Contract Source Code:
File 1 of 1 : HFT
/**
* SPDX-License-Identifier: UNLICENSED
*/
pragma solidity 0.8.11;
library SafeMath {
/**
* @dev Returns the addition of two unsigned integers, with an overflow flag.
*
* _Available since v3.4._
*/
function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
unchecked {
uint256 c = a + b;
if (c < a) return (false, 0);
return (true, c);
}
}
/**
* @dev Returns the substraction of two unsigned integers, with an overflow flag.
*
* _Available since v3.4._
*/
function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
unchecked {
if (b > a) return (false, 0);
return (true, a - b);
}
}
/**
* @dev Returns the multiplication of two unsigned integers, with an overflow flag.
*
* _Available since v3.4._
*/
function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
unchecked {
// Gas optimization: this is cheaper than requiring 'a' not being zero, but the
// benefit is lost if 'b' is also tested.
// See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
if (a == 0) return (true, 0);
uint256 c = a * b;
if (c / a != b) return (false, 0);
return (true, c);
}
}
/**
* @dev Returns the division of two unsigned integers, with a division by zero flag.
*
* _Available since v3.4._
*/
function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
unchecked {
if (b == 0) return (false, 0);
return (true, a / b);
}
}
/**
* @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
*
* _Available since v3.4._
*/
function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
unchecked {
if (b == 0) return (false, 0);
return (true, a % b);
}
}
/**
* @dev Returns the addition of two unsigned integers, reverting on
* overflow.
*
* Counterpart to Solidity's `+` operator.
*
* Requirements:
*
* - Addition cannot overflow.
*/
function add(uint256 a, uint256 b) internal pure returns (uint256) {
return a + b;
}
/**
* @dev Returns the subtraction of two unsigned integers, reverting on
* overflow (when the result is negative).
*
* Counterpart to Solidity's `-` operator.
*
* Requirements:
*
* - Subtraction cannot overflow.
*/
function sub(uint256 a, uint256 b) internal pure returns (uint256) {
return a - b;
}
/**
* @dev Returns the multiplication of two unsigned integers, reverting on
* overflow.
*
* Counterpart to Solidity's `*` operator.
*
* Requirements:
*
* - Multiplication cannot overflow.
*/
function mul(uint256 a, uint256 b) internal pure returns (uint256) {
return a * b;
}
/**
* @dev Returns the integer division of two unsigned integers, reverting on
* division by zero. The result is rounded towards zero.
*
* Counterpart to Solidity's `/` operator.
*
* Requirements:
*
* - The divisor cannot be zero.
*/
function div(uint256 a, uint256 b) internal pure returns (uint256) {
return a / b;
}
/**
* @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
* reverting when dividing by zero.
*
* Counterpart to Solidity's `%` operator. This function uses a `revert`
* opcode (which leaves remaining gas untouched) while Solidity uses an
* invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
*
* - The divisor cannot be zero.
*/
function mod(uint256 a, uint256 b) internal pure returns (uint256) {
return a % b;
}
/**
* @dev Returns the subtraction of two unsigned integers, reverting with custom message on
* overflow (when the result is negative).
*
* CAUTION: This function is deprecated because it requires allocating memory for the error
* message unnecessarily. For custom revert reasons use {trySub}.
*
* Counterpart to Solidity's `-` operator.
*
* Requirements:
*
* - Subtraction cannot overflow.
*/
function sub(
uint256 a,
uint256 b,
string memory errorMessage
) internal pure returns (uint256) {
unchecked {
require(b <= a, errorMessage);
return a - b;
}
}
/**
* @dev Returns the integer division of two unsigned integers, reverting with custom message on
* division by zero. The result is rounded towards zero.
*
* Counterpart to Solidity's `/` operator. Note: this function uses a
* `revert` opcode (which leaves remaining gas untouched) while Solidity
* uses an invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
*
* - The divisor cannot be zero.
*/
function div(
uint256 a,
uint256 b,
string memory errorMessage
) internal pure returns (uint256) {
unchecked {
require(b > 0, errorMessage);
return a / b;
}
}
/**
* @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
* reverting with custom message when dividing by zero.
*
* CAUTION: This function is deprecated because it requires allocating memory for the error
* message unnecessarily. For custom revert reasons use {tryMod}.
*
* Counterpart to Solidity's `%` operator. This function uses a `revert`
* opcode (which leaves remaining gas untouched) while Solidity uses an
* invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
*
* - The divisor cannot be zero.
