SwapPool

Swap pool contract. May or may not be covered by a backstop pool. Conceptionally, there are two ways to temporarily disable a pool: The owner can either pause the pool, disabling deposits, swaps & backstop, or the owner can set the pool cap to zero which only prevents deposits. The former is for security incidents, the latter for phasing out a pool.

SwapFees

struct SwapFees {
  uint32 lpFee;
  uint32 backstopFee;
  uint32 protocolFee;
}

totalLiabilities

uint256 totalLiabilities

The liabilities of the pool Cannot just use totalSupply() as the totalLiabilities will accumulate also the LP fees from swaps. This is fixed point number using the decimals of this pool

reserve

uint256 reserve

The amount of pool tokens usable for swaps This is fixed point number using the decimals of this pool

reserveWithSlippage

uint256 reserveWithSlippage

The amount of pool tokens plus the slippage The relationship with reserve is: reserveWithSlippage = slippageCurve.psi(reserve, totalLiabilities) However this relationship will never hold precisely and will deviate slightly for numerical reasons!! All code needs to work even if this relationship does not hold This is fixed point number using the decimals of this pool

insuranceWithdrawalTimelock

uint256 insuranceWithdrawalTimelock

maxCoverageRatioForSwapIn

uint256 maxCoverageRatioForSwapIn

protocolTreasury

address protocolTreasury

backstop

contract IBackstopPool backstop

router

contract IRouter router

slippageCurve

contract ISlippageCurve slippageCurve

deposit

function deposit(uint256 _depositAmount) external returns (uint256 _sharesToMint, int256 _fee)

Deposits amount of tokens into pool Will change cov ratio of pool, will increase delta to 0

Parameters

Name	Type	Description
_depositAmount	uint256	The amount to be deposited, an amount of pool tokens

Return Values

Name	Type	Description
_sharesToMint	uint256	Total number of pool lp tokens minted
_fee	int256	The slippage reward (a negative fee), fixed point number using the pool decimals

quoteDeposit

function quoteDeposit(uint256 _depositAmount) external view returns (uint256 _sharesToMint)

Get a quote for the effective amount of tokens for a deposit

Parameters

Name	Type	Description
_depositAmount	uint256	The amount to be deposited

Return Values

Name	Type	Description
_sharesToMint	uint256	Total number of pool LP tokens to be minted (incl. slippage)

withdraw

function withdraw(uint256 _sharesToBurn, uint256 _minimumAmount) external returns (uint256 _payoutAmount, int256 _fee)

Withdraws liquidity amount of asset ensuring minimum amount required

Parameters

Name	Type	Description
_sharesToBurn	uint256	The liquidity to be withdrawn, an amount of LP tokens
_minimumAmount	uint256	The minimum amount of returned pool tokens that will be accepted by user

Return Values

Name	Type	Description
_payoutAmount	uint256	Amount of pool tokens withdrawn after applying withdrawal fee
_fee	int256	The penalty due to slippage (a positive fee), fixed point number using the pool decimals

quoteWithdraw

function quoteWithdraw(uint256 _sharesToBurn) external view returns (uint256 _payoutAmount)

Get a quote for the effective amount of tokens for a withdrawal

Parameters

Name	Type	Description
_sharesToBurn	uint256	Total number of pool LP tokens to be burned

Return Values

Name	Type	Description
_payoutAmount	uint256	The amount to be withdrawn (incl. slippage)

quoteBackstopDrain

function quoteBackstopDrain(uint256 _amount) external view returns (uint256 _swapAmount)

Get a quote for the effective amount of tokens for a backstop drain

Parameters

Name	Type	Description
_amount	uint256	The amount of tokens to be withdrawn for backstop liquidity

Return Values

Name	Type	Description
_swapAmount	uint256	The amount to be withdrawn (incl. slippage)

quoteSwapInto

function quoteSwapInto(uint256 _amount) public view returns (uint256 _effectiveAmount)

Get a quote for the effective amount of tokens for a swap into

Parameters

Name	Type	Description
_amount	uint256	The amount of pool tokens to swap into the pool

Return Values

Name	Type	Description
_effectiveAmount	uint256	Effective amount, incl. slippage (penalty or rewards)

quoteSwapOut

function quoteSwapOut(uint256 _amount) public view returns (uint256 _effectiveAmount, uint256 _protocolFeeWithSlippage, uint256 _effectiveLpFee, uint256 _backstopFee)

Get a quote for the effective amount of tokens, incl. slippage and fees

Parameters

Name	Type	Description
_amount	uint256	The amount of pool asset to swap out of the pool

Return Values

Name	Type	Description
_effectiveAmount	uint256	Effective amount, incl. slippage and fees
_protocolFeeWithSlippage	uint256	The protocol fee that is to be sent to the treasury
_effectiveLpFee	uint256	The actual LP fee – totalLiabilities should be incremented by this value
_backstopFee	uint256	The effective backstop fee

coverage

function coverage() external view returns (uint256 _reserves, uint256 _liabilities)

returns pool coverage ratio

Return Values

Name	Type	Description
_reserves	uint256	Current amount of usable asset() tokens (without slippage)
_liabilities	uint256	total amount of asset deposited by liquidity providers

getExcessLiquidity

function getExcessLiquidity() external view returns (int256 _excessLiquidity)

Computes the excess liquidity that forms that valuation of the backstop pool is defined as b + C - B - L where

• b is reserve

• C is the amount of asset() tokens in the pool

• B is reserveWithSlippage

• L is totalLiabilities The excess liquidity is a fixed point number using the decimals of this pool

Return Values

Name	Type	Description
_excessLiquidity	int256	The total excess liquidity of this pool, can be negative

insuranceWithdrawalUnlock

function insuranceWithdrawalUnlock(address _liquidityProvider) external view returns (uint256 _unlockedOnBlockNo)

Return the earliest block no that insurance withdrawals are possible.

Parameters

Name	Type	Description
_liquidityProvider	address	Address of some account, usually the caller

Return Values

Name	Type	Description
_unlockedOnBlockNo	uint256	Block number of the first block after time lock runs out

sharesTargetWorth

function sharesTargetWorth(uint256 _sharesToBurn) public view returns (uint256 _amount)

Returns the worth of an amount of pool shares (LP tokens) in underlying principle

Parameters

Name	Type	Description
_sharesToBurn	uint256	The number of LP tokens to burn

Return Values

Name	Type	Description
_amount	uint256	The amount of asset() tokens that the shares are worth

swapFees

function swapFees() public view returns (uint256 _lpFee, uint256 _backstopFee, uint256 _protocolFee)

Return the configured swap fees for this pool

Return Values

Name	Type	Description
_lpFee	uint256	Fee that benefits the pool's LPers, in 0.0001% (e.g. 300 -> 0.0300%)
_backstopFee	uint256	Fee that benefits the backstop pool, in 0.0001% (e.g. 150 -> 0.0150%)
_protocolFee	uint256	Fee that benefits the protocol, in 0.0001% (e.g. 50 -> 0.0050%)