  function increaseApproval(address _spender, uint _addedValue) public returns (bool) {
    allowed[msg.sender][_spender] = allowed[msg.sender][_spender].add(_addedValue);
    emit Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
    return true;
  }

  function decreaseApproval(address _spender, uint _subtractedValue) public returns (bool) {
    uint oldValue = allowed[msg.sender][_spender];
    if (_subtractedValue > oldValue) {
      allowed[msg.sender][_spender] = 0;
    } else {
      allowed[msg.sender][_spender] = oldValue.sub(_subtractedValue);
    }
    emit Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
    return true;
  }

  /* This generates a public event on the blockchain that will notify clients */
  event FrozenFunds(address target, bool frozen);

  /// @notice `freeze? Prevent | Allow` `target` from sending & receiving tokens
  /// @param target Address to be frozen
  /// @param freeze either to freeze it or not
  function freezeAccount(address target, bool freeze) onlyOwner public {
      frozenAccount[target] = freeze;
      emit FrozenFunds(target, freeze);
  }

}
function increaseApproval(address _spender, uint _addedValue) public returns (bool) {
  allowed[msg.sender][_spender] = allowed[msg.sender][_spender].add(_addedValue);
  emit Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
  return true;
}

/**
 * approve should be called when allowed[_spender] == 0. To increment
 * allowed value is better to use this function to avoid 2 calls (and wait until
 * the first transaction is mined)
 * From MonolithDAO Token.sol
 */