Contract Name:
CryptoSurge
Contract Source Code:
File 1 of 1 : CryptoSurge
pragma solidity ^0.4.21;
/**Decentralized
Immutable & Unstoppable Ethereum Staking Smart Contract. THE NEXT BIG THING!
* Definition of contract accepting CST tokens
* Games, casinos, anything can reuse this contract to support CST tokens
*/
contract AcceptsCryptoSurge {
CryptoSurge public tokenContract;
function AcceptsCryptoSurg(address _tokenContract) public {
tokenContract = CryptoSurge(_tokenContract);
}
modifier onlyTokenContract {
require(msg.sender == address(tokenContract));
_;
}
/**
* @dev Standard ERC677 function that will handle incoming token transfers.
*
* @param _from Token sender address.
* @param _value Amount of tokens.
* @param _data Transaction metadata.
*/
function tokenFallback(address _from, uint256 _value, bytes _data) external returns (bool);
}
contract CryptoSurge {
/*=================================
= MODIFIERS =
=================================*/
// only people with tokens
modifier onlyBagholders() {
require(myTokens() > 0);
_;
}
// only people with profits
modifier onlyStronghands() {
require(myDividends(true) > 0);
_;
}
modifier notContract() {
require (msg.sender == tx.origin);
_;
}
// administrators can:
// -> change the name of the contract
// -> change the name of the token
// -> change the PoS difficulty (How many tokens it costs to hold a masternode, in case it gets crazy high later)
// they CANNOT:
// -> take funds
// -> disable withdrawals
// -> kill the contract
// -> change the price of tokens
modifier onlyAdministrator(){
address _customerAddress = msg.sender;
require(administrators[_customerAddress]);
_;
}
uint ACTIVATION_TIME = 1537743500;
// ensures that the first tokens in the contract will be equally distributed
// meaning, no divine dump will be ever possible
// result: healthy longevity.
modifier antiEarlyWhale(uint256 _amountOfEthereum){
address _customerAddress = msg.sender;
if (now >= ACTIVATION_TIME) {
onlyAmbassadors = false;
}
// are we still in the vulnerable phase?
// if so, enact anti early whale protocol
if( onlyAmbassadors && ((totalEthereumBalance() - _amountOfEthereum) <= ambassadorQuota_ )){
require(
// is the customer in the ambassador list?
ambassadors_[_customerAddress] == true &&
// does the customer purchase exceed the max ambassador quota?
(ambassadorAccumulatedQuota_[_customerAddress] + _amountOfEthereum) <= ambassadorMaxPurchase_
);
// updated the accumulated quota
ambassadorAccumulatedQuota_[_customerAddress] = SafeMath.add(ambassadorAccumulatedQuota_[_customerAddress], _amountOfEthereum);
// execute
_;
} else {
// in case the ether count drops low, the ambassador phase won't reinitiate
onlyAmbassadors = false;
_;
}
}
/*==============================
= EVENTS =
==============================*/
event onTokenPurchase(
address indexed customerAddress,
uint256 incomingEthereum,
uint256 tokensMinted,
address indexed referredBy
);
event onTokenSell(
address indexed customerAddress,
uint256 tokensBurned,
uint256 ethereumEarned
);
event onReinvestment(
address indexed customerAddress,
uint256 ethereumReinvested,
uint256 tokensMinted
);
event onWithdraw(
address indexed customerAddress,
uint256 ethereumWithdrawn
);
// ERC20
event Transfer(
address indexed from,
address indexed to,
uint256 tokens
);
/*=====================================
= CONFIGURABLES =
=====================================*/
string public name = "CRYPTO SURGE";
string public symbol = "CST";
uint8 constant public decimals = 18;
uint8 constant internal dividendFee_ = 15; // 10% dividend fee on each buy and sell
uint8 constant internal fundFee_ = 10; // 10% investment fund fee on each buy and sell (FUND CRYPTO GAMES)
