pragma solidity ^0.4.13;



contract ERC20Basic {

  uint256 public totalSupply;

  function balanceOf(address who) public constant returns (uint256);

  function transfer(address to, uint256 value) public returns (bool);

  event Transfer(address indexed from, address indexed to, uint256 value);

}



contract ERC20 is ERC20Basic {

  function allowance(address owner, address spender) public constant returns (uint256);

  function transferFrom(address from, address to, uint256 value) public returns (bool);

  function approve(address spender, uint256 value) public returns (bool);

  event Approval(address indexed owner, address indexed spender, uint256 value);

}



contract Ownable {

  address public owner;



  event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);



  /**

   * @dev The Ownable constructor sets the original `owner` of the contract to the sender

   * account.

   */

  function Ownable() {

    owner = msg.sender;

  }



  /**

   * @dev Throws if called by any account other than the owner.

   */

  modifier onlyOwner() {

    require(msg.sender == owner);

    _;

  }



  /**

   * @dev Allows the current owner to transfer control of the contract to a newOwner.

   * @param newOwner The address to transfer ownership to.

   */

  function transferOwnership(address newOwner) onlyOwner public {

    require(newOwner != address(0));

    OwnershipTransferred(owner, newOwner);

    owner = newOwner;

  }

}



library SaferMath {

  function mulX(uint256 a, uint256 b) internal constant returns (uint256) {

    uint256 c = a * b;

    assert(a == 0 || c / a == b);

    return c;

  }



  function divX(uint256 a, uint256 b) internal constant returns (uint256) {

    // assert(b > 0); // Solidity automatically throws when dividing by 0

    uint256 c = a / b;

    // assert(a == b * c + a % b); // There is no case in which this doesn't hold

    return c;

  }



  function sub(uint256 a, uint256 b) internal constant returns (uint256) {

    assert(b <= a);

    return a - b;

  }



  function add(uint256 a, uint256 b) internal constant returns (uint256) {

    uint256 c = a + b;

    assert(c >= a);

    return c;

  }

}



contract BasicToken is ERC20Basic {

  using SaferMath for uint256;

  mapping(address => uint256) balances;

  /**

  * @dev transfer token for a specified address

  * @param _to The address to transfer to.

  * @param _value The amount to be transferred.

  */

  function transfer(address _to, uint256 _value) public returns (bool) {

    require(_to != address(0));



    // SafeMath.sub will throw if there is not enough balance.

    balances[msg.sender] = balances[msg.sender].sub(_value);

    balances[_to] = balances[_to].add(_value);

    Transfer(msg.sender, _to, _value);

    return true;

  }



  /**

  * @dev Gets the balance of the specified address.

  * @param _owner The address to query the the balance of.

  * @return An uint256 representing the amount owned by the passed address.

  */

  function balanceOf(address _owner) public constant returns (uint256 balance) {

    return balances[_owner];

  }



}



contract StandardToken is ERC20, BasicToken {



  mapping (address => mapping (address => uint256)) allowed;





  /**

   * @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) {

    require(_to != address(0));



    uint256 _allowance = allowed[_from][msg.sender];



    // Check is not needed because sub(_allowance, _value) will already throw if this condition is not met

    // require (_value <= _allowance);



    balances[_from] = balances[_from].sub(_value);

    balances[_to] = balances[_to].add(_value);

    allowed[_from][msg.sender] = _allowance.sub(_value);

    Transfer(_from, _to, _value);

    return true;

  }



  /**

   * @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.

   *

   * Beware that changing an allowance with this method brings the risk that someone may use both the old

   * and the new allowance by unfortunate transaction ordering. One possible solution to mitigate this

   * race condition is to first reduce the spender's allowance to 0 and set the desired value afterwards:

   * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729

   * @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;

    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 constant returns (uint256 remaining) {

    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) returns (bool success) {

    allowed[msg.sender][_spender] = allowed[msg.sender][_spender].add(_addedValue);

    Approval(msg.sender, _spender, allowed[msg.sender][_spender]);

    return true;

  }



  function decreaseApproval (address _spender, uint _subtractedValue) returns (bool success) {

    uint oldValue = allowed[msg.sender][_spender];

    if (_subtractedValue > oldValue) {

      allowed[msg.sender][_spender] = 0;

    } else {

      allowed[msg.sender][_spender] = oldValue.sub(_subtractedValue);

    }

    Approval(msg.sender, _spender, allowed[msg.sender][_spender]);

    return true;

  }

}



contract DexAlpha is StandardToken, Ownable {



  string public constant name = "DexAlpha Tokens";

  string public constant symbol = "DXAT";

  uint8 public constant decimals = 8;



  uint256 public constant SUPPLY_CAP = 1000000000 * (10 ** uint256(decimals));



  address NULL_ADDRESS = address(0);



  uint public nonce = 0;



event NonceTick(uint nonce);

  function incNonce() {

    nonce += 1;

    if(nonce > 100) {

        nonce = 0;

    }

    NonceTick(nonce);

  }

  

  event PerformingDrop(uint count);

  function drop(address[] addresses, uint256 amount) public onlyOwner {

    uint256 amt = amount * 10**8;

    require(amt > 0);

    require(amt <= SUPPLY_CAP);

    PerformingDrop(addresses.length);

    

    // Multisend function

    assert(balances[owner] >= amt * addresses.length);

    for (uint i = 0; i < addresses.length; i++) {

      address recipient = addresses[i];

      if(recipient != NULL_ADDRESS) {

        balances[owner] -= amt;

        balances[recipient] += amt;

        Transfer(owner, recipient, amt);

      }

    }

  }



  /**

   * @dev Constructor that gives msg.sender all of existing tokens..

   */

  function DexAlpha() {

    totalSupply = SUPPLY_CAP;

    balances[msg.sender] = SUPPLY_CAP;

  }

}