Introduction

Each asset supported by the ChumHum Protocol is integrated through a cToken contract, which is an EIP-20 compliant representation of balances supplied to the protocol. By minting cTokens, users (1) earn interest through the cToken's exchange rate, which increases in value relative to the underlying asset, and (2) gain the ability to use cTokens as collateral.

cTokens are the primary means of interacting with the ChumHum Protocol; when a user mints, redeems, borrows, repays a borrow, liquidates a borrow, or transfers cTokens, she will do so using the cToken contract.

There are currently two types of cTokens: CErc20 and CMATIC. Though both types expose the EIP-20 interface, CErc20 wraps an underlying ERC-20 asset, while CMATIC simply wraps Ether itself. As such, the core functions which involve transferring an asset into the protocol have slightly different interfaces depending on the type, each of which is shown below.

How do cTokens earn interest?

Each market has its own Supply interest rate (APR). Interest isn't distributed; instead, simply by holding cTokens, you'll earn interest.

cTokens accumulates interest through their exchange rate — over time, each cToken becomes convertible into an increasing amount of it's underlying asset, even while the number of cTokens in your wallet stays the same.

Do I need to calculate the cToken exchange rate?

When a market is launched, the cToken exchange rate (how much BNB one cBNB is worth) begins at 0.020000 — and increases at a rate equal to the compounding market interest rate. For example, after one year, the exchange rate might equal 0.021591.

Each user has the same cToken exchange rate; there’s nothing unique to your wallet that you have to worry about.

Can you walk me through an example?

Let’s say you supply 1,000 DAI to the ChumHum protocol, when the exchange rate is 0.020070; you would receive 49,825.61 cDAI (1,000/0.020070).

A few months later, you decide it’s time to withdraw your DAI from the protocol; the exchange rate is now 0.021591:

  • Your 49,825.61 cDAI is now equal to 1,075.78 DAI (49,825.61 * 0.021591)

  • You could withdraw 1,075.78 DAI, which would redeem all 49,825.61 cDAI

  • Or, you could withdraw a portion, such as your original 1,000 DAI, which would redeem 46,315.59 cDAI (keeping 3,510.01 cDAI in your wallet)

How do I view my cTokens?

Each cToken is visible on BscScan , and you should be able to view them in the list of tokens associated with your address

cToken balances have been integrated into Coinbase Wallet and MetaMask; other wallets may add cToken support

Can I transfer cTokens?

Yes, but exercise caution! By transferring cTokens, you’re transferring your balance of the underlying asset inside the ChumHum protocol. If you send a cToken to your friend, your balance (viewable in the ChumHum Interface ) will decline, and your friend will see their balance increase.

A cToken transfer will fail if the account has entered that cToken market and the transfer would have put the account into a state of negative liquidity .

Mint

The mint function transfers an asset into the protocol, which begins accumulating interest based on the current Supply Rate for the asset. The user receives a quantity of cTokens equal to the underlying tokens supplied, divided by the current Exchange Rate .

CErc20

function mint(uint mintAmount) returns (uint)
  • msg.sender : The account which shall supply the asset, and own the minted cTokens.
  • mintAmount : The amount of the asset to be supplied, in units of the underlying asset.
  • RETURN : 0 on success, otherwise an Error code

Before supplying an asset, users must first approve the cToken to access their token balance.

CMATIC

function mint() payable
  • msg.value payable : The amount of ether to be supplied, in wei.
  • msg.sender : The account which shall supply the ether, and own the minted cTokens.
  • RETURN : No return, reverts on error.

Solidity

Erc20 underlying = Erc20(0xToken...); // get a handle for the underlying asset contract
CErc20 cToken = CErc20(0x3FDA...); // get a handle for the corresponding cToken contract
underlying.approve(address(cToken), 100); // approve the transfer
assert(cToken.mint(100) == 0); // mint the cTokens and assert there is no error

Web3 1.0

const cToken = CMATIC.at(0x3FDB...);
await cToken.methods.mint().send({from: myAccount, value: 50});

Redeem

The redeem function converts a specified quantity of cTokens into the underlying asset, and returns them to the user. The amount of underlying tokens received is equal to the quantity of cTokens redeemed, multiplied by the current Exchange Rate . The amount redeemed must be less than the user's Account Liquidity and the market's available liquidity.

