> For the complete documentation index, see [llms.txt](https://document.sunprotocol.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://document.sunprotocol.io/zhi-neng-he-yue/shan-dui-he-yue.md).

# 闪兑合约

### 先查询报价

| 函数                       | 返回                                 |
| ------------------------ | ---------------------------------- |
| `usdtbuysun(usdtAmount)` | 输入 USDT 预计得到的 SUN，尚未扣用户设置的滑点保护     |
| `sunsellusdt(sunAmount)` | 卖出 SUN 预计得到的 USDT，已按合约的 3% 卖出税模型估算 |

### 买入 SUN

1. 用 `usdtbuysun(usdtAmount)` 查询预计结果。
2. 授权 USDT 给本合约。
3. 调用 `buySun(usdtAmount,slippageBps)`。

买入滑点 `slippageBps` 不能超过 `MAX_BUY_SLIPPAGE_BPS()`，当前源码上限为 `200`（2%）。例如 `100` 表示 1%。

### 卖出 SUN

1. 用 `sunsellusdt(sunAmount)` 查询税后预计结果。
2. 授权 SUN 给本合约。
3. 调用 `sellSun(sunAmount,slippageBps)`。

卖出滑点不能超过 `MAX_SELL_SLIPPAGE_BPS()`，当前源码上限为 `500`（5%）。实际成交受池子状态、价格变化影响。


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