*/
function mod(
uint256 a,
uint256 b,
string memory errorMessage
) internal pure returns (uint256) {
unchecked {
require(b > 0, errorMessage);
return a % b;
}
}
}
contract HFT {
/// @notice EIP-20 token name for this token
string public constant name = 'Hashflow';
/// @notice EIP-20 token symbol for this token
string public constant symbol = 'HFT';
/// @notice EIP-20 token decimals for this token
uint8 public constant decimals = 18;
/// @notice Total number of tokens in circulation
uint256 public totalSupply = 1_000_000_000e18; // 1 billion HFT
/// @notice Address which may mint new tokens
address public minter;
/// @notice The timestamp after which minting may occur (must be set to 4 years)
uint256 public mintingAllowedAfter;
/// @notice Minimum time between mints
uint32 public constant minimumTimeBetweenMints = 1 days * 365;
/// @notice Cap on the percentage of totalSupply that can be minted at each mint (set to 5% inflation currently)
uint8 public mintCap = 5;
/// @notice Allowance amounts on behalf of others
mapping(address => mapping(address => uint96)) internal allowances;
/// @notice Official record of token balances for each account
mapping(address => uint96) internal balances;
/// @notice A record of each accounts delegate
mapping(address => address) public delegates;
/// @notice A checkpoint for marking number of votes from a given block
struct Checkpoint {
uint32 fromBlock;
uint96 votes;
}
/// @notice A record of votes checkpoints for each account, by index
mapping(address => mapping(uint32 => Checkpoint)) public checkpoints;
/// @notice The number of checkpoints for each account
mapping(address => uint32) public numCheckpoints;
/// @notice The EIP-712 typehash for the contract's domain
bytes32 public constant DOMAIN_TYPEHASH =
keccak256(
'EIP712Domain(string name,uint256 chainId,address verifyingContract)'
);
/// @notice The EIP-712 typehash for the delegation struct used by the contract
bytes32 public constant DELEGATION_TYPEHASH =
keccak256('Delegation(address delegatee,uint256 nonce,uint256 expiry)');
/// @notice The EIP-712 typehash for the permit struct used by the contract
bytes32 public constant PERMIT_TYPEHASH =
keccak256(
'Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)'
);
/// @notice A record of states for signing / validating signatures
mapping(address => uint256) public nonces;
/// @notice An event that is emitted when the minter address is changed
event MinterChanged(address minter, address newMinter);
/// @notice An event that is emitted when the mint percentage is changed
event MintCapChanged(uint256 newMintCap);
/// @notice An event thats emitted when an account changes its delegate
event DelegateChanged(
address indexed delegator,
address indexed fromDelegate,
address indexed toDelegate
);
/// @notice An event thats emitted when a delegate account's vote balance changes
event DelegateVotesChanged(
address indexed delegate,
uint256 previousBalance,
uint256 newBalance
);
/// @notice The standard EIP-20 transfer event
event Transfer(address indexed from, address indexed to, uint256 amount);
/// @notice The standard EIP-20 approval event
event Approval(
address indexed owner,
address indexed spender,
uint256 amount
);
/**
* @notice Construct a new Hashflow token
* @param account The initial account to grant all the tokens
* @param minter_ The account with minting ability
* @param mintingAllowedAfter_ The timestamp after which minting may occur
*/
constructor(
address account,
address minter_,
uint256 mintingAllowedAfter_
) {
require(
mintingAllowedAfter_ >= block.timestamp + 1460 days,
'HFT::constructor: minting can only begin after 4 years'
);
require(
minter_ != address(0),
'HFT::constructor: minter_ cannot be zero address'
);
require(
account != address(0),
'HFT::constructor: account cannot be zero address'
);
balances[account] = uint96(totalSupply);
emit Transfer(address(0), account, totalSupply);
minter = minter_;
emit MinterChanged(address(0), minter);
mintingAllowedAfter = mintingAllowedAfter_;
}
/**
* @notice Change the minter address
* @param minter_ The address of the new minter
*/
function setMinter(address minter_) external {
require(
minter_ != address(0),
