Contract Source Code:
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.10;
import "./Math.sol";
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts/interfaces/IERC165.sol";
import "abdk-libraries-solidity/ABDKMath64x64.sol";
import "./interfaces/IStakingToken.sol";
import "./interfaces/IRankedMintingToken.sol";
import "./interfaces/IBurnableToken.sol";
import "./interfaces/IBurnRedeemable.sol";
contract XENCrypto is Context, IRankedMintingToken, IStakingToken, IBurnableToken, ERC20("XEN Crypto", "XEN") {
using Math for uint256;
using ABDKMath64x64 for int128;
using ABDKMath64x64 for uint256;
// INTERNAL TYPE TO DESCRIBE A XEN MINT INFO
struct MintInfo {
address user;
uint256 term;
uint256 maturityTs;
uint256 rank;
uint256 amplifier;
uint256 eaaRate;
}
// INTERNAL TYPE TO DESCRIBE A XEN STAKE
struct StakeInfo {
uint256 term;
uint256 maturityTs;
uint256 amount;
uint256 apy;
}
// PUBLIC CONSTANTS
uint256 public constant SECONDS_IN_DAY = 3_600 * 24;
uint256 public constant DAYS_IN_YEAR = 365;
uint256 public constant GENESIS_RANK = 1;
uint256 public constant MIN_TERM = 1 * SECONDS_IN_DAY - 1;
uint256 public constant MAX_TERM_START = 100 * SECONDS_IN_DAY;
uint256 public constant MAX_TERM_END = 1_000 * SECONDS_IN_DAY;
uint256 public constant TERM_AMPLIFIER = 15;
uint256 public constant TERM_AMPLIFIER_THRESHOLD = 5_000;
uint256 public constant REWARD_AMPLIFIER_START = 3_000;
uint256 public constant REWARD_AMPLIFIER_END = 1;
uint256 public constant EAA_PM_START = 100;
uint256 public constant EAA_PM_STEP = 1;
uint256 public constant EAA_RANK_STEP = 100_000;
uint256 public constant WITHDRAWAL_WINDOW_DAYS = 7;
uint256 public constant MAX_PENALTY_PCT = 99;
uint256 public constant XEN_MIN_STAKE = 0;
uint256 public constant XEN_MIN_BURN = 0;
uint256 public constant XEN_APY_START = 20;
uint256 public constant XEN_APY_DAYS_STEP = 90;
uint256 public constant XEN_APY_END = 2;
string public constant AUTHORS = "@MrJackLevin @lbelyaev faircrypto.org";
// PUBLIC STATE, READABLE VIA NAMESAKE GETTERS
uint256 public immutable genesisTs;
uint256 public globalRank = GENESIS_RANK;
uint256 public activeMinters;
uint256 public activeStakes;
uint256 public totalXenStaked;
// user address => XEN mint info
mapping(address => MintInfo) public userMints;
// user address => XEN stake info
mapping(address => StakeInfo) public userStakes;
// user address => XEN burn amount
mapping(address => uint256) public userBurns;
// CONSTRUCTOR
constructor() {
genesisTs = block.timestamp;
}
// PRIVATE METHODS
/**
* @dev calculates current MaxTerm based on Global Rank
* (if Global Rank crosses over TERM_AMPLIFIER_THRESHOLD)
*/
function _calculateMaxTerm() private view returns (uint256) {
if (globalRank > TERM_AMPLIFIER_THRESHOLD) {
uint256 delta = globalRank.fromUInt().log_2().mul(TERM_AMPLIFIER.fromUInt()).toUInt();
uint256 newMax = MAX_TERM_START + delta * SECONDS_IN_DAY;
return Math.min(newMax, MAX_TERM_END);
}
return MAX_TERM_START;
}
/**
* @dev calculates Withdrawal Penalty depending on lateness
*/
function _penalty(uint256 secsLate) private pure returns (uint256) {
// =MIN(2^(daysLate+3)/window-1,99)
uint256 daysLate = secsLate / SECONDS_IN_DAY;
if (daysLate > WITHDRAWAL_WINDOW_DAYS - 1) return MAX_PENALTY_PCT;
uint256 penalty = (uint256(1) << (daysLate + 3)) / WITHDRAWAL_WINDOW_DAYS - 1;
return Math.min(penalty, MAX_PENALTY_PCT);
}
/**
* @dev calculates net Mint Reward (adjusted for Penalty)
*/
function _calculateMintReward(
uint256 cRank,
uint256 term,
uint256 maturityTs,
uint256 amplifier,
uint256 eeaRate
) private view returns (uint256) {
uint256 secsLate = block.timestamp - maturityTs;
uint256 penalty = _penalty(secsLate);
uint256 rankDelta = Math.max(globalRank - cRank, 2);
uint256 EAA = (1_000 + eeaRate);
uint256 reward = getGrossReward(rankDelta, amplifier, term, EAA);
return (reward * (100 - penalty)) / 100;
}
/**
* @dev cleans up User Mint storage (gets some Gas credit;))
*/
function _cleanUpUserMint() private {
delete userMints[_msgSender()];
activeMinters--;
}
/**
* @dev calculates XEN Stake Reward
*/
function _calculateStakeReward(
uint256 amount,
uint256 term,
uint256 maturityTs,
uint256 apy
) private view returns (uint256) {
if (block.timestamp > maturityTs) {
uint256 rate = (apy * term * 1_000_000) / DAYS_IN_YEAR;
return (amount * rate) / 100_000_000;
}
return 0;
}
/**
* @dev calculates Reward Amplifier
*/
function _calculateRewardAmplifier() private view returns (uint256) {
uint256 amplifierDecrease = (block.timestamp - genesisTs) / SECONDS_IN_DAY;
if (amplifierDecrease < REWARD_AMPLIFIER_START) {
return Math.max(REWARD_AMPLIFIER_START - amplifierDecrease, REWARD_AMPLIFIER_END);
} else {
return REWARD_AMPLIFIER_END;
}
}
/**
* @dev calculates Early Adopter Amplifier Rate (in 1/000ths)
* actual EAA is (1_000 + EAAR) / 1_000
*/
function _calculateEAARate() private view returns (uint256) {
uint256 decrease = (EAA_PM_STEP * globalRank) / EAA_RANK_STEP;
if (decrease > EAA_PM_START) return 0;
return EAA_PM_START - decrease;
}
/**
* @dev calculates APY (in %)
*/
function _calculateAPY() private view returns (uint256) {
uint256 decrease = (block.timestamp - genesisTs) / (SECONDS_IN_DAY * XEN_APY_DAYS_STEP);
if (XEN_APY_START - XEN_APY_END < decrease) return XEN_APY_END;
return XEN_APY_START - decrease;
}
/**
* @dev creates User Stake
*/
function _createStake(uint256 amount, uint256 term) private {
userStakes[_msgSender()] = StakeInfo({
term: term,
maturityTs: block.timestamp + term * SECONDS_IN_DAY,
amount: amount,
apy: _calculateAPY()
});
activeStakes++;
totalXenStaked += amount;
}
// PUBLIC CONVENIENCE GETTERS
/**
* @dev calculates gross Mint Reward
*/
function getGrossReward(
uint256 rankDelta,
uint256 amplifier,
uint256 term,
uint256 eaa
) public pure returns (uint256) {
int128 log128 = rankDelta.fromUInt().log_2();
int128 reward128 = log128.mul(amplifier.fromUInt()).mul(term.fromUInt()).mul(eaa.fromUInt());
return reward128.div(uint256(1_000).fromUInt()).toUInt();
}
/**
* @dev returns User Mint object associated with User account address