CErc20 / CMATIC

function redeem(uint redeemTokens) returns (uint)
  • msg.sender : The account to which redeemed funds shall be transferred.
  • redeemTokens : The number of cTokens to be redeemed.
  • RETURN : 0 on success, otherwise an Error code

Solidity

CMATIC cToken = CMATIC(0x3FDB...);
require(cToken.redeem(7) == 0, "something went wrong");

Web3 1.0

const cToken = CErc20.at(0x3FDA...);
cToken.methods.redeem(1).send({from: ...});

Redeem Underlying

The redeem underlying function converts cTokens into a specified quantity of the underlying asset, and returns them to the user. The amount of cTokens redeemed is equal to the quantity of underlying tokens received, divided by the current Exchange Rate . The amount redeemed must be less than the user's Account Liquidity and the market's available liquidity.

CErc20 / CMATIC

function redeemUnderlying(uint redeemAmount) returns (uint)
  • msg.sender : The account to which redeemed funds shall be transferred.
  • redeemAmount : The amount of underlying to be redeemed.
  • RETURN : 0 on success, otherwise an Error code

Solidity

CMATIC cToken = CMATIC(0x3FDB...);
require(cToken.redeemUnderlying(50) == 0, "something went wrong");

Web3 1.0

const cToken = CErc20.at(0x3FDA...);
cToken.methods.redeemUnderlying(10).send({from: ...});

Borrow

The borrow function transfers an asset from the protocol to the user, and creates a borrow balance which begins accumulating interest based on the Borrow Rate for the asset. The amount borrowed must be less than the user's Account Liquidity and the market's available liquidity.

To borrow Ether, the borrower must be 'payable' (solidity).

CErc20 / CMATIC

function borrow(uint borrowAmount) returns (uint)
  • msg.sender : The account to which borrowed funds shall be transferred.
  • borrowAmount : The amount of the underlying asset to be borrowed.
  • RETURN : 0 on success, otherwise an Error code

Solidity

CErc20 cToken = CErc20(0x3FDA...);
require(cToken.borrow(100) == 0, "got collateral?");

Web3 1.0

const cToken = CMATIC.at(0x3FDB...);
await cToken.methods.borrow(50).send({from: 0xMyAccount});

Repay Borrow

The repay function transfers an asset into the protocol, reducing the user's borrow balance.

CErc20

function repayBorrow(uint repayAmount) returns (uint)
  • msg.sender : The account which borrowed the asset, and shall repay the borrow.
  • repayAmount : The amount of the underlying borrowed asset to be repaid. A value of -1 (i.e. 2 256 - 1) can be used to repay the full amount.
  • RETURN : 0 on success, otherwise an Error code

Before repaying an asset, users must first approve the cToken to access their token balance.

CMATIC

function repayBorrow() payable
  • msg.value payable : The amount of ether to be repaid, in wei.
  • msg.sender : The account which borrowed the asset, and shall repay the borrow.
  • RETURN : No return, reverts on error.

Solidity

CMATIC cToken = CMATIC(0x3FDB...);
require(cToken.repayBorrow.value(100)() == 0, "transfer approved?");

Web3 1.0

const cToken = CErc20.at(0x3FDA...);
cToken.methods.repayBorrow(10000).send({from: ...});

Repay Borrow Behalf

The repay function transfers an asset into the protocol, reducing the target user's borrow balance.

CErc20

function repayBorrowBehalf(address borrower, uint repayAmount) returns (uint)
  • msg.sender : The account which shall repay the borrow.
  • borrower : The account which borrowed the asset to be repaid.
  • repayAmount : The amount of the underlying borrowed asset to be repaid. A value of -1 (i.e. 2 256 - 1) can be used to repay the full amount.
  • RETURN : 0 on success, otherwise an Error code

Before repaying an asset, users must first approve the cToken to access their token balance.

CMATIC

function repayBorrowBehalf(address borrower) payable
  • msg.value payable : The amount of ether to be repaid, in wei.
  • msg.sender : The account which shall repay the borrow.
  • borrower : The account which borrowed the asset to be repaid.
  • RETURN : No return, reverts on error.

Solidity

CMATIC cToken = CMATIC(0x3FDB...);
require(cToken.repayBorrowBehalf.value(100)(0xBorrower) == 0, "transfer approved?");

Web3 1.0

const cToken = CErc20.at(0x3FDA...);
await cToken.methods.repayBorrowBehalf(0xBorrower, 10000).send({from: 0xPayer});

Transfer

Transfer is an ERC-20 method that allows accounts to send tokens to other Matic Chain addresses. A cToken transfer will fail if the account has entered that cToken market and the transfer would have put the account into a state of negative liquidity .

