Contract Addresses

Goerli Testnet Address

constant: 0x07e70721C1737a9D410bcd038BA7e82e8BC19e2a

rETHRate: 0xf2dD62922B5f0cb2a72dAeda711018d6F56EEb17

tapETH: 0x0C68f684324551b4B6Ff6DFc6314655f8e7d761a

WTapETH: 0x31CcC35cbed56B6e8f01E8207B1302f009ABC27c

stETHSwap: 0x79106c599A6A320DFB0686513631a92fF8343b44

rETHSwap: 0x9719443a2BBb5AB61744C1B3C71C2E3527101a91

applicationStableAsset: 0x44A54f1cc211cfCFfE8b83C22f44728F3Fa5004C

wETHAddress: '0xB4FBF271143F4FBf7B91A5ded31805e42b2208d6'

stETHAddress: '0x1643E812aE58766192Cf7D2Cf9567dF2C37e9B7F'

rETHAddress: '0x178e141a0e3b34152f73ff610437a7bf9b83267a'

Smart Contracts Overview

The main contracts of Tapio V1.5 are the following:

TapEth : contract of rebase token tapETH

WtapETH: contract of wrapped tapETH

StableAsset: contract of stableswap pool

StableAssetApplication: user contract interface for different stableSwap pools

Tapio Smart contracts UML diagram.

Contract TapETH

The contract TapETH is upgradable and uses the interface IERC20.

Write Methods

• proposeGovernance(address _governance)

  This function allows the current governance to set a new governance address.

• acceptGovernance(address _governance)

  This function allows the pending governance to be activated: to update the governance to the pending governance.

• addPool(address _pool)

  This function can be executed only by the governance to whitelist a stableSwap pool.

• removePool(address _pool)

  This function can be executed only by the governance to remove a whitelisted stableSwap pool.

• transferShares(address _recipient, uint256 _sharesAmount)

  This function allows the caller to transfer _sharesAmount shares of tapETH from his address to _recipient.

• transferSharesFrom(address _sender, address _recipient, uint256 _sharesAmount)

• This function allows the spender to transfer _sharesAmount shares of tapETH from to _sender to _recipient.

• mintShares(address _account, uint256 _tokenAmount)

• This function can be executed by a whitelisted stableSwap pool to mint _tokenAmount of tapETH for _account.

• burnShares(uint256 _tokenAmount)

• This function allows the caller to burn _tokenAmount of tapETH.

• burnSharesFrom(address _account, uint256 _tokenAmount)

• This function allows the spender to burn _tokenAmount of tapETH from the addresss _account.

View Methods

• getTotalPooledEther()

  This function returns the total supply of tapETH (uint256).

• getTotalShares()

  This function returns the total shares of tapETH (uint256).

• getSharesByPooledEth(uint256_tapETHAmount)

• This function returns the shares of tapETH (uint256) corresponding to _tapETHAmount of tapETH.

• getPooledEthByShares(uint256 _sharesAmount)

• This function returns the amount of tapETH (uint256) corresponding to `sharesAmount' shares of tapETH.

• setTotalSupply(uint256 _amount)

• This function can be only called by a whitelist stableSwap pool contract to increase the total supply of tapETH by _amount.

Contract WTapETH

The contract WTapETH is upgradable and inherits from the contract ERC20Permit.

Write Methods

• wrap(uint256 _tapETHAmount)

• This function allows the user to wrap _ tapETHAmount of tapETH that consisting in transferring _tapETHAmount of tapETH to the smart contract WTapETH and minting the corresponding shares amount in wtapETH.

• unwrap(uint256 _wtapETHAmount)

• This function allows the user to unwrap _wtapETHAmount of wtapETH that consisting in burning wtapETHAmount of wtapETH and sending from the smart contract WTapETH to the caller the corresponding amount of tapETH.

View Methodes

• getWtapETHByTapETH(uint256 _tapETHAmount)

• This function returns the amount of wtapETH that corresponds to _tapETHAmount of tapETH.

• getTapETHByWtapETH(uint256 _wtapETHAmount)

• This function returns the amount of tapETH that corresponds to _wtapETHAmount of wtapETH.

• tapETHPerToken()

• This function returns the amount of tapETH that corresponds to 1 wtapETH.

• tokensPerTapETH()

• This function returns the amount of wtapETH that corresponds to 1 tapETH.

Contract StableAsset

The contract StableAsset is upgradable and inherits from the contract ReentrancyGuard.

