Contract Name:
CougarMigration
Contract Source Code:
// SPDX-License-Identifier: MIT
pragma solidity 0.6.12;
import "@openzeppelin/contracts/math/SafeMath.sol";
import "@openzeppelin/contracts/utils/ReentrancyGuard.sol";
import "./libs/IBEP20.sol";
import "./libs/SafeBEP20.sol";
import "./libs/ICougarReferral.sol";
contract CougarMigration is ReentrancyGuard
{
using SafeMath for uint256;
using SafeBEP20 for IBEP20;
// The number of unclaimed COUGAR tokens the user has
mapping(address => uint256) public cougarUnclaimed;
// Last time user claimed COUGAR
mapping(address => uint256) public lastCougarClaimed;
event ReferralCommissionPaid(address indexed user, address indexed referrer, uint256 commissionAmount);
ICougarReferral public cougarReferral;
uint16 public referralCommissionRate = 300;
// Max referral commission rate: 3%.
uint16 public constant MAXIMUM_REFERRAL_COMMISSION_RATE = 300;
// COUGAR token
IBEP20 public COUGAR;
// Buy token
IBEP20 public BuyToken;
// Sale active
bool public isSaleActive;
// Claim active
bool public isClaimActive;
// Starting timestamp
uint256 public startingTimeStamp;
// Max Min timestamp 10 days
uint256 public constant MaxMinstartingTimeStamp = 864000;
// Total COUGAR sold
uint256 public totalCougarSold = 0;
// Price of presale COUGAR: 1 BuyToken
uint256 private constant BuyTokenPerCGS = 100;
// Time per percent
uint256 public timePerPercent = 1; // 10 minutes
// Max Time per percent
uint256 public constant maxTimePerPercent = 1800; // 30 minutes
// Max Buy Per User
uint256 public maxBuyPerUser = 200000000*(1e18); // decimal 18
uint256 public firstHarvestTimestamp;
address payable owner;
uint256 public constant COUGAR_HARDCAP = 200000000*(1e18);
modifier onlyOwner() {
require(msg.sender == owner, "You're not the owner");
_;
}
event TokenBuy(address user, uint256 tokens);
event TokenClaim(address user, uint256 tokens);
event MaxBuyPerUserUpdated(address user, uint256 previousRate, uint256 newRate);
constructor(
address _COUGAR,
uint256 _startingTimestamp,
address _BuyTokenAddress
) public {
COUGAR = IBEP20(_COUGAR);
BuyToken = IBEP20(_BuyTokenAddress);
isSaleActive = true;
isClaimActive = false;
owner = msg.sender;
startingTimeStamp = _startingTimestamp;
}
function setSaleActive(bool _isSaleActive) external onlyOwner {
isSaleActive = _isSaleActive;
}
function setClaimActive(bool _isClaimActive) external onlyOwner {
isClaimActive = _isClaimActive;
if (firstHarvestTimestamp == 0 && _isClaimActive) {
firstHarvestTimestamp = block.timestamp;
}
}
function buy(uint256 _amount, address _buyer, address _referrer) public nonReentrant {
require(isSaleActive, "Presale has not started");
require(
block.timestamp >= startingTimeStamp,
"Presale has not started"
);
address buyer = _buyer;
uint256 tokens = _amount.div(BuyTokenPerCGS).mul(100);
require(
totalCougarSold + tokens <= COUGAR_HARDCAP,
"Cougar presale hardcap reached"
);
require(
cougarUnclaimed[buyer] + tokens <= maxBuyPerUser,
"Your amount exceeds the max buy number"
);
BuyToken.safeTransferFrom(buyer, address(this), _amount);
cougarUnclaimed[buyer] = cougarUnclaimed[buyer].add(tokens);
totalCougarSold = totalCougarSold.add(tokens);
if (_amount > 0 && address(cougarReferral) != address(0) && _referrer != address(0) && _referrer != msg.sender) {
cougarReferral.recordReferral(msg.sender, _referrer);
}
emit TokenBuy(buyer, tokens);
}
function claim() external {
require(isClaimActive, "Claim is not allowed yet");
require(
cougarUnclaimed[msg.sender] > 0,
"User should have unclaimed COUGAR tokens"
);
require(
COUGAR.balanceOf(address(this)) >= cougarUnclaimed[msg.sender],
"There are not enough COUGAR tokens to transfer."
