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Minimal Proxy Contract for 0x33bb0e62d5e8c688e645dd46dfb48cd613250067
Contract Name:
Vyper_contract
Compiler Version
vyper:0.3.1
Contract Source Code (Vyper language format)
# @version 0.3.1 """ @title StableSwap @author Curve.Fi @license Copyright (c) Curve.Fi, 2020-2021 - all rights reserved @notice 3pool metapool implementation contract @dev ERC20 support for return True/revert, return True/False, return None """ interface ERC20: def approve(_spender: address, _amount: uint256): nonpayable def balanceOf(_owner: address) -> uint256: view interface Curve: def coins(i: uint256) -> address: view def get_virtual_price() -> uint256: view def calc_token_amount(amounts: uint256[BASE_N_COINS], deposit: bool) -> uint256: view def calc_withdraw_one_coin(_token_amount: uint256, i: int128) -> uint256: view def fee() -> uint256: view def get_dy(i: int128, j: int128, dx: uint256) -> uint256: view def exchange(i: int128, j: int128, dx: uint256, min_dy: uint256): nonpayable def add_liquidity(amounts: uint256[BASE_N_COINS], min_mint_amount: uint256): nonpayable def remove_liquidity_one_coin(_token_amount: uint256, i: int128, min_amount: uint256): nonpayable interface Factory: def convert_metapool_fees() -> bool: nonpayable def get_fee_receiver(_pool: address) -> address: view def admin() -> address: view interface ERC1271: def isValidSignature(_hash: bytes32, _signature: Bytes[65]) -> bytes32: view event Transfer: sender: indexed(address) receiver: indexed(address) value: uint256 event Approval: owner: indexed(address) spender: indexed(address) value: uint256 event TokenExchange: buyer: indexed(address) sold_id: int128 tokens_sold: uint256 bought_id: int128 tokens_bought: uint256 event TokenExchangeUnderlying: buyer: indexed(address) sold_id: int128 tokens_sold: uint256 bought_id: int128 tokens_bought: uint256 event AddLiquidity: provider: indexed(address) token_amounts: uint256[N_COINS] fees: uint256[N_COINS] invariant: uint256 token_supply: uint256 event RemoveLiquidity: provider: indexed(address) token_amounts: uint256[N_COINS] fees: uint256[N_COINS] token_supply: uint256 event RemoveLiquidityOne: provider: indexed(address) token_amount: uint256 coin_amount: uint256 token_supply: uint256 event RemoveLiquidityImbalance: provider: indexed(address) token_amounts: uint256[N_COINS] fees: uint256[N_COINS] invariant: uint256 token_supply: uint256 event RampA: old_A: uint256 new_A: uint256 initial_time: uint256 future_time: uint256 event StopRampA: A: uint256 t: uint256 BASE_POOL: constant(address) = 0xDcEF968d416a41Cdac0ED8702fAC8128A64241A2 BASE_N_COINS: constant(int128) = 2 BASE_COINS: constant(address[BASE_N_COINS]) = [0x853d955aCEf822Db058eb8505911ED77F175b99e, 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48] BASE_LP_TOKEN: constant(address) = 0x3175Df0976dFA876431C2E9eE6Bc45b65d3473CC N_COINS: constant(int128) = 2 MAX_COIN: constant(int128) = N_COINS - 1 PRECISION: constant(uint256) = 10 ** 18 FEE_DENOMINATOR: constant(uint256) = 10 ** 10 ADMIN_FEE: constant(uint256) = 5000000000 A_PRECISION: constant(uint256) = 100 MAX_A: constant(uint256) = 10 ** 6 MAX_A_CHANGE: constant(uint256) = 10 MIN_RAMP_TIME: constant(uint256) = 86400 EIP712_TYPEHASH: constant(bytes32) = keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)") PERMIT_TYPEHASH: constant(bytes32) = keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)") # keccak256("isValidSignature(bytes32,bytes)")[:4] << 224 ERC1271_MAGIC_VAL: constant(bytes32) = 0x1626ba7e00000000000000000000000000000000000000000000000000000000 VERSION: constant(String[8]) = "v5.0.0" factory: address coins: public(address[N_COINS]) balances: public(uint256[N_COINS]) fee: public(uint256) # fee * 1e10 initial_A: public(uint256) future_A: public(uint256) initial_A_time: public(uint256) future_A_time: public(uint256) rate_multiplier: uint256 name: public(String[64]) symbol: public(String[32]) balanceOf: public(HashMap[address, uint256]) allowance: public(HashMap[address, HashMap[address, uint256]]) totalSupply: public(uint256) DOMAIN_SEPARATOR: public(bytes32) nonces: public(HashMap[address, uint256]) @external def __init__(): # we do this to prevent the implementation contract from being used as a pool self.fee = 31337 @external def initialize( _name: String[32], _symbol: String[10], _coin: address, _rate_multiplier: uint256, _A: uint256, _fee: uint256 ): """ @notice Contract initializer @param _name Name of the new pool @param _symbol Token symbol @param _coin Addresses of ERC20 conracts of coins @param _rate_multiplier Rate multiplier for `_coin` (10 ** (36 - decimals)) @param _A Amplification coefficient multiplied by n ** (n - 1) @param _fee Fee to charge for exchanges """ # check if fee was already set to prevent initializing contract twice assert self.fee == 0 A: uint256 = _A * A_PRECISION self.coins = [_coin, BASE_LP_TOKEN] self.rate_multiplier = _rate_multiplier self.initial_A = A self.future_A = A self.fee = _fee self.factory = msg.sender name: String[64] = concat("Curve.fi Factory USD Metapool: ", _name) self.name = name self.symbol = concat(_symbol, "3CRV-f") for coin in BASE_COINS: ERC20(coin).approve(BASE_POOL, MAX_UINT256) self.DOMAIN_SEPARATOR = keccak256( _abi_encode(EIP712_TYPEHASH, keccak256(name), keccak256(VERSION), chain.id, self) ) # fire a transfer event so block explorers identify the contract as an ERC20 log Transfer(ZERO_ADDRESS, self, 0) ### ERC20 Functionality ### @view @external def decimals() -> uint256: """ @notice Get the number of decimals for this token @dev Implemented as a view method to reduce gas costs @return uint256 decimal places """ return 18 @internal def _transfer(_from: address, _to: address, _value: uint256): # # NOTE: vyper does not allow underflows # # so the following subtraction would revert on insufficient balance self.balanceOf[_from] -= _value self.balanceOf[_to] += _value log Transfer(_from, _to, _value) @external def transfer(_to : address, _value : uint256) -> bool: """ @dev Transfer token for a specified address @param _to The address to transfer to. @param _value The amount to be transferred. """ self._transfer(msg.sender, _to, _value) return True @external def transferFrom(_from : address, _to : address, _value : uint256) -> bool: """ @dev Transfer tokens from one address to another. @param _from address The address which you want to send tokens from @param _to address The address which you want to transfer to @param _value uint256 the amount of tokens to be transferred """ self._transfer(_from, _to, _value) _allowance: uint256 = self.allowance[_from][msg.sender] if _allowance != MAX_UINT256: self.allowance[_from][msg.sender] = _allowance - _value return True @external def approve(_spender : address, _value : uint256) -> bool: """ @notice Approve the passed address to transfer the specified amount of tokens on behalf of msg.sender @dev Beware that changing an allowance via this method brings the risk that someone may use both the old and new allowance by unfortunate transaction ordering: https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729 @param _spender The address which will transfer the funds @param _value The amount of tokens that may be transferred @return bool success """ self.allowance[msg.sender][_spender] = _value log Approval(msg.sender, _spender, _value) return True @external def permit( _owner: address, _spender: address, _value: uint256, _deadline: uint256, _v: uint8, _r: bytes32, _s: bytes32 ) -> bool: """ @notice Approves spender by owner's signature to expend owner's tokens. See https://eips.ethereum.org/EIPS/eip-2612. @dev Inspired by https://github.com/yearn/yearn-vaults/blob/main/contracts/Vault.vy#L753-L793 @dev Supports smart contract wallets which implement ERC1271 https://eips.ethereum.org/EIPS/eip-1271 @param _owner The address which is a source of funds and has signed the Permit. @param _spender The address which is allowed to spend the funds. @param _value The amount of tokens to be spent. @param _deadline The timestamp after which the Permit is no longer valid. @param _v The bytes[64] of the valid secp256k1 signature of permit by owner @param _r The bytes[0:32] of the valid secp256k1 signature of permit by owner @param _s The bytes[32:64] of