Contract 0x3a43A5851A3e3E0e25A3c1089670269786be1577 4

Txn Hash Method
Block
From
To
Value [Txn Fee]
0x3cc6bb0e986479d8405a41851964591f21ae1e17ee14a252824568933874c9b8Exchange229522742022-11-28 14:08:4022 mins ago0x78c9487575cfa7e22c5e25f61b4ceda245c1199e IN  0x3a43a5851a3e3e0e25a3c1089670269786be15770 AVAX0.003985625 25
0xdb728a9885d73d74fb9491750bd504ab5b8d9fb9c5fa3df17160c38df548e45eExchange229521962022-11-28 14:05:5725 mins ago0x03b3f61a2fc506a32db27c349b265fbfcea3889c IN  0x3a43a5851a3e3e0e25a3c1089670269786be15770 AVAX0.003558125 25
0x81563559f74ad293169866211173954608ef4b30df9da7896d261b9cc496d588Exchange229359812022-11-28 4:44:599 hrs 46 mins ago0x315b14c83ee3a70688af5db8bc3940fcc3cc99e8 IN  0x3a43a5851a3e3e0e25a3c1089670269786be15770 AVAX0.00406806229
0x7723997b7ab2088dcad110924c64f9c7de49424a7c610c6992c9eadf5e7e5216Exchange229350652022-11-28 4:13:2710 hrs 17 mins ago0x716b2cadf295b9651f511a3e73c33fb77428089c IN  0x3a43a5851a3e3e0e25a3c1089670269786be15770 AVAX0.004328555 27.5
0xf7185177d72fc0566f65146bf2af1e428da3d8554a3a44d353461bd69713369aExchange229335842022-11-28 3:22:0311 hrs 9 mins ago0x2012adb6314f6ba298be45036b8d3bd6c0f9f1e7 IN  0x3a43a5851a3e3e0e25a3c1089670269786be15770 AVAX0.003558125 25
0x5a9c6f8757bfa552c72ddbc507e583c0b9d4efbf8a2d45f952fe1abd3c0df281Exchange229335322022-11-28 3:20:1611 hrs 10 mins ago0x2012adb6314f6ba298be45036b8d3bd6c0f9f1e7 IN  0x3a43a5851a3e3e0e25a3c1089670269786be15770 AVAX0.003557825 25
0xd27e0f9ec2a2b3def2e8eca930948748c9de19908b1f988f6151a7adc68dd420Exchange229202952022-11-27 19:48:1118 hrs 42 mins ago0x5e7b048a6d9bd66f131d2bb0a50dbee775230316 IN  0x3a43a5851a3e3e0e25a3c1089670269786be15770 AVAX0.00350755 25
0xe8fd0174cfa4f9ddcd20053afb09dc06b9559c953fc33f4a80f7049c6562affaExchange229165972022-11-27 17:41:4320 hrs 49 mins ago0x48178fd7064b7513b0ee4d3f400b351ff092a97e IN  0x3a43a5851a3e3e0e25a3c1089670269786be15770 AVAX0.0037716125 26.5
0xabe9b37b1015bfa436694cfb78deb2c3379a16a9eb7c5596a4ab85bd9859dcecExchange229106072022-11-27 14:19:341 day 11 mins ago0xd49182c910b7f3ec0dc9f9749874cfe6b6f4b75f IN  0x3a43a5851a3e3e0e25a3c1089670269786be15770 AVAX0.00430447527
0x458dcd78393d2790bea8380f1ff93a5ba02a7e4730826f0a4fc5727fc1195999Exchange229079332022-11-27 12:48:401 day 1 hr ago0xc3dd0b4d4e17acc7c51eab7bcfecae6b28f37ec1 IN  0x3a43a5851a3e3e0e25a3c1089670269786be15770 AVAX0.00393445 25
0xdc2944c24d1abf6fad991cb4de05807e731a2c5906f839ba9427abf77dbc995aExchange229007172022-11-27 8:43:031 day 5 hrs ago0x87fc1313880d579039ac48db8b25428ed5f33c4a IN  0x3a43a5851a3e3e0e25a3c1089670269786be15770 AVAX0.003985625 25
0xacbd8e89d15c5ced6b888ca22d90ce6105e2c6401f10acbe19770759a0758ebdExchange228971662022-11-27 6:41:521 day 7 hrs ago0x2ffe865328884fa81ee720f1e989863da8d5367d IN  0x3a43a5851a3e3e0e25a3c1089670269786be15770 AVAX0.00393415 25
0x807f22f3d027768cbb42efe1710524c6e88cf7d608d91dde082016c77bb67cc0Remove_liquidity...228964912022-11-27 6:18:331 day 8 hrs ago0xf3eab2365c8689d7d429e9cf03c78b29f07907b1 IN  0x3a43a5851a3e3e0e25a3c1089670269786be15770 AVAX0.00347292429
