Precompiles

A precompile is a common functionality used in smart contracts that has been compiled in advance, so Ethereum nodes can run it more efficiently. From a contract's perspective, this is a single command like an opcode. The Frontier EVM used on Astar network provides several useful precompiled contracts. These contracts are implemented in our ecosystem as a native implementation. The precompiled contracts 0x01 through 0x08 are the same as those in Ethereum (see list below). Additionally, Astar implements precompiled contracts starting from 0x5001, that support new Astar features.

Ethereum Native Precompiles

Precompile	Address
ECRecover	0x0000000000000000000000000000000000000001
Sha256	0x0000000000000000000000000000000000000002
Ripemd160	0x0000000000000000000000000000000000000003
Identity	0x0000000000000000000000000000000000000004
Modexp	0x0000000000000000000000000000000000000005
Bn128Add	0x0000000000000000000000000000000000000006
Bn128Mul	0x0000000000000000000000000000000000000007
Bn128Pairing	0x0000000000000000000000000000000000000008

Astar Specific Precompiles

Precompile	Address
DappsStaking	0x0000000000000000000000000000000000005001
Sr25519	0x0000000000000000000000000000000000005002
SubstrateEcdsa	0x0000000000000000000000000000000000005003
XCM	0x0000000000000000000000000000000000005004
XVM	0x0000000000000000000000000000000000005005
assets-erc20	ASSET_PRECOMPILE_ADDRESS_PREFIX

The interface descriptions for these precompiles can be found in the precompiles folder: Astar repo. The Addresses can be checked in the Astar repo for each runtime in precompile.rs files.

Usage Example

Here we'll demonstrate how to interact with the dApp staking precompile using Remix IDE. Other precompiles can be accessed in a similar manner.

import "./DappsStaking.sol";
contract A {
    DappsStaking public constant DAPPS_STAKING = DappsStaking(0x0000000000000000000000000000000000005001);

    /// @notice Check current era
    function checkCurrentEra() public view {
        uint256 currentEra = DAPPS_STAKING.read_current_era();
    }
}

Example use: check current era and total staked amount in the pallet-dapps-staking for Shiden Network. For this example we will use Remix.

1. Copy DappsStaking.sol from Astar repo and create new contract in Remix:

2. Compile the dAppStaking contract:

3. The precompile does not need to be deployed since it is already on the network, but you will need to tell Remix where to find it. After you connect your EVM wallet to Shiden Network (same applies for Astar Network and for Shibuya Testnet) follow these steps:
   1. Open the Deploy tab.
   2. Use injected Web3 environment. It should point to Shiden Mainnet with ChainId 336.
   3. Make sure you have the selected dAppStaking contract.
   4. Provide the address of the precompiled contract 0x0000000000000000000000000000000000005001.
   5. The dApp Staking contract will appear under Deployed contracts.

4. Interact with the contract.
   1. Check the current era.
   2. Use the current era as input to check total staked amount on the network.