CoinGiver.sol

pragma solidity ^0.4.16;

contract Token {
    function balanceOf(address tokenOwner) public constant returns (uint balance);
    function transfer(address to, uint tokens) public returns (bool success);
}

contract CoinGiver {

    address public signerr;

    // first token, then claimer
    //mapping (address => mapping (address => bool)) rrr;
    mapping (address => mapping (address => bool)) public claimed;
    //mapping(uint => uint) mymap;
    mapping (address => mapping (address => uint256)) allowed;

    function CoinGiver() public {
        signerr = msg.sender;
    } 

    function giveCoins(bytes message, uint8 v, bytes32 r, bytes32 s) external {
        // For HDWallet, we don't need the prefix: hash = keccak256(message);
        bytes32 prefixedHash = keccak256(message);
        address realSigner = ecrecover(prefixedHash, v, r, s);
        require (realSigner == signerr);

        address tokenAddress = bytesToAddress(message, 0);
        address userAddress = bytesToAddress(message, 20); // sizeof(address)
        uint256 amount = bytesToUint256(message, 40);      // sizeof(address) * 2

        require(claimed[tokenAddress][userAddress] == false);
        Token(tokenAddress).transfer(userAddress, amount);
        claimed[tokenAddress][userAddress] = true;
    }

    function bytesToAddress(bytes _address, uint8 _offset) pure private returns (address) {
        uint160 m = 0;
        uint160 b = 0;

        for (uint8 i = 0; i < 20; i++) {
          m *= 256;
          b = uint160(_address[_offset + i]);
          m += (b);
        }
        
        return address(m);
    }

    function bytesToUint256(bytes _address, uint8 _offset) pure private returns (uint256) {
        uint256 m = 0;
        uint256 b = 0;

        for (uint8 i = 0; i < 32; i++) {
          m *= 256;
          b = uint160(_address[_offset + i]);
          m += b;
        }

        return m;
    }
}