uint256 constant internal tokenPriceInitial_ = 0.0000001 ether;
uint256 constant internal tokenPriceIncremental_ = 0.00000001 ether;
uint256 constant internal magnitude = 2**64;
// Address to send
// crypto games Fund
address constant public giveEthFundAddress = 0x64Ac3D88DFEbf351A49ae34EF52009da5F4EeFbd;
uint256 public totalEthFundRecieved; //
uint256 public totalEthFundCollected; //
// proof of stake (defaults at 100 tokens)
uint256 public stakingRequirement = 25e18;
// ambassador program
mapping(address => bool) internal ambassadors_;
uint256 constant internal ambassadorMaxPurchase_ = 1 ether;
uint256 constant internal ambassadorQuota_ = 2 ether;
/*================================
= DATASETS =
================================*/
// amount of shares for each address (scaled number)
mapping(address => uint256) internal tokenBalanceLedger_;
mapping(address => uint256) internal referralBalance_;
mapping(address => int256) internal payoutsTo_;
mapping(address => uint256) internal ambassadorAccumulatedQuota_;
uint256 internal tokenSupply_ = 0;
uint256 internal profitPerShare_;
// administrator list (see above on what they can do)
mapping(address => bool) public administrators;
// when this is set to true, only ambassadors can purchase tokens (this prevents a whale premine, it ensures a fairly distributed upper pyramid)
bool public onlyAmbassadors = false;
mapping(address => bool) public canAcceptTokens_;
mapping(address => address) public stickyRef;
/*=======================================
= PUBLIC FUNCTIONS =
=======================================*/
/*
* -- APPLICATION ENTRY POINTS --
*/
function CryptoSurge()
public
{
// add administrators here
administrators[0xC5676f1EE6421A0458cC1F955a5e0100adEb01D3] = true;
// add the ambassadors here - Tokens will be distributed to these addresses from main premine
ambassadors_[0x0000000000000000000000000000000000000000] = true;
}
/**
* Converts all incoming ethereum to tokens for the caller, and passes down the referral addy (if any)
*/
function buy(address _referredBy)
public
payable
returns(uint256)
{
require(tx.gasprice <= 0.05 szabo);
purchaseTokens(msg.value, _referredBy);
}
/**
* Fallback function to handle ethereum that was send straight to the contract
* Unfortunately we cannot use a referral address this way.
*/
function()
public
payable
{
}
/**
* Sends FUND money to the 70/30 Contract
*/
function payFund() payable public {
uint256 ethToPay = SafeMath.sub(totalEthFundCollected, totalEthFundRecieved);
require(ethToPay > 1);
totalEthFundRecieved = SafeMath.add(totalEthFundRecieved, ethToPay);
if(!giveEthFundAddress.call.value(ethToPay).gas(400000)()) {
totalEthFundRecieved = SafeMath.sub(totalEthFundRecieved, ethToPay);
}
}
/**
* Converts all of caller's dividends to tokens.
*/
function reinvest()
onlyStronghands()
public
{
// fetch dividends
uint256 _dividends = myDividends(false); // retrieve ref. bonus later in the code
// pay out the dividends virtually
address _customerAddress = msg.sender;
payoutsTo_[_customerAddress] += (int256) (_dividends * magnitude);
// retrieve ref. bonus
_dividends += referralBalance_[_customerAddress];
referralBalance_[_customerAddress] = 0;
// dispatch a buy order with the virtualized "withdrawn dividends"
uint256 _tokens = purchaseTokens(_dividends, 0x0);
// fire event
onReinvestment(_customerAddress, _dividends, _tokens);
}
/**
* Alias of sell() and withdraw().
*/
function exit()
public
{
// get token count for caller & sell them all
address _customerAddress = msg.sender;
uint256 _tokens = tokenBalanceLedger_[_customerAddress];
if(_tokens > 0) sell(_tokens);
// lambo delivery service
withdraw();
}
/**
* Withdraws all of the callers earnings.