Write Methodes

• mint(uint256[] calldata _amounts, uint256 _minMintAmount)

• This function allows the user to provide liquidity in the different tokens of the pool to mint at least _wtapETHAmount of tapETH. The Logic of the function consists of :

1. update token balances

2. calculate the new D value

3. calculate delta D = new D - old D

4. calculate mintAmount = delta D - feeAmount = delta D * ( 1- mintFee)

5. revert if mintAmount < _minMintAmount

6. mint mintAmount of tapETH for the caller

7. increase the total supply of tapETH by feeAmount

• swap(uint256 _i, uint256 _j, uint256 _dx, uint256 _minDy)

• This function allows the user to swap _dx amount of token index i to at least _minDy amount of token index j. The Logic of the function consists of:

1. update balance of token index i .

2. calculate the new balance of token index j: new y

3. calculate delta y = new y - old y

4. calculate outputAmount = delta y - feeAmount = delta y * ( 1- swapFee)

5. revert if outputAmount < _minDy

6. send outputAmount of token index j to the caller

7. increase the total supply of tapETH by feeAmount

• redeemProportion(uint256 _amount, uint256[] calldata _minRedeemAmounts)

• This function allows the user to redeem _amount of tapETH in order to receive at least _minRedeemAmounts[i] of each token index i. The Logic of the function consists of:

1. calculate redeemAmount = _amount - feeAmount = amount * ( 1 - redeemFee).

2. for each token i :

   • calculate tokenAmount = balances[i] * redeemAmount / D

   • revert if tokenAmount < minRedeemAmounts[i]

   • send tokenAmount of token index i to the caller

3. update D = D - _amount

4. burn _amount of tapETH from the caller

5. increase the totalSupply of tapETH by feeAmount

• redeemSingle(uint256 _amount, uint256 _i, uint256 _minRedeemAmount)

• This function allows the user to redeem _amount of tapETH in order to receive at least _minRedeemAmount of token index i. The Logic of the function consists of:

1. calculate redeemAmount = _amount - feeAmount = amount * ( 1 - redeemFee).

2. calculate the new amount of token i (new y ) for D = D - redeemAmount

3. calculate delta y = new y - old y

4. revert if delta y < _minRedeemAmount

5. send delta y of token index i to the caller

6. increase the total supply of tapETH by feeAmount

• redeemMulti(uint256[] calldata _amounts, uint256 _maxRedeemAmount)

• This function allows the user to redeem at most _maxRedeemAmount of tapETH to receive _amouns[i] of each token index i. The Logic of the function consists of:

1. update balance of each token index i .

2. calculate the new D

3. calculate delta D = new D - old D

4. calculate redeemAmount = delta D + feeAmount = delta D * ( 1 + redeemFee)

5. revert if redeemAmount > _maxRedeemAmount

6. for each token index i, send _amounts[i] to the caller

7. increase the total supply of tapETH by feeAmount

Functions to be executed only by the governance:

• proposeGovernance(address _governance)

  This function allows the current governance to set a new governance address.

• acceptGovernance(address _governance)

  This function allows the pending governance to be activated: to update the governance to the pending governance.

• setMintFee(uint256 _mintFee)

• This function allows the governance to update the mintFee.

• setSwapFee(uint256 _swapFee)

• This function allows the governance to update the swapFee.

• setRedeemFee(uint256 _redeemFee)

• This function allows the governance to update the redeemFee.

• pause()

• This function allows the governance to pause the mint, swap and redeem function.

• unpause()

• This function allows the governance to unpause the mint, swap and redeem function.

• setAdmin(address _account, bool _allowed)

• This function allows the governance to add an admin if _allowed is true or to remove an admin if _allowed is false.

• updateA(uint256 _futureA, uint256 _futureABlock)

• This function allows the governance to update the value of A to _futureA from the block _futureABlock.

Write Methodes

• getA()

• This function returns the current value of A.

• getMintAmount(uint256[] calldata _amounts)

• This function returns (uint256 mintAmount, uint256 fee) where mintAmount is the amount of tapETH to mint for the user, and fee is the mint fee.

• getSwapAmount(uint256 _i, uint256 _j, uint256 _dx)

• This function returns (uint256 amount, uint256 fee) where amount is the output amount in token of index j to send to the user, and fee is the swap fee.

• getRedeemProportionAmount( uint256 _amount)

• This function returns (uint256[] amounts, uint256 fee) where amounts[i] is the output amount in token of index i to send to the user, and fee is the redeem fee.

• getRedeemSingleAmount(uint256 _amount, uint256 _i)

• This function returns (uint256 amount, uint256 fee) where amount is the output amount in token of index i to send to the user, and fee is the redeem fee.

• getRedeemMultiAmount(uint256[] calldata _amounts)

• This function returns (uint256 amount, uint256 fee) where amount is the amount of tapETH to redeem and fee is the redeem fee.