the valid secp256k1 signature of permit by owner @return True, if transaction completes successfully """ assert _owner != ZERO_ADDRESS assert block.timestamp <= _deadline nonce: uint256 = self.nonces[_owner] digest: bytes32 = keccak256( concat( b"\x19\x01", self.DOMAIN_SEPARATOR, keccak256(_abi_encode(PERMIT_TYPEHASH, _owner, _spender, _value, nonce, _deadline)) ) ) if _owner.is_contract: sig: Bytes[65] = concat(_abi_encode(_r, _s), slice(convert(_v, bytes32), 31, 1)) # reentrancy not a concern since this is a staticcall assert ERC1271(_owner).isValidSignature(digest, sig) == ERC1271_MAGIC_VAL else: assert ecrecover(digest, convert(_v, uint256), convert(_r, uint256), convert(_s, uint256)) == _owner self.allowance[_owner][_spender] = _value self.nonces[_owner] = nonce + 1 log Approval(_owner, _spender, _value) return True ### StableSwap Functionality ### @view @internal def _A() -> uint256: """ Handle ramping A up or down """ t1: uint256 = self.future_A_time A1: uint256 = self.future_A if block.timestamp < t1: A0: uint256 = self.initial_A t0: uint256 = self.initial_A_time # Expressions in uint256 cannot have negative numbers, thus "if" if A1 > A0: return A0 + (A1 - A0) * (block.timestamp - t0) / (t1 - t0) else: return A0 - (A0 - A1) * (block.timestamp - t0) / (t1 - t0) else: # when t1 == 0 or block.timestamp >= t1 return A1 @view @external def admin_fee() -> uint256: return ADMIN_FEE @view @external def A() -> uint256: return self._A() / A_PRECISION @view @external def A_precise() -> uint256: return self._A() @pure @internal def _xp_mem(_rates: uint256[N_COINS], _balances: uint256[N_COINS]) -> uint256[N_COINS]: result: uint256[N_COINS] = empty(uint256[N_COINS]) for i in range(N_COINS): result[i] = _rates[i] * _balances[i] / PRECISION return result @pure @internal def get_D(_xp: uint256[N_COINS], _amp: uint256) -> uint256: """ D invariant calculation in non-overflowing integer operations iteratively A * sum(x_i) * n**n + D = A * D * n**n + D**(n+1) / (n**n * prod(x_i)) Converging solution: D[j+1] = (A * n**n * sum(x_i) - D[j]**(n+1) / (n**n prod(x_i))) / (A * n**n - 1) """ S: uint256 = 0 Dprev: uint256 = 0 for x in _xp: S += x if S == 0: return 0 D: uint256 = S Ann: uint256 = _amp * N_COINS for i in range(255): D_P: uint256 = D for x in _xp: D_P = D_P * D / (x * N_COINS) # If division by 0, this will be borked: only withdrawal will work. And that is good Dprev = D D = (Ann * S / A_PRECISION + D_P * N_COINS) * D / ((Ann - A_PRECISION) * D / A_PRECISION + (N_COINS + 1) * D_P) # Equality with the precision of 1 if D > Dprev: if D - Dprev <= 1: return D else: if Dprev - D <= 1: return D # convergence typically occurs in 4 rounds or less, this should be unreachable! # if it does happen the pool is borked and LPs can withdraw via `remove_liquidity` raise @view @internal def get_D_mem(_rates: uint256[N_COINS], _balances: uint256[N_COINS], _amp: uint256) -> uint256: xp: uint256[N_COINS] = self._xp_mem(_rates, _balances) return self.get_D(xp, _amp) @view @external def get_virtual_price() -> uint256: """ @notice The current virtual price of the pool LP token @dev Useful for calculating profits @return LP token virtual price normalized to 1e18 """ amp: uint256 = self._A() rates: uint256[N_COINS] = [self.rate_multiplier, Curve(BASE_POOL).get_virtual_price()] xp: uint256[N_COINS] = self._xp_mem(rates, self.balances) D: uint256 = self.get_D(xp, amp) # D is in the units similar to DAI (e.g. converted to precision 1e18) # When balanced, D = n * x_u - total virtual value of the portfolio return D * PRECISION / self.totalSupply @view @external def calc_token_amount(_amounts: uint256[N_COINS], _is_deposit: bool) -> uint256: """ @notice Calculate addition or reduction in token supply from a deposit or withdrawal @dev This calculation accounts for slippage, but not fees. Needed to prevent front-running, not for precise calculations! @param _amounts Amount of each coin being deposited @param _is_deposit set True for deposits, False for withdrawals @return Expected amount of LP tokens received """ amp: uint256 = self._A() rates: uint256[N_COINS] = [self.rate_multiplier, Curve(BASE_POOL).get_virtual_price()] balances: uint256[N_COINS] = self.balances D0: uint256 = self.get_D_mem(rates, balances, amp) for i in range(N_COINS): amount: uint256 = _amounts[i] if _is_deposit: balances[i] += amount else: balances[i] -= amount D1: uint256 = self.get_D_mem(rates, balances, amp) diff: uint256 = 0 if _is_deposit: diff = D1 - D0 else: diff = D0 - D1 return diff * self.totalSupply / D0 @external @nonreentrant('lock') def add_liquidity( _amounts: uint256[N_COINS], _min_mint_amount: uint256, _receiver: address = msg.sender ) -> uint256: """ @notice Deposit coins into the pool @param _amounts List of amounts of coins to deposit @param _min_mint_amount Minimum amount of LP tokens to mint from the deposit @param _receiver Address that owns the minted LP tokens @return Amount of LP tokens received by depositing """ amp: uint256 = self._A() rates: uint256[N_COINS] = [self.rate_multiplier, Curve(BASE_POOL).get_virtual_price()] # Initial invariant old_balances: uint256[N_COINS] = self.balances D0: uint256 = self.get_D_mem(rates, old_balances, amp) new_balances: uint256[N_COINS] = old_balances total_supply: uint256 = self.totalSupply for i in range(N_COINS): amount: uint256 = _amounts[i] if amount == 0: assert total_supply > 0 else: response: Bytes[32] = raw_call( self.coins[i], _abi_encode( msg.sender, self, amount, method_id=method_id("transferFrom(address,address,uint256)") ), max_outsize=32, ) if len(response) > 0: assert convert(response, bool) new_balances[i] += amount # Invariant after change D1: uint256 = self.get_D_mem(rates, new_balances, amp) assert D1 > D0 # We need to recalculate the invariant accounting for fees # to calculate fair user's share fees: uint256[N_COINS] = empty(uint256[N_COINS]) mint_amount: uint256 = 0 if total_supply > 0: # Only account for fees if we are not the first to deposit base_fee: uint256 = self.fee * N_COINS / (4 * (N_COINS - 1)) for i in range(N_COINS): ideal_balance: uint256 = D1 * old_balances[i] / D0 difference: uint256 = 0 new_balance: uint256 = new_balances[i] if ideal_balance > new_balance: difference = ideal_balance - new_balance else: difference = new_balance - ideal_balance fees[i] = base_fee * difference / FEE_DENOMINATOR self.balances[i] = new_balance - (fees[i] * ADMIN_FEE / FEE_DENOMINATOR) new_balances[i] -= fees[i] D2: uint256 = self.get_D_mem(rates, new_balances, amp) mint_amount = total_supply * (D2 - D0) / D0 else: self.balances = new_balances mint_amount = D1 # Take the dust if there was any assert mint_amount >= _min_mint_amount # Mint pool tokens total_supply += mint_amount self.balanceOf[_receiver] += mint_amount self.totalSupply = total_supply log Transfer(ZERO_ADDRESS, _receiver, mint_amount) log AddLiquidity(msg.sender, _amounts, fees, D1, total_supply) return mint_amount @view @internal def get_y(i: int128, j: int128, x: uint256, xp: uint256[N_COINS]) -> uint256: # x in the input is converted to the same price/precision assert i != j # dev: same coin assert j >= 0 # dev: j below zero assert j < N_COINS # dev: j above N_COINS # should be unreachable, but good for safety assert i >= 0 assert i < N_COINS amp: uint256 = self._A() D: uint256 = self.get_D(xp, amp) S_: uint256 = 0 _x: uint256 = 0 y_prev: uint256 = 0 c: uint256 = D Ann: uint256 = amp * N_COINS for _i in range(N_COINS): if _i == i: _x = x elif _i != j: _x = xp[_i] else: continue S_ += _x c = c * D / (_x * N_COINS) c = c * D * A_PRECISION / (Ann * N_COINS) b: uint256 = S_ + D * A_PRECISION / Ann # - D y: uint256 = D for _i in range(255): y_prev = y y = (y*y + c) / (2 * y + b - D) # Equality with the precision of 1 if y > y_prev: if y - y_prev <= 1: return y else: if y_prev - y <= 1: return y raise @view @external def get_dy(i: int128, j: int128, dx: uint256) -> uint256: """ @notice Calculate the current output dy given input dx @dev Index values can be found via the `coins` public getter method @param i Index value for the coin to send @param j Index valie of the coin to recieve @param dx Amount of `i` being exchanged @return Amount of `j` predicted """ rates: uint256[N_COINS] = [self.rate_multiplier, Curve(BASE_POOL).get_virtual_price()] xp: uint256[N_COINS] = self._xp_mem(rates, self.balances) x: uint256 = xp[i] + (dx * rates[i] / PRECISION) y: uint256 = self.get_y(i, j, x, xp) dy: uint256 = xp[j] - y - 1 fee: uint256 = self.fee * dy / FEE_DENOMINATOR return (dy - fee) * PRECISION / rates[j] @view @external def get_dy_underlying(i: int128, j: int128, dx: uint256) -> uint256: """ @notice Calculate the current output dy given input dx on underlying @dev Index values can be found via the `coins` public getter method @param i Index value for the coin to send @param j Index valie of the coin to recieve @param dx Amount of `i` being exchanged @return Amount of `j` predicted """ rates: uint256[N_COINS] = [self.rate_multiplier, Curve(BASE_POOL).get_virtual_price()] xp: uint256[N_COINS] = self._xp_mem(rates, self.balances) x: uint256 = 0 base_i: int128 = 0 base_j: int128 = 0 meta_i: int128 = 0 meta_j: int128 = 0 if i != 0: base_i = i - MAX_COIN meta_i = 1 if j != 0: base_j = j - MAX_COIN meta_j = 1 if i == 0: x = xp[i] + dx * (rates[0] / 10**18) else: if j == 0: # i is from BasePool # At first, get the amount of pool tokens base_inputs: uint256[BASE_N_COINS] = empty(uint256[BASE_N_COINS]) base_inputs[base_i] = dx # Token amount transformed to underlying "dollars" x = Curve(BASE_POOL).calc_token_amount(base_inputs, True) * rates[1] / PRECISION # Accounting for deposit/withdraw fees approximately x -= x * Curve(BASE_POOL).fee() / (2 * FEE_DENOMINATOR) # Adding number of pool tokens x += xp[MAX_COIN] else: # If both are from the base pool return Curve(BASE_POOL).get_dy(base_i, base_j, dx) # This pool is involved only when in-pool assets are used y: uint256 = self.get_y(meta_i, meta_j, x, xp) dy: uint256 = xp[meta_j] - y - 1 dy = (dy - self.fee * dy / FEE_DENOMINATOR) # If output is going via the metapool if j == 0: dy /= (rates[0] / 10**18) else: # j is from BasePool # The fee is already accounted for dy = Curve(BASE_POOL).calc_withdraw_one_coin(dy * PRECISION / rates[1], base_j) return dy @external @nonreentrant('lock') def exchange( i: int128, j: int128, _dx: uint256, _min_dy: uint256, _receiver: address = msg.sender, ) -> uint256: """ @notice Perform an exchange between two coins @dev Index values can be found via the `coins` public getter method @param i Index value for the coin to send @param j Index valie of the coin to recieve @param _dx Amount of `i` being exchanged @param _min_dy Minimum amount of `j` to receive @param _receiver Address that receives `j` @return Actual amount of `j` received """ rates: uint256[N_COINS] = [self.rate_multiplier, Curve(BASE_POOL).get_virtual_price()] old_balances: uint256[N_COINS] = self.balances xp: uint256[N_COINS] = self._xp_mem(rates, old_balances) x: uint256 = xp[i] + _dx * rates[i] / PRECISION y: uint256 = self.get_y(i, j, x, xp) dy: uint256 = xp[j] - y - 1 # -1 just in case there were some rounding errors dy_fee: uint256 = dy * self.fee / FEE_DENOMINATOR # Convert all to real units dy = (dy - dy_fee) * PRECISION / rates[j] assert dy >= _min_dy dy_admin_fee: uint256 = dy_fee * ADMIN_FEE / FEE_DENOMINATOR dy_admin_fee = dy_admin_fee * PRECISION / rates[j] # Change balances exactly in same way as we change actual ERC20 coin amounts self.balances[i] = old_balances[i] + _dx # When rounding errors happen, we undercharge admin fee in favor of LP self.balances[j] = old_balances[j] - dy - dy_admin_fee response: Bytes[32] = raw_call( self.coins[i], _abi_encode( msg.sender, self, _dx, method_id=method_id("transferFrom(address,address,uint256)") ), max_outsize=32, ) if len(response) > 0: assert convert(response, bool) response = raw_call( self.coins[j], _abi_encode(_receiver, dy, method_id=method_id("transfer(address,uint256)")), max_outsize=32, ) if len(response) > 0: assert convert(response, bool) log TokenExchange(msg.sender, i, _dx, j, dy) return dy @external @nonreentrant('lock') def exchange_underlying( i: int128, j: int128, _dx: uint256, _min_dy: uint256, _receiver: address = msg.sender, ) -> uint256: """ @notice Perform an exchange between two underlying coins @param i Index value for the underlying coin to send @param j Index valie of the underlying