# maTokens

Information generally about how maTokens work is given in the article here: [Aave's Interest-Bearing aTokens on Matic Network](https://aavegotchi.substack.com/p/aaves-interest-bearing-atokens-on).

### Conversion between aTokens and maTokens

The aToken bridging contract leverages the [Aave protocol](https://docs.aave.com/developers/the-core-protocol/atokens) to convert aToken values to maToken values and back. Exactly how this is done is given in the two functions below.

To convert an aToken value to a maToken value  or vise versa call the following functions on Ethereum on the aToken bridge contract which is at this address: `0x0D29aDA4c818A9f089107201eaCc6300e56E0d5c`

```solidity
 /**
  * @dev Converts aToken value to maToken value
  * @param _aTokenAddress aToken contract address
  * @param _aTokenValue aToken value to convert
  * @return maTokenValue_ The converted maToken value
  **/
 function getMATokenValue(address _aTokenAddress, uint256 _aTokenValue) 
   public 
   view 
   returns 
   (uint256 maTokenValue_) 
 {
   ILendingPool pool = IAToken(_aTokenAddress).POOL();
   uint256 liquidityIndex = pool.getReserveNormalizedIncome(
     IAToken(_aTokenAddress).UNDERLYING_ASSET_ADDRESS()
   );
   maTokenValue_ = p27Div(_aTokenValue, liquidityIndex);
 }
 
 /**
  * @dev Converts maToken value to aToken value
  * @param _aTokenAddress aToken contract address
  * @param _maTokenValue maToken value to convert
  * @return aTokenValue_ The converted aToken value
  **/
 function getATokenValue(address _aTokenAddress, uint256 _maTokenValue) 
   public 
   view 
   returns (uint256 aTokenValue_) 
 {
  ILendingPool pool = IAToken(_aTokenAddress).POOL();
  uint256 liquidityIndex = pool.getReserveNormalizedIncome(
    IAToken(_aTokenAddress).UNDERLYING_ASSET_ADDRESS()
  );
  aTokenValue_ = p27Mul(_maTokenValue, liquidityIndex);
 }
```

The source code for the aToken bridge contract is here: <https://github.com/aavegotchi/pos-portal/blob/master/contracts/root/RootChainManager/ATokenRootChainManager.sol>

Don't use the ABI on Etherscan to call these functions. Instead use the ABI at this link: <https://gist.github.com/mudgen/5da65e965e05ba08354f003aa86e6587>

### Getting aToken and maToken contract addresses

Use the functions below to get aTokens and maToken addresses.

```solidity
 /**
  * @dev Gets the maTokens contract address on Matic that is associate with
  * the aTokens contract on Ethereum.
  * @param _rootToken The aToken contract address on Ethereum
  * @return The maToken contract address on Matic.
  **/
function rootToChildToken(address _rootToken) external view returns (address)

 /**
  * @dev Gets the aTokens contract address on Ethereum that is associate with
  * the maTokens contract on Matic.
  * @param _childToken The maToken contract address on Matic
  * @return The aToken contract address on Ethereum.
  **/
function childToRootToken(address _childToken) external view returns (address)
```

The aToken addresses can be found on Etherscan or in [Aave documentation](https://docs.aave.com/developers/getting-started/deployed-contracts).

The aToken bridge to Matic only works with version 2 aToken contracts.