*/
function getUserMint() external view returns (MintInfo memory) {
return userMints[_msgSender()];
}
/**
* @dev returns XEN Stake object associated with User account address
*/
function getUserStake() external view returns (StakeInfo memory) {
return userStakes[_msgSender()];
}
/**
* @dev returns current AMP
*/
function getCurrentAMP() external view returns (uint256) {
return _calculateRewardAmplifier();
}
/**
* @dev returns current EAA Rate
*/
function getCurrentEAAR() external view returns (uint256) {
return _calculateEAARate();
}
/**
* @dev returns current APY
*/
function getCurrentAPY() external view returns (uint256) {
return _calculateAPY();
}
/**
* @dev returns current MaxTerm
*/
function getCurrentMaxTerm() external view returns (uint256) {
return _calculateMaxTerm();
}
// PUBLIC STATE-CHANGING METHODS
/**
* @dev accepts User cRank claim provided all checks pass (incl. no current claim exists)
*/
function claimRank(uint256 term) external {
uint256 termSec = term * SECONDS_IN_DAY;
require(termSec > MIN_TERM, "CRank: Term less than min");
require(termSec < _calculateMaxTerm() + 1, "CRank: Term more than current max term");
require(userMints[_msgSender()].rank == 0, "CRank: Mint already in progress");
// create and store new MintInfo
MintInfo memory mintInfo = MintInfo({
user: _msgSender(),
term: term,
maturityTs: block.timestamp + termSec,
rank: globalRank,
amplifier: _calculateRewardAmplifier(),
eaaRate: _calculateEAARate()
});
userMints[_msgSender()] = mintInfo;
activeMinters++;
emit RankClaimed(_msgSender(), term, globalRank++);
}
/**
* @dev ends minting upon maturity (and within permitted Withdrawal Time Window), gets minted XEN
*/
function claimMintReward() external {
MintInfo memory mintInfo = userMints[_msgSender()];
require(mintInfo.rank > 0, "CRank: No mint exists");
require(block.timestamp > mintInfo.maturityTs, "CRank: Mint maturity not reached");
// calculate reward and mint tokens
uint256 rewardAmount = _calculateMintReward(
mintInfo.rank,
mintInfo.term,
mintInfo.maturityTs,
mintInfo.amplifier,
mintInfo.eaaRate
) * 1 ether;
_mint(_msgSender(), rewardAmount);
_cleanUpUserMint();
emit MintClaimed(_msgSender(), rewardAmount);
}
/**
* @dev ends minting upon maturity (and within permitted Withdrawal time Window)
* mints XEN coins and splits them between User and designated other address
*/
function claimMintRewardAndShare(address other, uint256 pct) external {
MintInfo memory mintInfo = userMints[_msgSender()];
require(other != address(0), "CRank: Cannot share with zero address");
require(pct > 0, "CRank: Cannot share zero percent");
require(pct < 101, "CRank: Cannot share 100+ percent");
require(mintInfo.rank > 0, "CRank: No mint exists");
require(block.timestamp > mintInfo.maturityTs, "CRank: Mint maturity not reached");
// calculate reward
uint256 rewardAmount = _calculateMintReward(
mintInfo.rank,
mintInfo.term,
mintInfo.maturityTs,
mintInfo.amplifier,
mintInfo.eaaRate
) * 1 ether;
uint256 sharedReward = (rewardAmount * pct) / 100;
uint256 ownReward = rewardAmount - sharedReward;
// mint reward tokens
_mint(_msgSender(), ownReward);
_mint(other, sharedReward);
_cleanUpUserMint();
emit MintClaimed(_msgSender(), rewardAmount);
}
/**
* @dev ends minting upon maturity (and within permitted Withdrawal time Window)
* mints XEN coins and stakes 'pct' of it for 'term'
*/
function claimMintRewardAndStake(uint256 pct, uint256 term) external {
MintInfo memory mintInfo = userMints[_msgSender()];
// require(pct > 0, "CRank: Cannot share zero percent");
require(pct < 101, "CRank: Cannot share >100 percent");
require(mintInfo.rank > 0, "CRank: No mint exists");
require(block.timestamp > mintInfo.maturityTs, "CRank: Mint maturity not reached");
// calculate reward
uint256 rewardAmount = _calculateMintReward(
mintInfo.rank,
mintInfo.term,
mintInfo.maturityTs,
mintInfo.amplifier,
mintInfo.eaaRate
) * 1 ether;
uint256 stakedReward = (rewardAmount * pct) / 100;
uint256 ownReward = rewardAmount - stakedReward;
// mint reward tokens part
_mint(_msgSender(), ownReward);
_cleanUpUserMint();
emit MintClaimed(_msgSender(), rewardAmount);
// nothing to burn since we haven't minted this part yet
// stake extra tokens part
require(stakedReward > XEN_MIN_STAKE, "XEN: Below min stake");
require(term * SECONDS_IN_DAY > MIN_TERM, "XEN: Below min stake term");
require(term * SECONDS_IN_DAY < MAX_TERM_END + 1, "XEN: Above max stake term");
require(userStakes[_msgSender()].amount == 0, "XEN: stake exists");
_createStake(stakedReward, term);
emit Staked(_msgSender(), stakedReward, term);
}
/**
* @dev initiates XEN Stake in amount for a term (days)
*/
function stake(uint256 amount, uint256 term) external {
require(balanceOf(_msgSender()) >= amount, "XEN: not enough balance");
require(amount > XEN_MIN_STAKE, "XEN: Below min stake");
require(term * SECONDS_IN_DAY > MIN_TERM, "XEN: Below min stake term");
require(term * SECONDS_IN_DAY < MAX_TERM_END + 1, "XEN: Above max stake term");
require(userStakes[_msgSender()].amount == 0, "XEN: stake exists");
// burn staked XEN
_burn(_msgSender(), amount);
// create XEN Stake
_createStake(amount, term);
emit Staked(_msgSender(), amount, term);
}
/**
* @dev ends XEN Stake and gets reward if the Stake is mature
*/
function withdraw() external {
StakeInfo memory userStake = userStakes[_msgSender()];
require(userStake.amount > 0, "XEN: no stake exists");
uint256 xenReward = _calculateStakeReward(
userStake.amount,
userStake.term,
userStake.maturityTs,
userStake.apy
);
activeStakes--;
totalXenStaked -= userStake.amount;
// mint staked XEN (+ reward)
_mint(_msgSender(), userStake.amount + xenReward);
emit Withdrawn(_msgSender(), userStake.amount, xenReward);
delete userStakes[_msgSender()];
}
/**
* @dev burns XEN tokens and creates Proof-Of-Burn record to be used by connected DeFi services
*/
function burn(address user, uint256 amount) public {
require(amount > XEN_MIN_BURN, "Burn: Below min limit");
require(
IERC165(_msgSender()).supportsInterface(type(IBurnRedeemable).interfaceId),
