# VToken

## Venus's vToken Contract

Abstract base for vTokens

## Solidity API

```solidity
struct MintLocalVars {
  enum CarefulMath.MathError mathErr;
  uint256 exchangeRateMantissa;
  uint256 mintTokens;
  uint256 totalSupplyNew;
  uint256 accountTokensNew;
  uint256 actualMintAmount;
}
```

```solidity
struct RedeemLocalVars {
  enum CarefulMath.MathError mathErr;
  uint256 exchangeRateMantissa;
  uint256 redeemTokens;
  uint256 redeemAmount;
  uint256 totalSupplyNew;
  uint256 accountTokensNew;
}
```

```solidity
struct BorrowLocalVars {
  enum CarefulMath.MathError mathErr;
  uint256 accountBorrows;
  uint256 accountBorrowsNew;
  uint256 totalBorrowsNew;
}
```

```solidity
struct RepayBorrowLocalVars {
  enum TokenErrorReporter.Error err;
  enum CarefulMath.MathError mathErr;
  uint256 repayAmount;
  uint256 borrowerIndex;
  uint256 accountBorrows;
  uint256 accountBorrowsNew;
  uint256 totalBorrowsNew;
  uint256 actualRepayAmount;
}
```

#### transfer

Transfer `amount` tokens from `msg.sender` to `dst`

```solidity
function transfer(address dst, uint256 amount) external returns (bool)
```

**Parameters**

| Name   | Type    | Description                            |
| ------ | ------- | -------------------------------------- |
| dst    | address | The address of the destination account |
| amount | uint256 | The number of tokens to transfer       |

**Return Values**

| Name | Type | Description                           |
| ---- | ---- | ------------------------------------- |
| \[0] | bool | Whether or not the transfer succeeded |

***

#### transferFrom

Transfer `amount` tokens from `src` to `dst`

```solidity
function transferFrom(address src, address dst, uint256 amount) external returns (bool)
```

**Parameters**

| Name   | Type    | Description                            |
| ------ | ------- | -------------------------------------- |
| src    | address | The address of the source account      |
| dst    | address | The address of the destination account |
| amount | uint256 | The number of tokens to transfer       |

**Return Values**

| Name | Type | Description                           |
| ---- | ---- | ------------------------------------- |
| \[0] | bool | Whether or not the transfer succeeded |

***

#### approve

Approve `spender` to transfer up to `amount` from `src`

```solidity
function approve(address spender, uint256 amount) external returns (bool)
```

**Parameters**

| Name    | Type    | Description                                                               |
| ------- | ------- | ------------------------------------------------------------------------- |
| spender | address | The address of the account which may transfer tokens                      |
| amount  | uint256 | The number of tokens that are approved (type(uint256).max means infinite) |

**Return Values**

| Name | Type | Description                           |
| ---- | ---- | ------------------------------------- |
| \[0] | bool | Whether or not the approval succeeded |

***

#### balanceOfUnderlying

Get the underlying balance of the `owner`

```solidity
function balanceOfUnderlying(address owner) external returns (uint256)
```

**Parameters**

| Name  | Type    | Description                         |
| ----- | ------- | ----------------------------------- |
| owner | address | The address of the account to query |

**Return Values**

| Name | Type    | Description                               |
| ---- | ------- | ----------------------------------------- |
| \[0] | uint256 | The amount of underlying owned by `owner` |

***

#### totalBorrowsCurrent

Returns the current total borrows plus accrued interest

```solidity
function totalBorrowsCurrent() external returns (uint256)
```

**Return Values**

| Name | Type    | Description                     |
| ---- | ------- | ------------------------------- |
| \[0] | uint256 | The total borrows with interest |

***

#### borrowBalanceCurrent

Accrue interest to updated borrowIndex and then calculate account's borrow balance using the updated borrowIndex

```solidity
function borrowBalanceCurrent(address account) external returns (uint256)
```

**Parameters**

| Name    | Type    | Description                                                               |
| ------- | ------- | ------------------------------------------------------------------------- |
| account | address | The address whose balance should be calculated after updating borrowIndex |

**Return Values**

| Name | Type    | Description            |
| ---- | ------- | ---------------------- |
| \[0] | uint256 | The calculated balance |

***

#### seize

Transfers collateral tokens (this market) to the liquidator.

```solidity
function seize(address liquidator, address borrower, uint256 seizeTokens) external returns (uint256)
```

