Curve DAO Token

Curve DAO Token (CRV) is based on the ERC-20 token standard as defined at EIP-20.

Contract Source & Deployment

Curve DAO Token contract is deployed to the Ethereum mainnet at: 0xD533a949740bb3306d119CC777fa900bA034cd52.
Source code available on Github.
Deployment hash: 0x5dc4a688b63cea09bf4d73a695175b77572792a2e2b3656297809ad3596d4bfe

For a broader understanding of the use case of the CRV token, check out Understanding CRV.

Contract Info Methods¶

`admin`¶

CRV.admin() -> address: view

Getter for the admin of the contract.

Returns: admin (address).

Source code

admin: public(address)

@external
def __init__(_name: String[64], _symbol: String[32], _decimals: uint256):
    """
    @notice Contract constructor
    @param _name Token full name
    @param _symbol Token symbol
    @param _decimals Number of decimals for token
    """
    ...

    self.admin = msg.sender

    ...

Example

>>> CRV.admin()
'0x40907540d8a6C65c637785e8f8B742ae6b0b9968'

`name`¶

CRV.name() -> String[64]

Getter for the name of the token. Name of the token can be changed by calling the set_name function.

Returns: token name (String[64]).

Source code

name: public(String[64])

@external
def __init__(_name: String[64], _symbol: String[32], _decimals: uint256):
    """
    @notice Contract constructor
    @param _name Token full name
    @param _symbol Token symbol
    @param _decimals Number of decimals for token
    """
    init_supply: uint256 = INITIAL_SUPPLY * 10 ** _decimals
    self.name = _name

    ...

Example

>>> CRV.name()
'Curve DAO Token'

`symbol`¶

CRV.symbol() -> String[32]

Getter of the token symbol. Symbol of the token can be changed by calling the set_name function.

Returns: token symbol (String[32]).

Source code

symbol: public(String[32])

@external
def __init__(_name: String[64], _symbol: String[32], _decimals: uint256):
    """
    @notice Contract constructor
    @param _name Token full name
    @param _symbol Token symbol
    @param _decimals Number of decimals for token
    """
    ... 

    self.symbol = _symbol

    ...

Example

>>> CRV.symbol()
'CRV'

`avaliable_supply`¶

CRV.avaliably_supply() -> uint256

Getter for the current number of CRV tokens - claimed of unclaimed - in existence.

Returns: currently existing tokens (uint256).

Source code

@internal
@view
def _available_supply() -> uint256:
    return self.start_epoch_supply + (block.timestamp - self.start_epoch_time) * self.rate

@external
@view
def available_supply() -> uint256:
    """
    @notice Current number of tokens in existence (claimed or unclaimed)
    """
    return self._available_supply()

Example

>>> CRV.avaliable_supply()
1953676805157446496269106603

`totalSupply`¶

CRV.totalSupply() -> uint256

Getter for the total number of tokens in existence.

Returns: total supply (uint256).

Source code

@external
@view
def totalSupply() -> uint256:
    """
    @notice Total number of tokens in existence.
    """
    return self.total_supply

Example

>>> CRV.totalSupply()
1950555367872773429287303134

`decimals`¶

CRV.decimals() -> uint256: view

Getter of the decimals of the token.

Returns: decimals (uint256).

Source code

decimals: public(uint256)

@external
def __init__(_name: String[64], _symbol: String[32], _decimals: uint256):
    """
    @notice Contract constructor
    @param _name Token full name
    @param _symbol Token symbol
    @param _decimals Number of decimals for token
    """
    ...

    self.decimals = _decimals

    ...

Example

>>> CRV.decimals()
18

`balanceOf`¶

CRV.balanceOf(arg0: address) -> address: view

Getter for the crv token balance of a specific address.

Returns: balance (uint256).

Input	Type	Description
`arg0`	`address`	wallet to check CRV balance for

Source code

balanceOf: public(HashMap[address, uint256])

Example

>>> CRV.balanceOf('0xd061D61a4d941c39E5453435B6345Dc261C2fcE0')
2187980063734121847368

Transfer Methods¶

`transfer`¶

CRV.transfer(_to: address, _value: uint256) -> bool:

Function to transfer _value tokens from msg.sender to _to. Transfers to ZERO_ADDRESS are not allowed.

Returns: true (bool).

Emits: Transfer

Input	Type	Description
`_to`	`address`	receiver address
`_value`	`uint256`	amount of tokens to send

Warning

Vyper does not allow underflows, so the subtraction in this function will revert on an insufficient balance.

