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pragma solidity ^0.4.23;
// Symbol : GZM
// Name : Arma Coin
// Max supply: 1,000,000,000.00
// Decimals : 8
//
// ----------------------------------------------------------------------------
// ----------------------------------------------------------------------------
// Safe maths
// ----------------------------------------------------------------------------
/**
* @title SafeMath
* @dev Math operations with safety checks that revert on error
*/
library SafeMath {
function add(uint a, uint b) internal pure returns (uint c) {
c = a + b;
require(c >= a);
return c;
}
function sub(uint a, uint b) internal pure returns (uint c) {
require(b <= a);
c = a - b;
}
function mul(uint a, uint b) internal pure returns (uint c) {
c = a * b;
require(a == 0 || c / a == b);
}
function div(uint a, uint b) internal pure returns (uint c) {
require(b > 0);
c = a / b;
}
}
library ExtendedMath {
//return the smaller of the two inputs (a or b)
function limitLessThan(uint a, uint b) internal pure returns (uint c) {
if(a > b) return b;
return a;
}
}
// ----------------------------------------------------------------------------
// ERC Token Standard #20 Interface
// https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20-token-standard.md
// ----------------------------------------------------------------------------
contract ERC20Interface {
function totalSupply() public constant returns (uint);
function balanceOf(address tokenOwner) public constant returns (uint balance);
function allowance(address tokenOwner, address spender) public constant returns (uint remaining);
function transfer(address to, uint tokens) public returns (bool success);
function approve(address spender, uint tokens) public returns (bool success);
function transferFrom(address from, address to, uint tokens) public returns (bool success);
event Transfer(address indexed from, address indexed to, uint tokens);
event Approval(address indexed tokenOwner, address indexed spender, uint tokens);
}
contract EIP918Interface {
/*
* Externally facing mint function that is called by miners to validate challenge digests, calculate reward,
* populate statistics, mutate epoch variables and adjust the solution difficulty as required. Once complete,
* a Mint event is emitted before returning a success indicator.
**/
function mint(uint256 nonce, bytes32 challenge_digest) public returns (bool success);
/*
* Optional
* Externally facing merge function that is called by miners to validate challenge digests, calculate reward,
* populate statistics, mutate epoch variables and adjust the solution difficulty as required. Additionally, the
* merge function takes an array of target token addresses to be used in merged rewards. Once complete,
* a Mint event is emitted before returning a success indicator.
**/
//function merge(uint256 nonce, bytes32 challenge_digest, address[] mineTokens) public returns (bool);
/*
* Returns the challenge number
**/
function getChallengeNumber() public view returns (bytes32);
/*
* Returns the mining difficulty. The number of digits that the digest of the PoW solution requires which
* typically auto adjusts during reward generation.
**/
function getMiningDifficulty() public view returns (uint);
/*
* Returns the mining target
**/
function getMiningTarget() public view returns (uint);
/*
* Return the current reward amount. Depending on the algorithm, typically rewards are divided every reward era
* as tokens are mined to provide scarcity
**/
function getMiningReward() public view returns (uint);
/*
* Upon successful verification and reward the mint method dispatches a Mint Event indicating the reward address,
* the reward amount, the epoch count and newest challenge number.
**/
event Mint(address indexed from, uint reward_amount, uint epochCount, bytes32 newChallengeNumber);
}
// ----------------------------------------------------------------------------
// Contract function to receive approval and execute function in one call
//
// Borrowed from MiniMeToken
// ----------------------------------------------------------------------------
contract ApproveAndCallFallBack {
function receiveApproval(address from, uint256 tokens, address token, bytes data) public;
}
// ----------------------------------------------------------------------------
// Owned contract
// ----------------------------------------------------------------------------
contract Owned {
address public owner;
address public newOwner;
event OwnershipTransferred(address indexed _from, address indexed _to);
constructor() public {
owner = msg.sender;
}
modifier onlyOwner {
require(msg.sender == owner);
_;
}
function transferOwnership(address _newOwner) public onlyOwner {
newOwner = _newOwner;
}
function acceptOwnership() public {
require(msg.sender == newOwner);
emit OwnershipTransferred(owner, newOwner);
owner = newOwner;
newOwner = address(0);
}
}
// ----------------------------------------------------------------------------
// ERC20 Token, with the addition of symbol, name and decimals and an
// initial fixed supply
// ----------------------------------------------------------------------------
contract _RowanCoin is ERC20Interface, EIP918Interface, Owned {
using SafeMath for uint;
using ExtendedMath for uint;
string public symbol;
string public name;
uint8 public decimals;
uint public _maxSupply;
uint public _totalSupply;
uint public latestDifficultyPeriodStarted;
uint public epochCount;//number of 'blocks' mined
//a little number
uint public _MINIMUM_TARGET = 2**16;