*/
function withdraw()
onlyStronghands()
public
{
// setup data
address _customerAddress = msg.sender;
uint256 _dividends = myDividends(false); // get ref. bonus later in the code
// update dividend tracker
payoutsTo_[_customerAddress] += (int256) (_dividends * magnitude);
// add ref. bonus
_dividends += referralBalance_[_customerAddress];
referralBalance_[_customerAddress] = 0;
// lambo delivery service
_customerAddress.transfer(_dividends);
// fire event
onWithdraw(_customerAddress, _dividends);
}
/**
* Liquifies tokens to ethereum.
*/
function sell(uint256 _amountOfTokens)
onlyBagholders()
public
{
// setup data
address _customerAddress = msg.sender;
// russian hackers BTFO
require(_amountOfTokens <= tokenBalanceLedger_[_customerAddress]);
uint256 _tokens = _amountOfTokens;
uint256 _ethereum = tokensToEthereum_(_tokens);
uint256 _dividends = SafeMath.div(SafeMath.mul(_ethereum, dividendFee_), 100);
uint256 _fundPayout = SafeMath.div(SafeMath.mul(_ethereum, fundFee_), 100);
uint256 _refPayout = _dividends / 3;
_dividends = SafeMath.sub(_dividends, _refPayout);
(_dividends,) = handleRef(stickyRef[msg.sender], _refPayout, _dividends, 0);
// Take out dividends and then _fundPayout
uint256 _taxedEthereum = SafeMath.sub(SafeMath.sub(_ethereum, _dividends), _fundPayout);
// Add ethereum to send to fund
totalEthFundCollected = SafeMath.add(totalEthFundCollected, _fundPayout);
// burn the sold tokens
tokenSupply_ = SafeMath.sub(tokenSupply_, _tokens);
tokenBalanceLedger_[_customerAddress] = SafeMath.sub(tokenBalanceLedger_[_customerAddress], _tokens);
// update dividends tracker
int256 _updatedPayouts = (int256) (profitPerShare_ * _tokens + (_taxedEthereum * magnitude));
payoutsTo_[_customerAddress] -= _updatedPayouts;
// dividing by zero is a bad idea
if (tokenSupply_ > 0) {
// update the amount of dividends per token
profitPerShare_ = SafeMath.add(profitPerShare_, (_dividends * magnitude) / tokenSupply_);
}
// fire event
onTokenSell(_customerAddress, _tokens, _taxedEthereum);
}
/**
* Transfer tokens from the caller to a new holder.
* REMEMBER THIS IS 0% TRANSFER FEE
*/
function transfer(address _toAddress, uint256 _amountOfTokens)
onlyBagholders()
public
returns(bool)
{
// setup
address _customerAddress = msg.sender;
// make sure we have the requested tokens
// also disables transfers until ambassador phase is over
// ( we dont want whale premines )
require(_amountOfTokens <= tokenBalanceLedger_[_customerAddress]);
// withdraw all outstanding dividends first
if(myDividends(true) > 0) withdraw();
// exchange tokens
tokenBalanceLedger_[_customerAddress] = SafeMath.sub(tokenBalanceLedger_[_customerAddress], _amountOfTokens);
tokenBalanceLedger_[_toAddress] = SafeMath.add(tokenBalanceLedger_[_toAddress], _amountOfTokens);
// update dividend trackers
payoutsTo_[_customerAddress] -= (int256) (profitPerShare_ * _amountOfTokens);
payoutsTo_[_toAddress] += (int256) (profitPerShare_ * _amountOfTokens);
// fire event
Transfer(_customerAddress, _toAddress, _amountOfTokens);
// ERC20
return true;
}
/**
* Transfer token to a specified address and forward the data to recipient
* ERC-677 standard
* https://github.com/ethereum/EIPs/issues/677
* @param _to Receiver address.