**Parameters**

| Name        | Type    | Description                             |
| ----------- | ------- | --------------------------------------- |
| liquidator  | address | The account receiving seized collateral |
| borrower    | address | The account having collateral seized    |
| seizeTokens | uint256 | The number of vTokens to seize          |

**Return Values**

| Name | Type    | Description                                                                                      |
| ---- | ------- | ------------------------------------------------------------------------------------------------ |
| \[0] | uint256 | uint Returns 0 on success, otherwise returns a failure code (see ErrorReporter.sol for details). |

***

#### \_setPendingAdmin

Begins transfer of admin rights. The newPendingAdmin must call `_acceptAdmin` to finalize the transfer.

```solidity
function _setPendingAdmin(address payable newPendingAdmin) external returns (uint256)
```

**Parameters**

| Name            | Type            | Description        |
| --------------- | --------------- | ------------------ |
| newPendingAdmin | address payable | New pending admin. |

**Return Values**

| Name | Type    | Description                                                                                      |
| ---- | ------- | ------------------------------------------------------------------------------------------------ |
| \[0] | uint256 | uint Returns 0 on success, otherwise returns a failure code (see ErrorReporter.sol for details). |

***

#### \_acceptAdmin

Accepts transfer of admin rights. msg.sender must be pendingAdmin

```solidity
function _acceptAdmin() external returns (uint256)
```

**Return Values**

| Name | Type    | Description                                                                                      |
| ---- | ------- | ------------------------------------------------------------------------------------------------ |
| \[0] | uint256 | uint Returns 0 on success, otherwise returns a failure code (see ErrorReporter.sol for details). |

***

#### \_setReserveFactor

accrues interest and sets a new reserve factor for the protocol using `_setReserveFactorFresh`

```solidity
function _setReserveFactor(uint256 newReserveFactorMantissa_) external returns (uint256)
```

**Return Values**

| Name | Type    | Description                                                                                      |
| ---- | ------- | ------------------------------------------------------------------------------------------------ |
| \[0] | uint256 | uint Returns 0 on success, otherwise returns a failure code (see ErrorReporter.sol for details). |

***

#### setAccessControlManager

Sets the address of the access control manager of this contract

```solidity
function setAccessControlManager(address newAccessControlManagerAddress) external returns (uint256)
```

**Parameters**

| Name                           | Type    | Description                        |
| ------------------------------ | ------- | ---------------------------------- |
| newAccessControlManagerAddress | address | New address for the access control |

**Return Values**

| Name | Type    | Description                           |
| ---- | ------- | ------------------------------------- |
| \[0] | uint256 | uint 0=success, otherwise will revert |

***

#### \_reduceReserves

Accrues interest and reduces reserves by transferring to protocol share reserve

```solidity
function _reduceReserves(uint256 reduceAmount_) external virtual returns (uint256)
```

**Parameters**

| Name           | Type    | Description                     |
| -------------- | ------- | ------------------------------- |
| reduceAmount\_ | uint256 | Amount of reduction to reserves |

**Return Values**

| Name | Type    | Description                                                                                      |
| ---- | ------- | ------------------------------------------------------------------------------------------------ |
| \[0] | uint256 | uint Returns 0 on success, otherwise returns a failure code (see ErrorReporter.sol for details). |

***

#### allowance

Get the current allowance from `owner` for `spender`

```solidity
function allowance(address owner, address spender) external view returns (uint256)
```

**Parameters**

| Name    | Type    | Description                                                  |
| ------- | ------- | ------------------------------------------------------------ |
| owner   | address | The address of the account which owns the tokens to be spent |
| spender | address | The address of the account which may transfer tokens         |

**Return Values**

| Name | Type    | Description                                                                 |
| ---- | ------- | --------------------------------------------------------------------------- |
| \[0] | uint256 | The number of tokens allowed to be spent (type(uint256).max means infinite) |

***

#### balanceOf

Get the token balance of the `owner`

```solidity
function balanceOf(address owner) external view returns (uint256)
```

**Parameters**

| Name  | Type    | Description                         |
| ----- | ------- | ----------------------------------- |
| owner | address | The address of the account to query |

**Return Values**

| Name | Type    | Description                           |
| ---- | ------- | ------------------------------------- |
| \[0] | uint256 | The number of tokens owned by `owner` |

***

#### getAccountSnapshot

Get a snapshot of the account's balances, and the cached exchange rate

```solidity
function getAccountSnapshot(address account) external view returns (uint256, uint256, uint256, uint256)
```

**Parameters**

| Name    | Type    | Description                        |
| ------- | ------- | ---------------------------------- |
| account | address | Address of the account to snapshot |