'HFT::setMinter: minter_ cannot be zero address'
);
require(
msg.sender == minter,
'HFT::setMinter: only the minter can change the minter address'
);
minter = minter_;
emit MinterChanged(minter, minter_);
}
function setMintCap(uint256 mintCap_) external {
require(
msg.sender == minter,
'HFT::setMintCap: only the minter can change the mint cap'
);
require(
mintCap_ <= 100,
'HFT::setMintCap: mint cap should be between 0 and 100'
);
mintCap = uint8(mintCap_);
emit MintCapChanged(uint256(mintCap));
}
/**
* @notice Mint new tokens
* @param dst The address of the destination account
*/
function mint(address dst) external {
require(msg.sender == minter, 'HFT::mint: only the minter can mint');
require(
block.timestamp >= mintingAllowedAfter,
'HFT::mint: minting not allowed yet or exceeds mint cap'
);
require(
dst != address(0),
'HFT::mint: cannot transfer to the zero address'
);
// record the mint
mintingAllowedAfter = SafeMath.add(
block.timestamp,
minimumTimeBetweenMints
);
uint96 amount = safe96(
SafeMath.div(SafeMath.mul(totalSupply, uint256(mintCap)), 100),
'HFT::mint: amount exceeds 96 bits'
);
totalSupply = safe96(
SafeMath.add(totalSupply, amount),
'HFT::mint: totalSupply exceeds 96 bits'
);
// transfer the amount to the recipient
balances[dst] = add96(
balances[dst],
amount,
'HFT::mint: transfer amount overflows'
);
emit Transfer(address(0), dst, amount);
// move delegates
_moveDelegates(address(0), delegates[dst], amount);
}
/**
* @notice Get the number of tokens `spender` is approved to spend on behalf of `account`
* @param account The address of the account holding the funds
* @param spender The address of the account spending the funds
* @return The number of tokens approved
*/
function allowance(address account, address spender)
external
view
returns (uint256)
{
return allowances[account][spender];
}
/**
* @notice Approve `spender` to transfer up to `amount` from `src`
* @dev This will overwrite the approval amount for `spender`
* and is subject to issues noted [here](https://eips.ethereum.org/EIPS/eip-20#approve)
* @param spender The address of the account which may transfer tokens
* @param rawAmount The number of tokens that are approved (2^256-1 means infinite)
* @return Whether or not the approval succeeded
*/
function approve(address spender, uint256 rawAmount)
external
returns (bool)
{
_approve(msg.sender, spender, rawAmount);
return true;
}
/**
* @notice Atomically increases the allowance granted to `spender` by the caller.
* @dev This is an alternative to {approve} that can be used as a mitigation for
* problems described in {IERC20-approve}.
* @param spender The address of the account which may transfer tokens
* @param rawAmount The number of tokens that are approved (2^256-1 means infinite)
* @return Whether or not the approval succeeded
*/
function increaseAllowance(address spender, uint256 rawAmount)
external
returns (bool)
{
_approve(
msg.sender,
spender,
allowances[msg.sender][spender] + rawAmount
);
return true;
}
/**
* @notice Atomically increases the allowance granted to `spender` by the caller.
* @dev This is an alternative to {approve} that can be used as a mitigation for
* problems described in {IERC20-approve}.
* @param spender The address of the account which may transfer tokens
* @param rawAmount The number of tokens that are approved (2^256-1 means infinite)
* @return Whether or not the approval succeeded
*/
function decreaseAllowance(address spender, uint256 rawAmount)
external
returns (bool)
{
_approve(
msg.sender,
spender,
allowances[msg.sender][spender] - rawAmount
);
return true;
}
/**
* @notice Triggers an approval from owner to spends
* @param owner The address to approve from
* @param spender The address to be approved
* @param rawAmount The number of tokens that are approved (2^256-1 means infinite)
* @param deadline The time at which to expire the signature
* @param v The recovery byte of the signature
* @param r Half of the ECDSA signature pair
* @param s Half of the ECDSA signature pair
*/
function permit(
address owner,
address spender,
uint256 rawAmount,
uint256 deadline,
uint8 v,
bytes32 r,
bytes32 s
) external {
uint96 amount;
if (rawAmount == type(uint256).max) {
