pragma solidity ^0.4.8;

/**
 * SafeMath
 */
contract SafeMath {
  function assert(bool assertion) internal {
    if (!assertion) {
      throw;
    }
  }
  
  function safeMul(uint256 a, uint256 b) internal returns (uint256) {
    uint256 c = a * b;
    assert(a == 0 || c / a == b);
    return c;
  }

  function safeDiv(uint256 a, uint256 b) internal returns (uint256) {
    assert(b > 0);
    uint256 c = a / b;
    assert(a == b * c + a % b);
    return c;
  }

  function safeSub(uint256 a, uint256 b) internal returns (uint256) {
    assert(b <= a);
    return a - b;
  }

  function safeAdd(uint256 a, uint256 b) internal returns (uint256) {
    uint256 c = a + b;
    assert(c>=a && c>=b);
    return c;
  }
}

contract BKB is SafeMath{
    string public name;
    string public symbol;
    uint8 public decimals;
    uint256 public totalSupply;
	address public owner;

    mapping (address => uint256) public balanceOf;
	mapping (address => uint256) public freezeOf;
    mapping (address => mapping (address => uint256)) public allowance;

    event Transfer(address indexed from, address indexed to, uint256 value);

    event Burn(address indexed from, uint256 value);
	
    event Freeze(address indexed from, uint256 value);
	
    event Unfreeze(address indexed from, uint256 value);

    /* Initial */
    function BKB(uint256 initialSupply, string tokenName, uint8 decimalUnits, string tokenSymbol) {
        balanceOf[msg.sender] = initialSupply;    // Owner
        totalSupply = initialSupply;              // Total Supply
        name = tokenName;                         // Name
        symbol = tokenSymbol;                     // Symbol
        decimals = decimalUnits;                  // decimals
		owner = msg.sender;
    }

    /* Transfer */
    function transfer(address _to, uint256 _value) {
        if (_to == 0x0) throw; 
		if (_value <= 0) throw; 
        if (balanceOf[msg.sender] < _value) throw; 
        if (balanceOf[_to] + _value < balanceOf[_to]) throw; 
        balanceOf[msg.sender] = SafeMath.safeSub(balanceOf[msg.sender], _value);   
        balanceOf[_to] = SafeMath.safeAdd(balanceOf[_to], _value); 
        Transfer(msg.sender, _to, _value);  
    }

    /* Approve */
    function approve(address _spender, uint256 _value) returns (bool success) {
		if (_spender == 0x0) throw;
		if (_value <= 0) throw; 
        allowance[msg.sender][_spender] = _value;
        return true;
    }
       

    /* transferFrom */
    function transferFrom(address _from, address _to, uint256 _value) returns (bool success) {
        if (_to == 0x0) throw;     
		if (_value <= 0) throw; 
        if (balanceOf[_from] < _value) throw; 
        if (balanceOf[_to] + _value < balanceOf[_to]) throw;
        if (_value > allowance[_from][msg.sender]) throw;
        balanceOf[_from] = SafeMath.safeSub(balanceOf[_from], _value); 
        balanceOf[_to] = SafeMath.safeAdd(balanceOf[_to], _value); 
        allowance[_from][msg.sender] = SafeMath.safeSub(allowance[_from][msg.sender], _value);
        Transfer(_from, _to, _value);
        return true;
    }

    function burn(uint256 _value) returns (bool success) {
        if (balanceOf[msg.sender] < _value) throw; 
		if (_value <= 0) throw; 
        balanceOf[msg.sender] = SafeMath.safeSub(balanceOf[msg.sender], _value);
        totalSupply = SafeMath.safeSub(totalSupply,_value);
        Burn(msg.sender, _value);
        return true;
    }
	
	function freeze(uint256 _value) returns (bool success) {
        if (balanceOf[msg.sender] < _value) throw; 
		if (_value <= 0) throw; 
        balanceOf[msg.sender] = SafeMath.safeSub(balanceOf[msg.sender], _value); 
        freezeOf[msg.sender] = SafeMath.safeAdd(freezeOf[msg.sender], _value);
        Freeze(msg.sender, _value);
        return true;
    }
	
	function unfreeze(uint256 _value) returns (bool success) {
        if (freezeOf[msg.sender] < _value) throw; 
		if (_value <= 0) throw; 
        freezeOf[msg.sender] = SafeMath.safeSub(freezeOf[msg.sender], _value); 
		balanceOf[msg.sender] = SafeMath.safeAdd(balanceOf[msg.sender], _value);
        Unfreeze(msg.sender, _value);
        return true;
    }
	
	function withdrawEther(uint256 amount) {
		if(msg.sender != owner)throw;
		owner.transfer(amount);
	}
	
	function() payable {
    }
}