);
if (lastCougarClaimed[msg.sender] == 0) {
lastCougarClaimed[msg.sender] = firstHarvestTimestamp;
}
uint256 allowedPercentToClaim = block
.timestamp
.sub(lastCougarClaimed[msg.sender])
.div(timePerPercent);
require(
allowedPercentToClaim > 0,
"User cannot claim COUGAR tokens when Percent is 0%"
);
if (allowedPercentToClaim > 100) {
allowedPercentToClaim = 100;
// ensure they cannot claim more than they have.
}
lastCougarClaimed[msg.sender] = block.timestamp;
uint256 cougarToClaim = cougarUnclaimed[msg.sender]
.mul(allowedPercentToClaim)
.div(100);
cougarUnclaimed[msg.sender] = cougarUnclaimed[msg.sender].sub(cougarToClaim);
COUGAR.safeTransfer(msg.sender, cougarToClaim);
payReferralCommission(msg.sender, cougarToClaim);
emit TokenClaim(msg.sender, cougarToClaim);
}
function withdrawFunds() external onlyOwner {
BuyToken.safeTransfer(msg.sender, BuyToken.balanceOf(address(this)));
}
function withdrawUnsoldCOUGAR() external onlyOwner {
uint256 amount = COUGAR.balanceOf(address(this)) - totalCougarSold;
COUGAR.safeTransfer(msg.sender, amount);
}
function emergencyWithdraw() external onlyOwner {
COUGAR.safeTransfer(msg.sender, COUGAR.balanceOf(address(this)));
}
function updateMaxBuyPerUser(uint256 _maxBuyPerUser) external onlyOwner {
require(_maxBuyPerUser <= COUGAR_HARDCAP, "COUGAR::updateMaxBuyPerUser: maxBuyPerUser must not exceed the hardcap.");
emit MaxBuyPerUserUpdated(msg.sender, maxBuyPerUser, _maxBuyPerUser);
maxBuyPerUser = _maxBuyPerUser;
}
function updateTimePerPercent(uint256 _timePerPercent) external onlyOwner {
require(_timePerPercent <= maxTimePerPercent, "COUGAR::updateTimePerPercent: updateTimePerPercent must not exceed the maxTimePerPercent.");
timePerPercent = _timePerPercent;
}
function updateStartingTimeStamp(uint256 _startingTimeStamp) external onlyOwner {
require(_startingTimeStamp <= (startingTimeStamp+MaxMinstartingTimeStamp), "COUGAR::updateTimePerPercent: updateTimePerPercent must not exceed the MaxstartingTimeStamp.");
require(_startingTimeStamp >= (startingTimeStamp-MaxMinstartingTimeStamp), "COUGAR::updateTimePerPercent: updateTimePerPercent must not exceed the MinstartingTimeStamp.");
startingTimeStamp = _startingTimeStamp;
}
// Update referral commission rate by the owner
function setReferralCommissionRate(uint16 _referralCommissionRate) public onlyOwner {
require(_referralCommissionRate <= MAXIMUM_REFERRAL_COMMISSION_RATE, "setReferralCommissionRate: invalid referral commission rate basis points");
referralCommissionRate = _referralCommissionRate;
}
// Update the referral contract address by the owner
function setCougarReferral(ICougarReferral _cougarReferral) public onlyOwner {
cougarReferral = _cougarReferral;
}
// Pay referral commission to the referrer who referred this user.
function payReferralCommission(address _user, uint256 _pending) internal {
if (address(cougarReferral) != address(0) && referralCommissionRate > 0) {
address referrer = cougarReferral.getReferrer(_user);
uint256 commissionAmount = _pending.mul(referralCommissionRate).div(1e4);
if (referrer != address(0) && commissionAmount > 0) {
COUGAR.safeTransfer(referrer, commissionAmount);
cougarReferral.recordReferralCommission(referrer, commissionAmount);
emit ReferralCommissionPaid(_user, referrer, commissionAmount);
}
}
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
import "./IBEP20.sol";
import "@openzeppelin/contracts/math/SafeMath.sol";
import "@openzeppelin/contracts/utils/Address.sol";
/**
* @title SafeBEP20
* @dev Wrappers around BEP20 operations that throw on failure (when the token
* contract returns false). Tokens that return no value (and instead revert or
* throw on failure) are also supported, non-reverting calls are assumed to be
* successful.
