API

A state transition on a Derion pool is done by calling the swap function on the pool contract. The same function can also be statically called to perform input and output estimation.

function swap(
    Param memory param,
    Payment memory payment
) returns (uint256 amountIn, uint256 amountOut, uint256 price)

struct Param {
    uint256 sideIn;
    uint256 sideOut;
    address helper;
    bytes payload;
}

struct Payment {
    address utr;
    bytes payer;
    address recipient;
}

Sides

There are 3 sides in a pool:

• SIDE_LONG = 0x10

• SIDE_SHORT = 0x20

• SIDE_LP = 0x30

sideIn and sideOut represent the state transistion types:

• opening Long/Short/LP position will have sideIn = 0

• closing Long/Short/LP position will have sideOut = 0

Helper

• helper: Helper contract address

• payload: data will be passed to Helper.swapToState contract call internally by the swap function.

• amountIn: is the maximum amount of sideIn token that will be spent in the swap transaction

// encode payload
bytes memory payload = abi.encode(sideIn, sideOut, amountIn);
// decode payload
(sideIn, sideOut, amountIn) = abi.decode(payload, (uint256, uint256, uint256));

Note: sideIn and sideOut must be passed twice: first in the Param, and another time packed in Helper's payload.

Payment

recipient is the target account that the token output will be transfered to.

See Derivative Tokens for ERC-1155 position token and id specification.

There are 2 methods of payments:

Direct Token Approval

If payer is an empty bytes, the utr param will be ignored, and swap require a direct approval from msg.sender to transfer the sideIn token in. This mode is recommended for inter-contract interaction only.

ERC-6120

If payer is the 20 bytes address of the paying account, the swap call is expected to be invoked over an ERC-6120's execution by that payer account.

The utr is the address of the ERC-6120 contract that invoke this call.

utr.exec([
    // amountOutMin can be configured here
], [{
    inputs: [{
        mode: PAYMENT,
        eip: 20,
        token: tokenIn,
        id: 0,
        amountIn: amountInMax,
        recipient: pool.address,
    }],
    code: pool.address,
    data: (await pool.populateTransaction.swap({
        sideIn: 0,
        sideOut: SIDE_LONG, // open Long
        helper: helper.address,
        payload: abiCoder.encode(
            ["uint", "uint", "uint"],
            [0, SIDE_LONG, amountIn],
        ),
    }, {
        utr: utr.address,
        payer: signer.address,
        recipient: recipient,
    })).data,
}])