Source code

event Transfer:
    _from: indexed(address)
    _to: indexed(address)
    _value: uint256

@external
def transfer(_to : address, _value : uint256) -> bool:
    """
    @notice Transfer `_value` tokens from `msg.sender` to `_to`
    @dev Vyper does not allow underflows, so the subtraction in
        this function will revert on an insufficient balance
    @param _to The address to transfer to
    @param _value The amount to be transferred
    @return bool success
    """
    assert _to != ZERO_ADDRESS  # dev: transfers to 0x0 are not allowed
    self.balanceOf[msg.sender] -= _value
    self.balanceOf[_to] += _value
    log Transfer(msg.sender, _to, _value)
    return True

Example

>>> CRV.transfer('0x7a16fF8270133F063aAb6C9977183D9e72835428', 1)
'true'

`transferFrom`¶

CRV.transferFrom(_from: address, _to: address, _value: uint256) -> bool:

Function to transfer _value tokens from _from_ to _to. Transfers to ZERO_ADDRESS are not allowed.

Returns: true (bool).

Emits: Transfer

Input	Type	Description
`_from`	`address`	address to send tokens from
`_to`	`address`	receiver address
`_value`	`uint256`	amount of tokens to send

Warning

Vyper does not allow underflows, so the subtraction in this function will revert on an insufficient balance.

Source code

event Transfer:
    _from: indexed(address)
    _to: indexed(address)
    _value: uint256

@external
def transferFrom(_from : address, _to : address, _value : uint256) -> bool:
    """
    @notice Transfer `_value` tokens from `_from` to `_to`
    @param _from address The address which you want to send tokens from
    @param _to address The address which you want to transfer to
    @param _value uint256 the amount of tokens to be transferred
    @return bool success
    """
    assert _to != ZERO_ADDRESS  # dev: transfers to 0x0 are not allowed
    # NOTE: vyper does not allow underflows
    #       so the following subtraction would revert on insufficient balance
    self.balanceOf[_from] -= _value
    self.balanceOf[_to] += _value
    self.allowances[_from][msg.sender] -= _value
    log Transfer(_from, _to, _value)
    return True

Example

>>> CRV.transferFrom('0x7a16fF8270133F063aAb6C9977183D9e72835428', '0x68BEDE1d0bc6BE6d215f8f8Ee4ee8F9faB97fE7a', 1)
'true'

Allowances¶

`allowance`¶

CRV.allowance(_owner: address, _spender: address) -> uint256

Getter method to check the amount of tokens that an owner allowed to a spender.

Returns: amount of tokens (uint256) _owner is allowed to _spender.

Input	Type	Description
`_owner`	`address`	owner address
`_spender`	`address`	spender address

Source code

allowances: HashMap[address, HashMap[address, uint256]]

@external
@view
def allowance(_owner : address, _spender : address) -> uint256:
    """
    @notice Check the amount of tokens that an owner allowed to a spender
    @param _owner The address which owns the funds
    @param _spender The address which will spend the funds
    @return uint256 specifying the amount of tokens still available for the spender
    """
    return self.allowances[_owner][_spender]

Example

>>> CRV.allowance(0x7a16fF8270133F063aAb6C9977183D9e72835428 ,0x68BEDE1d0bc6BE6d215f8f8Ee4ee8F9faB97fE7a)
0

`approve`¶

CRV.approve(_spender: address, _value: uint256) -> bool:

Function to approve _spender to transfer _value tokens on behalf of msg.sender.

Returns: true (bool).

Emits: Approval

Input	Type	Description
`_spender`	`address`	spender address
`_value`	`uint256`	amount to approce

Source code

event Approval:
    _owner: indexed(address)
    _spender: indexed(address)
    _value: uint256

allowances: HashMap[address, HashMap[address, uint256]]

@external
def approve(_spender : address, _value : uint256) -> bool:
    """
    @notice Approve `_spender` to transfer `_value` tokens on behalf of `msg.sender`
    @dev Approval may only be from zero -> nonzero or from nonzero -> zero in order
        to mitigate the potential race condition described here:
        https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
    @param _spender The address which will spend the funds
    @param _value The amount of tokens to be spent
    @return bool success
    """
    assert _value == 0 or self.allowances[msg.sender][_spender] == 0
    self.allowances[msg.sender][_spender] = _value
    log Approval(msg.sender, _spender, _value)
    return True

Example

>>> CRV.approve(todo)

Minting and Burning¶

`minter`¶

CRV.minter() -> address: view

Getter for the minter contract address. The minter address can only be set once (at deployment) and not altered after.