0x403f3eb3c7351ff2dcc7dea3d318a0685b851e74e2ccd397e3e1c432838b14d0Remove_liquidity...228959922022-11-27 6:01:191 day 8 hrs ago0x292b9a879d24e22ddb1e0e5bb9934398130e2fe1 IN  0x3a43a5851a3e3e0e25a3c1089670269786be15770 AVAX0.0029945 25
0xb571dc041101ced30a16302573c2d7eed2d079dfe7f0e3931679a804838edbbbExchange228934672022-11-27 4:34:271 day 9 hrs ago0x863c9aade08c7e024a4c7a2884c6024711ccb11a IN  0x3a43a5851a3e3e0e25a3c1089670269786be15770 AVAX0.00350695 25
0x4109d9db365869a232bdfc15c728ec5e5494be5728b2fb3fcc685e92733086deExchange228739392022-11-26 17:25:221 day 21 hrs ago0x6f2be2b9938b18a141dc6c6f696c16cc6ab0e9e6 IN  0x3a43a5851a3e3e0e25a3c1089670269786be15770 AVAX0.003985625 25
0xd959ee196c5e5e48f4e79f56067d114ea5959bb8310ddc6a0b38a2bbfbac064aExchange228733492022-11-26 17:05:171 day 21 hrs ago0xff18311ccdbe86e54d266f07eaec2668bee9f9f3 IN  0x3a43a5851a3e3e0e25a3c1089670269786be15770 AVAX0.00393445 25
0x1f3041b5bdb32333a253ae2a79a1302e52d9856ea9b30a1b269f9e44432464c1Add_liquidity228683302022-11-26 14:13:382 days 17 mins ago0xa77ce92a601d504a6d64af843eb5a3994616969c IN  0x3a43a5851a3e3e0e25a3c1089670269786be15770 AVAX0.0043622425 27.5
0xb866edd95bd738ee4131307962fd397940168affc34630754a347a59eefc1fa7Approve228677412022-11-26 13:53:172 days 37 mins ago0x9fb7563a1969f034e8feb83e499c967d31538e86 IN  0x3a43a5851a3e3e0e25a3c1089670269786be15770 AVAX0.000832312 26.5
0xea79b48ef61ebf88d1e19160b049f5a01716d28c6dbeaf0727b6eb454f5113b5Exchange228676712022-11-26 13:50:492 days 40 mins ago0x5057f8d48367119fdc0cdc5101a872cb665f957b IN  0x3a43a5851a3e3e0e25a3c1089670269786be15770 AVAX0.003985625 25
0xd2488064e523fdc0c8f5599aa02337a6c6c032f0f3c9c732799b28fd037ddf57Approve228501682022-11-26 3:32:502 days 10 hrs ago0xb5564b1a37d52fee291081964973eac0e9f08dee IN  0x3a43a5851a3e3e0e25a3c1089670269786be15770 AVAX0.000832312 26.5
0x15be606cae7e8cee1bb89ec0a8818646e161dc7dcf43fcb88ec78ac08ca98a8fExchange228438592022-11-25 23:52:512 days 14 hrs ago0xfe51263bd0d075dc5441e89ecd1f6d63ff41e02e IN  0x3a43a5851a3e3e0e25a3c1089670269786be15770 AVAX0.0043848475 27.5
0xa96d70fc7f489e55c46db4b99857dc0b1f24ef354633d11ad5d6f6aacd2763baExchange228373482022-11-25 20:07:142 days 18 hrs ago0x9af22e3d024d39db58f9a12979179cd28a9b8b2d IN  0x3a43a5851a3e3e0e25a3c1089670269786be15770 AVAX0.0079682550
0x78086b77bedf03fcb6e82477940e55e49e53ac11b687fd29fd99f5470d12d017Exchange228372492022-11-25 20:03:472 days 18 hrs ago0x9af22e3d024d39db58f9a12979179cd28a9b8b2d IN  0x3a43a5851a3e3e0e25a3c1089670269786be15770 AVAX0.007865950
0x59d3d7504dbc38cf33eb2bc82255e2c5eeacf524cb51885016e67b473af6bb45Exchange228368402022-11-25 19:49:252 days 18 hrs ago0xdbefc66685ca9c8226d7de04d0293c7c02e052d4 IN  0x3a43a5851a3e3e0e25a3c1089670269786be15770 AVAX0.007865950
[ Download CSV Export 
Latest 1 internal transaction
Parent Txn Hash Block From To Value
0x77b379a9ea3e1cbbd4d91feff911c5ef9ee368143ed06369d486caf454fe665e82413982021-12-14 20:16:23348 days 18 hrs ago 0xb17b674d9c5cb2e441f8e196a2f048a81355d031  Contract Creation0 AVAX
[ Download CSV Export 
Loading

