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HintHelpers.md

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HintHelpers.sol

View Source: contracts/HintHelpers.sol

↗ Extends: LiquityBase, HintHelpersStorage, CheckContract

HintHelpers

Events

event SortedTrovesAddressChanged(address  _sortedTrovesAddress);
event TroveManagerAddressChanged(address  _troveManagerAddress);

Functions

setAddresses

function setAddresses(address _liquityBaseParamsAddress, address _sortedTrovesAddress, address _troveManagerAddress) external nonpayable onlyOwner

Arguments

Name Type Description
_liquityBaseParamsAddress address
_sortedTrovesAddress address
_troveManagerAddress address
Source Code 
function setAddresses(
        address _liquityBaseParamsAddress,
        address _sortedTrovesAddress,
        address _troveManagerAddress
    )
        external
        onlyOwner
    {
        checkContract(_liquityBaseParamsAddress);
        checkContract(_sortedTrovesAddress);
        checkContract(_troveManagerAddress);

        liquityBaseParams = ILiquityBaseParams(_liquityBaseParamsAddress);
        sortedTroves = ISortedTroves(_sortedTrovesAddress);
        troveManager = ITroveManager(_troveManagerAddress);

        emit SortedTrovesAddressChanged(_sortedTrovesAddress);
        emit TroveManagerAddressChanged(_troveManagerAddress);

    }

getRedemptionHints

function getRedemptionHints(uint256 _ZUSDamount, uint256 _price, uint256 _maxIterations) external view
returns(firstRedemptionHint address, partialRedemptionHintNICR uint256, truncatedZUSDamount uint256)

Arguments

Name Type Description
_ZUSDamount uint256
_price uint256
_maxIterations uint256
Source Code 
function getRedemptionHints(
        uint _ZUSDamount, 
        uint _price,
        uint _maxIterations
    )
        external
        view
        returns (
            address firstRedemptionHint,
            uint partialRedemptionHintNICR,
            uint truncatedZUSDamount
        )
    {
        ISortedTroves sortedTrovesCached = sortedTroves;

        uint remainingZUSD = _ZUSDamount;
        address currentTroveuser = sortedTrovesCached.getLast();

        while (currentTroveuser != address(0) && troveManager.getCurrentICR(currentTroveuser, _price) < liquityBaseParams.MCR()) {
            currentTroveuser = sortedTrovesCached.getPrev(currentTroveuser);
        }

        firstRedemptionHint = currentTroveuser;

        if (_maxIterations == 0) {
            _maxIterations = uint(-1);
        }

        while (currentTroveuser != address(0) && remainingZUSD > 0 && _maxIterations-- > 0) {
            uint netZUSDDebt = _getNetDebt(troveManager.getTroveDebt(currentTroveuser))
                .add(troveManager.getPendingZUSDDebtReward(currentTroveuser));

            if (netZUSDDebt > remainingZUSD) {
                if (netZUSDDebt > MIN_NET_DEBT) {
                    uint maxRedeemableZUSD = LiquityMath._min(remainingZUSD, netZUSDDebt.sub(MIN_NET_DEBT));

                    uint ETH = troveManager.getTroveColl(currentTroveuser)
                        .add(troveManager.getPendingETHReward(currentTroveuser));

                    uint newColl = ETH.sub(maxRedeemableZUSD.mul(DECIMAL_PRECISION).div(_price));
                    uint newDebt = netZUSDDebt.sub(maxRedeemableZUSD);

                    uint compositeDebt = _getCompositeDebt(newDebt);
                    partialRedemptionHintNICR = LiquityMath._computeNominalCR(newColl, compositeDebt);

                    remainingZUSD = remainingZUSD.sub(maxRedeemableZUSD);
                }
                break;
            } else {
                remainingZUSD = remainingZUSD.sub(netZUSDDebt);
            }

            currentTroveuser = sortedTrovesCached.getPrev(currentTroveuser);
        }

        truncatedZUSDamount = _ZUSDamount.sub(remainingZUSD);
    }

getApproxHint

function getApproxHint(uint256 _CR, uint256 _numTrials, uint256 _inputRandomSeed) external view
returns(hintAddress address, diff uint256, latestRandomSeed uint256)

Arguments

Name Type Description
_CR uint256
_numTrials uint256
_inputRandomSeed uint256
Source Code 
function getApproxHint(uint _CR, uint _numTrials, uint _inputRandomSeed)
        external
        view
        returns (address hintAddress, uint diff, uint latestRandomSeed)
    {
        uint arrayLength = troveManager.getTroveOwnersCount();

        if (arrayLength == 0) {
            return (address(0), 0, _inputRandomSeed);
        }

        hintAddress = sortedTroves.getLast();
        diff = LiquityMath._getAbsoluteDifference(_CR, troveManager.getNominalICR(hintAddress));
        latestRandomSeed = _inputRandomSeed;

        uint i = 1;

        while (i < _numTrials) {
            latestRandomSeed = uint(keccak256(abi.encodePacked(latestRandomSeed)));

            uint arrayIndex = latestRandomSeed % arrayLength;
            address currentAddress = troveManager.getTroveFromTroveOwnersArray(arrayIndex);
            uint currentNICR = troveManager.getNominalICR(currentAddress);

            // check if abs(current - CR) > abs(closest - CR), and update closest if current is closer
            uint currentDiff = LiquityMath._getAbsoluteDifference(currentNICR, _CR);

            if (currentDiff < diff) {
                diff = currentDiff;
                hintAddress = currentAddress;
            }
            i++;
        }
    }

computeNominalCR

function computeNominalCR(uint256 _coll, uint256 _debt) external pure
returns(uint256)

Arguments

Name Type Description
_coll uint256
_debt uint256
Source Code 
function computeNominalCR(uint _coll, uint _debt) external pure returns (uint) {
        return LiquityMath._computeNominalCR(_coll, _debt);
    }

computeCR

function computeCR(uint256 _coll, uint256 _debt, uint256 _price) external pure
returns(uint256)

Arguments

Name Type Description
_coll uint256
_debt uint256
_price uint256
Source Code 
function computeCR(uint _coll, uint _debt, uint _price) external pure returns (uint) {
        return LiquityMath._computeCR(_coll, _debt, _price);
    }

Contracts