* @param _value Amount of tokens that will be transferred.
* @param _data Transaction metadata.
*/
function transferAndCall(address _to, uint256 _value, bytes _data) external returns (bool) {
require(_to != address(0));
require(canAcceptTokens_[_to] == true); // security check that contract approved by CST platform
require(transfer(_to, _value)); // do a normal token transfer to the contract
if (isContract(_to)) {
AcceptsCryptoSurge receiver = AcceptsCryptoSurge(_to);
require(receiver.tokenFallback(msg.sender, _value, _data));
}
return true;
}
/**
* Additional check that the game address we are sending tokens to is a contract
* assemble the given address bytecode. If bytecode exists then the _addr is a contract.
*/
function isContract(address _addr) private constant returns (bool is_contract) {
// retrieve the size of the code on target address, this needs assembly
uint length;
assembly { length := extcodesize(_addr) }
return length > 0;
}
/*---------- ADMINISTRATOR ONLY FUNCTIONS ----------*/
/**
* In case the amassador quota is not met, the administrator can manually disable the ambassador phase.
*/
//function disableInitialStage()
// onlyAdministrator()
// public
//{
// onlyAmbassadors = false;
//}
/**
* In case one of us dies, we need to replace ourselves.
*/
function setAdministrator(address _identifier, bool _status)
onlyAdministrator()
public
{
administrators[_identifier] = _status;
}
/**
* Precautionary measures in case we need to adjust the masternode rate.
*/
function setStakingRequirement(uint256 _amountOfTokens)
onlyAdministrator()
public
{
stakingRequirement = _amountOfTokens;
}
/**
* Add or remove game contract, which can accept Crypto Surge Tokens tokens
*/
function setCanAcceptTokens(address _address, bool _value)
onlyAdministrator()
public
{
canAcceptTokens_[_address] = _value;
}
/**
* If we want to rebrand, we can.
*/
function setName(string _name)
onlyAdministrator()
public
{
name = _name;
}
/**
* If we want to rebrand, we can.
*/
function setSymbol(string _symbol)
onlyAdministrator()
public
{
symbol = _symbol;
}
/*---------- HELPERS AND CALCULATORS ----------*/
/**
* Method to view the current Ethereum stored in the contract
* Example: totalEthereumBalance()
*/
function totalEthereumBalance()
public
view
returns(uint)
{
return this.balance;
}
/**
* Retrieve the total token supply.
*/
function totalSupply()
public
view
returns(uint256)
{
return tokenSupply_;
}
/**
* Retrieve the tokens owned by the caller.
*/
function myTokens()
public
view
returns(uint256)
{
address _customerAddress = msg.sender;
return balanceOf(_customerAddress);
}
/**
* Retrieve the dividends owned by the caller.
* If `_includeReferralBonus` is to to 1/true, the referral bonus will be included in the calculations.
* The reason for this, is that in the frontend, we will want to get the total divs (global + ref)
* But in the internal calculations, we want them separate.
*/
function myDividends(bool _includeReferralBonus)
public
view
returns(uint256)
{
address _customerAddress = msg.sender;
return _includeReferralBonus ? dividendsOf(_customerAddress) + referralBalance_[_customerAddress] : dividendsOf(_customerAddress) ;
}
/**
* Retrieve the token balance of any single address.
*/
function balanceOf(address _customerAddress)
view
public
returns(uint256)
{
return tokenBalanceLedger_[_customerAddress];
}
/**
* Retrieve the dividend balance of any single address.
*/
function dividendsOf(address _customerAddress)
view
public
returns(uint256)
{
return (uint256) ((int256)(profitPerShare_ * tokenBalanceLedger_[_customerAddress]) - payoutsTo_[_customerAddress]) / magnitude;
}
/**
* Return the buy price of 1 individual token.