Minimal Proxy Contract for 0x697434ca761d4f86b553784b69f4f37f5edf54df

Contract Name:
Vyper_contract

Compiler Version
vyper:0.2.15

Optimization Enabled:
N/A

Other Settings:
, None license
Decompile ByteCode

Contract Source Code (Vyper language format)

# @version 0.2.15
"""
@title StableSwap
@author Curve.Fi
@license Copyright (c) Curve.Fi, 2020-2021 - all rights reserved
@notice 2 coin pool implementation with no lending
@dev ERC20 support for return True/revert, return True/False, return None
"""

from vyper.interfaces import ERC20

interface Factory:
    def convert_fees() -> bool: nonpayable
    def get_fee_receiver(_pool: address) -> address: view
    def admin() -> address: 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 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


N_COINS: constant(int128) = 2
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

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_multipliers: uint256[N_COINS]

name: public(String[64])
symbol: public(String[32])

balanceOf: public(HashMap[address, uint256])
allowance: public(HashMap[address, HashMap[address, uint256]])
totalSupply: public(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],
    _coins: address[4],
    _rate_multipliers: uint256[4],
    _A: uint256,
    _fee: uint256,
):
    """
    @notice Contract constructor
    @param _name Name of the new pool
    @param _symbol Token symbol
    @param _coins List of all ERC20 conract addresses of coins
    @param _rate_multipliers List of number of decimals in coins
    @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

    for i in range(N_COINS):
        coin: address = _coins[i]
        if coin == ZERO_ADDRESS:
            break
        self.coins[i] = coin
        self.rate_multipliers[i] = _rate_multipliers[i]

    A: uint256 = _A * A_PRECISION
    self.initial_A = A
    self.future_A = A
    self.fee = _fee
    self.factory = msg.sender

    self.name = concat("Curve.fi Factory Plain Pool: ", _name)
    self.symbol = concat(_symbol, "-f")

    # 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


### StableSwap Functionality ###

@view
@external
def get_balances() -> uint256[N_COINS]:
    return self.balances


@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
    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 * D / _xp[0] * D / _xp[1] / (N_COINS)**2
        Dprev: uint256 = 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()
    xp: uint256[N_COINS] = self._xp_mem(self.rate_multipliers, 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()
    balances: uint256[N_COINS] = self.balances

    D0: uint256 = self.get_D_mem(self.rate_multipliers, 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(self.rate_multipliers, 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()
    old_balances: uint256[N_COINS] = self.balances
    rates: uint256[N_COINS] = self.rate_multipliers

    # Initial invariant
    D0: uint256 = self.get_D_mem(rates, old_balances, amp)

    total_supply: uint256 = self.totalSupply
    new_balances: uint256[N_COINS] = old_balances
    for i in range(N_COINS):
        amount: uint256 = _amounts[i]
        if amount > 0:
            response: Bytes[32] = raw_call(
                self.coins[i],
                concat(
                    method_id("transferFrom(address,address,uint256)"),
                    convert(msg.sender, bytes32),
                    convert(self, bytes32),
                    convert(amount, bytes32),
                ),
                max_outsize=32,
            )
            if len(response) > 0:
                assert convert(response, bool)  # dev: failed transfer
            new_balances[i] += amount
            # end "safeTransferFrom"
        else:
            assert total_supply != 0  # dev: initial deposit requires all coins

    # 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, "Slippage screwed you"

    # 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:
    """
    Calculate x[j] if one makes x[i] = x

    Done by solving quadratic equation iteratively.
    x_1**2 + x_1 * (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 != 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_multipliers
    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]


