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 Uomi 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, Uomi implements precompiled contracts that support new Uomi features.

Ethereum Native Precompiles

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

Uomi Specific Precompiles

Precompile	Address
Sr25519	0x0000000000000000000000000000000000005002
SubstrateECDSA	0x0000000000000000000000000000000000005003
Assets-erc20	ASSET_PRECOMPILE_ADDRESS_PREFIX
UomiEngine	0x00000000000000000000000000000000756f6D69

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

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Usage example

Here we'll demonstrate a simple smart contract that can interact with Sr25519 precompile

// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity ^0.8.0;

contract Sr25519Caller {
    address constant precompileAddress = 0x0000000000000000000000000000000000005002;

    function verify(bytes32 publicKey, bytes memory signature, bytes memory message) public view returns (bool) {
        (bool success, bytes memory result) = precompileAddress.staticcall(
            abi.encodeWithSignature("verify(bytes32,bytes,bytes)", publicKey, signature, message)
        );
        require(success, "Failed to call precompile");
        return abi.decode(result, (bool));
    }
}