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The evm Contract

The evm contract is one of the core contracts on each IOTA Smart Contracts chain.

The evm core contract provides the necessary infrastructure to accept Ethereum transactions and execute EVM code. It also includes the implementation of the ISC Magic contract.

note

For more information about how ISC supports EVM contracts, refer to the EVM section.

Entry Points​

Most entry points of the evm core contract are meant to be accessed through the JSON-RPC service provided automatically by the Wasp node so that the end users can use standard EVM tools like MetaMask. We only list the entry points not exposed through the JSON-RPC interface in this document.

init()​

Called automatically when the ISC is deployed.

Some parameters of the evm contract can be specified by passing them to the root contract init entry point:

  • evmg (optional GenesisAlloc): The genesis allocation. The balance of all accounts must be 0.

  • evmbk (optional int32 - default: keep all): Amount of EVM blocks to keep in the state.

  • evmchid (optional uint16 - default: 1074): EVM chain iD

    caution

    Re-using an existing Chain ID is not recommended and can be a security risk. For serious usage, register a unique Chain ID on Chainlist and use that instead of the default. It is not possible to change the EVM chain ID after deployment.

  • evmw (optional GasRatio - default: 1:1): The ISC to EVM gas ratio.

registerERC20NativeToken​

Registers an ERC20 contract to act as a proxy for the native tokens, at address 0x107402xxxxxxxx00000000000000000000000000, where xxxxxxxx is the little-endian encoding of the foundry serial number.

Only the foundry owner can call this endpoint.

Parameters​

  • fs (uint32): The foundry serial number
  • n (string): The token name
  • t (string): The ticker symbol
  • d (uint8): The token decimals

You can call this endpoint with the wasp-cli register-erc20-native-token command. See wasp-cli chain register-erc20-native-token -h for instructions on how to use the command.

registerERC20NativeTokenOnRemoteChain​

Registers an ERC20 contract to act as a proxy for the native tokens on another chain.

The foundry must be controlled by this chain. Only the foundry owner can call this endpoint.

This endpoint is intended to be used in case the foundry is controlled by chain A, and the owner of the foundry wishes to register the ERC20 contract on chain B. In that case, the owner must call this endpoint on chain A with target = chain B. The request to chain B is then sent as an on-ledger request. After a few minutes, call getERC20ExternalNativeTokensAddress on chain B to find out the address of the ERC20 contract.

Parameters​

  • fs (uint32): The foundry serial number
  • n (string): The token name
  • t (string): The ticker symbol
  • d (uint8): The token decimals
  • A (uint8): The target chain address, where the ERC20 contract will be registered.

You can call this endpoint with the wasp-cli register-erc20-native-token-on-remote-chain command. See wasp-cli chain register-erc20-native-token-on-remote-chain -h for instructions on how to use the command.

registerERC20ExternalNativeToken​

Registers an ERC20 contract to act as a proxy for the native tokens.

Only an alias address can call this endpoint.

If the foundry is controlled by another ISC chain, the foundry owner can call registerERC20NativeTokenOnRemoteChain on that chain, which will automatically call this endpoint on the chain set as target.

Parameters​

  • fs (uint32): The foundry serial number
  • n (string): The token name
  • t (string): The ticker symbol
  • d (uint8): The token decimals
  • T (TokenScheme): The native token scheme

registerERC721NFTCollection​

Registers an ERC721 contract to act as a proxy for an NFT collection, at address 0x107404xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx, where xxx... is the first 17 bytes of the collection ID.

The call will fail if the address is taken by another collection with the same prefix.

Parameters​

  • C (NTFID): The collection ID

Views​

getERC20ExternalNativeTokensAddress​

Returns the address of an ERC20 contract registered with registerERC20NativeTokenOnRemoteChain.

Only the foundry owner can call this endpoint.

Parameters​

  • N (NativeTokenID): The native token ID

Schemas​

GenesisAlloc​

GenesisAlloc is encoded as the concatenation of:

  • Amount of accounts n (uint32).
  • n times:
    • Ethereum address ([]byte prefixed with uint32 size).
    • Account code ([]byte prefixed with uint32 size).
    • Amount of storage key/value pairs m(uint32).
    • m times:
      • Key ([]byte prefixed with uint32 size).
      • Value([]byte prefixed with uint32 size).
    • Account balance (must be 0)([]byte prefixed with uint32 size).
    • Account nonce (uint64).
    • Account private key (may be used for tests)(uint64).