Contract Source Code:

pragma solidity ^0.5.7;

library SafeMath {
    function add(uint256 a, uint256 b) internal pure returns (uint256 c) {
        c = a + b;
        assert(c >= a);
        return c;
    }

    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        assert(b <= a);
        return a - b;
    }

    function mul(uint256 a, uint256 b) internal pure returns (uint256 c) {
        if (a == 0) {
            return 0;
        }
        c = a * b;
        assert(c / a == b);
        return c;
    }

    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        assert(b > 0);
        uint256 c = a / b;
        assert(a == b * c + a % b);
        return a / b;
    }

    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b != 0);
        return a % b;
    }
}

interface IERC20{
    function name() external view returns (string memory);
    function symbol() external view returns (string memory);
    function decimals() external view returns (uint8);
    function totalSupply() external view returns (uint256);
    function balanceOf(address owner) external view returns (uint256);
    function transfer(address to, uint256 value) external returns (bool);
    function transferFrom(address from, address to, uint256 value) external returns (bool);
    function approve(address spender, uint256 value) external returns (bool);
    function allowance(address owner, address spender) external view returns (uint256);

    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

contract Ownable {
    address internal _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    constructor () internal {
        _owner = msg.sender;
        emit OwnershipTransferred(address(0), _owner);
    }

    function owner() public view returns (address) {
        return _owner;
    }

    modifier onlyOwner() {
        require(msg.sender == _owner);
        _;
    }

    function transferOwnership(address newOwner) external onlyOwner {
        require(newOwner != address(0));
        _owner = newOwner;
        emit OwnershipTransferred(_owner, newOwner);
    }

    function rescueTokens(address tokenAddress, address receiver, uint256 amount) external onlyOwner {
        IERC20 _token = IERC20(tokenAddress);
        require(receiver != address(0));

        uint256 balance = _token.balanceOf(address(this));

        require(balance >= amount);

        assert(_token.transfer(receiver, amount));
    }
}

contract EhdToken is Ownable, IERC20 {
    using SafeMath for uint256;

    string  private  _name     = "EthereumHD";
    string  private  _symbol   = "EHD";
    uint8   private  _decimals = 18;              // 18 decimals
    uint256 private  _cap      = 210000000000000000000000000;   // 0.21 billion
    uint256 private  _totalSupply;

    mapping (address => bool) private _minter;
    event Mint(address indexed to, uint256 value);
    event MinterChanged(address account, bool state);

    mapping (address => uint256) private _balances;
    mapping (address => mapping (address => uint256)) private _allowed;

    event Donate(address indexed account, uint256 amount);

    constructor() public {
        _minter[msg.sender] = true;
    }

    function () external payable {
        emit Donate(msg.sender, msg.value);
    }

    function name() public view returns (string memory) {
        return _name;
    }

    function symbol() public view returns (string memory) {
        return _symbol;
    }

    function decimals() public view returns (uint8) {
        return _decimals;
    }

    function cap() public view returns (uint256) {
        return _cap;
    }

    function totalSupply() public view returns (uint256) {
        return _totalSupply;
    }

    function balanceOf(address owner) public view returns (uint256) {
        return _balances[owner];
    }

    function allowance(address owner, address spender) public view returns (uint256) {
        return _allowed[owner][spender];
    }

    function transfer(address to, uint256 value) public returns (bool) {
        _transfer(msg.sender, to, value);
        return true;
    }

    function approve(address spender, uint256 value) public returns (bool) {
        _approve(msg.sender, spender, value);
        return true;
    }

    function increaseAllowance(address spender, uint256 addedValue) public returns (bool) {
        _approve(msg.sender, spender, _allowed[msg.sender][spender].add(addedValue));
        return true;
    }

    function decreaseAllowance(address spender, uint256 subtractedValue) public returns (bool) {
        _approve(msg.sender, spender, _allowed[msg.sender][spender].sub(subtractedValue));
        return true;
    }

    function transferFrom(address from, address to, uint256 value) public returns (bool) {
        _transfer(from, to, value);
        return true;
    }

    function burn(address from, uint256 value) public returns (bool) {
        _transfer(from, address(0) , value);
        return true;
    }
    
    function _transfer(address from, address to, uint256 value) internal {
        _balances[from] = _balances[from].sub(value);
        _balances[to]   = _balances[to].add(value);
        emit Transfer(from, to, value);
    }

    function _approve(address owner, address spender, uint256 value) internal {
        require(owner   != address(0));
        require(spender != address(0));

        _allowed[owner][spender] = value;
        emit Approval(owner, spender, value);
    }

    modifier onlyMinter() {
        require(_minter[msg.sender]);
        _;
    }

    function isMinter(address account) public view returns (bool) {
        return _minter[account];
    }

    function setMinterState(address account, bool state) external onlyOwner {
        _minter[account] = state;
        emit MinterChanged(account, state);
    }

    function mint(address to, uint256 value) public onlyMinter returns (bool) {
        _mint(to, value);
        return true;
    }

    function _mint(address account, uint256 value) internal {
        require(_totalSupply.add(value) <= _cap);
        require(account != address(0));

        _totalSupply       = _totalSupply.add(value);
        _balances[account] = _balances[account].add(value);

        emit Mint(account, value);
        emit Transfer(address(0), account, value);
    }
}