"Burn: not a supported contract"
);
_spendAllowance(user, _msgSender(), amount);
_burn(user, amount);
userBurns[user] += amount;
IBurnRedeemable(_msgSender()).onTokenBurned(user, amount);
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.10;
interface IStakingToken {
event Staked(address indexed user, uint256 amount, uint256 term);
event Withdrawn(address indexed user, uint256 amount, uint256 reward);
function stake(uint256 amount, uint256 term) external;
function withdraw() external;
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.10;
interface IRankedMintingToken {
event RankClaimed(address indexed user, uint256 term, uint256 rank);
event MintClaimed(address indexed user, uint256 rewardAmount);
function claimRank(uint256 term) external;
function claimMintReward() external;
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.10;
interface IBurnableToken {
function burn(address user, uint256 amount) external;
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.10;
interface IBurnRedeemable {
event Redeemed(
address indexed user,
address indexed xenContract,
address indexed tokenContract,
uint256 xenAmount,
uint256 tokenAmount
);
function onTokenBurned(address user, uint256 amount) external;
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.10;
import "abdk-libraries-solidity/ABDKMath64x64.sol";
library Math {
function min(uint256 a, uint256 b) external pure returns (uint256) {
if (a > b) return b;
return a;
}
function max(uint256 a, uint256 b) external pure returns (uint256) {
if (a > b) return a;
return b;
}
function logX64(uint256 x) external pure returns (int128) {
return ABDKMath64x64.log_2(ABDKMath64x64.fromUInt(x));
}
}
// SPDX-License-Identifier: BSD-4-Clause
/*
* ABDK Math 64.64 Smart Contract Library. Copyright © 2019 by ABDK Consulting.
* Author: Mikhail Vladimirov <[email protected]>
*/
pragma solidity ^0.8.0;
/**
* Smart contract library of mathematical functions operating with signed
* 64.64-bit fixed point numbers. Signed 64.64-bit fixed point number is
* basically a simple fraction whose numerator is signed 128-bit integer and
* denominator is 2^64. As long as denominator is always the same, there is no
* need to store it, thus in Solidity signed 64.64-bit fixed point numbers are
* represented by int128 type holding only the numerator.
*/
library ABDKMath64x64 {
/*
* Minimum value signed 64.64-bit fixed point number may have.
*/
int128 private constant MIN_64x64 = -0x80000000000000000000000000000000;
/*
* Maximum value signed 64.64-bit fixed point number may have.
*/
int128 private constant MAX_64x64 = 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF;
/**
* Convert signed 256-bit integer number into signed 64.64-bit fixed point
* number. Revert on overflow.
*
* @param x signed 256-bit integer number
* @return signed 64.64-bit fixed point number
*/
function fromInt (int256 x) internal pure returns (int128) {
unchecked {
require (x >= -0x8000000000000000 && x <= 0x7FFFFFFFFFFFFFFF);
return int128 (x << 64);
}
}
/**
* Convert signed 64.64 fixed point number into signed 64-bit integer number
* rounding down.
*
* @param x signed 64.64-bit fixed point number
* @return signed 64-bit integer number
*/
function toInt (int128 x) internal pure returns (int64) {
unchecked {
return int64 (x >> 64);
}
}
/**
* Convert unsigned 256-bit integer number into signed 64.64-bit fixed point
* number. Revert on overflow.
*
* @param x unsigned 256-bit integer number
* @return signed 64.64-bit fixed point number
*/
function fromUInt (uint256 x) internal pure returns (int128) {
unchecked {
require (x <= 0x7FFFFFFFFFFFFFFF);
return int128 (int256 (x << 64));
}
}
/**
* Convert signed 64.64 fixed point number into unsigned 64-bit integer
* number rounding down. Revert on underflow.
*
* @param x signed 64.64-bit fixed point number
* @return unsigned 64-bit integer number
*/
function toUInt (int128 x) internal pure returns (uint64) {
unchecked {
require (x >= 0);
return uint64 (uint128 (x >> 64));
}
}
/**
* Convert signed 128.128 fixed point number into signed 64.64-bit fixed point
* number rounding down. Revert on overflow.
*
* @param x signed 128.128-bin fixed point number
* @return signed 64.64-bit fixed point number
*/
function from128x128 (int256 x) internal pure returns (int128) {
unchecked {
int256 result = x >> 64;
require (result >= MIN_64x64 && result <= MAX_64x64);
return int128 (result);
}
}
/**
* Convert signed 64.64 fixed point number into signed 128.128 fixed point
* number.
*
* @param x signed 64.64-bit fixed point number
* @return signed 128.128 fixed point number
*/
function to128x128 (int128 x) internal pure returns (int256) {
unchecked {
return int256 (x) << 64;
}
}
/**
* Calculate x + y. Revert on overflow.
*
* @param x signed 64.64-bit fixed point number
* @param y signed 64.64-bit fixed point number
* @return signed 64.64-bit fixed point number
*/
function add (int128 x, int128 y) internal pure returns (int128) {
unchecked {
int256 result = int256(x) + y;
require (result >= MIN_64x64 && result <= MAX_64x64);
return int128 (result);
}
}
/**
* Calculate x - y. Revert on overflow.
*
* @param x signed 64.64-bit fixed point number
* @param y signed 64.64-bit fixed point number
* @return signed 64.64-bit fixed point number
*/
function sub (int128 x, int128 y) internal pure returns (int128) {
unchecked {
int256 result = int256(x) - y;
require (result >= MIN_64x64 && result <= MAX_64x64);
return int128 (result);
}
}
/**
* Calculate x * y rounding down. Revert on overflow.
*
* @param x signed 64.64-bit fixed point number
* @param y signed 64.64-bit fixed point number
* @return signed 64.64-bit fixed point number
*/
function mul (int128 x, int128 y) internal pure returns (int128) {
unchecked {
int256 result = int256(x) * y >> 64;
require (result >= MIN_64x64 && result <= MAX_64x64);
return int128 (result);
}
}
/**
* Calculate x * y rounding towards zero, where x is signed 64.64 fixed point
* number and y is signed 256-bit integer number. Revert on overflow.
