# Sequential Dutch Auctioneer (SDA) The [Base SDA contract](https://github.com/Bond-Protocol/bond-contracts/blob/master/src/bases/BondBaseSDA.sol) is an implementation of the Auctioneer Interface that uses a Sequential Dutch Auction pricing system to buy a target amount of quote tokens or sell a target amount of base tokens over the duration of a market. The contract is abstract since it leaves final implementation of the `createMarket` function to a contract that inherits it. ## Data Structures (Structs) ### MarketParams Parameters to create a new SDA market. Encoded as bytes and provided as input to `createMarket`. ```solidity struct MarketParams { ERC20 payoutToken; ERC20 quoteToken; address callbackAddr; bool capacityInQuote; uint256 capacity; uint256 formattedInitialPrice; uint256 formattedMinimumPrice; uint32 debtBuffer; uint48 vesting; uint48 conclusion; uint32 depositInterval; int8 scaleAdjustment; } ```
FieldTypeDescription
payoutTokenERC20 (address)Payout Token (token paid out by market and provided by creator)
quoteTokenERC20 (address)Quote Token (token to be received by the market and provided by purchaser)
callbackAddraddressCallback contract address, should conform to IBondCallback. If 0x00, tokens will be transferred from market owner. Using a callback requires whitelisting by the protocol
capacityInQuoteboolIs Capacity in Quote Token?
capacityuint256Capacity (amount in quote token decimals or amount in payout token decimals). Set capacityInQuote flag appropriately
formattedInitialPriceuint256Initial price of the market as a ratio of quote tokens per payout token, see note below on formatting
formattedMinimumPriceuint256Minimum price of the market as a ratio of quote tokens per payout token, see note below on formatting
debtBufferuint32Debt buffer. Percent with 3 decimals. Percentage over the initial debt to allow the market to accumulate at anyone time. Works as a circuit breaker for the market in case external conditions incentivize massive buying (e.g. stablecoin depeg). Minimum is the greater of 10% or initial max payout as a percentage of capacity
vestinguint48Is fixed term ? Vesting length (seconds) : Vesting expiry (timestamp). A 'vesting' param longer than 50 years is considered a timestamp for fixed expiry
conclusionuint48Timestamp that the market will conclude on. Must be at least 1 day (86400 seconds) after creation
depositIntervaluint32Target deposit interval for purchases (in seconds). Determines the maxPayout of the market. Minimum is 1 hour (3600 seconds)
scaleAdjustmentint8Market scaling adjustment factor, ranges from -24 to +24. See note below on how to calculate
#### Calculating Formatted Price and Scale Adjustment In order to support a broad range of tokens, with different decimal configurations and prices, we calculate an optimal scaling factor for each market. Specifically, the scale adjustment allows the SDA to support tokens with 6 to 18 configured decimals and with prices that differ by up to 24 decimal places (if the tokens have the configured decimals, less if not). To implement this, the market creator must provide a scale adjustment factor and format the price correctly. First, you need the price of each token in a common unit, e.g. dollars or ether. Then, if $$\Phi\_p$$ is the price of the payout token and $$\Phi\_q$$ is the price of quote token in the common unit, it can expressed in base 10 (or scientific) notation as: $$ \Phi\_p = \phi\_p \times 10^{d\_{\phi p}} $$ $$ \Phi\_q = \phi\_q \times 10^{d\_{\phi q}} $$ where: * $$\phi\_p$$ is the coefficient of the payout token price and ​$$d\_{\phi p}$$​ is the number of price decimals for the payout token (aka the significand of the price). * $$\phi\_q$$​ is the coefficient of the quote token price and $$d\_{\phi q}$$​ is the number of price decimals for the quote token. Example: If the price of WETH is $1,500, then we would deconstruct it as $$1.5 \times 10^3$$​. Therefore $$\phi = 1.5$$ and $$d\_{\phi} = 3$$. Now, using the price values and the configured number of decimals for each token, we can calculate the scale adjustment. $$ s = d\_p - d\_q - \left\lfloor\frac{d\_{\phi p} - d\_{\phi q}}{2}\right\rfloor $$ where: * $$d\_p$$ is the configured payout token decimals (e.g. WETH has 18 configured decimals) * $$d\_q$$ is the configured quote token decimals. * $$d\_{\phi p}$$ and $$d\_{\phi q}$$ are as defined above. Example: * Let WETH be the quote token and OHM be the payout token. WETH has 18 configured decimals and OHM has 9 configured decimals. Assume the market price of WETH is $1,500 -> $$1.5 \times 10^3$$and the market price of OHM is $10 -> $$1 \times 10^1$$.