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与SPL代币交互 (Interacting with SPL Tokens)

The ERC-20 SPL-Wrapper contract provides an access to native Solana tokens, registered in the SPL-token contract, through the ERC-20 interface.

ERC-20 SPL封装器合约通过 ERC-20 接口提供访问在 SPL-token 合约中注册的原生 Solana 代币的入口。

This allows interaction of the Solana applications with EVM(Solidity/Vyper/etc.) bytecode contracts. ERC-20 SPL-Wrapper can also be used to transfer funds in Solana tokens using Ethereum wallets such as Metamask.

这使得 Solana 应用程序与 EVM(Solidity/Vyper/等)字节码合约进行交互。ERC-20 SPL封装器还能用于帮助Metamask 等以太坊钱包以 Solana 代币转移资金。

Contract is implemented in Rust as part of Neon EVM program.

作为 Neon EVM 程序的一部分，Contract 在 Rust 中实现。

Source codes:
源代码：

Rust source code

Solidity wrapper source code

合约接口(Contract interface)​

interface IERC20 {
    function decimals() external view returns (uint8);
    function totalSupply() external view returns (uint256);
    function balanceOf(address who) external view returns (uint256);
    function allowance(address ow ERC-20 SPL-Wrapperer, address spender) external view returns (uint256);
    function transfer(address to, uint256 value) external returns (bool);
    function approve(address spender, uint256 value) external returns (bool);
    function transferFrom(address from, address to, uint256 value) external returns (bool);

    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);

    function approveSolana(bytes32 spender, uint64 value) external returns (bool);
    event ApprovalSolana(address indexed owner, bytes32 indexed spender, uint64 value);
}

Functionality of interface modules:
接口各模块功能：

  • decimals() --- Returns the number of decimals used to get its user representation. For example, if decimals equals 2, a balance of 505 tokens should be displayed to a user as 5,05 (505 / 10 * 2).
    小数位() --- 返回用于获取其用户代表性的小数位数。例如，如果小数等于 2，则应向用户显示 505 个代币的余额为 5,05 (505 / 10 * 2)。

  • totalSupply() --- Returns the amount of tokens in existence.
    总供给() --- 返回代币存在总量。

  • balanceOf(address account) --- Returns the amount of tokens owned by the account.
    余额(地址账户) --- 返回账户拥有的代币数量。

  • allowance(address owner, address spender) --- Returns the remaining number of tokens that a spender will be allowed to spend on behalf of the owner through transferFrom. This is zero by default.
    津贴(地址所有者，地址花费者) --- 返回允许花费者通过 转账 (transferFrom) 代表拥有者花费的剩余代币数量。默认情况下为零。

  • transfer(address recipient, uint256 amount) --- Sends the specified amount of tokens from the caller's account balance to the recipient's account balance.
    转发者(地址回执, 256单位数量) --- 将指定数量的代币从调用者的帐户余额发送到接收者的帐户余额。

  • approve(address spender, uint256 amount) --- Sets an amount as the spender's allowance over the caller's tokens.
    同意金额(地址花费者, 256单位数量) --- 将金额设置为花费者对调用者代币的津贴。

  • transferFrom(address sender, address recipient, uint256 amount) --- Transfer the amount of tokens from the sender to the recipient.
    转账(地址所有者, 地址回执, uint256数量) --- 将代币数额从发送者转移到收件人。

  • approveSolana(bytes32 spender, uint64 value) --- Allows Solana user spender to withdraw from the caller's account multiple times, up to the value amount. Only one Solana spender can exists at the time. Translates into spl-token Approve instruction.
    Solana同意金额(32字节花费者, uint64值) --- 允许 Solana 用户花费者多次从调用者的账户中提款，最高可达价值 设置的金额。同一时刻只能存在一个 Solana 消费者。翻译成 spl-token 批准指令。

限制(Restrictions)​

According to SPL token structure, u64 is used to store the balance (In ERC-20 it's u256). Based on u64, maximum balance and transfer amounts are restricted by (2\^64-1)/(10\^9) (for 9 decimals accuracy).

根据 SPL 代币结构，u64 用于存储余额(在 ERC-20 中为 u256)。基于 u64，最大余额和转账金额受 (2\^64-1)/(10\^9) 限制(精确到小数点后 9 位)。

找到代币账户地址(Finding the Token Account address)​

Token account for a given wallet address is a program-derived account consisting of three constants, the Ethereum wallet address itself, ERC-20 contract address, and the token mint.

给定钱包地址的代币账户是一个由程序派生的账户，由三个常量组成，即以太坊钱包地址本身、ERC-20 合约地址和代币铸币厂。

The account address can be derived in Rust with:

账户地址可以从Rust中产生：

const ACCOUNT_SEED_VERSION: u8 = 1;

fn token_address(owner: &H160, contract: &H160, mint: &Pubkey, neon_evm: &Pubkey) {
    let seeds: &[&[u8]] = &[&[ACCOUNT_SEED_VERSION], b"ERC20Balance", &mint.to_bytes(), contract.as_bytes(), owner.as_bytes()];
    Pubkey::find_program_address(seeds, neon_evm)
}

创建代币账户 (Creating the Token Account)​

Accounts hold token balances and are created using the ERC20CreateTokenAccount instruction.

账户持有代币余额，并使用 ERC20CreateTokenAccount 指令创建。

This instruction can be created in Rust with:
这条指令可以在 Rust 中创建：

fn create_token_account(funding: Pubkey, owner: H160, contract: H160, mint: Pubkey, neon_evm: Pubkey) {
    let (token_address, _) = token_address(&owner, &contract, &mint, &neon_evm);
    let (wallet_address, _) = Pubkey::find_program_address(&[&[ACCOUNT_SEED_VERSION], owner.as_bytes()], &neon_evm);
    let (contract_address, _) = Pubkey::find_program_address(&[&[ACCOUNT_SEED_VERSION], contract.as_bytes()], &neon_evm);

    Instruction::new_with_bincode(
        neon_evm,
        &(15_u8),
        vec![
            AccountMeta::new(funding, true),
            AccountMeta::new(token_address, false),
            AccountMeta::new_readonly(wallet_address, false),
            AccountMeta::new_readonly(contract_address, false),
            AccountMeta::new_readonly(mint, false),
            AccountMeta::new_readonly(system_program::id(), false),
            AccountMeta::new_readonly(spl_token::id(), false),
            AccountMeta::new_readonly(sysvar::rent::id(), false)
        ]
    )
}