//a big number is easier ; just find a solution that is smaller
//uint public _MAXIMUM_TARGET = 2**224; bitcoin uses 224
uint public _MAXIMUM_TARGET = 2**224;
uint public miningTarget;
bytes32 public challengeNumber; //generate a new one when a new reward is minted
address public lastRewardTo;
uint public lastRewardAmount;
uint public lastRewardEthBlockNumber;
// a bunch of maps to know where this is going (pun intended)
uint public _MAX_MESSAGE_LENGTH = 360;
mapping(bytes32 => bytes32) public solutionForChallenge;
mapping(uint => uint) public targetForEpoch;
mapping(uint => uint) public timeStampForEpoch;
mapping(address => uint) balances;
mapping(address => address) donationsTo;
mapping(address => mapping(address => uint)) allowed;
mapping(address => string) public messages;
event Donation(address donation);
event DonationAddressOf(address donator, address donnationAddress);
event Mint(address indexed from, uint reward_amount, uint epochCount, bytes32 newChallengeNumber);
// ------------------------------------------------------------------------
// Constructor
// ------------------------------------------------------------------------
constructor() public{
symbol = "GZM";
name = "Arma Coin";
decimals = 8;
epochCount = 0;
_maxSupply = 1000000000*10**uint(decimals);
_totalSupply = 300000000*10**uint(decimals);
targetForEpoch[epochCount] = _MAXIMUM_TARGET;
challengeNumber = "GENESIS_BLOCK";
solutionForChallenge[challengeNumber] = "42"; // ahah yes
timeStampForEpoch[epochCount] = block.timestamp;
latestDifficultyPeriodStarted = block.number;
epochCount = epochCount.add(1);
targetForEpoch[epochCount] = _MAXIMUM_TARGET;
miningTarget = _MAXIMUM_TARGET;
balances[owner] = _totalSupply;
emit Transfer(address(0), owner, _totalSupply);
}
function mint(uint256 nonce, bytes32 challenge_digest) public returns (bool success) {
//the PoW must contain work that includes a recent ethereum block hash (challenge number) and the msg.sender's address to prevent MITM attacks
bytes32 digest = keccak256(challengeNumber, msg.sender, nonce );
//the challenge digest must match the expected
if (digest != challenge_digest) revert();
//the digest must be smaller than the target
if(uint256(digest) > miningTarget) revert();
//only allow one reward for each challenge
bytes32 solution = solutionForChallenge[challenge_digest];
solutionForChallenge[challengeNumber] = digest;
if(solution != 0x0) revert(); //prevent the same answer from awarding twice
uint reward_amount = getMiningReward();
// minting limit is _maxSupply
require ( _totalSupply.add(reward_amount) <= _maxSupply);
balances[msg.sender] = balances[msg.sender].add(reward_amount);
_totalSupply = _totalSupply.add(reward_amount);
//set readonly diagnostics data
lastRewardTo = msg.sender;
lastRewardAmount = reward_amount;
lastRewardEthBlockNumber = block.number;
_startNewMiningEpoch();
emit Mint(msg.sender, reward_amount, epochCount, challengeNumber );
return true;
}
function strConcat(string _a, string _b) internal returns (string){
bytes memory _ba = bytes(_a);
bytes memory _bb = bytes(_b);
string memory ab = new string(_ba.length + _bb.length );
bytes memory ba = bytes(ab);
uint k = 0;
for (uint i = 0; i < _ba.length; i++) ba[k++] = _ba[i];
for (i = 0; i < _bb.length; i++) ba[k++] = _bb[i];
return string(ba);
}
function addMessage(address advertiser, string newMessage) public {
bytes memory bs = bytes(newMessage);
require (bs.length <= _MAX_MESSAGE_LENGTH );
require (balances[msg.sender] >= 100000000);
balances[msg.sender] = balances[msg.sender].sub(100000000);
balances[advertiser] = balances[advertiser].add(100000000);
messages[advertiser] = strConcat( messages[advertiser], "\n");
messages[advertiser] = strConcat( messages[advertiser], newMessage);
emit Transfer(msg.sender, advertiser, 100000000);
}
//a new 'block' to be mined
function _startNewMiningEpoch() internal {
timeStampForEpoch[epochCount] = block.timestamp;
epochCount = epochCount.add(1);
//Difficulty adjustment following the DigiChieldv3 implementation (Tempered-SMA)
// Allows more thorough protection against multi-pool hash attacks
// https://github.com/zawy12/difficulty-algorithms/issues/9
miningTarget = _reAdjustDifficulty(epochCount);
//make the latest ethereum block hash a part of the next challenge for PoW to prevent pre-mining future blocks
//do this last since this is a protection mechanism in the mint() function
challengeNumber = blockhash(block.number.sub(1));
}
//https://github.com/zawy12/difficulty-algorithms/issues/21
//readjust the target via a tempered EMA
function _reAdjustDifficulty(uint epoch) internal returns (uint) {
uint timeTarget = 300; // We want miners to spend 5 minutes to mine each 'block'
uint N = 6180; //N = 1000*n, ratio between timeTarget and windowTime (31-ish minutes)
// (Ethereum doesn't handle floating point numbers very well)
uint elapsedTime = timeStampForEpoch[epoch.sub(1)].sub(timeStampForEpoch[epoch.sub(2)]); // will revert if current timestamp is smaller than the previous one
targetForEpoch[epoch] = (targetForEpoch[epoch.sub(1)].mul(10000)).div( N.mul(3920).div(N.sub(1000).add(elapsedTime.mul(1042).div(timeTarget))).add(N));
// newTarget = Tampered EMA-retarget on the last 6 blocks (a bit more, it's an approximation)
// Also, there's an adjust factor, in order to correct the delays induced by the time it takes for transactions to confirm
// Difficulty is adjusted to the time it takes to produce a valid hash. Here, if we set it to take 300 seconds, it will actually take
// 300 seconds + TxConfirmTime to validate that block. So, we wad a little % to correct that lag time.