CErc20 / CMATIC

function transfer(address recipient, uint256 amount) returns (bool)
  • recipient : The transfer recipient address.
  • amount : The amount of cTokens to transfer.
  • RETURN : Returns a boolean value indicating whether or not the operation succeeded.

Solidity

CMATIC cToken = CMATIC(0x3FDB...);
cToken.transfer(0xABCD..., 100000000000);

Web3 1.0

const cToken = CErc20.at(0x3FDA...);
await cToken.methods.transfer(0xABCD..., 100000000000).send({from: 0xSender});

Liquidate Borrow

A user who has negative account liquidity is subject to liquidation by other users of the protocol to return his/her account liquidity back to positive (i.e. above the collateral requirement). When a liquidation occurs, a liquidator may repay some or all of an outstanding borrow on behalf of a borrower and in return receive a discounted amount of collateral held by the borrower; this discount is defined as the liquidation incentive.

A liquidator may close up to a certain fixed percentage (i.e. close factor) of any individual outstanding borrow of the underwater account. Unlike in v1, liquidators must interact with each cToken contract in which they wish to repay a borrow and seize another asset as collateral. When collateral is seized, the liquidator is transferred cTokens, which they may redeem the same as if they had supplied the asset themselves. Users must approve each cToken contract before calling liquidate (i.e. on the borrowed asset which they are repaying), as they are transferring funds into the contract.

CErc20

function liquidateBorrow(address borrower, uint amount, address collateral) returns (uint)
  • msg.sender : The account which shall liquidate the borrower by repaying their debt and seizing their collateral.
  • borrower : The account with negative account liquidity that shall be liquidated.
  • repayAmount : The amount of the borrowed asset to be repaid and converted into collateral, specified in units of the underlying borrowed asset.
  • cTokenCollateral : The address of the cToken currently held as collateral by a borrower, that the liquidator shall seize.
  • RETURN : 0 on success, otherwise an Error code

Before supplying an asset, users must first approve the cToken to access their token balance.

CMATIC

function liquidateBorrow(address borrower, address cTokenCollateral) payable
  • msg.value payable : The amount of ether to be repaid and converted into collateral, in wei.
  • msg.sender : The account which shall liquidate the borrower by repaying their debt and seizing their collateral.
  • borrower : The account with negative account liquidity that shall be liquidated.
  • cTokenCollateral : The address of the cToken currently held as collateral by a borrower, that the liquidator shall seize.
  • RETURN : No return, reverts on error.

Solidity

CMATIC cToken = CMATIC(0x3FDB...);
CErc20 cTokenCollateral = CErc20(0x3FDA...);
require(cToken.liquidateBorrow.value(100)(0xBorrower, cTokenCollateral) == 0, "borrower underwater??");

Web3 1.0

const cToken = CErc20.at(0x3FDA...);
const cTokenCollateral = CMATIC.at(0x3FDB...);
await cToken.methods.liquidateBorrow(0xBorrower, 33, cTokenCollateral).send({from: 0xLiquidator});

Key Events

Event Description

Mint(address minter, uint mintAmount, uint mintTokens)

Emitted upon a successful Mint .

Redeem(address redeemer, uint redeemAmount, uint redeemTokens)

Emitted upon a successful Redeem .

Borrow(address borrower, uint borrowAmount, uint accountBorrows, uint totalBorrows)

Emitted upon a successful Borrow .

RepayBorrow(address payer, address borrower, uint repayAmount, uint accountBorrows, uint totalBorrows)

Emitted upon a successful Repay Borrow .

LiquidateBorrow(address liquidator, address borrower, uint repayAmount, address cTokenCollateral, uint seizeTokens)

Emitted upon a successful Liquidate Borrow .

Error Codes

Code Name Description

0

NO_ERROR

Not a failure.

1

UNAUTHORIZED

The sender is not authorized to perform this action.

2

BAD_INPUT

An invalid argument was supplied by the caller.

3

COMPTROLLER_REJECTION

The action would violate the Comptroller policy.

4

COMPTROLLER_CALCULATION_ERROR

An internal calculation has failed in the Comptroller.

5

INTEREST_RATE_MODEL_ERROR

The interest rate model returned an invalid value.

6

INVALID_ACCOUNT_PAIR

The specified combination of accounts is invalid.

7

INVALID_CLOSE_AMOUNT_REQUESTED

The amount to liquidate is invalid.

8

INVALID_COLLATERAL_FACTOR

The collateral factor is invalid.

9

MATH_ERROR

A math calculation error occurred.

