Uniswap V2 Swap Math – Basic Concepts and Calculations Explained

So it looks like you read the "sqrtPriceX96" by querying the "slot0" function on the pair contract, then you call the "swap" method on the pair contract. this takes recipient, a true or false which indicated which way you are swapping, the amount, and the "sqrtPriceX96". It also looks like they have a "Quoter" contract that gives you the amount out for the frontend I assume.

Here are some links to the new interfaces:

pool read fuctions: https://docs.uniswap.org/protocol/reference/core/interfaces/pool/IUniswapV3PoolState#slot0

pool write functions: https://docs.uniswap.org/protocol/reference/core/interfaces/pool/IUniswapV3PoolActions#swap

quoter functions: https://docs.uniswap.org/protocol/reference/periphery/interfaces/IQuoter

Ok so I think I figured it out, studying the token's source code, this is a common scheme to "cash out" taxes/fees charged on every token trade or transfer.

What are taxes/fees? Taxes/fees are a percentage of the transaction value of every transaction back to the token contract. They are paid in tokens, not in ETH.

So when you buy 1,000,000 shitcoins, and tax is currently 10%, it means you get only 900,000 shitcoins and 100,000 shitcoins are sent right back to the token contract which acts as a wallet holding the accumulated taxes.

Token devs justify taxes/fees with "ongoing marketing expenses" for growing the project (whatever...). Taxes are also used as a device to artificially prop up a token's price, by taxing token sales higher during the first hours or days of a launch. You'll think twice before dumping that shitcoin minutes after you bought it, when you stand to lose half or more of your investment to "taxes".

Accumulating all these tokens poses a problem for the token dev, in that he needs to frequently "cash out" his "tax tokens" that accumulate over time.

Why not piggyback on your token holder's transactions and make THEM pay the gas for swapping the dev's accumulated tokens, and also front-run their sells so that you get a slightly higher ETH value for the tokens?

That's exactly what is happening here; as soon as a minimum amount of tax/fee tokens have accumulated, the smart contract swaps the loot into ETH and sends it to the token dev, and it does so BEFORE whatever swap was requested by the token holder, dinging the liquidity pool, causing a slightly lower sale price for the original investor.

In short: It's a system to cash out tax/fee tokens once they have reached a threshold, and make unsuspecting token holders pay the gas for the transaaction, AND also effectively doubling the tax by front-running one's own token holders sell txns.

No judgement though... it's all in the open so buyer beware.