*
* @param x signed 64.64 fixed point number
* @param y signed 256-bit integer number
* @return signed 256-bit integer number
*/
function muli (int128 x, int256 y) internal pure returns (int256) {
unchecked {
if (x == MIN_64x64) {
require (y >= -0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF &&
y <= 0x1000000000000000000000000000000000000000000000000);
return -y << 63;
} else {
bool negativeResult = false;
if (x < 0) {
x = -x;
negativeResult = true;
}
if (y < 0) {
y = -y; // We rely on overflow behavior here
negativeResult = !negativeResult;
}
uint256 absoluteResult = mulu (x, uint256 (y));
if (negativeResult) {
require (absoluteResult <=
0x8000000000000000000000000000000000000000000000000000000000000000);
return -int256 (absoluteResult); // We rely on overflow behavior here
} else {
require (absoluteResult <=
0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF);
return int256 (absoluteResult);
}
}
}
}
/**
* Calculate x * y rounding down, where x is signed 64.64 fixed point number
* and y is unsigned 256-bit integer number. Revert on overflow.
*
* @param x signed 64.64 fixed point number
* @param y unsigned 256-bit integer number
* @return unsigned 256-bit integer number
*/
function mulu (int128 x, uint256 y) internal pure returns (uint256) {
unchecked {
if (y == 0) return 0;
require (x >= 0);
uint256 lo = (uint256 (int256 (x)) * (y & 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF)) >> 64;
uint256 hi = uint256 (int256 (x)) * (y >> 128);
require (hi <= 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF);
hi <<= 64;
require (hi <=
0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF - lo);
return hi + lo;
}
}
/**
* Calculate x / y rounding towards zero. Revert on overflow or when y is
* zero.
*
* @param x signed 64.64-bit fixed point number
* @param y signed 64.64-bit fixed point number
* @return signed 64.64-bit fixed point number
*/
function div (int128 x, int128 y) internal pure returns (int128) {
unchecked {
require (y != 0);
int256 result = (int256 (x) << 64) / y;
require (result >= MIN_64x64 && result <= MAX_64x64);
return int128 (result);
}
}
/**
* Calculate x / y rounding towards zero, where x and y are signed 256-bit
* integer numbers. Revert on overflow or when y is zero.
*
* @param x signed 256-bit integer number
* @param y signed 256-bit integer number
* @return signed 64.64-bit fixed point number
*/
function divi (int256 x, int256 y) internal pure returns (int128) {
unchecked {
require (y != 0);
bool negativeResult = false;
if (x < 0) {
x = -x; // We rely on overflow behavior here
negativeResult = true;
}
if (y < 0) {
y = -y; // We rely on overflow behavior here
negativeResult = !negativeResult;
}
uint128 absoluteResult = divuu (uint256 (x), uint256 (y));
if (negativeResult) {
require (absoluteResult <= 0x80000000000000000000000000000000);
return -int128 (absoluteResult); // We rely on overflow behavior here
} else {
require (absoluteResult <= 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF);
return int128 (absoluteResult); // We rely on overflow behavior here
}
}
}
/**
* Calculate x / y rounding towards zero, where x and y are unsigned 256-bit
* integer numbers. Revert on overflow or when y is zero.
*
* @param x unsigned 256-bit integer number
* @param y unsigned 256-bit integer number
* @return signed 64.64-bit fixed point number
*/
function divu (uint256 x, uint256 y) internal pure returns (int128) {
unchecked {
require (y != 0);
uint128 result = divuu (x, y);
require (result <= uint128 (MAX_64x64));
return int128 (result);
}
}
/**
* Calculate -x. Revert on overflow.
*
* @param x signed 64.64-bit fixed point number
* @return signed 64.64-bit fixed point number
*/
function neg (int128 x) internal pure returns (int128) {
unchecked {
require (x != MIN_64x64);
return -x;
}
}
/**
* Calculate |x|. Revert on overflow.
*
* @param x signed 64.64-bit fixed point number
* @return signed 64.64-bit fixed point number
*/
function abs (int128 x) internal pure returns (int128) {
unchecked {
require (x != MIN_64x64);
return x < 0 ? -x : x;
}
}
/**
* Calculate 1 / x rounding towards zero. Revert on overflow or when x is
* zero.
*
* @param x signed 64.64-bit fixed point number
* @return signed 64.64-bit fixed point number
*/
function inv (int128 x) internal pure returns (int128) {
unchecked {
require (x != 0);
int256 result = int256 (0x100000000000000000000000000000000) / x;
require (result >= MIN_64x64 && result <= MAX_64x64);
return int128 (result);
}
}
/**
* Calculate arithmetics average of x and y, i.e. (x + y) / 2 rounding down.
*
* @param x signed 64.64-bit fixed point number
* @param y signed 64.64-bit fixed point number
* @return signed 64.64-bit fixed point number
*/
function avg (int128 x, int128 y) internal pure returns (int128) {
unchecked {
return int128 ((int256 (x) + int256 (y)) >> 1);
}
}
/**
* Calculate geometric average of x and y, i.e. sqrt (x * y) rounding down.
* Revert on overflow or in case x * y is negative.
*
* @param x signed 64.64-bit fixed point number
* @param y signed 64.64-bit fixed point number
* @return signed 64.64-bit fixed point number
*/
function gavg (int128 x, int128 y) internal pure returns (int128) {
unchecked {
int256 m = int256 (x) * int256 (y);
require (m >= 0);
require (m <
0x4000000000000000000000000000000000000000000000000000000000000000);
return int128 (sqrtu (uint256 (m)));
}
}
/**
* Calculate x^y assuming 0^0 is 1, where x is signed 64.64 fixed point number
* and y is unsigned 256-bit integer number. Revert on overflow.
