Surplus Collateral

In addition to paying and receiving surplus collateral in the input/output of swap, mint and burn calls user can directly deposit, withdraw or transfer their surplus collateral balance.

All of these surplus collateral use callpath 0 with specific

Deposits

To deposit surplus collateral, the user should call the following user command:

userCmd(1, abi.encode(
    73,     // Fixed sub-command code
    recv,   // address
    value,  // uint128
    token   // address
))

• recv - The address the surplus collateral will be credited

• value - The total amount deposited

• token - The address of the ERC20 token deposited or address(0) for native Ethereum)

Note that deposit will use transferFrom() in to deposit the surplus collateral, so the user must approve or permit at least value amount of the token. In the case of native Ethereum, the deposit is collected from msg.value so the user must attach at least the amount matching the value parameter to the Ethereum transaction.

For EIP-2612 compliant tokens, users can deposit using an off-chain permit signature avoiding the need to approve the DEX contract:

userCmd(0, abi.encode(
    83,     // Fixed sub-command code
    recv,       // address
    value,      // uint128
    token,      // address
    deadline,   // uint256
    v,          // uint8
    r,          // bytes32
    s           // bytes32
))

• deadline - The deadline for the permit call

• v, r, s - The EIP-712 signature to be passed directly to the token contract

Withdraw

To withdraw surplus collateral, the user should call the following user command:

userCmd(0, abi.encode(
    74,     // Fixed sub-command code
    recv,   // address
    value,  // uint128
    token   // address
))

• recv - The address the surplus collateral will be sent to

• value - The total amount to withdraw from surplus collateral. 0 is treated as a magic value that will withdraw the entire balance.

• token - The address of the ERC20 token or address(0) for native Ethereum)

Transfer

Users can also bilaterally transfer surplus liquidity between owner addresses:

userCmd(0, abi.encode(
    75,     // Fixed sub-command code
    recv,   // address
    value,  // uint128
    token   // address
))

• recv - The address the surplus collateral will be transferred to

• value - The total amount to transfer from surplus collateral. 0 is treated as a magic value that will withdraw the entire balance.

• token - The address of the ERC20 token or address(0) for native Ethereum