​ * Then, the scale adjustment is $$s = 9 - 18 - \left\lfloor\frac{1-3}{2}\right\rfloor = -9 + 1 = -8$$​ Once we have the scale adjustment, we can format the initial price using the variables defined above. We're starting the market at the current market price by using the token prices at the time of creation. This is optimal in most situations, but there may be circumstances where it makes sense to choose a different starting price (e.g. you want delayed activity or activity only if the price increases in the short-term). $$ \Phi\_0 = \frac{\phi\_p}{\phi\_q} \times 10^{36 + s + d\_q - d\_p +d\_{\phi p} - d\_{\phi q}} $$ Example: Continuing with the WETH and OHM example from above, we format the initial price as: $$ \Phi\_0 = \frac{1}{1.5} \times 10^{36+(-8)+18-9+1-3} = 0.666.. \times 10^{35} = 0.00666.. \times 10^{37} $$ The difference between the scale and the full decimal difference can result in the price ratio shifting some decimal places. However, we can find the appropriate price factor by considering what we expect the ratio to be from the initial prices. 10 / 1500 = 0.00666.., so we can see the proper price factor is 10^37. The minimum formatted price can then be extrapolated from the initial price. The above initial price example can be interpreted as 0.00666.. WETH per OHM. Therefore, if you want to receive a minimum of 0.005 WETH per OHM, you would set minimum price as: $$\Phi\_{min} = 0.005 \times 10^{37}$$. Any alternative way to confirm your minimum price is correct is to redo the same calculation as used to determine initial price, with an updated minimum price for the payout token. Using the 0.005 WETH per OHM value, that would be an OHM price of $7.5 ($1500 x 0.005 = $7.5). ### BondMarket The BondMarket struct contains the core data about a bond market. ```solidity struct BondMarket { address owner; ERC20 payoutToken; ERC20 quoteToken; address callbackAddr; bool capacityInQuote; uint256 capacity; uint256 totalDebt; uint256 minPrice; uint256 maxPayout; uint256 sold; uint256 purchased; uint256 scale; } ```
FieldTypeDescription
owneraddress Market owner. Sends payout tokens, receives quote tokens (defaults to creator)
payoutTokenERC20 (address)Payout Token (token paid out by market and provided by creator)
quoteTokenERC20 (address)Quote Token (token to be received by the market and provided by purchaser)
callbackAddraddressAddress to call for any operations on bond purchase. Must inherit to IBondCallback
capacityInQuoteboolCapacity limit is in payment token (true) or in payout (false, default)
capacityuint256Capacity remaining
totalDebtuint256Total payout token debt from market
minPriceuint256Minimum price (debt will stop decaying to maintain this)
maxPayoutuint256Max payout tokens out in one order
solduint256Payout tokens out
purchaseduint256Quote tokens in
scaleuint256Scaling factor for the market (see MarketParams struct)
### BondTerms ```solidity struct BondTerms { uint256 controlVariable; uint256 maxDebt; uint48 vesting; uint48 conclusion; } ```
FieldTypeDescription
controlVariableuint256Scaling variable for price
maxDebtuint256Max payout token debt accrued
vestinguint48Length of time from deposit to expiry if fixed-term, vesting timestamp if fixed-expiry
conclusionuint48Timestamp when market no longer offered
### BondMetadata ```solidity struct BondMetadata { uint48 lastTune; uint48 lastDecay; uint32 length; uint32 depositInterval; uint32 tuneInterval; uint32 tuneAdjustmentDelay; uint32 debtDecayInterval; uint256 tuneIntervalCapacity; uint256 tuneBelowCapacity; uint256 lastTuneDebt; } ```
FieldTypeDescription
lastTuneuint48Last timestamp when control variable was tuned
lastDecayuint48Last timestamp when market was created and debt was decayed
