pragma solidity ^0.4.8;

/**
* Math operations with safety checks
*/
contract SafeMath {
  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;
  }

  function assert(bool assertion) internal {
    if (!assertion) {
      throw;
    }
  }
}
contract ETHT is SafeMath{
  string public name;
  string public symbol;
  uint8 public decimals;
  uint256 public totalSupply;
  address public owner;

  /* This creates an array with all balances */
  mapping (address => uint256) public balanceOf;
  mapping (address => uint256) public freezeOf;
  mapping (address => mapping (address => uint256)) public allowance;

  /* This generates a public event on the blockchain that will notify clients */
  event Transfer(address indexed from, address indexed to, uint256 value);

  /* This notifies clients about the amount burnt */
  event Burn(address indexed from, uint256 value);
	
  /* This notifies clients about the amount frozen */
  event Freeze(address indexed from, uint256 value);
	
  /* This notifies clients about the amount unfrozen */
  event Unfreeze(address indexed from, uint256 value);

  /* Initializes contract with initial supply tokens to the creator of the contract */
  function ETHT(
    uint256 initialSupply,
    string tokenName,
    uint8 decimalUnits,
    string tokenSymbol
  ) {
    balanceOf[msg.sender] = initialSupply;              // Give the creator all initial tokens
    totalSupply = initialSupply;                        // Update total supply
    name = tokenName;                                   // Set the name for display purposes
    symbol = tokenSymbol;                               // Set the symbol for display purposes
    decimals = decimalUnits;                            // Amount of decimals for display purposes
    owner = msg.sender;
  }

  /* Send coins */
  function transfer(address _to, uint256 _value) {
    if (_to == 0x0) throw;                               // Prevent transfer to 0x0 address. Use burn() instead
    if (_value <= 0) throw; 
    if (balanceOf[msg.sender] < _value) throw;           // Check if the sender has enough
    if (balanceOf[_to] + _value < balanceOf[_to]) throw; // Check for overflows
    balanceOf[msg.sender] = SafeMath.safeSub(balanceOf[msg.sender], _value);                     // Subtract from the sender
    balanceOf[_to] = SafeMath.safeAdd(balanceOf[_to], _value);                            // Add the same to the recipient
    Transfer(msg.sender, _to, _value);                   // Notify anyone listening that this transfer took place
  }

  /* Allow another contract to spend some tokens in your behalf */
  function approve(address _spender, uint256 _value)
  returns (bool success) {
    if (_value <= 0) throw; 
    allowance[msg.sender][_spender] = _value;
    return true;
  }
       

  /* A contract attempts to get the coins */
  function transferFrom(address _from, address _to, uint256 _value) returns (bool success) {
    if (_to == 0x0) throw;                                // Prevent transfer to 0x0 address. Use burn() instead
    if (_value <= 0) throw; 
    if (balanceOf[_from] < _value) throw;                 // Check if the sender has enough
    if (balanceOf[_to] + _value < balanceOf[_to]) throw;  // Check for overflows
    if (_value > allowance[_from][msg.sender]) throw;     // Check allowance
    balanceOf[_from] = SafeMath.safeSub(balanceOf[_from], _value);                           // Subtract from the sender
    balanceOf[_to] = SafeMath.safeAdd(balanceOf[_to], _value);                             // Add the same to the recipient
    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;            // Check if the sender has enough
    if (_value <= 0) throw; 
    balanceOf[msg.sender] = SafeMath.safeSub(balanceOf[msg.sender], _value);                      // Subtract from the sender
    totalSupply = SafeMath.safeSub(totalSupply,_value);                                // Updates totalSupply
    Burn(msg.sender, _value);
    return true;
  }
	
  function freeze(uint256 _value) returns (bool success) {
    if (balanceOf[msg.sender] < _value) throw;            // Check if the sender has enough
    if (_value <= 0) throw; 
    balanceOf[msg.sender] = SafeMath.safeSub(balanceOf[msg.sender], _value);                      // Subtract from the sender
    freezeOf[msg.sender] = SafeMath.safeAdd(freezeOf[msg.sender], _value);                                // Updates totalSupply
    Freeze(msg.sender, _value);
    return true;
  }
	
  function unfreeze(uint256 _value) returns (bool success) {
    if (freezeOf[msg.sender] < _value) throw;            // Check if the sender has enough
    if (_value <= 0) throw; 
    freezeOf[msg.sender] = SafeMath.safeSub(freezeOf[msg.sender], _value);                      // Subtract from the sender
    balanceOf[msg.sender] = SafeMath.safeAdd(balanceOf[msg.sender], _value);
    Unfreeze(msg.sender, _value);
    return true;
  }
	
  // transfer balance to owner
  function withdrawEther(uint256 amount) {
    if(msg.sender != owner)throw;
    owner.transfer(amount);
  }
	
  // can accept ether
  function() payable {
  }
}