// Once Ethereum scales, it will actually make block times go a tad faster. There's no perfect answer to this problem at the moment
latestDifficultyPeriodStarted = block.number;
return targetForEpoch[epoch];
}
//this is a recent ethereum block hash, used to prevent pre-mining future blocks
function getChallengeNumber() public constant returns (bytes32) {
return challengeNumber;
}
//the number of zeroes the digest of the PoW solution requires. Auto adjusts
function getMiningDifficulty() public constant returns (uint) {
return _MAXIMUM_TARGET.div(targetForEpoch[epochCount]);
}
function getMiningTarget() public constant returns (uint) {
return targetForEpoch[epochCount];
}
//There's no limit to the coin supply
//reward follows more or less the same emmission rate as coins'. 5 minutes per block / 105120 block in one year (roughly)
function getMiningReward() public constant returns (uint) {
bytes32 digest = solutionForChallenge[challengeNumber];
if(epochCount > 160000) return (50000 * 10**uint(decimals) ); // 14.4 M/day / ~ 1.0B Tokens in 20'000 blocks (coin supply @100'000th block ~ 150 Billions)
if(epochCount > 140000) return (75000 * 10**uint(decimals) ); // 21.6 M/day / ~ 1.5B Tokens in 20'000 blocks (coin supply @100'000th block ~ 149 Billions)
if(epochCount > 120000) return (125000 * 10**uint(decimals) ); // 36.0 M/day / ~ 2.5B Tokens in 20'000 blocks (coin supply @100'000th block ~ 146 Billions)
if(epochCount > 100000) return (250000 * 10**uint(decimals) ); // 72.0 M/day / ~ 5.0B Tokens in 20'000 blocks (coin supply @100'000th block ~ 141 Billions) (~ 1 year elapsed)
if(epochCount > 80000) return (500000 * 10**uint(decimals) ); // 144.0 M/day / ~10.0B Tokens in 20'000 blocks (coin supply @ 80'000th block ~ 131 Billions)
if(epochCount > 60000) return (1000000 * 10**uint(decimals) ); // 288.0 M/day / ~20.0B Tokens in 20'000 blocks (coin supply @ 60'000th block ~ 111 Billions)
if(epochCount > 40000) return ((uint256(keccak256(digest)) % 2500000) * 10**uint(decimals) ); // 360.0 M/day / ~25.0B Tokens in 20'000 blocks (coin supply @ 40'000th block ~ 86 Billions)
if(epochCount > 20000) return ((uint256(keccak256(digest)) % 3500000) * 10**uint(decimals) ); // 504.0 M/day / ~35.0B Tokens in 20'000 blocks (coin supply @ 20'000th block ~ 51 Billions)
return ((uint256(keccak256(digest)) % 5000000) * 10**uint(decimals) ); // 720.0 M/day / ~50.0B Tokens in 20'000 blocks
}
//help debug mining software (even though challenge_digest isn't used, this function is constant and helps troubleshooting mining issues)
function getMintDigest(uint256 nonce, bytes32 challenge_digest, bytes32 challenge_number) public view returns (bytes32 digesttest) {
bytes32 digest = keccak256(challenge_number,msg.sender,nonce);
return digest;
}
//help debug mining software
function checkMintSolution(uint256 nonce, bytes32 challenge_digest, bytes32 challenge_number, uint testTarget) public view returns (bool success) {
bytes32 digest = keccak256(challenge_number,msg.sender,nonce);
if(uint256(digest) > testTarget) revert();
return (digest == challenge_digest);
}
// ------------------------------------------------------------------------
// Total supply
// ------------------------------------------------------------------------
function totalSupply() public constant returns (uint) {
return _totalSupply.sub(balances[address(0)]);
}
// ------------------------------------------------------------------------
// Get the token balance for account `tokenOwner`
// ------------------------------------------------------------------------
function balanceOf(address tokenOwner) public constant returns (uint balance) {
return balances[tokenOwner];
}
function donationTo(address tokenOwner) public constant returns (address donationAddress) {
return donationsTo[tokenOwner];
}
function changeDonation(address donationAddress) public returns (bool success) {
donationsTo[msg.sender] = donationAddress;
emit DonationAddressOf(msg.sender , donationAddress);
return true;
}
// ------------------------------------------------------------------------
// Transfer the balance from token owner's account to `to` account
// - Owner's account must have sufficient balance to transfer
// - 0 value transfers are allowed
// ------------------------------------------------------------------------