**Return Values**

| Name | Type    | Description                                                             |
| ---- | ------- | ----------------------------------------------------------------------- |
| \[0] | uint256 | (possible error, token balance, borrow balance, exchange rate mantissa) |
| \[1] | uint256 |                                                                         |
| \[2] | uint256 |                                                                         |
| \[3] | uint256 |                                                                         |

***

#### supplyRatePerBlock

Returns the current per-block supply interest rate for this vToken

```solidity
function supplyRatePerBlock() external view returns (uint256)
```

**Return Values**

| Name | Type    | Description                                        |
| ---- | ------- | -------------------------------------------------- |
| \[0] | uint256 | The supply interest rate per block, scaled by 1e18 |

***

#### borrowRatePerBlock

Returns the current per-block borrow interest rate for this vToken

```solidity
function borrowRatePerBlock() external view returns (uint256)
```

**Return Values**

| Name | Type    | Description                                        |
| ---- | ------- | -------------------------------------------------- |
| \[0] | uint256 | The borrow interest rate per block, scaled by 1e18 |

***

#### getCash

Get cash balance of this vToken in the underlying asset

```solidity
function getCash() external view returns (uint256)
```

**Return Values**

| Name | Type    | Description                                             |
| ---- | ------- | ------------------------------------------------------- |
| \[0] | uint256 | The quantity of underlying asset owned by this contract |

***

#### setReduceReservesBlockDelta

Governance function to set new threshold of block difference after which funds will be sent to the protocol share reserve

```solidity
function setReduceReservesBlockDelta(uint256 newReduceReservesBlockDelta_) external
```

**Parameters**

| Name                          | Type    | Description            |
| ----------------------------- | ------- | ---------------------- |
| newReduceReservesBlockDelta\_ | uint256 | block difference value |

***

#### setProtocolShareReserve

Sets protocol share reserve contract address

```solidity
function setProtocolShareReserve(address payable protcolShareReserve_) external
```

**Parameters**

| Name                  | Type            | Description                                    |
| --------------------- | --------------- | ---------------------------------------------- |
| protcolShareReserve\_ | address payable | The address of protocol share reserve contract |

***

#### initialize

Initialize the money market

```solidity
function initialize(contract ComptrollerInterface comptroller_, contract InterestRateModelV8 interestRateModel_, uint256 initialExchangeRateMantissa_, string name_, string symbol_, uint8 decimals_) public
```

**Parameters**

| Name                          | Type                          | Description                               |
| ----------------------------- | ----------------------------- | ----------------------------------------- |
| comptroller\_                 | contract ComptrollerInterface | The address of the Comptroller            |
| interestRateModel\_           | contract InterestRateModelV8  | The address of the interest rate model    |
| initialExchangeRateMantissa\_ | uint256                       | The initial exchange rate, scaled by 1e18 |
| name\_                        | string                        | EIP-20 name of this token                 |
| symbol\_                      | string                        | EIP-20 symbol of this token               |
| decimals\_                    | uint8                         | EIP-20 decimal precision of this token    |

***

#### exchangeRateCurrent

Accrue interest then return the up-to-date exchange rate

```solidity
function exchangeRateCurrent() public returns (uint256)
```

**Return Values**

| Name | Type    | Description                             |
| ---- | ------- | --------------------------------------- |
| \[0] | uint256 | Calculated exchange rate scaled by 1e18 |

***

#### accrueInterest

Applies accrued interest to total borrows and reserves

```solidity
function accrueInterest() public virtual returns (uint256)
```

***

#### \_setComptroller

Sets a new comptroller for the market

```solidity
function _setComptroller(contract ComptrollerInterface newComptroller) public returns (uint256)
```

**Return Values**

| Name | Type    | Description                                                                                      |
| ---- | ------- | ------------------------------------------------------------------------------------------------ |
| \[0] | uint256 | uint Returns 0 on success, otherwise returns a failure code (see ErrorReporter.sol for details). |

***

#### \_setInterestRateModel

Accrues interest and updates the interest rate model using \_setInterestRateModelFresh

```solidity
function _setInterestRateModel(contract InterestRateModelV8 newInterestRateModel_) public returns (uint256)
```

**Parameters**

| Name                   | Type                         | Description                        |
| ---------------------- | ---------------------------- | ---------------------------------- |
| newInterestRateModel\_ | contract InterestRateModelV8 | The new interest rate model to use |