*
* @param x signed 64.64-bit fixed point number
* @param y uint256 value
* @return signed 64.64-bit fixed point number
*/
function pow (int128 x, uint256 y) internal pure returns (int128) {
unchecked {
bool negative = x < 0 && y & 1 == 1;
uint256 absX = uint128 (x < 0 ? -x : x);
uint256 absResult;
absResult = 0x100000000000000000000000000000000;
if (absX <= 0x10000000000000000) {
absX <<= 63;
while (y != 0) {
if (y & 0x1 != 0) {
absResult = absResult * absX >> 127;
}
absX = absX * absX >> 127;
if (y & 0x2 != 0) {
absResult = absResult * absX >> 127;
}
absX = absX * absX >> 127;
if (y & 0x4 != 0) {
absResult = absResult * absX >> 127;
}
absX = absX * absX >> 127;
if (y & 0x8 != 0) {
absResult = absResult * absX >> 127;
}
absX = absX * absX >> 127;
y >>= 4;
}
absResult >>= 64;
} else {
uint256 absXShift = 63;
if (absX < 0x1000000000000000000000000) { absX <<= 32; absXShift -= 32; }
if (absX < 0x10000000000000000000000000000) { absX <<= 16; absXShift -= 16; }
if (absX < 0x1000000000000000000000000000000) { absX <<= 8; absXShift -= 8; }
if (absX < 0x10000000000000000000000000000000) { absX <<= 4; absXShift -= 4; }
if (absX < 0x40000000000000000000000000000000) { absX <<= 2; absXShift -= 2; }
if (absX < 0x80000000000000000000000000000000) { absX <<= 1; absXShift -= 1; }
uint256 resultShift = 0;
while (y != 0) {
require (absXShift < 64);
if (y & 0x1 != 0) {
absResult = absResult * absX >> 127;
resultShift += absXShift;
if (absResult > 0x100000000000000000000000000000000) {
absResult >>= 1;
resultShift += 1;
}
}
absX = absX * absX >> 127;
absXShift <<= 1;
if (absX >= 0x100000000000000000000000000000000) {
absX >>= 1;
absXShift += 1;
}
y >>= 1;
}
require (resultShift < 64);
absResult >>= 64 - resultShift;
}
int256 result = negative ? -int256 (absResult) : int256 (absResult);
require (result >= MIN_64x64 && result <= MAX_64x64);
return int128 (result);
}
}
/**
* Calculate sqrt (x) rounding down. Revert if x < 0.
*
* @param x signed 64.64-bit fixed point number
* @return signed 64.64-bit fixed point number
*/
function sqrt (int128 x) internal pure returns (int128) {
unchecked {
require (x >= 0);
return int128 (sqrtu (uint256 (int256 (x)) << 64));
}
}
/**
* Calculate binary logarithm of x. Revert if x <= 0.
*
* @param x signed 64.64-bit fixed point number
* @return signed 64.64-bit fixed point number
*/
function log_2 (int128 x) internal pure returns (int128) {
unchecked {
require (x > 0);
int256 msb = 0;
int256 xc = x;
if (xc >= 0x10000000000000000) { xc >>= 64; msb += 64; }
if (xc >= 0x100000000) { xc >>= 32; msb += 32; }
if (xc >= 0x10000) { xc >>= 16; msb += 16; }
if (xc >= 0x100) { xc >>= 8; msb += 8; }
if (xc >= 0x10) { xc >>= 4; msb += 4; }
if (xc >= 0x4) { xc >>= 2; msb += 2; }
if (xc >= 0x2) msb += 1; // No need to shift xc anymore
int256 result = msb - 64 << 64;
uint256 ux = uint256 (int256 (x)) << uint256 (127 - msb);
for (int256 bit = 0x8000000000000000; bit > 0; bit >>= 1) {
ux *= ux;
uint256 b = ux >> 255;
ux >>= 127 + b;
result += bit * int256 (b);
}
return int128 (result);
}
}
/**
* Calculate natural logarithm of x. Revert if x <= 0.
*
* @param x signed 64.64-bit fixed point number
* @return signed 64.64-bit fixed point number
*/
function ln (int128 x) internal pure returns (int128) {
unchecked {
require (x > 0);
return int128 (int256 (
uint256 (int256 (log_2 (x))) * 0xB17217F7D1CF79ABC9E3B39803F2F6AF >> 128));
}
}
/**
* Calculate binary exponent of x. Revert on overflow.
*
* @param x signed 64.64-bit fixed point number
* @return signed 64.64-bit fixed point number
*/
function exp_2 (int128 x) internal pure returns (int128) {
unchecked {
require (x < 0x400000000000000000); // Overflow
if (x < -0x400000000000000000) return 0; // Underflow
uint256 result = 0x80000000000000000000000000000000;
if (x & 0x8000000000000000 > 0)
result = result * 0x16A09E667F3BCC908B2FB1366EA957D3E >> 128;
if (x & 0x4000000000000000 > 0)
result = result * 0x1306FE0A31B7152DE8D5A46305C85EDEC >> 128;
if (x & 0x2000000000000000 > 0)
result = result * 0x1172B83C7D517ADCDF7C8C50EB14A791F >> 128;
if (x & 0x1000000000000000 > 0)
result = result * 0x10B5586CF9890F6298B92B71842A98363 >> 128;
if (x & 0x800000000000000 > 0)
result = result * 0x1059B0D31585743AE7C548EB68CA417FD >> 128;
if (x & 0x400000000000000 > 0)
result = result * 0x102C9A3E778060EE6F7CACA4F7A29BDE8 >> 128;
if (x & 0x200000000000000 > 0)
result = result * 0x10163DA9FB33356D84A66AE336DCDFA3F >> 128;
if (x & 0x100000000000000 > 0)
result = result * 0x100B1AFA5ABCBED6129AB13EC11DC9543 >> 128;
if (x & 0x80000000000000 > 0)
result = result * 0x10058C86DA1C09EA1FF19D294CF2F679B >> 128;
if (x & 0x40000000000000 > 0)
result = result * 0x1002C605E2E8CEC506D21BFC89A23A00F >> 128;
if (x & 0x20000000000000 > 0)
result = result * 0x100162F3904051FA128BCA9C55C31E5DF >> 128;
if (x & 0x10000000000000 > 0)
result = result * 0x1000B175EFFDC76BA38E31671CA939725 >> 128;
if (x & 0x8000000000000 > 0)
result = result * 0x100058BA01FB9F96D6CACD4B180917C3D >> 128;
if (x & 0x4000000000000 > 0)
result = result * 0x10002C5CC37DA9491D0985C348C68E7B3 >> 128;
if (x & 0x2000000000000 > 0)
result = result * 0x1000162E525EE054754457D5995292026 >> 128;
if (x & 0x1000000000000 > 0)
result = result * 0x10000B17255775C040618BF4A4ADE83FC >> 128;
if (x & 0x800000000000 > 0)
result = result * 0x1000058B91B5BC9AE2EED81E9B7D4CFAB >> 128;
if (x & 0x400000000000 > 0)
result = result * 0x100002C5C89D5EC6CA4D7C8ACC017B7C9 >> 128;
if (x & 0x200000000000 > 0)
result = result * 0x10000162E43F4F831060E02D839A9D16D >> 128;
if (x & 0x100000000000 > 0)
result = result * 0x100000B1721BCFC99D9F890EA06911763 >> 128;
if (x & 0x80000000000 > 0)
result = result * 0x10000058B90CF1E6D97F9CA14DBCC1628 >> 128;