10

MARKET_NOT_FRESH

Interest has not been properly accrued.

11

MARKET_NOT_LISTED

The market is not currently listed by its Comptroller.

12

TOKEN_INSUFFICIENT_ALLOWANCE

ERC-20 contract must allow Money Market contract to call transferFrom . The current allowance is either 0 or less than the requested supply, repayBorrow or liquidate amount.

13

TOKEN_INSUFFICIENT_BALANCE

Caller does not have sufficient balance in the ERC-20 contract to complete the desired action.

14

TOKEN_INSUFFICIENT_CASH

The market does not have a sufficient cash balance to complete the transaction. You may attempt this transaction again later.

15

TOKEN_TRANSFER_IN_FAILED

Failure in ERC-20 when transfering token into the market.

16

TOKEN_TRANSFER_OUT_FAILED

Failure in ERC-20 when transfering token out of the market.

17

TOKEN_PRICE_ERROR

Failure in ERC-20 when price of token is invalid.

Failure Info

Code Name

0

ACCEPT_ADMIN_PENDING_ADMIN_CHECK

1

ACCRUE_INTEREST_ACCUMULATED_INTEREST_CALCULATION_FAILED

2

ACCRUE_INTEREST_BORROW_RATE_CALCULATION_FAILED

3

ACCRUE_INTEREST_NEW_BORROW_INDEX_CALCULATION_FAILED

4

ACCRUE_INTEREST_NEW_TOTAL_BORROWS_CALCULATION_FAILED

5

ACCRUE_INTEREST_NEW_TOTAL_RESERVES_CALCULATION_FAILED

6

ACCRUE_INTEREST_SIMPLE_INTEREST_FACTOR_CALCULATION_FAILED

7

BORROW_ACCRUE_INTEREST_FAILED

8

BORROW_CASH_NOT_ABUMLABLE

9

BORROW_FRESHNESS_CHECK

10

BORROW_NEW_TOTAL_BALANCE_CALCULATION_FAILED

11

BORROW_NEW_ACCOUNT_BORROW_BALANCE_CALCULATION_FAILED

12

BORROW_MARKET_NOT_LISTED

13

BORROW_COMPTROLLER_REJECTION

14

LIQUIDATE_ACCRUE_BORROW_INTEREST_FAILED

15

LIQUIDATE_ACCRUE_COLLATERAL_INTEREST_FAILED

16

LIQUIDATE_COLLATERAL_FRESHNESS_CHECK

17

LIQUIDATE_COMPTROLLER_REJECTION

18

LIQUIDATE_COMPTROLLER_CALCULATE_AMOUNT_SEIZE_FAILED

19

LIQUIDATE_CLOSE_AMOUNT_IS_UINT_MAX

20

LIQUIDATE_CLOSE_AMOUNT_IS_ZERO

21

LIQUIDATE_FRESHNESS_CHECK

22

LIQUIDATE_LIQUIDATOR_IS_BORROWER

23

LIQUIDATE_REPAY_BORROW_FRESH_FAILED

24

LIQUIDATE_SEIZE_BALANCE_INCREMENT_FAILED

25

LIQUIDATE_SEIZE_BALANCE_DECREMENT_FAILED

26

LIQUIDATE_SEIZE_COMPTROLLER_REJECTION

27

LIQUIDATE_SEIZE_LIQUIDATOR_IS_BORROWER

28

LIQUIDATE_SEIZE_TOO_MUCH

29

MINT_ACCRUE_INTEREST_FAILED

30

MINT_COMPTROLLER_REJECTION

31

MINT_EXCHANGE_CALCULATION_FAILED

32

MINT_EXCHANGE_RATE_READ_FAILED

33

MINT_FRESHNESS_CHECK

34

MINT_NEW_ACCOUNT_BALANCE_CALCULATION_FAILED

35

MINT_NEW_TOTAL_SUPPLY_CALCULATION_FAILED

36

MINT_TRANSFER_IN_FAILED

37

MINT_TRANSFER_IN_NOT_POSSIBLE

38

REDEEM_ACCRUE_INTEREST_FAILED

39

REDEEM_COMPTROLLER_REJECTION

40

REDEEM_EXCHANGE_TOKENS_CALCULATION_FAILED

41

REDEEM_EXCHANGE_AMOUNT_CALCULATION_FAILED

42

REDEEM_EXCHANGE_RATE_READ_FAILED

43

REDEEM_FRESHNESS_CHECK

44

REDEEM_NEW_ACCOUNT_BALANCE_CALCULATION_FAILED

45

REDEEM_NEW_TOTAL_SUPPLY_CALCULATION_FAILED

46

REDEEM_TRANSFER_OUT_NOT_POSSIBLE

47