lengthuint32Time from creation to conclusion
depositIntervaluint32Target frequency of deposits
tuneIntervaluint32Frequency of tuning
tuneAdjustmentDelayuint32Time to implement downward tuning adjustments
debtDecayIntervaluint32Interval over which debt should decay completely
tuneIntervalCapacityuint256Capacity expected to be used during a tuning interval
tuneBelowCapacityuint256Capacity that the next tuning will occur at
lastTuneDebtuint256Target debt calculated at last tuning
## Methods ### closeMarket ```solidity function closeMarket(uint256 id_) external nonpayable ``` Disable existing bond marketMust be market owner #### Parameters | Name | Type | Description | | ---- | ------- | --------------------- | | id\_ | uint256 | ID of market to close | ### createMarket ```solidity function createMarket(bytes params_) external nonpayable returns (uint256) ``` Creates a new bond market *See specific auctioneer implementations for details on encoding the parameters.* #### Parameters | Name | Type | Description | | -------- | ----- | ----------------------------------------------------------------------- | | params\_ | bytes | Configuration data needed for market creation, encoded in a bytes array | #### Returns | Name | Type | Description | | ---- | ------- | --------------------- | | id | uint256 | ID of new bond market | ### currentCapacity ```solidity function currentCapacity(uint256 id_) external view returns (uint256) ``` Returns current capacity of a market #### Parameters | Name | Type | Description | | ---- | ------- | ----------- | | id\_ | uint256 | undefined | #### Returns | Name | Type | Description | | ---- | ------- | ----------- | | \_0 | uint256 | undefined | ### currentControlVariable ```solidity function currentControlVariable(uint256 id_) external view returns (uint256) ``` Up to date control variable *Accounts for control variable adjustment* #### Parameters | Name | Type | Description | | ---- | ------- | ------------ | | id\_ | uint256 | ID of market | #### Returns | Name | Type | Description | | ---- | ------- | ---------------------------------------------------- | | \_0 | uint256 | Control variable for market in payout token decimals | ### currentDebt ```solidity function currentDebt(uint256 id_) external view returns (uint256) ``` Calculate debt factoring in decay *Accounts for debt decay since last deposit* #### Parameters | Name | Type | Description | | ---- | ------- | ------------ | | id\_ | uint256 | ID of market | #### Returns | Name | Type | Description | | ---- | ------- | ------------------------------------------------ | | \_0 | uint256 | Current debt for market in payout token decimals | ### getAggregator ```solidity function getAggregator() external view returns (contract IBondAggregator) ``` Returns the Aggregator that services the Auctioneer #### Returns | Name | Type | Description | | ---- | ------------------------ | ----------- | | \_0 | contract IBondAggregator | undefined | ### getMarketInfoForPurchase ```solidity function getMarketInfoForPurchase(uint256 id_) external view returns (address owner, address callbackAddr, contract ERC20 payoutToken, contract ERC20 quoteToken, uint48 vesting, uint256 maxPayout) ``` Provides information for the Teller to execute purchases on a Market #### Parameters | Name | Type | Description | | ---- | ------- | ----------- | | id\_ | uint256 | Market ID | #### Returns | Name | Type | Description | | ------------ | -------------- | --------------------------------------------------------------------------------- | | owner | address | Address of the market owner (tokens transferred from this address if no callback) | | callbackAddr | address | Address of the callback contract to get tokens for payouts | | payoutToken | contract ERC20 | Payout Token (token paid out) for the Market | | quoteToken | contract ERC20 | Quote Token (token received) for the Market | | vesting | uint48 | Timestamp or duration for vesting, implementation-dependent | | maxPayout | uint256 | Maximum amount of payout tokens you can purchase in one transaction | ### getTeller ```solidity function getTeller() external view