🏗️ 第04课：以太坊架构——世界计算机的蓝图

区块链基础 阶段一 ✅ 验证通过

📖 一、以太坊是什么？

Vitalik Buterin在2013年提出：以太坊 = 去中心化的世界计算机。不仅仅是货币（如Bitcoin），而是可编程的区块链平台——智能合约让它成为"图灵完备"的分布式计算引擎。

📖 二、以太坊分层架构

📖 三、EVM——以太坊虚拟机

3.1 EVM是什么？

EVM是以太坊的运行时环境，一个基于栈的虚拟机。所有智能合约最终编译为EVM字节码在EVM中执行。

3.2 EVM执行模型

💻 四、代码实战：EVM字节码解析器

// evm-opcodes.js — EVM操作码解析器 ✅验证通过

// EVM操作码表（部分）
const OPCODES = {
  '0x00': { name: 'STOP',    gas: 0,   stack: 0, desc: '停止执行' },
  '0x01': { name: 'ADD',     gas: 3,   stack: 2, desc: '加法 a + b' },
  '0x02': { name: 'MUL',     gas: 5,   stack: 2, desc: '乘法 a * b' },
  '0x03': { name: 'SUB',     gas: 3,   stack: 2, desc: '减法 a - b' },
  '0x10': { name: 'LT',      gas: 3,   stack: 2, desc: '小于比较 a < b' },
  '0x54': { name: 'SLOAD',   gas: 200, stack: 1, desc: '从存储读取' },
  '0x55': { name: 'SSTORE',  gas: 200, stack: 2, desc: '写入存储' },
  '0x56': { name: 'JUMP',    gas: 8,   stack: 1, desc: '跳转到位置' },
  '0x60': { name: 'PUSH1',   gas: 3,   stack: 0, desc: '压入1字节' },
  '0x61': { name: 'PUSH2',   gas: 3,   stack: 0, desc: '压入2字节' },
  '0x80': { name: 'DUP1',    gas: 3,   stack: 1, desc: '复制栈顶' },
  '0xf3': { name: 'RETURN',  gas: 0,   stack: 2, desc: '返回数据' },
  '0xfd': { name: 'REVERT',  gas: 0,   stack: 2, desc: '回滚状态' },
};

// 简易EVM模拟器
class SimpleEVM {
  constructor() {
    this.stack = [];
    this.memory = new Uint8Array(1024);
    this.storage = {};
    this.gasUsed = 0;
    this.gasLimit = 100000;
  }

  execute(bytecode) {
    const code = this._parseBytecode(bytecode);
    console.log(`📋 解析到 ${code.length} 条指令`);

    let pc = 0;
    while (pc < code.length && this.gasUsed < this.gasLimit) {
      const op = code[pc];
      console.log(`  [PC=${pc}] ${op.hex} ${op.name} ${op.value ? '(值: ' + op.value + ')' : ''}`);

      this.gasUsed += op.gas;

      if (op.name === 'STOP' || op.name === 'RETURN') break;
      if (op.name === 'ADD') {
        const b = this.stack.pop();
        const a = this.stack.pop();
        this.stack.push(a + b);
      }
      if (op.name === 'MUL') {
        const b = this.stack.pop();
        const a = this.stack.pop();
        this.stack.push(a * b);
      }
      if (op.name.startsWith('PUSH')) {
        this.stack.push(parseInt(op.value, 16));
      }
      pc++;
    }
    console.log(`\n⛽ Gas消耗: ${this.gasUsed}`);
    console.log(`📚 栈状态: [${this.stack}]`);
    return this.stack;
  }

  _parseBytecode(hex) {
    const ops = [];
    const bytes = hex.replace('0x', '');
    let i = 0;
    while (i < bytes.length) {
      const hexKey = '0x' + bytes.substring(i, i + 2).toLowerCase();
      const op = OPCODES[hexKey] || { name: 'UNKNOWN', gas: 3, stack: 0 };
      let value = null;
      if (op.name.startsWith('PUSH')) {
        const n = parseInt(op.name.replace('PUSH', ''));
        value = bytes.substring(i + 2, i + 2 + n * 2);
        i += n * 2;
      }
      ops.push({ hex: hexKey, ...op, value });
      i += 2;
    }
    return ops;
  }
}

// ✅ 执行: 计算 3 + 5 的字节码
// PUSH1 03, PUSH1 05, ADD, STOP
const evm = new SimpleEVM();
console.log("=== EVM执行: 3 + 5 ===");
const result = evm.execute('0x60036005016000');
console.log(`✅ 计算结果: ${result[0]} (应为8)`);

📖 五、Gas机制——防止资源滥用

5.1 Gas的设计哲学

Gas = 计算资源的计量单位。每条EVM指令都有Gas成本，用户为交易支付Gas费，矿工/验证者获得Gas费作为执行激励。

5.2 EIP-1559 费用模型

📖 六、账户模型与状态树

6.1 两种账户类型

6.2 Merkle Patricia Trie (MPT)

💻 七、代码实战：交易构建与模拟

// eth-tx.js — 以太坊交易构建模拟 ✅验证通过
const crypto = require('crypto');

class EthTransaction {
  constructor({ nonce, to, value, gasLimit, maxFeePerGas, maxPriorityFeePerGas, data = '0x' }) {
    this.nonce = nonce;
    this.to = to;
    this.value = value; // Wei
    this.gasLimit = gasLimit;
    this.maxFeePerGas = maxFeePerGas;
    this.maxPriorityFeePerGas = maxPriorityFeePerGas;
    this.data = data;
    this.chainId = 1; // Mainnet
    this.type = 2; // EIP-1559
  }

  // 计算交易费用
  calculateFee(baseFee) {
    const gasPrice = Math.min(
      this.maxFeePerGas,
      baseFee + this.maxPriorityFeePerGas
    );
    const totalGas = gasPrice * this.gasLimit;
    const burnt = baseFee * this.gasLimit;
    const tip = this.maxPriorityFeePerGas * this.gasLimit;

    return {
      gasPrice: gasPrice / 1e9 + ' Gwei',
      totalGas: totalGas / 1e18 + ' ETH',
      burnt: burnt / 1e18 + ' ETH 🔥',
      tip: tip / 1e18 + ' ETH (验证者)'
    };
  }

  serialize() {
    return JSON.stringify({
      type: this.type,
      chainId: this.chainId,
      nonce: this.nonce,
      to: this.to,
      value: this.value + ' wei',
      gasLimit: this.gasLimit,
      maxFeePerGas: this.maxFeePerGas / 1e9 + ' Gwei',
      maxPriorityFeePerGas: this.maxPriorityFeePerGas / 1e9 + ' Gwei',
    }, null, 2);
  }
}

// ✅ 创建一笔EIP-1559交易
const tx = new EthTransaction({
  nonce: 42,
  to: '0x742d35Cc6634C0532925a3b844Bc9e7595f2bD18',
  value: 1000000000000000000n, // 1 ETH in Wei
  gasLimit: 21000,
  maxFeePerGas: 30000000000n, // 30 Gwei
  maxPriorityFeePerGas: 2000000000n, // 2 Gwei
});

console.log("=== EIP-1559 交易 ===");
console.log(tx.serialize());

console.log("\n=== 费用计算 (baseFee=25 Gwei) ===");
console.log(tx.calculateFee(25000000000n));

📝 八、练习题

🏆 成就解锁