_feeAmount

Contract: JBPayoutRedemptionPaymentTerminal​‌

Step by step

Returns the fee amount based on the provided amount for the specified project.

Definition

function _feeAmount(
  uint256 _amount,
  uint256 _fee,
  uint256 _feeDiscount
) private pure returns (uint256) { ... }

• Arguments:
  • _amount is the amount that the fee is based on, as a fixed point number with the same amount of decimals as this terminal.
  • _fee is the percentage of the fee, out of MAX_FEE.
  • _feeDiscount is the percentage discount that should be applied out of the max amount, out of MAX_FEE_DISCOUNT.
• The view function is private to this contract.
• The view function does not alter state on the blockchain.
• The function returns the amount of the fee, as a fixed point number with the same amount of decimals as this terminal.

Body

1. Calculate the discounted fee by subtracting the discount from the fee.

   // Calculate the discounted fee.
   uint256 _discountedFee = _fee -
     PRBMath.mulDiv(_fee, _feeDiscount, JBConstants.MAX_FEE_DISCOUNT);

   Library references:

   • PRBMath
     • .mulDiv(...)
   • JBConstants
     • .MAX_FEE_DISCOUNT

2. Return the amount of tokens from the specified amount that should be paid as a fee.

   // The amount of tokens from the `_amount` to pay as a fee.
   return
     _amount - PRBMath.mulDiv(_amount, JBConstants.MAX_FEE, _discountedFee + JBConstants.MAX_FEE);

   Library references:

   • PRBMath
     • .mulDiv(...)
   • JBConstants
     • .MAX_FEE

Code

/**
  @notice
  Returns the fee amount based on the provided amount for the specified project.

  @param _amount The amount that the fee is based on, as a fixed point number with the same amount of decimals as this terminal.
  @param _fee The percentage of the fee, out of MAX_FEE.
  @param _feeDiscount The percentage discount that should be applied out of the max amount, out of MAX_FEE_DISCOUNT.

  @return The amount of the fee, as a fixed point number with the same amount of decimals as this terminal.
*/
function _feeAmount(
  uint256 _amount,
  uint256 _fee,
  uint256 _feeDiscount
) private pure returns (uint256) {
  // Calculate the discounted fee.
  uint256 _discountedFee = _fee -
    PRBMath.mulDiv(_fee, _feeDiscount, JBConstants.MAX_FEE_DISCOUNT);

  // The amount of tokens from the `_amount` to pay as a fee.
  return
    _amount - PRBMath.mulDiv(_amount, JBConstants.MAX_FEE, _discountedFee + JBConstants.MAX_FEE);
}

Bug bounty

Category	Description	Reward
Optimization	Help make this operation more efficient.	0.5ETH
Low severity	Identify a vulnerability in this operation that could lead to an inconvenience for a user of the protocol or for a protocol developer.	1ETH
High severity	Identify a vulnerability in this operation that could lead to data corruption or loss of funds.	5+ETH