amount = type(uint96).max;
} else {
amount = safe96(rawAmount, 'HFT::permit: amount exceeds 96 bits');
}
bytes32 domainSeparator = keccak256(
abi.encode(
DOMAIN_TYPEHASH,
keccak256(bytes(name)),
getChainId(),
address(this)
)
);
bytes32 structHash = keccak256(
abi.encode(
PERMIT_TYPEHASH,
owner,
spender,
rawAmount,
nonces[owner]++,
deadline
)
);
bytes32 digest = keccak256(
abi.encodePacked('\x19\x01', domainSeparator, structHash)
);
address signatory = ecrecover(digest, v, r, s);
require(signatory != address(0), 'HFT::permit: invalid signature');
require(signatory == owner, 'HFT::permit: unauthorized');
require(block.timestamp <= deadline, 'HFT::permit: signature expired');
allowances[owner][spender] = amount;
emit Approval(owner, spender, amount);
}
/**
* @notice Get the number of tokens held by the `account`
* @param account The address of the account to get the balance of
* @return The number of tokens held
*/
function balanceOf(address account) external view returns (uint256) {
return balances[account];
}
/**
* @notice Transfer `amount` tokens from `msg.sender` to `dst`
* @param dst The address of the destination account
* @param rawAmount The number of tokens to transfer
* @return Whether or not the transfer succeeded
*/
function transfer(address dst, uint256 rawAmount) external returns (bool) {
uint96 amount = safe96(
rawAmount,
'HFT::transfer: amount exceeds 96 bits'
);
_transferTokens(msg.sender, dst, amount);
return true;
}
/**
* @notice Transfer `amount` tokens from `src` to `dst`
* @param src The address of the source account
* @param dst The address of the destination account
* @param rawAmount The number of tokens to transfer
* @return Whether or not the transfer succeeded
*/
function transferFrom(
address src,
address dst,
uint256 rawAmount
) external returns (bool) {
address spender = msg.sender;
uint96 spenderAllowance = allowances[src][spender];
uint96 amount = safe96(
rawAmount,
'HFT::approve: amount exceeds 96 bits'
);
if (spender != src && spenderAllowance != type(uint96).max) {
uint96 newAllowance = sub96(
spenderAllowance,
amount,
'HFT::transferFrom: transfer amount exceeds spender allowance'
);
allowances[src][spender] = newAllowance;
emit Approval(src, spender, newAllowance);
}
_transferTokens(src, dst, amount);
return true;
}
/**
* @notice Delegate votes from `msg.sender` to `delegatee`
* @param delegatee The address to delegate votes to
*/
function delegate(address delegatee) public {
return _delegate(msg.sender, delegatee);
}
/**
* @notice Delegates votes from signatory to `delegatee`
* @param delegatee The address to delegate votes to
* @param nonce The contract state required to match the signature
* @param expiry The time at which to expire the signature
* @param v The recovery byte of the signature
* @param r Half of the ECDSA signature pair
* @param s Half of the ECDSA signature pair
*/
function delegateBySig(
address delegatee,
uint256 nonce,
uint256 expiry,
uint8 v,
bytes32 r,
bytes32 s
) public {
bytes32 domainSeparator = keccak256(
abi.encode(
DOMAIN_TYPEHASH,
keccak256(bytes(name)),
getChainId(),
address(this)
)
);
bytes32 structHash = keccak256(
abi.encode(DELEGATION_TYPEHASH, delegatee, nonce, expiry)
);
bytes32 digest = keccak256(
abi.encodePacked('\x19\x01', domainSeparator, structHash)
);
address signatory = ecrecover(digest, v, r, s);
require(
signatory != address(0),
'HFT::delegateBySig: invalid signature'
);
require(
nonce == nonces[signatory]++,
'HFT::delegateBySig: invalid nonce'
);
require(
block.timestamp <= expiry,
'HFT::delegateBySig: signature expired'
);
return _delegate(signatory, delegatee);
}
/**
* @notice Gets the current votes balance for `account`
* @param account The address to get votes balance
* @return The number of current votes for `account`
*/
function getCurrentVotes(address account) external view returns (uint96) {
uint32 nCheckpoints = numCheckpoints[account];
return
nCheckpoints > 0 ? checkpoints[account][nCheckpoints - 1].votes : 0;
}
/**
* @notice Determine the prior number of votes for an account as of a block number
* @dev Block number must be a finalized block or else this function will revert to prevent misinformation.