@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
    @return Actual amount of `j` received
    """
    rates: uint256[N_COINS] = self.rate_multipliers
    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, "Exchange resulted in fewer coins than expected"

    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],
        concat(
            method_id("transferFrom(address,address,uint256)"),
            convert(msg.sender, bytes32),
            convert(self, bytes32),
            convert(_dx, bytes32),
        ),
        max_outsize=32,
    )
    if len(response) > 0:
        assert convert(response, bool)

    response = raw_call(
        self.coins[j],
        concat(
            method_id("transfer(address,uint256)"),
            convert(_receiver, bytes32),
            convert(dy, bytes32),
        ),
        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 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], "Withdrawal resulted in fewer coins than expected"
        self.balances[i] = old_balance - value
        amounts[i] = value

        response: Bytes[32] = raw_call(
            self.coins[i],
            concat(
                method_id("transfer(address,uint256)"),
                convert(_receiver, bytes32),
                convert(value, bytes32),
            ),
            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_multipliers
    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],
                concat(
                    method_id("transfer(address,uint256)"),
                    convert(_receiver, bytes32),
                    convert(amount, bytes32),
                ),
                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, "Slippage screwed you"

    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


@pure
@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 + x_1 * (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_multipliers
    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, "Not enough coins removed"

    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],
        concat(
            method_id("transfer(address,uint256)"),
            convert(_receiver, bytes32),
            convert(dy[0], bytes32),
        ),
        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():
    receiver: address = Factory(self.factory).get_fee_receiver(self)

    for i in range(N_COINS):
        coin: address = self.coins[i]
        fees: uint256 = ERC20(coin).balanceOf(self) - self.balances[i]
        raw_call(
            coin,
            concat(
                method_id("transfer(address,uint256)"),
                convert(receiver, bytes32),
                convert(fees, bytes32)
            )
        )