**Return Values**

| Name | Type    | Description                                                                                      |
| ---- | ------- | ------------------------------------------------------------------------------------------------ |
| \[0] | uint256 | uint Returns 0 on success, otherwise returns a failure code (see ErrorReporter.sol for details). |

***

#### exchangeRateStored

Calculates the exchange rate from the underlying to the VToken

```solidity
function exchangeRateStored() public view returns (uint256)
```

**Return Values**

| Name | Type    | Description                             |
| ---- | ------- | --------------------------------------- |
| \[0] | uint256 | Calculated exchange rate scaled by 1e18 |

***

#### borrowBalanceStored

Return the borrow balance of account based on stored data

```solidity
function borrowBalanceStored(address account) public view returns (uint256)
```

**Parameters**

| Name    | Type    | Description                                    |
| ------- | ------- | ---------------------------------------------- |
| account | address | The address whose balance should be calculated |

**Return Values**

| Name | Type    | Description            |
| ---- | ------- | ---------------------- |
| \[0] | uint256 | The calculated balance |

***

#### transferOutUnderlyingFlashLoan

Transfers the underlying asset to the specified address for flash loan operations.

```solidity
function transferOutUnderlyingFlashLoan(address payable to, uint256 amount) external
```

Can only be called by the Comptroller contract. This function performs the actual transfer of the underlying asset and tracks the flash loan amount.

**Parameters**

| Name   | Type            | Description                                              |
| ------ | --------------- | -------------------------------------------------------- |
| to     | address payable | The address to which the underlying asset is transferred |
| amount | uint256         | The amount of the underlying asset to transfer           |

***

#### transferInUnderlyingFlashLoan

Transfers the underlying asset from the specified address for flash loan repayment.

```solidity
function transferInUnderlyingFlashLoan(
    address payable from,
    uint256 repaymentAmount,
    uint256 totalFee,
    uint256 protocolFee
) external returns (uint256)
```

Can only be called by the Comptroller contract. This function performs the actual transfer of the underlying asset for flash loan repayment and handles protocol fee distribution to the protocol share reserve.

**Parameters**

| Name            | Type            | Description                                                             |
| --------------- | --------------- | ----------------------------------------------------------------------- |
| from            | address payable | The address from which the underlying asset is transferred              |
| repaymentAmount | uint256         | The amount of the underlying asset to transfer                          |
| totalFee        | uint256         | The total fee amount for the flash loan                                 |
| protocolFee     | uint256         | The protocol fee amount to be transferred to the protocol share reserve |

**Return Values**

| Name | Type    | Description                      |
| ---- | ------- | -------------------------------- |
| \[0] | uint256 | The actual amount transferred in |

***

#### calculateFlashLoanFee

Calculates the total fee and protocol fee for a flash loan amount. Reverts if flash loans are disabled.

```solidity
function calculateFlashLoanFee(uint256 amount)
    public
    view
    returns (uint256, uint256);
```

**Parameters**

| Name   | Type    | Description                  |
| ------ | ------- | ---------------------------- |
| amount | uint256 | The amount of the flash loan |

**Return Values**

| Name | Type    | Description                                                           |
| ---- | ------- | --------------------------------------------------------------------- |
| \[0] | uint256 | The total fee for the flash loan                                      |
| \[1] | uint256 | The portion of the total fees that goes to the protocol share reserve |

***

#### setFlashLoanEnabled

Sets flash loan status for the market. Governance-restricted.

```solidity
function setFlashLoanEnabled(bool enabled) external returns (uint256)
```

**Parameters**

| Name    | Type | Description                                  |
| ------- | ---- | -------------------------------------------- |
| enabled | bool | True to enable flash loans, false to disable |

**Return Values**

| Name | Type    | Description                         |
| ---- | ------- | ----------------------------------- |
| \[0] | uint256 | Status code (e.g., success/failure) |

***

#### setFlashLoanFeeMantissa

Updates the flash loan fee parameters. Governance-restricted.

```solidity
function setFlashLoanFeeMantissa(
    uint256 flashLoanFeeMantissa_,
    uint256 flashLoanProtocolShare_
)
    external
    returns (uint256);
```

**Parameters**

| Name                     | Type    | Description                             |
| ------------------------ | ------- | --------------------------------------- |
| flashLoanFeeMantissa\_   | uint256 | New flash loan fee (scaled by 1e18)     |
| flashLoanProtocolShare\_ | uint256 | New protocol fee share (scaled by 1e18) |

**Return Values**

| Name | Type    | Description                         |
| ---- | ------- | ----------------------------------- |
| \[0] | uint256 | Status code (e.g., success/failure) |

***