* To use this library you can add a `using SafeBEP20 for IBEP20;` statement to your contract,
* which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
*/
library SafeBEP20 {
using SafeMath for uint256;
using Address for address;
function safeTransfer(
IBEP20 token,
address to,
uint256 value
) internal {
_callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
}
function safeTransferFrom(
IBEP20 token,
address from,
address to,
uint256 value
) internal {
_callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
}
/**
* @dev Deprecated. This function has issues similar to the ones found in
* {IBEP20-approve}, and its usage is discouraged.
*
* Whenever possible, use {safeIncreaseAllowance} and
* {safeDecreaseAllowance} instead.
*/
function safeApprove(
IBEP20 token,
address spender,
uint256 value
) internal {
// safeApprove should only be called when setting an initial allowance,
// or when resetting it to zero. To increase and decrease it, use
// 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
// solhint-disable-next-line max-line-length
require(
(value == 0) || (token.allowance(address(this), spender) == 0),
"SafeBEP20: approve from non-zero to non-zero allowance"
);
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
}
function safeIncreaseAllowance(
IBEP20 token,
address spender,
uint256 value
) internal {
uint256 newAllowance = token.allowance(address(this), spender).add(value);
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
}
function safeDecreaseAllowance(
IBEP20 token,
address spender,
uint256 value
) internal {
uint256 newAllowance = token.allowance(address(this), spender).sub(
value,
"SafeBEP20: decreased allowance below zero"
);
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
}
/**
* @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
* on the return value: the return value is optional (but if data is returned, it must not be false).
* @param token The token targeted by the call.
* @param data The call data (encoded using abi.encode or one of its variants).
*/
function _callOptionalReturn(IBEP20 token, bytes memory data) private {
// We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
// we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
// the target address contains contract code and also asserts for success in the low-level call.
bytes memory returndata = address(token).functionCall(data, "SafeBEP20: low-level call failed");
if (returndata.length > 0) {
// Return data is optional
// solhint-disable-next-line max-line-length
require(abi.decode(returndata, (bool)), "SafeBEP20: BEP20 operation did not succeed");
}
}
}
// SPDX-License-Identifier: MIT
pragma solidity 0.6.12;
interface ICougarReferral {
/**
* @dev Record referral.
*/
function recordReferral(address user, address referrer) external;
/**
* @dev Record referral commission.
*/
function recordReferralCommission(address referrer, uint256 commission) external;
/**
* @dev Get the referrer address that referred the user.
*/
function getReferrer(address user) external view returns (address);
}
// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity >=0.4.0;
interface IBEP20 {
/**
* @dev Returns the amount of tokens in existence.
*/
function totalSupply() external view returns (uint256);
/**
* @dev Returns the token decimals.
*/
function decimals() external view returns (uint8);
/**
* @dev Returns the token symbol.
*/
function symbol() external view returns (string memory);
/**
* @dev Returns the token name.
*/
function name() external view returns (string memory);
/**
* @dev Returns the bep token owner.
*/
function getOwner() external view returns (address);
/**
* @dev Returns the amount of tokens owned by `account`.
*/
function balanceOf(address account) external view returns (uint256);
/**
* @dev Moves `amount` tokens from the caller's account to `recipient`.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* Emits a {Transfer} event.
*/
function transfer(address recipient, uint256 amount) external returns (bool);
/**
* @dev Returns the remaining number of tokens that `spender` will be
* allowed to spend on behalf of `owner` through {transferFrom}. This is
* zero by default.
*
* This value changes when {approve} or {transferFrom} are called.