Contract ABI

[{"name":"Transfer","inputs":[{"name":"sender","type":"address","indexed":true},{"name":"receiver","type":"address","indexed":true},{"name":"value","type":"uint256","indexed":false}],"anonymous":false,"type":"event"},{"name":"Approval","inputs":[{"name":"owner","type":"address","indexed":true},{"name":"spender","type":"address","indexed":true},{"name":"value","type":"uint256","indexed":false}],"anonymous":false,"type":"event"},{"name":"TokenExchange","inputs":[{"name":"buyer","type":"address","indexed":true},{"name":"sold_id","type":"int128","indexed":false},{"name":"tokens_sold","type":"uint256","indexed":false},{"name":"bought_id","type":"int128","indexed":false},{"name":"tokens_bought","type":"uint256","indexed":false}],"anonymous":false,"type":"event"},{"name":"AddLiquidity","inputs":[{"name":"provider","type":"address","indexed":true},{"name":"token_amounts","type":"uint256[2]","indexed":false},{"name":"fees","type":"uint256[2]","indexed":false},{"name":"invariant","type":"uint256","indexed":false},{"name":"token_supply","type":"uint256","indexed":false}],"anonymous":false,"type":"event"},{"name":"RemoveLiquidity","inputs":[{"name":"provider","type":"address","indexed":true},{"name":"token_amounts","type":"uint256[2]","indexed":false},{"name":"fees","type":"uint256[2]","indexed":false},{"name":"token_supply","type":"uint256","indexed":false}],"anonymous":false,"type":"event"},{"name":"RemoveLiquidityOne","inputs":[{"name":"provider","type":"address","indexed":true},{"name":"token_amount","type":"uint256","indexed":false},{"name":"coin_amount","type":"uint256","indexed":false},{"name":"token_supply","type":"uint256","indexed":false}],"anonymous":false,"type":"event"},{"name":"RemoveLiquidityImbalance","inputs":[{"name":"provider","type":"address","indexed":true},{"name":"token_amounts","type":"uint256[2]","indexed":false},{"name":"fees","type":"uint256[2]","indexed":false},{"name":"invariant","type":"uint256","indexed":false},{"name":"token_supply","type":"uint256","indexed":false}],"anonymous":false,"type":"event"},{"name":"RampA","inputs":[{"name":"old_A","type":"uint256","indexed":false},{"name":"new_A","type":"uint256","indexed":false},{"name":"initial_time","type":"uint256","indexed":false},{"name":"future_time","type":"uint256","indexed":false}],"anonymous":false,"type":"event"},{"name":"StopRampA","inputs":[{"name":"A","type":"uint256","indexed":false},{"name":"t","type":"uint256","indexed":false}],"anonymous":false,"type":"event"},{"stateMutability":"nonpayable","type":"constructor","inputs":[],"outputs":[]},{"stateMutability":"nonpayable","type":"function","name":"initialize","inputs":[{"name":"_name","type":"string"},{"name":"_symbol","type":"string"},{"name":"_coins","type":"address[4]"},{"name":"_rate_multipliers","type":"uint256[4]"},{"name":"_A","type":"uint256"},{"name":"_fee","type":"uint256"}],"outputs":[],"gas":471502},{"stateMutability":"view","type":"function","name":"decimals","inputs":[],"outputs":[{"name":"","type":"uint256"}],"gas":318},{"stateMutability":"nonpayable","type":"function","name":"transfer","inputs":[{"name":"_to","type":"address"},{"name":"_value","type":"uint256"}],"outputs":[{"name":"","type":"bool"}],"gas":77977},{"stateMutability":"nonpayable","type":"function","name":"transferFrom","inputs":[{"name":"_from","type":"address"},{"name":"_to","type":"address"},{"name":"_value","type":"uint256"}],"outputs":[{"name":"","type":"bool"}],"gas":115912},{"stateMutability":"nonpayable","type":"function","name":"approve","inputs":[{"name":"_spender","type":"address"},{"name":"_value","type":"uint256"}],"outputs":[{"name":"","type":"bool"}],"gas":37851},{"stateMutability":"view","type":"function","name":"get_balances","inputs":[],"outputs":[{"name":"","type":"uint256[2]"}],"gas":4707},{"stateMutability":"view","type":"function","name":"admin_fee","inputs":[],"outputs":[{"name":"","type":"uint256"}],"gas":468},{"stateMutability":"view","type":"function","name":"A","inputs":[],"outputs":[{"name":"","type":"uint256"}],"gas":10764},{"stateMutability":"view","type":"function","name":"A_precise","inputs":[],"outputs":[{"name":"","type":"uint256"}],"gas":10726},{"stateMutability":"view","type":"function","name":"get_virtual_price","inputs":[],"outputs":[{"name":"","type":"uint256"}],"gas":848656},{"stateMutability":"view","type":"function","name":"calc_token_amount","inputs":[{"name":"_amounts","type":"uint256[2]"},{"name":"_is_deposit","type":"bool"}],"outputs":[{"name":"","type":"uint256"}],"gas":3336308},{"stateMutability":"nonpayable","type":"function","name":"add_liquidity","inputs":[{"name":"_amounts","type":"uint256[2]"},{"name":"_min_mint_amount","type":"uint256"}],"outputs":[{"name":"","type":"uint256"}]},{"stateMutability":"nonpayable","type":"function","name":"add_liquidity","inputs":[{"name":"_amounts","type":"uint256[2]"},{"name":"_min_mint_amount","type":"uint256"},{"name":"_receiver","type":"address"}],"outputs":[{"name":"","type":"uint256