returns (contract IBondTeller) ``` Returns the Teller that services the Auctioneer #### Returns | Name | Type | Description | | ------ | -------------------- | ------------------------------------------------------- | | teller | contract IBondTeller | Address of the Teller contract servicing the Auctioneer | ### isInstantSwap ```solidity function isInstantSwap(uint256 id_) external view returns (bool) ``` Does market send payout immediately #### Parameters | Name | Type | Description | | ---- | ------- | ----------------------- | | id\_ | uint256 | Market ID to search for | #### Returns | Name | Type | Description | | ---- | ---- | ----------- | | \_0 | bool | undefined | ### isLive ```solidity function isLive(uint256 id_) external view returns (bool) ``` Is a given market accepting deposits #### Parameters | Name | Type | Description | | ---- | ------- | ------------ | | id\_ | uint256 | ID of market | #### Returns | Name | Type | Description | | ---- | ---- | ----------- | | \_0 | bool | undefined | ### marketPrice ```solidity function marketPrice(uint256 id_) external view returns (uint256) ``` Calculate current market price of payout token in quote tokens *Accounts for debt and control variable decay since last deposit (vs \_marketPrice())* #### Parameters | Name | Type | Description | | ---- | ------- | ------------ | | id\_ | uint256 | ID of market | #### Returns | Name | Type | Description | | ---- | ------- | ---------------------------------------------------------- | | \_0 | uint256 | Price for market in configured decimals (see MarketParams) | ### marketScale ```solidity function marketScale(uint256 id_) external view returns (uint256) ``` Scale value to use when converting between quote token and payout token amounts with marketPrice() #### Parameters | Name | Type | Description | | ---- | ------- | ------------ | | id\_ | uint256 | ID of market | #### Returns | Name | Type | Description | | ---- | ------- | ------------------------------------------------ | | \_0 | uint256 | Scaling factor for market in configured decimals | ### maxAmountAccepted ```solidity function maxAmountAccepted(uint256 id_, address referrer_) external view returns (uint256) ``` Returns maximum amount of quote token accepted by the market #### Parameters | Name | Type | Description | | ---------- | ------- | --------------------------------------------------------------------------------------------------------------------------------------------------- | | id\_ | uint256 | ID of market | | referrer\_ | address | Address of referrer, used to get fees to calculate accurate payout amount. Inputting the zero address will take into account just the protocol fee. | #### Returns | Name | Type | Description | | ---- | ------- | ----------- | | \_0 | uint256 | undefined | ### ownerOf ```solidity function ownerOf(uint256 id_) external view returns (address) ``` Returns the address of the market owner #### Parameters | Name | Type | Description | | ---- | ------- | ------------ | | id\_ | uint256 | ID of market | #### Returns | Name | Type | Description | | ---- | ------- | ----------- | | \_0 | address | undefined | ### payoutFor ```solidity function payoutFor(uint256 amount_, uint256 id_, address referrer_) external view returns (uint256) ``` Payout due for amount of quote tokens *Accounts for debt and control variable decay so it is up to date* #### Parameters | Name | Type | Description | | ---------- | ------- | --------------------------------------------------------------------------------------------------------------------------------------------------- | | amount\_ | uint256 | Amount of quote tokens to spend | | id\_ | uint256 | ID of market | | referrer\_ | address | Address of referrer, used to get fees to calculate accurate payout amount. Inputting the zero address will take into account just the protocol fee. | #### Returns | Name | Type | Description | | ---- | ------- | ---------------------------------- | | \_0 | uint256 | amount of payout tokens to be paid | ### pullOwnership ```solidity function pullOwnership(uint256 id_) external nonpayable ``` Accept ownership of a marketMust be market newOwner *The