Install:

npm i @cremafinance/crema-sdk

Build:

npm run build

Instructions:

import { TokenSwap } from '@cremafinance/crema-sdk'
const swap = await new TokenSwap(conn, swapProgramId, swapKey, null).load()
const amountOut: any = await swap.preSwapA(amountIn) // a->b
const amountOut: any = await swap.preSwapB(amountIn) // b->a

Parameters Description：

amountIn: Decimal (using decimal.js repo)

Liquidity Calculation Formula

Assuming the current price is $P_{c}$，the price range that users add liquidity in is $[P_{a},P_{b}]$

$ \LARGE L = \begin {cases} ¦ {Δx} \over {1 \over {\sqrt{P_{a}}}} - {1 \over {\sqrt{P_{b}}}} &, \text P_{c} < P_{a} \
¦ {Δy} \over {\sqrt{P_{b}} - \sqrt{P_{a}}} &, \text P_{c} > P_{b}\ ¦ {{Δx} \over {1 \over {\sqrt{P_{c}}}} - {1 \over {\sqrt{P_{b}}}}} = {{Δy} \over {\sqrt{P_{c}} - \sqrt{P_{a}}}} &, \text P_{c} \in [P_{a},P_{b}] \
\end {cases} $