if (x & 0x40000000000 > 0)
result = result * 0x1000002C5C863B73F016468F6BAC5CA2B >> 128;
if (x & 0x20000000000 > 0)
result = result * 0x100000162E430E5A18F6119E3C02282A5 >> 128;
if (x & 0x10000000000 > 0)
result = result * 0x1000000B1721835514B86E6D96EFD1BFE >> 128;
if (x & 0x8000000000 > 0)
result = result * 0x100000058B90C0B48C6BE5DF846C5B2EF >> 128;
if (x & 0x4000000000 > 0)
result = result * 0x10000002C5C8601CC6B9E94213C72737A >> 128;
if (x & 0x2000000000 > 0)
result = result * 0x1000000162E42FFF037DF38AA2B219F06 >> 128;
if (x & 0x1000000000 > 0)
result = result * 0x10000000B17217FBA9C739AA5819F44F9 >> 128;
if (x & 0x800000000 > 0)
result = result * 0x1000000058B90BFCDEE5ACD3C1CEDC823 >> 128;
if (x & 0x400000000 > 0)
result = result * 0x100000002C5C85FE31F35A6A30DA1BE50 >> 128;
if (x & 0x200000000 > 0)
result = result * 0x10000000162E42FF0999CE3541B9FFFCF >> 128;
if (x & 0x100000000 > 0)
result = result * 0x100000000B17217F80F4EF5AADDA45554 >> 128;
if (x & 0x80000000 > 0)
result = result * 0x10000000058B90BFBF8479BD5A81B51AD >> 128;
if (x & 0x40000000 > 0)
result = result * 0x1000000002C5C85FDF84BD62AE30A74CC >> 128;
if (x & 0x20000000 > 0)
result = result * 0x100000000162E42FEFB2FED257559BDAA >> 128;
if (x & 0x10000000 > 0)
result = result * 0x1000000000B17217F7D5A7716BBA4A9AE >> 128;
if (x & 0x8000000 > 0)
result = result * 0x100000000058B90BFBE9DDBAC5E109CCE >> 128;
if (x & 0x4000000 > 0)
result = result * 0x10000000002C5C85FDF4B15DE6F17EB0D >> 128;
if (x & 0x2000000 > 0)
result = result * 0x1000000000162E42FEFA494F1478FDE05 >> 128;
if (x & 0x1000000 > 0)
result = result * 0x10000000000B17217F7D20CF927C8E94C >> 128;
if (x & 0x800000 > 0)
result = result * 0x1000000000058B90BFBE8F71CB4E4B33D >> 128;
if (x & 0x400000 > 0)
result = result * 0x100000000002C5C85FDF477B662B26945 >> 128;
if (x & 0x200000 > 0)
result = result * 0x10000000000162E42FEFA3AE53369388C >> 128;
if (x & 0x100000 > 0)
result = result * 0x100000000000B17217F7D1D351A389D40 >> 128;
if (x & 0x80000 > 0)
result = result * 0x10000000000058B90BFBE8E8B2D3D4EDE >> 128;
if (x & 0x40000 > 0)
result = result * 0x1000000000002C5C85FDF4741BEA6E77E >> 128;
if (x & 0x20000 > 0)
result = result * 0x100000000000162E42FEFA39FE95583C2 >> 128;
if (x & 0x10000 > 0)
result = result * 0x1000000000000B17217F7D1CFB72B45E1 >> 128;
if (x & 0x8000 > 0)
result = result * 0x100000000000058B90BFBE8E7CC35C3F0 >> 128;
if (x & 0x4000 > 0)
result = result * 0x10000000000002C5C85FDF473E242EA38 >> 128;
if (x & 0x2000 > 0)
result = result * 0x1000000000000162E42FEFA39F02B772C >> 128;
if (x & 0x1000 > 0)
result = result * 0x10000000000000B17217F7D1CF7D83C1A >> 128;
if (x & 0x800 > 0)
result = result * 0x1000000000000058B90BFBE8E7BDCBE2E >> 128;
if (x & 0x400 > 0)
result = result * 0x100000000000002C5C85FDF473DEA871F >> 128;
if (x & 0x200 > 0)
result = result * 0x10000000000000162E42FEFA39EF44D91 >> 128;
if (x & 0x100 > 0)
result = result * 0x100000000000000B17217F7D1CF79E949 >> 128;
if (x & 0x80 > 0)
result = result * 0x10000000000000058B90BFBE8E7BCE544 >> 128;
if (x & 0x40 > 0)
result = result * 0x1000000000000002C5C85FDF473DE6ECA >> 128;
if (x & 0x20 > 0)
result = result * 0x100000000000000162E42FEFA39EF366F >> 128;
if (x & 0x10 > 0)
result = result * 0x1000000000000000B17217F7D1CF79AFA >> 128;
if (x & 0x8 > 0)
result = result * 0x100000000000000058B90BFBE8E7BCD6D >> 128;
if (x & 0x4 > 0)
result = result * 0x10000000000000002C5C85FDF473DE6B2 >> 128;
if (x & 0x2 > 0)
result = result * 0x1000000000000000162E42FEFA39EF358 >> 128;
if (x & 0x1 > 0)
result = result * 0x10000000000000000B17217F7D1CF79AB >> 128;
result >>= uint256 (int256 (63 - (x >> 64)));
require (result <= uint256 (int256 (MAX_64x64)));
return int128 (int256 (result));
}
}
/**
* Calculate natural exponent of x. Revert on overflow.
*
* @param x signed 64.64-bit fixed point number
* @return signed 64.64-bit fixed point number
*/
function exp (int128 x) internal pure returns (int128) {
unchecked {
require (x < 0x400000000000000000); // Overflow
if (x < -0x400000000000000000) return 0; // Underflow
return exp_2 (
int128 (int256 (x) * 0x171547652B82FE1777D0FFDA0D23A7D12 >> 128));
}
}
/**
* Calculate x / y rounding towards zero, where x and y are unsigned 256-bit
* integer numbers. Revert on overflow or when y is zero.
*
* @param x unsigned 256-bit integer number
* @param y unsigned 256-bit integer number
* @return unsigned 64.64-bit fixed point number
*/
function divuu (uint256 x, uint256 y) private pure returns (uint128) {
unchecked {
require (y != 0);
uint256 result;
if (x <= 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF)
result = (x << 64) / y;
else {
uint256 msb = 192;
uint256 xc = x >> 192;
if (xc >= 0x100000000) { xc >>= 32; msb += 32; }
if (xc >= 0x10000) { xc >>= 16; msb += 16; }
if (xc >= 0x100) { xc >>= 8; msb += 8; }
if (xc >= 0x10) { xc >>= 4; msb += 4; }
if (xc >= 0x4) { xc >>= 2; msb += 2; }
if (xc >= 0x2) msb += 1; // No need to shift xc anymore
result = (x << 255 - msb) / ((y - 1 >> msb - 191) + 1);
require (result <= 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF);
uint256 hi = result * (y >> 128);
uint256 lo = result * (y & 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF);
uint256 xh = x >> 192;
uint256 xl = x << 64;
if (xl < lo) xh -= 1;
xl -= lo; // We rely on overflow behavior here
lo = hi << 128;
if (xl < lo) xh -= 1;
xl -= lo; // We rely on overflow behavior here
assert (xh == hi >> 128);
result += xl / y;
}
require (result <= 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF);
return uint128 (result);
}
}
/**
* Calculate sqrt (x) rounding down, where x is unsigned 256-bit integer
* number.