* @param account The address of the account to check
* @param blockNumber The block number to get the vote balance at
* @return The number of votes the account had as of the given block
*/
function getPriorVotes(address account, uint256 blockNumber)
public
view
returns (uint96)
{
require(
blockNumber < block.number,
'HFT::getPriorVotes: not yet determined'
);
uint32 nCheckpoints = numCheckpoints[account];
if (nCheckpoints == 0) {
return 0;
}
// First check most recent balance
if (checkpoints[account][nCheckpoints - 1].fromBlock <= blockNumber) {
return checkpoints[account][nCheckpoints - 1].votes;
}
// Next check implicit zero balance
if (checkpoints[account][0].fromBlock > blockNumber) {
return 0;
}
uint32 lower = 0;
uint32 upper = nCheckpoints - 1;
while (upper > lower) {
uint32 center = upper - (upper - lower) / 2; // ceil, avoiding overflow
Checkpoint memory cp = checkpoints[account][center];
if (cp.fromBlock == blockNumber) {
return cp.votes;
} else if (cp.fromBlock < blockNumber) {
lower = center;
} else {
upper = center - 1;
}
}
return checkpoints[account][lower].votes;
}
function _delegate(address delegator, address delegatee) internal {
address currentDelegate = delegates[delegator];
uint96 delegatorBalance = balances[delegator];
delegates[delegator] = delegatee;
emit DelegateChanged(delegator, currentDelegate, delegatee);
_moveDelegates(currentDelegate, delegatee, delegatorBalance);
}
function _approve(
address caller,
address spender,
uint256 rawAmount
) internal {
uint96 amount;
if (rawAmount == type(uint256).max) {
amount = type(uint96).max;
} else {
amount = safe96(rawAmount, 'HFT::approve: amount exceeds 96 bits');
}
allowances[caller][spender] = amount;
emit Approval(caller, spender, amount);
}
function _transferTokens(
address src,
address dst,
uint96 amount
) internal {
require(
src != address(0),
'HFT::_transferTokens: cannot transfer from the zero address'
);
require(
dst != address(0),
'HFT::_transferTokens: cannot transfer to the zero address'
);
balances[src] = sub96(
balances[src],
amount,
'HFT::_transferTokens: transfer amount exceeds balance'
);
balances[dst] = add96(
balances[dst],
amount,
'HFT::_transferTokens: transfer amount overflows'
);
emit Transfer(src, dst, amount);
_moveDelegates(delegates[src], delegates[dst], amount);
}
function _moveDelegates(
address srcRep,
address dstRep,
uint96 amount
) internal {
if (srcRep != dstRep && amount > 0) {
if (srcRep != address(0)) {
uint32 srcRepNum = numCheckpoints[srcRep];
uint96 srcRepOld = srcRepNum > 0
? checkpoints[srcRep][srcRepNum - 1].votes
: 0;
uint96 srcRepNew = sub96(
srcRepOld,
amount,
'HFT::_moveDelegates: vote amount underflows'
);
_writeCheckpoint(srcRep, srcRepNum, srcRepOld, srcRepNew);
}
if (dstRep != address(0)) {
uint32 dstRepNum = numCheckpoints[dstRep];
uint96 dstRepOld = dstRepNum > 0
? checkpoints[dstRep][dstRepNum - 1].votes
: 0;
uint96 dstRepNew = add96(
dstRepOld,
amount,
'HFT::_moveDelegates: vote amount overflows'
);
_writeCheckpoint(dstRep, dstRepNum, dstRepOld, dstRepNew);
}
}
}
function _writeCheckpoint(
address delegatee,
uint32 nCheckpoints,
uint96 oldVotes,
uint96 newVotes
) internal {
uint32 blockNumber = safe32(
block.number,
'HFT::_writeCheckpoint: block number exceeds 32 bits'
);
if (
nCheckpoints > 0 &&
checkpoints[delegatee][nCheckpoints - 1].fromBlock == blockNumber
) {
checkpoints[delegatee][nCheckpoints - 1].votes = newVotes;
} else {
checkpoints[delegatee][nCheckpoints] = Checkpoint(
blockNumber,
newVotes
);
numCheckpoints[delegatee] = nCheckpoints + 1;
}
emit DelegateVotesChanged(delegatee, oldVotes, newVotes);
}
function safe32(uint256 n, string memory errorMessage)
internal
pure
returns (uint32)
{
require(n < 2**32, errorMessage);
return uint32(n);
}
function safe96(uint256 n, string memory errorMessage)
internal
pure
returns (uint96)
{
require(n < 2**96, errorMessage);
return uint96(n);
}
function add96(
uint96 a,
uint96 b,
string memory errorMessage
) internal pure returns (uint96) {
uint96 c = a + b;
require(c >= a, errorMessage);
return c;
}
function sub96(
uint96 a,
uint96 b,
string memory errorMessage
) internal pure returns (uint96) {
require(b <= a, errorMessage);
return a - b;
}
function getChainId() internal view returns (uint256) {
uint256 chainId;
assembly {
chainId := chainid()
}
return chainId;
}
}