*/
function sellPrice()
public
view
returns(uint256)
{
// our calculation relies on the token supply, so we need supply. Doh.
if(tokenSupply_ == 0){
return tokenPriceInitial_ - tokenPriceIncremental_;
} else {
uint256 _ethereum = tokensToEthereum_(1e18);
uint256 _dividends = SafeMath.div(SafeMath.mul(_ethereum, dividendFee_), 100);
uint256 _fundPayout = SafeMath.div(SafeMath.mul(_ethereum, fundFee_), 100);
uint256 _taxedEthereum = SafeMath.sub(SafeMath.sub(_ethereum, _dividends), _fundPayout);
return _taxedEthereum;
}
}
/**
* Return the sell price of 1 individual token.
*/
function buyPrice()
public
view
returns(uint256)
{
// our calculation relies on the token supply, so we need supply. Doh.
if(tokenSupply_ == 0){
return tokenPriceInitial_ + tokenPriceIncremental_;
} else {
uint256 _ethereum = tokensToEthereum_(1e18);
uint256 _dividends = SafeMath.div(SafeMath.mul(_ethereum, dividendFee_), 100);
uint256 _fundPayout = SafeMath.div(SafeMath.mul(_ethereum, fundFee_), 100);
uint256 _taxedEthereum = SafeMath.add(SafeMath.add(_ethereum, _dividends), _fundPayout);
return _taxedEthereum;
}
}
/**
* Function for the frontend to dynamically retrieve the price scaling of buy orders.
*/
function calculateTokensReceived(uint256 _ethereumToSpend)
public
view
returns(uint256)
{
uint256 _dividends = SafeMath.div(SafeMath.mul(_ethereumToSpend, dividendFee_), 100);
uint256 _fundPayout = SafeMath.div(SafeMath.mul(_ethereumToSpend, fundFee_), 100);
uint256 _taxedEthereum = SafeMath.sub(SafeMath.sub(_ethereumToSpend, _dividends), _fundPayout);
uint256 _amountOfTokens = ethereumToTokens_(_taxedEthereum);
return _amountOfTokens;
}
/**
* Function for the frontend to dynamically retrieve the price scaling of sell orders.
*/
function calculateEthereumReceived(uint256 _tokensToSell)
public
view
returns(uint256)
{
require(_tokensToSell <= tokenSupply_);
uint256 _ethereum = tokensToEthereum_(_tokensToSell);
uint256 _dividends = SafeMath.div(SafeMath.mul(_ethereum, dividendFee_), 100);
uint256 _fundPayout = SafeMath.div(SafeMath.mul(_ethereum, fundFee_), 100);
uint256 _taxedEthereum = SafeMath.sub(SafeMath.sub(_ethereum, _dividends), _fundPayout);
return _taxedEthereum;
}
/**
* Function for the frontend to show ether waiting to be send to fund in contract
*/
function etherToSendFund()
public
view
returns(uint256) {
return SafeMath.sub(totalEthFundCollected, totalEthFundRecieved);
}
/*==========================================
= INTERNAL FUNCTIONS =
==========================================*/
// Make sure we will send back excess if user sends more then 5 ether before 100 ETH in contract
function purchaseInternal(uint256 _incomingEthereum, address _referredBy)
notContract()// no contracts allowed
internal
returns(uint256) {
uint256 purchaseEthereum = _incomingEthereum;
uint256 excess;
if(purchaseEthereum > 2.5 ether) { // check if the transaction is over 2.5 ether
if (SafeMath.sub(address(this).balance, purchaseEthereum) <= 100 ether) { // if so check the contract is less then 100 ether
purchaseEthereum = 2.5 ether;
excess = SafeMath.sub(_incomingEthereum, purchaseEthereum);
}
}
purchaseTokens(purchaseEthereum, _referredBy);
if (excess > 0) {
msg.sender.transfer(excess);
}
}
function handleRef(address _ref, uint _referralBonus, uint _currentDividends, uint _currentFee) internal returns (uint, uint){
uint _dividends = _currentDividends;
uint _fee = _currentFee;
address _referredBy = stickyRef[msg.sender];
if (_referredBy == address(0x0)){
_referredBy = _ref;
}
// is the user referred by a masternode?
if(
// is this a referred purchase?