REDUCE_RESERVES_ACCRUE_INTEREST_FAILED

48

REDUCE_RESERVES_ADMIN_CHECK

49

REDUCE_RESERVES_CASH_NOT_ABUMLABLE

50

REDUCE_RESERVES_FRESH_CHECK

51

REDUCE_RESERVES_VALIDATION

52

REPAY_BEHALF_ACCRUE_INTEREST_FAILED

53

REPAY_BORROW_ACCRUE_INTEREST_FAILED

54

REPAY_BORROW_ACCUMULATED_BALANCE_CALCULATION_FAILED

55

REPAY_BORROW_COMPTROLLER_REJECTION

56

REPAY_BORROW_FRESHNESS_CHECK

57

REPAY_BORROW_NEW_ACCOUNT_BORROW_BALANCE_CALCULATION_FAILED

58

REPAY_BORROW_NEW_TOTAL_BALANCE_CALCULATION_FAILED

59

REPAY_BORROW_TRANSFER_IN_NOT_POSSIBLE

60

SET_COLLATERAL_FACTOR_OWNER_CHECK

61

SET_COLLATERAL_FACTOR_VALIDATION

62

SET_COMPTROLLER_OWNER_CHECK

63

SET_INTEREST_RATE_MODEL_ACCRUE_INTEREST_FAILED

64

SET_INTEREST_RATE_MODEL_FRESH_CHECK

65

SET_INTEREST_RATE_MODEL_OWNER_CHECK

66

SET_MAX_ASSETS_OWNER_CHECK

67

SET_ORACLE_MARKET_NOT_LISTED

68

SET_PENDING_ADMIN_OWNER_CHECK

69

SET_RESERVE_FACTOR_ACCRUE_INTEREST_FAILED

70

SET_RESERVE_FACTOR_ADMIN_CHECK

71

SET_RESERVE_FACTOR_FRESH_CHECK

72

SET_RESERVE_FACTOR_BOUNDS_CHECK

73

TRANSFER_COMPTROLLER_REJECTION

74

TRANSFER_NOT_ALLOWED

75

TRANSFER_NOT_ENOUGH

76

TRANSFER_TOO_MUCH

77

ADD_RESERVES_ACCRUE_INTEREST_FAILED

78

ADD_RESERVES_FRESH_CHECK

79

ADD_RESERVES_TRANSFER_IN_NOT_POSSIBLE

80

TOKEN_GET_UNDERLYING_PRICE_ERROR

81

REPAY_BUM_COMPTROLLER_REJECTION

82

REPAY_BUM_FRESHNESS_CHECK

83

BUM_MINT_EXCHANGE_CALCULATION_FAILED

84

SFT_MINT_NEW_ACCOUNT_BALANCE_CALCULATION_FAILED

85

REDEEM_FEE_CALCULATION_FAILED

Exchange Rate

Each cToken is convertible into an ever increasing quantity of the underlying asset, as interest accrues in the market. The exchange rate between a cToken and the underlying asset is equal to:

exchangeRate = (getCash() + totalBorrows() - totalReserves()) / totalSupply()

CErc20 / CMATIC

function exchangeRateCurrent() returns (uint)
  • RETURN : The current exchange rate as an unsigned integer, scaled by 1e18.

Solidity

CErc20 cToken = CToken(0x3FDA...);
uint exchangeRateMantissa = cToken.exchangeRateCurrent();

Web3 1.0

const cToken = CMATIC.at(0x3FDB...);
const exchangeRate = (await cToken.methods.exchangeRateCurrent().call()) / 1e18;

Tip: note the use of call vs. send to invoke the function from off-chain without incurring gas costs.

Get Cash

Cash is the amount of underlying balance owned by this cToken contract. One may query the total amount of cash currently available to this market.

CErc20 / CMATIC

function getCash() returns (uint)
  • RETURN : The quantity of underlying asset owned by the contract.

Solidity

CErc20 cToken = CToken(0x3FDA...);
uint cash = cToken.getCash();

Web3 1.0

const cToken = CMATIC.at(0x3FDB...);
const cash = (await cToken.methods.getCash().call());

Total Borrow

Total Borrows is the amount of underlying currently loaned out by the market, and the amount upon which interest is accumulated to suppliers of the market.