Returns: minter contract (address).

Source code

minter: public(address)

Example

>>> CRV.minter()
'0xd061D61a4d941c39E5453435B6345Dc261C2fcE0'

`mint`¶

CRV.mint(_to: address, _value: uint256) -> bool:

Function to mint _value (uint256) and assign them to _to (address).

Returns: True (bool)

Emits: Transfer

Input	Type	Description
`_to`	`address`	receiver of the minted tokens
`_value`	`uint256`	amount to mint

Source code

event Transfer:
    _from: indexed(address)
    _to: indexed(address)
    _value: uint256

@external
def mint(_to: address, _value: uint256) -> bool:
    """
    @notice Mint `_value` tokens and assign them to `_to`
    @dev Emits a Transfer event originating from 0x00
    @param _to The account that will receive the created tokens
    @param _value The amount that will be created
    @return bool success
    """
    assert msg.sender == self.minter  # dev: minter only
    assert _to != ZERO_ADDRESS  # dev: zero address

    if block.timestamp >= self.start_epoch_time + RATE_REDUCTION_TIME:
        self._update_mining_parameters()

    _total_supply: uint256 = self.total_supply + _value
    assert _total_supply <= self._available_supply()  # dev: exceeds allowable mint amount
    self.total_supply = _total_supply

    self.balanceOf[_to] += _value
    log Transfer(ZERO_ADDRESS, _to, _value)

    return True

Example

>>> CRV.mint("0x0000000000000000000000000000000000000000", 1000000000000000000)
False

`burn`¶

CRV.burn(_value: uint256) -> bool

Function to burn _value tokens belonging to the caller of the function.

Retruns: True (bool).

Emits: Transfer

Input	Type	Description
`_value`	`uint256`	amount to burn

Source code

event Transfer:
    _from: indexed(address)
    _to: indexed(address)
    _value: uint256

@external
def burn(_value: uint256) -> bool:
    """
    @notice Burn `_value` tokens belonging to `msg.sender`
    @dev Emits a Transfer event with a destination of 0x00
    @param _value The amount that will be burned
    @return bool success
    """
    self.balanceOf[msg.sender] -= _value
    self.total_supply -= _value

    log Transfer(msg.sender, ZERO_ADDRESS, _value)
    return True

Example

>>> CRV.burn(1000000000000000000)
True

`mintable_in_timeframe`¶

CRV.mintable_in_timeframe(start: uint256, end: uint256) -> uint256

Getter for mintable supply from start timestamp till end timestamp.

Returns: amount of mintable tokens (uint256).

Input	Type	Description
`start`	`uint256`	start timestamp
`end`	`uint256`	end timestamp

Source code

@external
@view
def mintable_in_timeframe(start: uint256, end: uint256) -> uint256:
    """
    @notice How much supply is mintable from start timestamp till end timestamp
    @param start Start of the time interval (timestamp)
    @param end End of the time interval (timestamp)
    @return Tokens mintable from `start` till `end`
    """
    assert start <= end  # dev: start > end
    to_mint: uint256 = 0
    current_epoch_time: uint256 = self.start_epoch_time
    current_rate: uint256 = self.rate

    # Special case if end is in future (not yet minted) epoch
    if end > current_epoch_time + RATE_REDUCTION_TIME:
        current_epoch_time += RATE_REDUCTION_TIME
        current_rate = current_rate * RATE_DENOMINATOR / RATE_REDUCTION_COEFFICIENT

    assert end <= current_epoch_time + RATE_REDUCTION_TIME  # dev: too far in future

    for i in range(999):  # Curve will not work in 1000 years. Darn!
        if end >= current_epoch_time:
            current_end: uint256 = end
            if current_end > current_epoch_time + RATE_REDUCTION_TIME:
                current_end = current_epoch_time + RATE_REDUCTION_TIME

            current_start: uint256 = start
            if current_start >= current_epoch_time + RATE_REDUCTION_TIME:
                break  # We should never get here but what if...
            elif current_start < current_epoch_time:
                current_start = current_epoch_time

            to_mint += current_rate * (current_end - current_start)

            if start >= current_epoch_time:
                break

        current_epoch_time -= RATE_REDUCTION_TIME
        current_rate = current_rate * RATE_REDUCTION_COEFFICIENT / RATE_DENOMINATOR  # double-division with rounding made rate a bit less => good
        assert current_rate <= INITIAL_RATE  # This should never happen

    return to_mint

Example

>>> CRV.mintable_in_timeframe(1682892000, 1683496800)
3726756852824660365468800

CRV Emissions¶

Bug

If the formulas below do not render, please make sure to refresh the site. A solution is being worked on.