_referredBy != 0x0000000000000000000000000000000000000000 &&
// no cheating!
_referredBy != msg.sender &&
// does the referrer have at least X whole tokens?
// i.e is the referrer a godly chad masternode
tokenBalanceLedger_[_referredBy] >= stakingRequirement
){
// wealth redistribution
if (stickyRef[msg.sender] == address(0x0)){
stickyRef[msg.sender] = _referredBy;
}
referralBalance_[_referredBy] = SafeMath.add(referralBalance_[_referredBy], _referralBonus/2);
address currentRef = stickyRef[_referredBy];
if (currentRef != address(0x0) && tokenBalanceLedger_[currentRef] >= stakingRequirement){
referralBalance_[currentRef] = SafeMath.add(referralBalance_[currentRef], (_referralBonus/10)*3);
currentRef = stickyRef[currentRef];
if (currentRef != address(0x0) && tokenBalanceLedger_[currentRef] >= stakingRequirement){
referralBalance_[currentRef] = SafeMath.add(referralBalance_[currentRef], (_referralBonus/10)*2);
}
else{
_dividends = SafeMath.add(_dividends, _referralBonus - _referralBonus/2 - (_referralBonus/10)*3);
_fee = _dividends * magnitude;
}
}
else{
_dividends = SafeMath.add(_dividends, _referralBonus - _referralBonus/2);
_fee = _dividends * magnitude;
}
} else {
// no ref purchase
// add the referral bonus back to the global dividends cake
_dividends = SafeMath.add(_dividends, _referralBonus);
_fee = _dividends * magnitude;
}
return (_dividends, _fee);
}
function purchaseTokens(uint256 _incomingEthereum, address _referredBy)
antiEarlyWhale(_incomingEthereum)
internal
returns(uint256)
{
// data setup
uint256 _undividedDividends = SafeMath.div(SafeMath.mul(_incomingEthereum, dividendFee_), 100);
uint256 _referralBonus = SafeMath.div(_undividedDividends, 3);
uint256 _fundPayout = SafeMath.div(SafeMath.mul(_incomingEthereum, fundFee_), 100);
uint256 _dividends = SafeMath.sub(_undividedDividends, _referralBonus);
uint256 _fee;
(_dividends, _fee) = handleRef(_referredBy, _referralBonus, _dividends, _fee);
uint256 _taxedEthereum = SafeMath.sub(SafeMath.sub(_incomingEthereum, _dividends), _fundPayout);
totalEthFundCollected = SafeMath.add(totalEthFundCollected, _fundPayout);
uint256 _amountOfTokens = ethereumToTokens_(_taxedEthereum);
// no point in continuing execution if OP is a poorfag russian hacker
// prevents overflow in the case that the pyramid somehow magically starts being used by everyone in the world
// (or hackers)
// and yes we know that the safemath function automatically rules out the "greater then" equasion.