*
* @param x unsigned 256-bit integer number
* @return unsigned 128-bit integer number
*/
function sqrtu (uint256 x) private pure returns (uint128) {
unchecked {
if (x == 0) return 0;
else {
uint256 xx = x;
uint256 r = 1;
if (xx >= 0x100000000000000000000000000000000) { xx >>= 128; r <<= 64; }
if (xx >= 0x10000000000000000) { xx >>= 64; r <<= 32; }
if (xx >= 0x100000000) { xx >>= 32; r <<= 16; }
if (xx >= 0x10000) { xx >>= 16; r <<= 8; }
if (xx >= 0x100) { xx >>= 8; r <<= 4; }
if (xx >= 0x10) { xx >>= 4; r <<= 2; }
if (xx >= 0x8) { r <<= 1; }
r = (r + x / r) >> 1;
r = (r + x / r) >> 1;
r = (r + x / r) >> 1;
r = (r + x / r) >> 1;
r = (r + x / r) >> 1;
r = (r + x / r) >> 1;
r = (r + x / r) >> 1; // Seven iterations should be enough
uint256 r1 = x / r;
return uint128 (r < r1 ? r : r1);
}
}
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/introspection/IERC165.sol)
pragma solidity ^0.8.0;
/**
* @dev Interface of the ERC165 standard, as defined in the
* https://eips.ethereum.org/EIPS/eip-165[EIP].
*
* Implementers can declare support of contract interfaces, which can then be
* queried by others ({ERC165Checker}).
*
* For an implementation, see {ERC165}.
*/
interface IERC165 {
/**
* @dev Returns true if this contract implements the interface defined by
* `interfaceId`. See the corresponding
* https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
* to learn more about how these ids are created.
*
* This function call must use less than 30 000 gas.
*/
function supportsInterface(bytes4 interfaceId) external view returns (bool);
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)
pragma solidity ^0.8.0;
/**
* @dev Provides information about the current execution context, including the
* sender of the transaction and its data. While these are generally available
* via msg.sender and msg.data, they should not be accessed in such a direct
* manner, since when dealing with meta-transactions the account sending and
* paying for execution may not be the actual sender (as far as an application
* is concerned).
*
* This contract is only required for intermediate, library-like contracts.
*/
abstract contract Context {
function _msgSender() internal view virtual returns (address) {
return msg.sender;
}
function _msgData() internal view virtual returns (bytes calldata) {
return msg.data;
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/IERC20Metadata.sol)
pragma solidity ^0.8.0;
import "../IERC20.sol";
/**
* @dev Interface for the optional metadata functions from the ERC20 standard.
*
* _Available since v4.1._
*/
interface IERC20Metadata is IERC20 {
/**
* @dev Returns the name of the token.
*/
function name() external view returns (string memory);
/**
* @dev Returns the symbol of the token.
*/
function symbol() external view returns (string memory);
/**
* @dev Returns the decimals places of the token.
*/
function decimals() external view returns (uint8);
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/IERC20.sol)
pragma solidity ^0.8.0;
/**
* @dev Interface of the ERC20 standard as defined in the EIP.
*/
interface IERC20 {
/**
* @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);
/**
* @dev Returns the amount of tokens in existence.
*/
function totalSupply() external view returns (uint256);
/**
* @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 `to`.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* Emits a {Transfer} event.
*/
function transfer(address to, 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 `from` to `to` 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 from,
address to,
uint256 amount
) external returns (bool);
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (token/ERC20/ERC20.sol)
pragma solidity ^0.8.0;
import "./IERC20.sol";
import "./extensions/IERC20Metadata.sol";
import "../../utils/Context.sol";
/**
* @dev Implementation of the {IERC20} interface.
*
* This implementation is agnostic to the way tokens are created. This means
* that a supply mechanism has to be added in a derived contract using {_mint}.
* For a generic mechanism see {ERC20PresetMinterPauser}.
*
* TIP: For a detailed writeup see our guide
* https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
* to implement supply mechanisms].
*
* We have followed general OpenZeppelin Contracts guidelines: functions revert
* instead returning `false` on failure. This behavior is nonetheless
* conventional and does not conflict with the expectations of ERC20
* applications.
*
* Additionally, an {Approval} event is emitted on calls to {transferFrom}.
* This allows applications to reconstruct the allowance for all accounts just
* by listening to said events. Other implementations of the EIP may not emit
* these events, as it isn't required by the specification.
*
* Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
* functions have been added to mitigate the well-known issues around setting
* allowances. See {IERC20-approve}.
*/
contract ERC20 is Context, IERC20, IERC20Metadata {
mapping(address => uint256) private _balances;
mapping(address => mapping(address => uint256)) private _allowances;
uint256 private _totalSupply;
string private _name;
string private _symbol;
/**
* @dev Sets the values for {name} and {symbol}.
*
* The default value of {decimals} is 18. To select a different value for
* {decimals} you should overload it.
*
* All two of these values are immutable: they can only be set once during
* construction.
*/
constructor(string memory name_, string memory symbol_) {
_name = name_;
_symbol = symbol_;
}
/**
* @dev Returns the name of the token.
*/
function name() public view virtual override returns (string memory) {
return _name;
}
/**
* @dev Returns the symbol of the token, usually a shorter version of the
* name.
*/
function symbol() public view virtual override returns (string memory) {
return _symbol;
}
/**
* @dev Returns the number of decimals used to get its user representation.
* For example, if `decimals` equals `2`, a balance of `505` tokens should
* be displayed to a user as `5.05` (`505 / 10 ** 2`).
*
* Tokens usually opt for a value of 18, imitating the relationship between
* Ether and Wei. This is the value {ERC20} uses, unless this function is
* overridden;
*
* NOTE: This information is only used for _display_ purposes: it in
* no way affects any of the arithmetic of the contract, including
* {IERC20-balanceOf} and {IERC20-transfer}.
*/
function decimals() public view virtual override returns (uint8) {
return 18;
}
/**
* @dev See {IERC20-totalSupply}.
*/
function totalSupply() public view virtual override returns (uint256) {
return _totalSupply;
}
/**
* @dev See {IERC20-balanceOf}.
*/
function balanceOf(address account) public view virtual override returns (uint256) {
return _balances[account];
}
/**
* @dev See {IERC20-transfer}.
*
* Requirements:
*
* - `to` cannot be the zero address.