coin to receive @param _dx Amount of `i` being exchanged @param _min_dy Minimum amount of `j` to receive @param _receiver Address that receives `j` @return Actual amount of `j` received """ rates: uint256[N_COINS] = [self.rate_multiplier, Curve(BASE_POOL).get_virtual_price()] old_balances: uint256[N_COINS] = self.balances xp: uint256[N_COINS] = self._xp_mem(rates, old_balances) base_coins: address[BASE_N_COINS] = BASE_COINS dy: uint256 = 0 base_i: int128 = 0 base_j: int128 = 0 meta_i: int128 = 0 meta_j: int128 = 0 x: uint256 = 0 input_coin: address = ZERO_ADDRESS output_coin: address = ZERO_ADDRESS if i == 0: input_coin = self.coins[0] else: base_i = i - MAX_COIN meta_i = 1 input_coin = base_coins[base_i] if j == 0: output_coin = self.coins[0] else: base_j = j - MAX_COIN meta_j = 1 output_coin = base_coins[base_j] response: Bytes[32] = raw_call( input_coin, _abi_encode( msg.sender, self, _dx, method_id=method_id("transferFrom(address,address,uint256)") ), max_outsize=32, ) if len(response) > 0: assert convert(response, bool) dx: uint256 = _dx if i == 0 or j == 0: if i == 0: x = xp[i] + dx * rates[i] / PRECISION else: # i is from BasePool # At first, get the amount of pool tokens base_inputs: uint256[BASE_N_COINS] = empty(uint256[BASE_N_COINS]) base_inputs[base_i] = dx coin_i: address = self.coins[MAX_COIN] # Deposit and measure delta x = ERC20(coin_i).balanceOf(self) Curve(BASE_POOL).add_liquidity(base_inputs, 0) # Need to convert pool token to "virtual" units using rates # dx is also different now dx = ERC20(coin_i).balanceOf(self) - x x = dx * rates[MAX_COIN] / PRECISION # Adding number of pool tokens x += xp[MAX_COIN] y: uint256 = self.get_y(meta_i, meta_j, x, xp) # Either a real coin or token dy = xp[meta_j] - y - 1 # -1 just in case there were some rounding errors dy_fee: uint256 = dy * self.fee / FEE_DENOMINATOR # Convert all to real units # Works for both pool coins and real coins dy = (dy - dy_fee) * PRECISION / rates[meta_j] dy_admin_fee: uint256 = dy_fee * ADMIN_FEE / FEE_DENOMINATOR dy_admin_fee = dy_admin_fee * PRECISION / rates[meta_j] # Change balances exactly in same way as we change actual ERC20 coin amounts self.balances[meta_i] = old_balances[meta_i] + dx # When rounding errors happen, we undercharge admin fee in favor of LP self.balances[meta_j] = old_balances[meta_j] - dy - dy_admin_fee # Withdraw from the base pool if needed if j > 0: out_amount: uint256 = ERC20(output_coin).balanceOf(self) Curve(BASE_POOL).remove_liquidity_one_coin(dy, base_j, 0) dy = ERC20(output_coin).balanceOf(self) - out_amount assert dy >= _min_dy else: # If both are from the base pool dy = ERC20(output_coin).balanceOf(self) Curve(BASE_POOL).exchange(base_i, base_j, dx, _min_dy) dy = ERC20(output_coin).balanceOf(self) - dy response = raw_call( output_coin, _abi_encode(_receiver, dy, method_id=method_id("transfer(address,uint256)")), max_outsize=32, ) if len(response) > 0: assert convert(response, bool) log TokenExchangeUnderlying(msg.sender, i, dx, j, dy) return dy @external @nonreentrant('lock') def remove_liquidity( _burn_amount: uint256, _min_amounts: uint256[N_COINS], _receiver: address = msg.sender ) -> uint256[N_COINS]: """ @notice Withdraw coins from the pool @dev Withdrawal amounts are based on current deposit ratios @param _burn_amount Quantity of LP tokens to burn in the withdrawal @param _min_amounts Minimum amounts of underlying coins to receive @param _receiver Address that receives the withdrawn coins @return List of amounts of coins that were withdrawn """ total_supply: uint256 = self.totalSupply amounts: uint256[N_COINS] = empty(uint256[N_COINS]) for i in range(N_COINS): old_balance: uint256 = self.balances[i] value: uint256 = old_balance * _burn_amount / total_supply assert value >= _min_amounts[i] self.balances[i] = old_balance - value amounts[i] = value response: Bytes[32] = raw_call( self.coins[i], _abi_encode(_receiver, value, method_id=method_id("transfer(address,uint256)")), max_outsize=32, ) if len(response) > 0: assert convert(response, bool) total_supply -= _burn_amount self.balanceOf[msg.sender] -= _burn_amount self.totalSupply = total_supply log Transfer(msg.sender, ZERO_ADDRESS, _burn_amount) log RemoveLiquidity(msg.sender, amounts, empty(uint256[N_COINS]), total_supply) return amounts @external @nonreentrant('lock') def remove_liquidity_imbalance( _amounts: uint256[N_COINS], _max_burn_amount: uint256, _receiver: address = msg.sender ) -> uint256: """ @notice Withdraw coins from the pool in an imbalanced amount @param _amounts List of amounts of underlying coins to withdraw @param _max_burn_amount Maximum amount of LP token to burn in the withdrawal @param _receiver Address that receives the withdrawn coins @return Actual amount of the LP token burned in the withdrawal """ amp: uint256 = self._A() rates: uint256[N_COINS] = [self.rate_multiplier, Curve(BASE_POOL).get_virtual_price()] old_balances: uint256[N_COINS] = self.balances D0: uint256 = self.get_D_mem(rates, old_balances, amp) new_balances: uint256[N_COINS] = old_balances for i in range(N_COINS): amount: uint256 = _amounts[i] if amount != 0: new_balances[i] -= amount response: Bytes[32] = raw_call( self.coins[i], _abi_encode(_receiver, amount, method_id=method_id("transfer(address,uint256)")), max_outsize=32, ) if len(response) > 0: assert convert(response, bool) D1: uint256 = self.get_D_mem(rates, new_balances, amp) fees: uint256[N_COINS] = empty(uint256[N_COINS]) base_fee: uint256 = self.fee * N_COINS / (4 * (N_COINS - 1)) for i in range(N_COINS): ideal_balance: uint256 = D1 * old_balances[i] / D0 difference: uint256 = 0 new_balance: uint256 = new_balances[i] if ideal_balance > new_balance: difference = ideal_balance - new_balance else: difference = new_balance - ideal_balance fees[i] = base_fee * difference / FEE_DENOMINATOR self.balances[i] = new_balance - (fees[i] * ADMIN_FEE / FEE_DENOMINATOR) new_balances[i] -= fees[i] D2: uint256 = self.get_D_mem(rates, new_balances, amp) total_supply: uint256 = self.totalSupply burn_amount: uint256 = ((D0 - D2) * total_supply / D0) + 1 assert burn_amount > 1 # dev: zero tokens burned assert burn_amount <= _max_burn_amount total_supply -= burn_amount self.totalSupply = total_supply self.balanceOf[msg.sender] -= burn_amount log Transfer(msg.sender, ZERO_ADDRESS, burn_amount) log RemoveLiquidityImbalance(msg.sender, _amounts, fees, D1, total_supply) return burn_amount @view @internal def get_y_D(A: uint256, i: int128, xp: uint256[N_COINS], D: uint256) -> uint256: """ Calculate x[i] if one reduces D from being calculated for xp to D Done by solving quadratic equation iteratively. x_1**2 + x1 * (sum' - (A*n**n - 1) * D / (A * n**n)) = D ** (n + 1) / (n ** (2 * n) * prod' * A) x_1**2 + b*x_1 = c x_1 = (x_1**2 + c) / (2*x_1 + b) """ # x in the input is converted to the same price/precision assert i >= 0 # dev: i below zero assert i < N_COINS # dev: i above N_COINS S_: uint256 = 0 _x: uint256 = 0 y_prev: uint256 = 0 c: uint256 = D Ann: uint256 = A * N_COINS for _i in range(N_COINS): if _i != i: _x = xp[_i] else: continue S_ += _x c = c * D / (_x * N_COINS) c = c * D * A_PRECISION / (Ann * N_COINS) b: uint256 = S_ + D * A_PRECISION / Ann y: uint256 = D for _i in range(255): y_prev = y y = (y*y + c) / (2 * y + b - D) # Equality with the precision of 1 if y > y_prev: if y - y_prev <= 1: return y else: if y_prev - y <= 1: return y raise @view @internal def _calc_withdraw_one_coin(_burn_amount: uint256, i: int128) -> uint256[2]: # First, need to calculate # * Get current D # * Solve Eqn against y_i for D - _token_amount amp: uint256 = self._A() rates: uint256[N_COINS] = [self.rate_multiplier, Curve(BASE_POOL).get_virtual_price()] xp: uint256[N_COINS] = self._xp_mem(rates, self.balances) D0: uint256 = self.get_D(xp, amp) total_supply: uint256 = self.totalSupply D1: uint256 = D0 - _burn_amount * D0 / total_supply new_y: uint256 = self.get_y_D(amp, i, xp, D1) base_fee: uint256 = self.fee * N_COINS / (4 * (N_COINS - 1)) xp_reduced: uint256[N_COINS] = empty(uint256[N_COINS]) for j in range(N_COINS): dx_expected: uint256 = 0 xp_j: uint256 = xp[j] if j == i: dx_expected = xp_j * D1 / D0 - new_y else: dx_expected = xp_j - xp_j * D1 / D0 xp_reduced[j] = xp_j - base_fee * dx_expected / FEE_DENOMINATOR dy: uint256 = xp_reduced[i] - self.get_y_D(amp, i, xp_reduced, D1) dy_0: uint256 = (xp[i] - new_y) * PRECISION / rates[i] # w/o fees dy = (dy - 1) * PRECISION / rates[i] # Withdraw less to account for rounding errors return [dy, dy_0 - dy] @view @external def calc_withdraw_one_coin(_burn_amount: uint256, i: int128) -> uint256: """ @notice Calculate the amount received when withdrawing a single coin @param _burn_amount Amount of LP tokens to burn in the withdrawal @param i Index value of the coin to withdraw @return Amount of coin received """ return self._calc_withdraw_one_coin(_burn_amount, i)[0] @external @nonreentrant('lock') def remove_liquidity_one_coin( _burn_amount: uint256, i: int128, _min_received: uint256, _receiver: address = msg.sender, ) -> uint256: """ @notice Withdraw a single coin from the pool @param _burn_amount Amount of LP tokens to burn in the withdrawal @param i Index value of the coin to withdraw @param _min_received Minimum amount of coin to receive @param _receiver Address that receives the withdrawn coins @return Amount of coin received """ dy: uint256[2] = self._calc_withdraw_one_coin(_burn_amount, i) assert dy[0] >= _min_received self.balances[i] -= (dy[0] + dy[1] * ADMIN_FEE / FEE_DENOMINATOR) total_supply: uint256 = self.totalSupply - _burn_amount self.totalSupply = total_supply self.balanceOf[msg.sender] -= _burn_amount log Transfer(msg.sender, ZERO_ADDRESS, _burn_amount) response: Bytes[32] = raw_call( self.coins[i], _abi_encode(_receiver, dy[0], method_id=method_id("transfer(address,uint256)")), max_outsize=32, ) if len(response) > 0: assert convert(response, bool) log RemoveLiquidityOne(msg.sender, _burn_amount, dy[0], total_supply) return dy[0] @external def ramp_A(_future_A: uint256, _future_time: uint256): assert msg.sender == Factory(self.factory).admin() # dev: only owner assert block.timestamp >= self.initial_A_time + MIN_RAMP_TIME assert _future_time >= block.timestamp + MIN_RAMP_TIME # dev: insufficient time _initial_A: uint256 = self._A() _future_A_p: uint256 = _future_A * A_PRECISION assert _future_A > 0 and _future_A < MAX_A if _future_A_p < _initial_A: assert _future_A_p * MAX_A_CHANGE >= _initial_A else: assert _future_A_p <= _initial_A * MAX_A_CHANGE self.initial_A = _initial_A self.future_A = _future_A_p self.initial_A_time = block.timestamp self.future_A_time = _future_time log RampA(_initial_A, _future_A_p, block.timestamp, _future_time) @external def stop_ramp_A(): assert msg.sender == Factory(self.factory).admin() # dev: only owner current_A: uint256 = self._A() self.initial_A = current_A self.future_A = current_A self.initial_A_time = block.timestamp self.future_A_time = block.timestamp # now (block.timestamp < t1) is always False, so we return saved A log StopRampA(current_A, block.timestamp) @view @external def admin_balances(i: uint256) -> uint256: return ERC20(self.coins[i]).balanceOf(self) - self.balances[i] @external def withdraw_admin_fees(): # transfer coin 0 to Factory and call `convert_fees` to swap it for coin 1 factory: address = self.factory coin: address = self.coins[0] amount: uint256 = ERC20(coin).balanceOf(self) - self.balances[0] if amount > 0: response: Bytes[32] = raw_call( coin, _abi_encode(factory, amount, method_id=method_id("transfer(address,uint256)")), max_outsize=32, ) if len(response) > 0: assert convert(response, bool) Factory(factory).convert_metapool_fees() # transfer coin 1 to the receiver coin = self.coins[1] amount = ERC20(coin).balanceOf(self) - self.balances[1] if amount > 0: receiver: address = Factory(factory).get_fee_receiver(self) response: Bytes[32] = raw_call( coin, _abi_encode(receiver, amount, method_id=method_id("transfer(address,uint256)")), max_outsize=32, ) if len(response) > 0: assert convert(response, bool) @view @external def version() -> String[8]: """ @notice Get the version of this token contract """ return VERSION
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A contract address hosts a smart contract, which is a set of code stored on the blockchain that runs when predetermined conditions are met. Learn more about addresses in our Knowledge Base.