# IScaledBalanceToken

Defines the basic interface for a scaled-balance token.

## Mint

```solidity
event Mint(address caller, address onBehalfOf, uint256 value, uint256 balanceIncrease, uint256 index)
```

*Emitted after the mint action*

### Parameters

| Name            | Type    | Description                                                                                         |
| --------------- | ------- | --------------------------------------------------------------------------------------------------- |
| caller          | address | The address performing the mint                                                                     |
| onBehalfOf      | address | The address of the user that will receive the minted tokens                                         |
| value           | uint256 | The scaled-up amount being minted (based on user entered amount and balance increase from interest) |
| balanceIncrease | uint256 | The increase in scaled-up balance since the last action of 'onBehalfOf'                             |
| index           | uint256 | The next liquidity index of the reserve                                                             |

## Burn

```solidity
event Burn(address from, address target, uint256 value, uint256 balanceIncrease, uint256 index)
```

*Emitted after the burn action*\
*If the burn function does not involve a transfer of the underlying asset, the target defaults to zero address*

### Parameters

| Name            | Type    | Description                                                                              |
| --------------- | ------- | ---------------------------------------------------------------------------------------- |
| from            | address | The address from which the tokens will be burned                                         |
| target          | address | The address that will receive the underlying, if any                                     |
| value           | uint256 | The scaled-up amount being burned (user entered amount - balance increase from interest) |
| balanceIncrease | uint256 | The increase in scaled-up balance since the last action of 'from'                        |
| index           | uint256 | The next liquidity index of the reserve                                                  |

## scaledBalanceOf

```solidity
function scaledBalanceOf(address user) external view returns (uint256)
```

Returns the scaled balance of the user.

*The scaled balance is the sum of all the updated stored balance divided by the reserve's liquidity index*\
*at the moment of the update*

### Parameters

| Name | Type    | Description                          |
| ---- | ------- | ------------------------------------ |
| user | address | The user whose balance is calculated |

### Return Values

| Name | Type    | Description                    |
| ---- | ------- | ------------------------------ |
| \[0] | uint256 | The scaled balance of the user |

## getScaledUserBalanceAndSupply

```solidity
function getScaledUserBalanceAndSupply(address user) external view returns (uint256, uint256)
```

Returns the scaled balance of the user and the scaled total supply.

### Parameters

| Name | Type    | Description             |
| ---- | ------- | ----------------------- |
| user | address | The address of the user |

### Return Values

| Name | Type    | Description                    |
| ---- | ------- | ------------------------------ |
| \[0] | uint256 | The scaled balance of the user |
| \[1] | uint256 | The scaled total supply        |

## scaledTotalSupply

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

Returns the scaled total supply of the scaled balance token. Represents sum(debt/index)

### Return Values

| Name | Type    | Description             |
| ---- | ------- | ----------------------- |
| \[0] | uint256 | The scaled total supply |

## getPreviousIndex

```solidity
function getPreviousIndex(address user) external view returns (uint256)
```

Returns last index interest was accrued to the user's balance

### Parameters

| Name | Type    | Description             |
| ---- | ------- | ----------------------- |
| user | address | The address of the user |

### Return Values

| Name | Type    | Description                                                                 |
| ---- | ------- | --------------------------------------------------------------------------- |
| \[0] | uint256 | The last index interest was accrued to the user's balance, expressed in ray |