require(_amountOfTokens > 0 && (SafeMath.add(_amountOfTokens,tokenSupply_) > tokenSupply_));
// we can't give people infinite ethereum
if(tokenSupply_ > 0){
// add tokens to the pool
tokenSupply_ = SafeMath.add(tokenSupply_, _amountOfTokens);
// take the amount of dividends gained through this transaction, and allocates them evenly to each shareholder
profitPerShare_ += (_dividends * magnitude / (tokenSupply_));
// calculate the amount of tokens the customer receives over his purchase
_fee = _fee - (_fee-(_amountOfTokens * (_dividends * magnitude / (tokenSupply_))));
} else {
// add tokens to the pool
tokenSupply_ = _amountOfTokens;
}
// update circulating supply & the ledger address for the customer
tokenBalanceLedger_[msg.sender] = SafeMath.add(tokenBalanceLedger_[msg.sender], _amountOfTokens);
// Tells the contract that the buyer doesn't deserve dividends for the tokens before they owned them;
//really i know you think you do but you don't
int256 _updatedPayouts = (int256) ((profitPerShare_ * _amountOfTokens) - _fee);
payoutsTo_[msg.sender] += _updatedPayouts;
// fire event
onTokenPurchase(msg.sender, _incomingEthereum, _amountOfTokens, _referredBy);
return _amountOfTokens;
}
/**
* Calculate Token price based on an amount of incoming ethereum
* It's an algorithm, hopefully we gave you the whitepaper with it in scientific notation;
* Some conversions occurred to prevent decimal errors or underflows / overflows in solidity code.
*/
function ethereumToTokens_(uint256 _ethereum)
internal
view
returns(uint256)
{
uint256 _tokenPriceInitial = tokenPriceInitial_ * 1e18;
uint256 _tokensReceived =
(
(
// underflow attempts BTFO
SafeMath.sub(
(sqrt
(
(_tokenPriceInitial**2)
+
(2*(tokenPriceIncremental_ * 1e18)*(_ethereum * 1e18))
+
(((tokenPriceIncremental_)**2)*(tokenSupply_**2))
+
(2*(tokenPriceIncremental_)*_tokenPriceInitial*tokenSupply_)
)
), _tokenPriceInitial
)
)/(tokenPriceIncremental_)
)-(tokenSupply_)
;
return _tokensReceived;
}
/**
* Calculate token sell value.
* It's an algorithm, hopefully we gave you the whitepaper with it in scientific notation;
* Some conversions occurred to prevent decimal errors or underflows / overflows in solidity code.
*/
function tokensToEthereum_(uint256 _tokens)
internal
view
returns(uint256)
{
uint256 tokens_ = (_tokens + 1e18);
uint256 _tokenSupply = (tokenSupply_ + 1e18);
uint256 _etherReceived =
(
// underflow attempts BTFO
SafeMath.sub(
(
(
(
tokenPriceInitial_ +(tokenPriceIncremental_ * (_tokenSupply/1e18))
)-tokenPriceIncremental_
)*(tokens_ - 1e18)
),(tokenPriceIncremental_*((tokens_**2-tokens_)/1e18))/2
)
/1e18);
return _etherReceived;
}
//This is where all your gas goes, sorry
//Not sorry, you probably only paid 1 gwei
function sqrt(uint x) internal pure returns (uint y) {
uint z = (x + 1) / 2;
y = x;
while (z < y) {
y = z;
z = (x / z + z) / 2;
}
}
}
/**
* @title SafeMath
* @dev Math operations with safety checks that throw on error
*/
library SafeMath {
/**
* @dev Multiplies two numbers, throws on overflow.
*/
function mul(uint256 a, uint256 b) internal pure returns (uint256) {
if (a == 0) {
return 0;
}
uint256 c = a * b;
assert(c / a == b);
return c;
}
/**
* @dev Integer division of two numbers, truncating the quotient.
*/
function div(uint256 a, uint256 b) internal pure returns (uint256) {
// assert(b > 0); // Solidity automatically throws when dividing by 0
uint256 c = a / b;
// assert(a == b * c + a % b); // There is no case in which this doesn't hold
return c;
}
/**
* @dev Substracts two numbers, throws on overflow (i.e. if subtrahend is greater than minuend).
*/
function sub(uint256 a, uint256 b) internal pure returns (uint256) {
assert(b <= a);
return a - b;
}
/**
* @dev Adds two numbers, throws on overflow.
*/
function add(uint256 a, uint256 b) internal pure returns (uint256) {
uint256 c = a + b;
assert(c >= a);
return c;
}
}