*/
function allowance(address _owner, address spender) external view returns (uint256);
/**
* @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* IMPORTANT: Beware that changing an allowance with this method brings the risk
* that someone may use both the old and the new allowance by unfortunate
* transaction ordering. One possible solution to mitigate this race
* condition is to first reduce the spender's allowance to 0 and set the
* desired value afterwards:
* https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
*
* Emits an {Approval} event.
*/
function approve(address spender, uint256 amount) external returns (bool);
/**
* @dev Moves `amount` tokens from `sender` to `recipient` using the
* allowance mechanism. `amount` is then deducted from the caller's
* allowance.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* Emits a {Transfer} event.
*/
function transferFrom(
address sender,
address recipient,
uint256 amount
) external returns (bool);
/**
* @dev Emitted when `value` tokens are moved from one account (`from`) to
* another (`to`).
*
* Note that `value` may be zero.
*/
event Transfer(address indexed from, address indexed to, uint256 value);
/**
* @dev Emitted when the allowance of a `spender` for an `owner` is set by
* a call to {approve}. `value` is the new allowance.
*/
event Approval(address indexed owner, address indexed spender, uint256 value);
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.8.0;
/**
* @dev Contract module that helps prevent reentrant calls to a function.
*
* Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
* available, which can be applied to functions to make sure there are no nested
* (reentrant) calls to them.
*
* Note that because there is a single `nonReentrant` guard, functions marked as
* `nonReentrant` may not call one another. This can be worked around by making
* those functions `private`, and then adding `external` `nonReentrant` entry
* points to them.
*
* TIP: If you would like to learn more about reentrancy and alternative ways
* to protect against it, check out our blog post
* https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
*/
abstract contract ReentrancyGuard {
// Booleans are more expensive than uint256 or any type that takes up a full
// word because each write operation emits an extra SLOAD to first read the
// slot's contents, replace the bits taken up by the boolean, and then write
// back. This is the compiler's defense against contract upgrades and
// pointer aliasing, and it cannot be disabled.
// The values being non-zero value makes deployment a bit more expensive,
// but in exchange the refund on every call to nonReentrant will be lower in
// amount. Since refunds are capped to a percentage of the total
// transaction's gas, it is best to keep them low in cases like this one, to
// increase the likelihood of the full refund coming into effect.
uint256 private constant _NOT_ENTERED = 1;
uint256 private constant _ENTERED = 2;
uint256 private _status;
constructor () internal {
_status = _NOT_ENTERED;
}
/**
* @dev Prevents a contract from calling itself, directly or indirectly.
* Calling a `nonReentrant` function from another `nonReentrant`
* function is not supported. It is possible to prevent this from happening
* by making the `nonReentrant` function external, and make it call a
* `private` function that does the actual work.
*/
modifier nonReentrant() {
// On the first call to nonReentrant, _notEntered will be true
require(_status != _ENTERED, "ReentrancyGuard: reentrant call");
// Any calls to nonReentrant after this point will fail
_status = _ENTERED;
_;
// By storing the original value once again, a refund is triggered (see
// https://eips.ethereum.org/EIPS/eip-2200)
_status = _NOT_ENTERED;
}
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.2 <0.8.0;
/**
* @dev Collection of functions related to the address type
*/
library Address {
/**
* @dev Returns true if `account` is a contract.
*
* [IMPORTANT]
* ====
* It is unsafe to assume that an address for which this function returns
* false is an externally-owned account (EOA) and not a contract.
*
* Among others, `isContract` will return false for the following
* types of addresses:
*
* - an externally-owned account
* - a contract in construction
* - an address where a contract will be created
* - an address where a contract lived, but was destroyed
* ====
*/
function isContract(address account) internal view returns (bool) {
// This method relies on extcodesize, which returns 0 for contracts in
// construction, since the code is only stored at the end of the
// constructor execution.
uint256 size;
// solhint-disable-next-line no-inline-assembly
assembly { size := extcodesize(account) }
return size > 0;
}
/**
* @dev Replacement for Solidity's `transfer`: sends `amount` wei to
* `recipient`, forwarding all available gas and reverting on errors.
*
* https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
* of certain opcodes, possibly making contracts go over the 2300 gas limit
* imposed by `transfer`, making them unable to receive funds via
* `transfer`. {sendValue} removes this limitation.