Mining parameters are used to determine the token emissions. The emissions are based on epochs (one year). With every passing epoch, the rate will be reduced, thereby reducing the entire CRV emissions.

The rate can be reduced by invoking the update_mining_parameters() function. While this function is accessible to anyone, an attempt to call it will be reverted if a year hasn't elapsed since the last update. When the function is successfully executed, the mining_epoch increments by 1, and the start_epoch_time is updated to the timestamp of that function call. Moreover, the update_mining_parameters() function will be automatically triggered if someone tries to mint CRV before the scheduled rate reduction.

\[rate_{future} = rate_{current} * \frac{\text{RATE_DENOMINATOR}}{\text{RATE_REDUCTION_COEFFICIENT}}\]

with:

$\text{RATE_DENOMINATOR} = 10^{18}$ $\text{RATE_REDUCTION_COEFFICIENT} = 2^{\frac{1}{4}} * 10^{18}$

Effectively, every rate reduction decreases the CRV inflation by around 15.9%.

`mining_epoch`¶

CRV.mining_epoch() -> int128: view

Getter for the current mining epoch. The mining epoch is incremented by 1 every time update_mining_parameters() is successfully called. At deployment, mining_epoch was set to -1.

Returns: mining epoch (int128).

Source code

mining_epoch: public(int128)

@external
def __init__(_name: String[64], _symbol: String[32], _decimals: uint256):
    """
    @notice Contract constructor
    @param _name Token full name
    @param _symbol Token symbol
    @param _decimals Number of decimals for token
    """
    ...

    self.mining_epoch = -1

    ...

@internal
def _update_mining_parameters():
    """
    @dev Update mining rate and supply at the start of the epoch
        Any modifying mining call must also call this
    """
    _rate: uint256 = self.rate
    _start_epoch_supply: uint256 = self.start_epoch_supply

    self.start_epoch_time += RATE_REDUCTION_TIME
    self.mining_epoch += 1

    if _rate == 0:
        _rate = INITIAL_RATE
    else:
        _start_epoch_supply += _rate * RATE_REDUCTION_TIME
        self.start_epoch_supply = _start_epoch_supply
        _rate = _rate * RATE_DENOMINATOR / RATE_REDUCTION_COEFFICIENT

    self.rate = _rate

    log UpdateMiningParameters(block.timestamp, _rate, _start_epoch_supply)

Example

>>> CRV.mining_epoch()
2

`start_epoch_time`¶

CRV.start_epoch_time() -> uint256: view

Getter for the start times of the current mining epoch.

Returns: timestamp (uint256).

Source code

start_epoch_time: public(uint256)

@external
def __init__(_name: String[64], _symbol: String[32], _decimals: uint256):
    """
    @notice Contract constructor
    @param _name Token full name
    @param _symbol Token symbol
    @param _decimals Number of decimals for token
    """
    ...

    self.start_epoch_time = block.timestamp + INFLATION_DELAY - RATE_REDUCTION_TIME

    ...

Example

>>> CRV.start_epoch_time()
1660429048 -> 'Sat Aug 13 2022 22:17:28 GMT+0000'

`rate`¶

CRV.rate() -> uint256: view

Getter for the current rate of CRV emissions.

Returns: current rate (uint256).

Tip

rate is denominated in emissions per second. Emissions per day: 6.161965695807970181 * 86400 = 532393.8361178086

Source code

rate: public(uint256)

@external
def __init__(_name: String[64], _symbol: String[32], _decimals: uint256):
    """
    @notice Contract constructor
    @param _name Token full name
    @param _symbol Token symbol
    @param _decimals Number of decimals for token
    """
    ...

    self.rate = 0

    ...

Example

>>> CRV.rate()
6161965695807970181

`update_mining_parameters`¶

update_mining_parameters()

Function to update the mining parameters for the Curve DAO Token ($CRV).

Emits: UpdateMiningParameters

Tip

This function can be called by anyone. However, the call will revert if block.timestamp is less than or equal to start_epoch_time + RATE_REDUCTION_TIME, indicating that one year has not yet passed.