* - the caller must have a balance of at least `amount`.
*/
function transfer(address to, uint256 amount) public virtual override returns (bool) {
address owner = _msgSender();
_transfer(owner, to, amount);
return true;
}
/**
* @dev See {IERC20-allowance}.
*/
function allowance(address owner, address spender) public view virtual override returns (uint256) {
return _allowances[owner][spender];
}
/**
* @dev See {IERC20-approve}.
*
* NOTE: If `amount` is the maximum `uint256`, the allowance is not updated on
* `transferFrom`. This is semantically equivalent to an infinite approval.
*
* Requirements:
*
* - `spender` cannot be the zero address.
*/
function approve(address spender, uint256 amount) public virtual override returns (bool) {
address owner = _msgSender();
_approve(owner, spender, amount);
return true;
}
/**
* @dev See {IERC20-transferFrom}.
*
* Emits an {Approval} event indicating the updated allowance. This is not
* required by the EIP. See the note at the beginning of {ERC20}.
*
* NOTE: Does not update the allowance if the current allowance
* is the maximum `uint256`.
*
* Requirements:
*
* - `from` and `to` cannot be the zero address.
* - `from` must have a balance of at least `amount`.
* - the caller must have allowance for ``from``'s tokens of at least
* `amount`.
*/
function transferFrom(
address from,
address to,
uint256 amount
) public virtual override returns (bool) {
address spender = _msgSender();
_spendAllowance(from, spender, amount);
_transfer(from, to, amount);
return true;
}
/**
* @dev Atomically increases the allowance granted to `spender` by the caller.
*
* This is an alternative to {approve} that can be used as a mitigation for
* problems described in {IERC20-approve}.
*
* Emits an {Approval} event indicating the updated allowance.
*
* Requirements:
*
* - `spender` cannot be the zero address.
*/
function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
address owner = _msgSender();
_approve(owner, spender, allowance(owner, spender) + addedValue);
return true;
}
/**
* @dev Atomically decreases the allowance granted to `spender` by the caller.
*
* This is an alternative to {approve} that can be used as a mitigation for
* problems described in {IERC20-approve}.
*
* Emits an {Approval} event indicating the updated allowance.
*
* Requirements:
*
* - `spender` cannot be the zero address.
* - `spender` must have allowance for the caller of at least
* `subtractedValue`.
*/
function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
address owner = _msgSender();
uint256 currentAllowance = allowance(owner, spender);
require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
unchecked {
_approve(owner, spender, currentAllowance - subtractedValue);
}
return true;
}
/**
* @dev Moves `amount` of tokens from `from` to `to`.
*
* This internal function is equivalent to {transfer}, and can be used to
* e.g. implement automatic token fees, slashing mechanisms, etc.
*
* Emits a {Transfer} event.
*
* Requirements:
*
* - `from` cannot be the zero address.
* - `to` cannot be the zero address.
* - `from` must have a balance of at least `amount`.
*/
function _transfer(
address from,
address to,
uint256 amount
) internal virtual {
require(from != address(0), "ERC20: transfer from the zero address");
require(to != address(0), "ERC20: transfer to the zero address");
_beforeTokenTransfer(from, to, amount);
uint256 fromBalance = _balances[from];
require(fromBalance >= amount, "ERC20: transfer amount exceeds balance");
unchecked {
_balances[from] = fromBalance - amount;
}
_balances[to] += amount;
emit Transfer(from, to, amount);
_afterTokenTransfer(from, to, amount);
}
/** @dev Creates `amount` tokens and assigns them to `account`, increasing
* the total supply.
*
* Emits a {Transfer} event with `from` set to the zero address.
*
* Requirements:
*
* - `account` cannot be the zero address.
*/
function _mint(address account, uint256 amount) internal virtual {
require(account != address(0), "ERC20: mint to the zero address");
_beforeTokenTransfer(address(0), account, amount);
_totalSupply += amount;
_balances[account] += amount;
emit Transfer(address(0), account, amount);
_afterTokenTransfer(address(0), account, amount);
}
/**
* @dev Destroys `amount` tokens from `account`, reducing the
* total supply.
*
* Emits a {Transfer} event with `to` set to the zero address.
*
* Requirements:
*
* - `account` cannot be the zero address.
* - `account` must have at least `amount` tokens.
*/
function _burn(address account, uint256 amount) internal virtual {
require(account != address(0), "ERC20: burn from the zero address");
_beforeTokenTransfer(account, address(0), amount);
uint256 accountBalance = _balances[account];
require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
unchecked {
_balances[account] = accountBalance - amount;
}
_totalSupply -= amount;
emit Transfer(account, address(0), amount);
_afterTokenTransfer(account, address(0), amount);
}
/**
* @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
*
* This internal function is equivalent to `approve`, and can be used to
* e.g. set automatic allowances for certain subsystems, etc.
*
* Emits an {Approval} event.
*
* Requirements:
*
* - `owner` cannot be the zero address.
* - `spender` cannot be the zero address.
*/
function _approve(
address owner,
address spender,
uint256 amount
) internal virtual {
require(owner != address(0), "ERC20: approve from the zero address");
require(spender != address(0), "ERC20: approve to the zero address");
_allowances[owner][spender] = amount;
emit Approval(owner, spender, amount);
}
/**
* @dev Updates `owner` s allowance for `spender` based on spent `amount`.
*
* Does not update the allowance amount in case of infinite allowance.
* Revert if not enough allowance is available.
*
* Might emit an {Approval} event.
*/
function _spendAllowance(
address owner,
address spender,
uint256 amount
) internal virtual {
uint256 currentAllowance = allowance(owner, spender);
if (currentAllowance != type(uint256).max) {
require(currentAllowance >= amount, "ERC20: insufficient allowance");
unchecked {
_approve(owner, spender, currentAllowance - amount);
}
}
}
/**
* @dev Hook that is called before any transfer of tokens. This includes
* minting and burning.
*
* Calling conditions:
*
* - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
* will be transferred to `to`.
* - when `from` is zero, `amount` tokens will be minted for `to`.
* - when `to` is zero, `amount` of ``from``'s tokens will be burned.
* - `from` and `to` are never both zero.
*
* To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
*/
function _beforeTokenTransfer(
address from,
address to,
uint256 amount
) internal virtual {}
/**
* @dev Hook that is called after any transfer of tokens. This includes
* minting and burning.
*
* Calling conditions:
*
* - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
* has been transferred to `to`.
* - when `from` is zero, `amount` tokens have been minted for `to`.
* - when `to` is zero, `amount` of ``from``'s tokens have been burned.
* - `from` and `to` are never both zero.
*
* To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
*/
function _afterTokenTransfer(
address from,
address to,
uint256 amount
) internal virtual {}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (interfaces/IERC165.sol)
pragma solidity ^0.8.0;
import "../utils/introspection/IERC165.sol";