*
* https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
*
* IMPORTANT: because control is transferred to `recipient`, care must be
* taken to not create reentrancy vulnerabilities. Consider using
* {ReentrancyGuard} or the
* https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
*/
function sendValue(address payable recipient, uint256 amount) internal {
require(address(this).balance >= amount, "Address: insufficient balance");
// solhint-disable-next-line avoid-low-level-calls, avoid-call-value
(bool success, ) = recipient.call{ value: amount }("");
require(success, "Address: unable to send value, recipient may have reverted");
}
/**
* @dev Performs a Solidity function call using a low level `call`. A
* plain`call` is an unsafe replacement for a function call: use this
* function instead.
*
* If `target` reverts with a revert reason, it is bubbled up by this
* function (like regular Solidity function calls).
*
* Returns the raw returned data. To convert to the expected return value,
* use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
*
* Requirements:
*
* - `target` must be a contract.
* - calling `target` with `data` must not revert.
*
* _Available since v3.1._
*/
function functionCall(address target, bytes memory data) internal returns (bytes memory) {
return functionCall(target, data, "Address: low-level call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
* `errorMessage` as a fallback revert reason when `target` reverts.
*
* _Available since v3.1._
*/
function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
return functionCallWithValue(target, data, 0, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but also transferring `value` wei to `target`.
*
* Requirements:
*
* - the calling contract must have an ETH balance of at least `value`.
* - the called Solidity function must be `payable`.
*
* _Available since v3.1._
*/
function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
}
/**
* @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
* with `errorMessage` as a fallback revert reason when `target` reverts.
*
* _Available since v3.1._
*/
function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
require(address(this).balance >= value, "Address: insufficient balance for call");
require(isContract(target), "Address: call to non-contract");
// solhint-disable-next-line avoid-low-level-calls
(bool success, bytes memory returndata) = target.call{ value: value }(data);
return _verifyCallResult(success, returndata, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but performing a static call.
*
* _Available since v3.3._
*/
function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
return functionStaticCall(target, data, "Address: low-level static call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
* but performing a static call.
*
* _Available since v3.3._
*/
function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {
require(isContract(target), "Address: static call to non-contract");
// solhint-disable-next-line avoid-low-level-calls
(bool success, bytes memory returndata) = target.staticcall(data);
return _verifyCallResult(success, returndata, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but performing a delegate call.
*
* _Available since v3.4._
*/
function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
return functionDelegateCall(target, data, "Address: low-level delegate call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
* but performing a delegate call.
*
* _Available since v3.4._
*/
function functionDelegateCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
require(isContract(target), "Address: delegate call to non-contract");
// solhint-disable-next-line avoid-low-level-calls
(bool success, bytes memory returndata) = target.delegatecall(data);
return _verifyCallResult(success, returndata, errorMessage);
}
function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {
if (success) {
return returndata;
} else {
// Look for revert reason and bubble it up if present
if (returndata.length > 0) {
// The easiest way to bubble the revert reason is using memory via assembly
// solhint-disable-next-line no-inline-assembly
assembly {
let returndata_size := mload(returndata)
revert(add(32, returndata), returndata_size)
}
} else {
revert(errorMessage);
}
}
}
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.8.0;
/**
* @dev Wrappers over Solidity's arithmetic operations with added overflow
* checks.
*
* Arithmetic operations in Solidity wrap on overflow. This can easily result
* in bugs, because programmers usually assume that an overflow raises an
* error, which is the standard behavior in high level programming languages.
* `SafeMath` restores this intuition by reverting the transaction when an
* operation overflows.
*
* Using this library instead of the unchecked operations eliminates an entire
* class of bugs, so it's recommended to use it always.
*/
library SafeMath {
/**
* @dev Returns the addition of two unsigned integers, with an overflow flag.
*
* _Available since v3.4._
*/
function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
uint256 c = a + b;
if (c < a) return (false, 0);
return (true, c);
}
/**
* @dev Returns the substraction of two unsigned integers, with an overflow flag.
*
* _Available since v3.4._
*/
function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
if (b > a) return (false, 0);
return (true, a - b);
}
/**
* @dev Returns the multiplication of two unsigned integers, with an overflow flag.
