Unit Definition

DYSON.sol

• decimals is set to be the number 18

  • uint8 public constant decimals = 18;

sDYSON.sol

• decimals is set to be the number 18

  • uint8 public constant decimals = 18;

• STAKING_RATE_BASE_UNIT

  • uint private constant STAKING_RATE_BASE_UNIT = 1e18;

  • In the sDYSON.sol contract, obtaining the staking rate for staking DYSON in exchange for sDYSON involves adjusting the scale. The staking rate returned by getStakingRate is scaled at 1e18, and to correct this scale, it needs to be divided by STAKING_RATE_BASE_UNIT. For instance, when calling getStakingRate with a lock duration of 86400, the returned value might be 71087213555991969. To obtain the accurate staking rate, we perform the division: 71087213555991969 / 1e18 = 0.071. Therefore, the corrected staking rate is 7.1%.

Farm.sol

• MAX_AP_RATIO

  • int128 private constant MAX_AP_RATIO = 2**64;

  • When using the _calcRewardAmount function in the Farm contract, the formula is defined as: reward = reserve * (1 - 2^(-amount/w)) The result of 2^(-amount/w) will be scaled in 2**64 because the exp_2 of ABDKMath64x64 library is used to execute a binary exponent calculation, which returns the result in a 64.64 fixed point number. Therefore, at this point, we use MAX_AP_RATIO instead of 1 to align the scale, resulting in the modified formula: reward = reserve * (MAX_AP_RATIO - 2^(-amount/w)) This adjustment ensures that the scaling is consistent throughout the calculation.

• BONUS_BASE_UNIT

  • uint private constant BONUS_BASE_UNIT = 1e18;

  • When utilizing the grantSP function in the Farm contract, the bonus of the user obtained from the Gauge contract is scaled in 1e18, so we use BONUS_BASE_UNIT to align the scale during the calculation.

Gauge.sol

• REWARD_RATE_BASE_UNIT

  • uint private constant REWARD_RATE_BASE_UNIT = 1e18;

  • When utilizing the newRewardRate function in the Gauge contract, the formula for the new reward rate is defined as follows: newRewardRate = totalSupply * slope / REWARD_RATE_BASE_UNIT + base; Because the totalSupply and slope are scaled in 1e18 , we need to divide the result by 1e18 after the multiplication calculation to maintain the correct scale.

Pair.sol & Router.sol

• MAX_FEE_RATIO

  • uint internal constant MAX_FEE_RATIO = 2**64;

  • When utilizing the calcNewFeeRatio function in the Pair contract, the formula is defined as: newFeeRatio = oldFeeRatio / 2^(elapsedTime / halfLife) The result of 2^(elapsedTime / halfLife) will be scaled in 2**64 because the exp_2 of ABDKMath64x64 library is used to execute a binary exponent calculation, which returns the result in a 64.64 fixed point number. It means that the feeRatio is stored in 2**64 scale. Therefore, when we calculate the swap fee in _swap0in or _swap1in functions, we have to divide the feeRatio by MAX_FEE_RATIO to maintain the correct scale.

  • Similarly, when utilizing the fairPrice function in the Router contract, it applies the same logic as described above.