Source code

event UpdateMiningParameters:
    time: uint256
    rate: uint256
    supply: uint256

# Supply parameters
INITIAL_SUPPLY: constant(uint256) = 1_303_030_303
INITIAL_RATE: constant(uint256) = 274_815_283 * 10 ** 18 / YEAR  # leading to 43% premine
RATE_REDUCTION_TIME: constant(uint256) = YEAR
RATE_REDUCTION_COEFFICIENT: constant(uint256) = 1189207115002721024  # 2 ** (1/4) * 1e18
RATE_DENOMINATOR: constant(uint256) = 10 ** 18
INFLATION_DELAY: constant(uint256) = 86400

# Supply variables
mining_epoch: public(int128)
start_epoch_time: public(uint256)
rate: public(uint256)

start_epoch_supply: uint256

@external
def update_mining_parameters():
    """
    @notice Update mining rate and supply at the start of the epoch
    @dev Callable by any address, but only once per epoch
        Total supply becomes slightly larger if this function is called late
    """
    assert block.timestamp >= self.start_epoch_time + RATE_REDUCTION_TIME  # dev: too soon!
    self._update_mining_parameters()

@internal
def _update_mining_parameters():
    """
    @dev Update mining rate and supply at the start of the epoch
        Any modifying mining call must also call this
    """
    _rate: uint256 = self.rate
    _start_epoch_supply: uint256 = self.start_epoch_supply

    self.start_epoch_time += RATE_REDUCTION_TIME
    self.mining_epoch += 1

    if _rate == 0:
        _rate = INITIAL_RATE
    else:
        _start_epoch_supply += _rate * RATE_REDUCTION_TIME
        self.start_epoch_supply = _start_epoch_supply
        _rate = _rate * RATE_DENOMINATOR / RATE_REDUCTION_COEFFICIENT

    self.rate = _rate

    log UpdateMiningParameters(block.timestamp, _rate, _start_epoch_supply)

Example

>>> CRV.update_mining_parameters()

`start_epoch_time_write`¶

CRV.start_epoch_time_write() -> uint256

Function to get the current mining epoch start while simultaneously updating mining parameters (if possible).

Returns: timestamp (uint256).

Source code

start_epoch_time: public(uint256)

@external
def start_epoch_time_write() -> uint256:
    """
    @notice Get timestamp of the current mining epoch start
            while simultaneously updating mining parameters
    @return Timestamp of the epoch
    """
    _start_epoch_time: uint256 = self.start_epoch_time
    if block.timestamp >= _start_epoch_time + RATE_REDUCTION_TIME:
        self._update_mining_parameters()
        return self.start_epoch_time
    else:
        return _start_epoch_time

Example

>>> CRV.start_epoch_time_write()

`future_epoch_time_write`¶

CRV.future_epoch_time_write() -> uint256

Function to get the next mining epoch start while simultaneously updating mining parameters (if possible).

Returns: timestamp (uint256).

Source code

@external
def future_epoch_time_write() -> uint256:
    """
    @notice Get timestamp of the next mining epoch start
            while simultaneously updating mining parameters
    @return Timestamp of the next epoch
    """
    _start_epoch_time: uint256 = self.start_epoch_time
    if block.timestamp >= _start_epoch_time + RATE_REDUCTION_TIME:
        self._update_mining_parameters()
        return self.start_epoch_time + RATE_REDUCTION_TIME
    else:
        return _start_epoch_time + RATE_REDUCTION_TIME

Example

>>> CRV.future_epoch_time_write()

Curve DAO Token

Contract Info Methods¶

admin¶

name¶

symbol¶

avaliable_supply¶

totalSupply¶

decimals¶

balanceOf¶

Transfer Methods¶

transfer¶

transferFrom¶

Allowances¶

allowance¶

approve¶

Minting and Burning¶

minter¶

mint¶

burn¶

mintable_in_timeframe¶

CRV Emissions¶

mining_epoch¶

start_epoch_time¶

rate¶

update_mining_parameters¶

start_epoch_time_write¶

future_epoch_time_write¶

`admin`¶

`name`¶

`symbol`¶

`avaliable_supply`¶

`totalSupply`¶

`decimals`¶

`balanceOf`¶

`transfer`¶

`transferFrom`¶

`allowance`¶

`approve`¶

`minter`¶

`mint`¶

`burn`¶

`mintable_in_timeframe`¶

`mining_epoch`¶

`start_epoch_time`¶

`rate`¶

`update_mining_parameters`¶

`start_epoch_time_write`¶

`future_epoch_time_write`¶