*
* _Available since v3.4._
*/
function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
// Gas optimization: this is cheaper than requiring 'a' not being zero, but the
// benefit is lost if 'b' is also tested.
// See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
if (a == 0) return (true, 0);
uint256 c = a * b;
if (c / a != b) return (false, 0);
return (true, c);
}
/**
* @dev Returns the division of two unsigned integers, with a division by zero flag.
*
* _Available since v3.4._
*/
function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
if (b == 0) return (false, 0);
return (true, a / b);
}
/**
* @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
*
* _Available since v3.4._
*/
function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
if (b == 0) return (false, 0);
return (true, a % b);
}
/**
* @dev Returns the addition of two unsigned integers, reverting on
* overflow.
*
* Counterpart to Solidity's `+` operator.
*
* Requirements:
*
* - Addition cannot overflow.
*/
function add(uint256 a, uint256 b) internal pure returns (uint256) {
uint256 c = a + b;
require(c >= a, "SafeMath: addition overflow");
return c;
}
/**
* @dev Returns the subtraction of two unsigned integers, reverting on
* overflow (when the result is negative).
*
* Counterpart to Solidity's `-` operator.
*
* Requirements:
*
* - Subtraction cannot overflow.
*/
function sub(uint256 a, uint256 b) internal pure returns (uint256) {
require(b <= a, "SafeMath: subtraction overflow");
return a - b;
}
/**
* @dev Returns the multiplication of two unsigned integers, reverting on
* overflow.
*
* Counterpart to Solidity's `*` operator.
*
* Requirements:
*
* - Multiplication cannot overflow.
*/
function mul(uint256 a, uint256 b) internal pure returns (uint256) {
if (a == 0) return 0;
uint256 c = a * b;
require(c / a == b, "SafeMath: multiplication overflow");
return c;
}
/**
* @dev Returns the integer division of two unsigned integers, reverting on
* division by zero. The result is rounded towards zero.
*
* Counterpart to Solidity's `/` operator. Note: this function uses a
* `revert` opcode (which leaves remaining gas untouched) while Solidity
* uses an invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
*
* - The divisor cannot be zero.
*/
function div(uint256 a, uint256 b) internal pure returns (uint256) {
require(b > 0, "SafeMath: division by zero");
return a / b;
}
/**
* @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
* reverting when dividing by zero.
*
* Counterpart to Solidity's `%` operator. This function uses a `revert`
* opcode (which leaves remaining gas untouched) while Solidity uses an
* invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
*
* - The divisor cannot be zero.
*/
function mod(uint256 a, uint256 b) internal pure returns (uint256) {
require(b > 0, "SafeMath: modulo by zero");
return a % b;
}
/**
* @dev Returns the subtraction of two unsigned integers, reverting with custom message on
* overflow (when the result is negative).
*
* CAUTION: This function is deprecated because it requires allocating memory for the error
* message unnecessarily. For custom revert reasons use {trySub}.
*
* Counterpart to Solidity's `-` operator.
*
* Requirements:
*
* - Subtraction cannot overflow.
*/
function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
require(b <= a, errorMessage);
return a - b;
}
/**
* @dev Returns the integer division of two unsigned integers, reverting with custom message on
* division by zero. The result is rounded towards zero.
*
* CAUTION: This function is deprecated because it requires allocating memory for the error
* message unnecessarily. For custom revert reasons use {tryDiv}.
*
* Counterpart to Solidity's `/` operator. Note: this function uses a
* `revert` opcode (which leaves remaining gas untouched) while Solidity
* uses an invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
*
* - The divisor cannot be zero.
*/
function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
require(b > 0, errorMessage);
return a / b;
}
/**
* @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
* reverting with custom message when dividing by zero.
*
* CAUTION: This function is deprecated because it requires allocating memory for the error
* message unnecessarily. For custom revert reasons use {tryMod}.
*
* Counterpart to Solidity's `%` operator. This function uses a `revert`
* opcode (which leaves remaining gas untouched) while Solidity uses an
* invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
*
* - The divisor cannot be zero.
*/
function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
require(b > 0, errorMessage);
return a % b;
}
}