CErc20 / CMATIC

function totalBorrowsCurrent() returns (uint)
  • RETURN : The total amount of borrowed underlying, with interest.

Solidity

CErc20 cToken = CToken(0x3FDA...);
uint borrows = cToken.totalBorrowsCurrent();

Web3 1.0

const cToken = CMATIC.at(0x3FDB...);
const borrows = (await cToken.methods.totalBorrowsCurrent().call());

Borrow Balance

A user who borrows assets from the protocol is subject to accumulated interest based on the current borrow rate . Interest is accumulated every block and integrations may use this function to obtain the current value of a user's borrow balance with interest.

CErc20 / CMATIC

function borrowBalanceCurrent(address account) returns (uint)
  • account : The account which borrowed the assets.
  • RETURN : The user's current borrow balance (with interest) in units of the underlying asset.

Solidity

CErc20 cToken = CToken(0x3FDA...);
uint borrows = cToken.borrowBalanceCurrent(msg.caller);

Web3 1.0

const cToken = CMATIC.at(0x3FDB...);
const borrows = await cToken.methods.borrowBalanceCurrent(account).call();

Borrow Rate

At any point in time one may query the contract to get the current borrow rate per block.

CErc20 / CMATIC

function borrowRatePerBlock() returns (uint)
  • RETURN : The current borrow rate as an unsigned integer, scaled by 1e18.

Solidity

CErc20 cToken = CToken(0x3FDA...);
uint borrowRateMantissa = cToken.borrowRatePerBlock();

Web3 1.0

const cToken = CMATIC.at(0x3FDB...);
const borrowRate = (await cToken.methods.borrowRatePerBlock().call()) / 1e18;

Total Supply

Total Supply is the number of tokens currently in circulation in this cToken market. It is part of the EIP-20 interface of the cToken contract.

CErc20 / CMATIC

function totalSupply() returns (uint)
  • RETURN : The total number of tokens in circulation for the market.

Solidity

CErc20 cToken = CToken(0x3FDA...);
uint tokens = cToken.totalSupply();

Web3 1.0

const cToken = CMATIC.at(0x3FDB...);
const tokens = (await cToken.methods.totalSupply().call());

Underlying Balance

The user's underlying balance, representing their assets in the protocol, is equal to the user's cToken balance multiplied by the Exchange Rate .

CErc20 / CMATIC

function balanceOfUnderlying(address account) returns (uint)
  • account : The account to get the underlying balance of.
  • RETURN : The amount of underlying currently owned by the account.

Solidity

CErc20 cToken = CToken(0x3FDA...);
uint tokens = cToken.balanceOfUnderlying(msg.caller);

Web3 1.0

const cToken = CMATIC.at(0x3FDB...);
const tokens = await cToken.methods.balanceOfUnderlying(account).call();

Supply Rate

At any point in time one may query the contract to get the current supply rate per block. The supply rate is derived from the borrow rate , reserve factor and the amount of total borrows .

CErc20 / CMATIC

function supplyRatePerBlock() returns (uint)
  • RETURN : The current supply rate as an unsigned integer, scaled by 1e18.

Solidity

CErc20 cToken = CToken(0x3FDA...);
uint supplyRateMantissa = cToken.supplyRatePerBlock();

Web3 1.0

const cToken = CMATIC.at(0x3FDB...);
const supplyRate = (await cToken.methods.supplyRatePerBlock().call()) / 1e18;

Total Reserves

Reserves are an accounting entry in each cToken contract that represents a portion of historical interest set aside as cash which can be withdrawn or transferred through the protocol's governance. A small portion of borrower interest accrues into the protocol, determined by the reserve factor .

CErc20 / CMATIC

function totalReserves() returns (uint)
  • RETURN : The total amount of reserves held in the market.

Solidity

CErc20 cToken = CToken(0x3FDA...);
uint reserves = cToken.totalReserves();

Web3 1.0

const cToken = CMATIC.at(0x3FDB...);
const reserves = (await cToken.methods.totalReserves().call());

Reserve Factor

The reserve factor defines the portion of borrower interest that is converted into reserves .

CErc20 / CMATIC

function reserveFactorMantissa() returns (uint)
  • RETURN : The current reserve factor as an unsigned integer, scaled by 1e18.

Solidity

CErc20 cToken = CToken(0x3FDA...);
uint reserveFactorMantissa = cToken.reserveFactorMantissa();

Web3 1.0

const cToken = CMATIC.at(0x3FDB...);
const reserveFactor = (await cToken.methods.reserveFactorMantissa().call()) / 1e18;