PIL派链NFT铸造系统开发详细技术分析丨代码部署

// remove bsv and token from liquidity pool
public function removeLiquidity(PubKey sender, int lpAmount, Sig senderSig, int oldTokenBalance, int senderKeyIndex, int senderBalance,

                            int lpSenderBalance, int lpSenderKeyIndex, SigHashPreimage txPreimage) {
require(checkSig(senderSig, sender));

int oldBsvBalance = SigHash.value(txPreimage);

// withdraw amount
int bsvAmount = oldBsvBalance * lpAmount / this.lpToken.totalSupply();
int tokenAmount = oldTokenBalance * lpAmount / this.lpToken.totalSupply();

// burn the lp tokens
require(this.lpToken.burn(sender, lpSenderBalance, lpAmount, lpSenderKeyIndex));

// transfer tokens from pool to the sender
require(this.token.transferFrom(this.poolPubkey, sender, tokenAmount, oldTokenBalance, senderKeyIndex, senderBalance, senderKeyIndex));
// transfer bsvs to the sender
int newBsvBalance = oldBsvBalance - bsvAmount;

require(this.propagateState(newBsvBalance, txPreimage));

流动性提供者拥有的 LP Token 的数量来提取流动性（第 9 行和第 10 行）。提款后，LP Token 在第 13 行被烧毁。第 16 行将 Token 从池子中转移到流动性提供者。第 18 行和第 20 行对 BSV 做同样的事情。

请注意，除了合约输出之外，还需要在同一交易中的另一个输出将 BSV 返回给流动性提供者。