existing owner must call pushOwnership prior to the newOwner calling this function* #### Parameters | Name | Type | Description | | ---- | ------- | ----------- | | id\_ | uint256 | Market ID | ### purchaseBond ```solidity function purchaseBond(uint256 id_, uint256 amount_, uint256 minAmountOut_) external nonpayable returns (uint256 payout) ``` Exchange quote tokens for a bond in a specified marketMust be teller #### Parameters | Name | Type | Description | | -------------- | ------- | -------------------------------------------------------------------- | | id\_ | uint256 | ID of the Market the bond is being purchased from | | amount\_ | uint256 | Amount to deposit in exchange for bond (after fee has been deducted) | | minAmountOut\_ | uint256 | Minimum acceptable amount of bond to receive. Prevents frontrunning | #### Returns | Name | Type | Description | | ------ | ------- | --------------------------------------------------- | | payout | uint256 | Amount of payout token to be received from the bond | ### pushOwnership ```solidity function pushOwnership(uint256 id_, address newOwner_) external nonpayable ``` Designate a new owner of a market. Must be existing market owner to call. *Doesn't change permissions until newOwner calls pullOwnership* #### Parameters | Name | Type | Description | | ---------- | ------- | -------------------------------- | | id\_ | uint256 | Market ID | | newOwner\_ | address | New address to give ownership to | ### setAllowNewMarkets ```solidity function setAllowNewMarkets(bool status_) external nonpayable ``` Change the status of the auctioneer to allow creation of new markets *Setting to false and allowing active markets to end will sunset the auctioneer* #### Parameters | Name | Type | Description | | -------- | ---- | --------------------------------------------------------------- | | status\_ | bool | Allow market creation (true) : Disallow market creation (false) | ### setCallbackAuthStatus ```solidity function setCallbackAuthStatus(address creator_, bool status_) external nonpayable ``` Change whether a market creator is allowed to use a callback address in their markets or notMust be guardian *Callback is believed to be safe, but a whitelist is implemented to prevent abuse* #### Parameters | Name | Type | Description | | --------- | ------- | ------------------------------------------------- | | creator\_ | address | Address of market creator | | status\_ | bool | Allow callback (true) : Disallow callback (false) | ### setDefaults ```solidity function setDefaults(uint32[6] defaults_) external nonpayable ``` Set the auctioneer defaultsMust be policy *The defaults set here are important to avoid edge cases in market behavior, e.g. a very short market reacts doesn't tune wellOnly applies to new markets that are created after the change* #### Parameters | Name | Type | Description | | ---------- | ---------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | defaults\_ | uint32\[6] | Array of default values 1. Tune interval - amount of time between tuning adjustments 2. Tune adjustment delay - amount of time to apply downward tuning adjustments 3. Minimum debt decay interval - minimum amount of time to let debt decay to zero 4. Minimum deposit interval - minimum amount of time to wait between deposits 5. Minimum market duration - minimum amount of time a market can be created for 6. Minimum debt buffer - the minimum amount of debt over the initial debt to trigger a market shutdown | ### setIntervals ```solidity function setIntervals(uint256 id_, uint32[3] intervals_) external nonpayable ``` Set market intervals to different values than the defaultsMust be market owner *Changing the intervals could cause markets to behave in unexpected way tuneInterval should be greater than tuneAdjustmentDelay* #### Parameters | Name | Type | Description | | ----------- | ---------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | id\_ | uint256 | Market ID | | intervals\_ | uint32\[3] | Array of intervals (3) 1. Tune interval - Frequency of tuning 2. Tune adjustment delay - Time to implement downward tuning adjustments 3. 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