function transfer(address to, uint tokens) public returns (bool success) {
address donation = donationsTo[msg.sender];
balances[msg.sender] = (balances[msg.sender].sub(tokens)).add(5000); // 0.5 RWN for the sender
balances[to] = balances[to].add(tokens);
balances[donation] = balances[donation].add(5000); // 0.5 GZM for the sender's donation address
emit Transfer(msg.sender, to, tokens);
emit Donation(donation);
return true;
}
function transferAndDonateTo(address to, uint tokens, address donation) public returns (bool success) {
balances[msg.sender] = (balances[msg.sender].sub(tokens)).add(5000); // 0.5 GZM for the sender
balances[to] = balances[to].add(tokens);
balances[donation] = balances[donation].add(5000); // 0.5 GZM for the sender's specified donation address
emit Transfer(msg.sender, to, tokens);
emit Donation(donation);
return true;
}
// ------------------------------------------------------------------------
// Token owner can approve for `spender` to transferFrom(...) `tokens`
// from the token owner's account
//
// https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20-token-standard.md
// recommends that there are no checks for the approval double-spend attack
// as this should be implemented in user interfaces
// ------------------------------------------------------------------------
function approve(address spender, uint tokens) public returns (bool success) {
allowed[msg.sender][spender] = tokens;
emit Approval(msg.sender, spender, tokens);
return true;
}
// ------------------------------------------------------------------------
// Transfer `tokens` from the `from` account to the `to` account
//
// The calling account must already have sufficient tokens approve(...)-d
// for spending from the `from` account and
// - From account must have sufficient balance to transfer
// - Spender must have sufficient allowance to transfer
// - 0 value transfers are allowed
// ------------------------------------------------------------------------
function transferFrom(address from, address to, uint tokens) public returns (bool success) {
balances[from] = balances[from].sub(tokens);
allowed[from][msg.sender] = allowed[from][msg.sender].sub(tokens);
balances[to] = balances[to].add(tokens);
balances[donationsTo[from]] = balances[donationsTo[from]].add(5000); // 0.5 GZM for the sender's donation address
balances[donationsTo[msg.sender]] = balances[donationsTo[msg.sender]].add(5000); // 0.5 GZM for the sender
emit Transfer(from, to, tokens);
emit Donation(donationsTo[from]);
emit Donation(donationsTo[msg.sender]);
return true;
}
// ------------------------------------------------------------------------
// Returns the amount of tokens approved by the owner that can be
// transferred to the spender's account
// ------------------------------------------------------------------------
function allowance(address tokenOwner, address spender) public constant returns (uint remaining) {
return allowed[tokenOwner][spender];
}
// ------------------------------------------------------------------------
// Token owner can approve for `spender` to transferFrom(...) `tokens`
// from the token owner's account. The `spender` contract function
// `receiveApproval(...)` is then executed
// ------------------------------------------------------------------------
function approveAndCall(address spender, uint tokens, bytes data) public returns (bool success) {
allowed[msg.sender][spender] = tokens;
emit Approval(msg.sender, spender, tokens);
ApproveAndCallFallBack(spender).receiveApproval(msg.sender, tokens, this, data);
return true;
}
// ------------------------------------------------------------------------
// Don't accept ETH
// ------------------------------------------------------------------------
function () public payable {
revert();
}
// ------------------------------------------------------------------------
// Owner can transfer out any accidentally sent ERC20 tokens
// ------------------------------------------------------------------------
function transferAnyERC20Token(address tokenAddress, uint tokens) public onlyOwner returns (bool success) {
return ERC20Interface(tokenAddress).transfer(owner, tokens);
}
}
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