"}]},{"stateMutability":"view","type":"function","name":"get_dy","inputs":[{"name":"i","type":"int128"},{"name":"j","type":"int128"},{"name":"dx","type":"uint256"}],"outputs":[{"name":"","type":"uint256"}],"gas":2117591},{"stateMutability":"nonpayable","type":"function","name":"exchange","inputs":[{"name":"i","type":"int128"},{"name":"j","type":"int128"},{"name":"_dx","type":"uint256"},{"name":"_min_dy","type":"uint256"}],"outputs":[{"name":"","type":"uint256"}]},{"stateMutability":"nonpayable","type":"function","name":"exchange","inputs":[{"name":"i","type":"int128"},{"name":"j","type":"int128"},{"name":"_dx","type":"uint256"},{"name":"_min_dy","type":"uint256"},{"name":"_receiver","type":"address"}],"outputs":[{"name":"","type":"uint256"}]},{"stateMutability":"nonpayable","type":"function","name":"remove_liquidity","inputs":[{"name":"_burn_amount","type":"uint256"},{"name":"_min_amounts","type":"uint256[2]"}],"outputs":[{"name":"","type":"uint256[2]"}]},{"stateMutability":"nonpayable","type":"function","name":"remove_liquidity","inputs":[{"name":"_burn_amount","type":"uint256"},{"name":"_min_amounts","type":"uint256[2]"},{"name":"_receiver","type":"address"}],"outputs":[{"name":"","type":"uint256[2]"}]},{"stateMutability":"nonpayable","type":"function","name":"remove_liquidity_imbalance","inputs":[{"name":"_amounts","type":"uint256[2]"},{"name":"_max_burn_amount","type":"uint256"}],"outputs":[{"name":"","type":"uint256"}]},{"stateMutability":"nonpayable","type":"function","name":"remove_liquidity_imbalance","inputs":[{"name":"_amounts","type":"uint256[2]"},{"name":"_max_burn_amount","type":"uint256"},{"name":"_receiver","type":"address"}],"outputs":[{"name":"","type":"uint256"}]},{"stateMutability":"view","type":"function","name":"calc_withdraw_one_coin","inputs":[{"name":"_burn_amount","type":"uint256"},{"name":"i","type":"int128"}],"outputs":[{"name":"","type":"uint256"}],"gas":1100},{"stateMutability":"nonpayable","type":"function","name":"remove_liquidity_one_coin","inputs":[{"name":"_burn_amount","type":"uint256"},{"name":"i","type":"int128"},{"name":"_min_received","type":"uint256"}],"outputs":[{"name":"","type":"uint256"}]},{"stateMutability":"nonpayable","type":"function","name":"remove_liquidity_one_coin","inputs":[{"name":"_burn_amount","type":"uint256"},{"name":"i","type":"int128"},{"name":"_min_received","type":"uint256"},{"name":"_receiver","type":"address"}],"outputs":[{"name":"","type":"uint256"}]},{"stateMutability":"nonpayable","type":"function","name":"ramp_A","inputs":[{"name":"_future_A","type":"uint256"},{"name":"_future_time","type":"uint256"}],"outputs":[],"gas":162101},{"stateMutability":"nonpayable","type":"function","name":"stop_ramp_A","inputs":[],"outputs":[],"gas":157565},{"stateMutability":"view","type":"function","name":"admin_balances","inputs":[{"name":"i","type":"uint256"}],"outputs":[{"name":"","type":"uint256"}],"gas":7740},{"stateMutability":"nonpayable","type":"function","name":"withdraw_admin_fees","inputs":[],"outputs":[],"gas":33182},{"stateMutability":"view","type":"function","name":"coins","inputs":[{"name":"arg0","type":"uint256"}],"outputs":[{"name":"","type":"address"}],"gas":3093},{"stateMutability":"view","type":"function","name":"balances","inputs":[{"name":"arg0","type":"uint256"}],"outputs":[{"name":"","type":"uint256"}],"gas":3123},{"stateMutability":"view","type":"function","name":"fee","inputs":[],"outputs":[{"name":"","type":"uint256"}],"gas":3108},{"stateMutability":"view","type":"function","name":"initial_A","inputs":[],"outputs":[{"name":"","type":"uint256"}],"gas":3138},{"stateMutability":"view","type":"function","name":"future_A","inputs":[],"outputs":[{"name":"","type":"uint256"}],"gas":3168},{"stateMutability":"view","type":"function","name":"initial_A_time","inputs":[],"outputs":[{"name":"","type":"uint256"}],"gas":3198},{"stateMutability":"view","type":"function","name":"future_A_time","inputs":[],"outputs":[{"name":"","type":"uint256"}],"gas":3228},{"stateMutability":"view","type":"function","name":"name","inputs":[],"outputs":[{"name":"","type":"string"}],"gas":13488},{"stateMutability":"view","type":"function","name":"symbol","inputs":[],"outputs":[{"name":"","type":"string"}],"gas":11241},{"stateMutability":"view","type":"function","name":"balanceOf","inputs":[{"name":"arg0","type":"address"}],"outputs":[{"name":"","type":"uint256"}],"gas":3533},{"stateMutability":"view","type":"function","name":"allowance","inputs":[{"name":"arg0","type":"address"},{"name":"arg1","type":"address"}],"outputs":[{"name":"","type":"uint256"}],"gas":3778},{"stateMutability":"view","type":"function","name":"totalSupply","inputs":[],"outputs":[{"name":"","type":"uint256"}],"gas":3378}]

Block Transaction Gas Used Reward
Age Block Fee Address BC Fee Address Voting Power Jailed Incoming
Block Uncle Number Difficulty Gas Used Reward
Loading
Make sure to use the "Vote Down" button for any spammy posts, and the "Vote Up" for interesting conversations.