443 lines
17 KiB
Solidity
443 lines
17 KiB
Solidity
pragma solidity > 0.6.11;
|
|
|
|
// SPDX-License-Identifier: GPL-3.0-or-later
|
|
|
|
// TODO: assign bitmask values to contants
|
|
contract RedistributedDemurrageToken {
|
|
|
|
address public owner;
|
|
string public name;
|
|
string public symbol;
|
|
uint256 public decimals;
|
|
uint256 public totalSupply;
|
|
uint256 public minimumParticipantSpend;
|
|
uint256 constant ppmDivider = 100000000000000000000000000000000;
|
|
|
|
uint256 public immutable periodStart; // timestamp
|
|
uint256 public immutable periodDuration; // duration in SECONDS
|
|
uint256 public immutable taxLevel; // PPM per MINUTE
|
|
uint256 public demurrageModifier; // PPM uint128(block) | uint128(ppm)
|
|
|
|
bytes32[] public redistributions; // uint1(isFractional) | uint1(unused) | uint38(participants) | uint160(value) | uint56(period)
|
|
mapping (address => bytes32) account; // uint20(unused) | uint56(period) | uint160(value)
|
|
mapping (address => bool) minter;
|
|
mapping (address => mapping (address => uint256 ) ) allowance; // holder -> spender -> amount (amount is subject to demurrage)
|
|
|
|
address sinkAddress; // receives redistribuion remainders
|
|
|
|
event Transfer(address indexed _from, address indexed _to, uint256 _value);
|
|
event Approval(address indexed _owner, address indexed _spender, uint256 _value);
|
|
event Mint(address indexed _minter, address indexed _beneficiary, uint256 _value);
|
|
//event Debug(uint256 _foo);
|
|
event Decayed(uint256 indexed _period, uint256 indexed _periodCount, uint256 indexed _oldAmount, uint256 _newAmount);
|
|
event Redistribution(address indexed _account, uint256 indexed _period, uint256 _value);
|
|
|
|
constructor(string memory _name, string memory _symbol, uint8 _decimals, uint256 _taxLevelMinute, uint256 _periodMinutes, address _defaultSinkAddress) public {
|
|
owner = msg.sender;
|
|
minter[owner] = true;
|
|
periodStart = block.timestamp;
|
|
periodDuration = _periodMinutes * 60;
|
|
name = _name;
|
|
symbol = _symbol;
|
|
decimals = _decimals;
|
|
demurrageModifier = ppmDivider * 1000000; // Emulates 38 decimal places
|
|
demurrageModifier |= (1 << 128);
|
|
taxLevel = _taxLevelMinute; // 38 decimal places
|
|
sinkAddress = _defaultSinkAddress;
|
|
bytes32 initialRedistribution = toRedistribution(0, 0, 1);
|
|
redistributions.push(initialRedistribution);
|
|
minimumParticipantSpend = 10 ** uint256(_decimals);
|
|
}
|
|
|
|
// Given address will be allowed to call the mintTo() function
|
|
function addMinter(address _minter) public returns (bool) {
|
|
require(msg.sender == owner);
|
|
minter[_minter] = true;
|
|
return true;
|
|
}
|
|
|
|
/// ERC20
|
|
function balanceOf(address _account) public view returns (uint256) {
|
|
uint256 baseBalance;
|
|
uint256 anchorDemurrageAmount;
|
|
uint256 anchorDemurragePeriod;
|
|
uint256 currentDemurrageAmount;
|
|
uint256 periodCount;
|
|
|
|
baseBalance = getBaseBalance(_account);
|
|
anchorDemurrageAmount = toDemurrageAmount(demurrageModifier);
|
|
anchorDemurragePeriod = toDemurragePeriod(demurrageModifier);
|
|
|
|
periodCount = actualPeriod() - toDemurragePeriod(demurrageModifier);
|
|
|
|
currentDemurrageAmount = toTaxPeriodAmount(anchorDemurrageAmount, periodCount);
|
|
|
|
return (baseBalance * currentDemurrageAmount) / (ppmDivider * 1000000);
|
|
}
|
|
|
|
/// Balance unmodified by demurrage
|
|
function getBaseBalance(address _account) private view returns (uint256) {
|
|
return uint256(account[_account]) & 0x00ffffffffffffffffffffffffffffffffffffffff;
|
|
}
|
|
|
|
/// Increases base balance for a single account
|
|
function increaseBaseBalance(address _account, uint256 _delta) private returns (bool) {
|
|
uint256 oldBalance;
|
|
uint256 newBalance;
|
|
|
|
if (_delta == 0) {
|
|
return false;
|
|
}
|
|
|
|
oldBalance = getBaseBalance(_account);
|
|
newBalance = oldBalance + _delta;
|
|
require(uint160(newBalance) > uint160(oldBalance), 'ERR_WOULDWRAP'); // revert if increase would result in a wrapped value
|
|
account[_account] &= bytes32(0xffffffffffffffffffffffff0000000000000000000000000000000000000000);
|
|
account[_account] |= bytes32(newBalance & 0x00ffffffffffffffffffffffffffffffffffffffff);
|
|
return true;
|
|
}
|
|
|
|
/// Decreases base balance for a single account
|
|
function decreaseBaseBalance(address _account, uint256 _delta) private returns (bool) {
|
|
uint256 oldBalance;
|
|
uint256 newBalance;
|
|
|
|
if (_delta == 0) {
|
|
return false;
|
|
}
|
|
|
|
oldBalance = getBaseBalance(_account);
|
|
require(oldBalance >= _delta, 'ERR_OVERSPEND'); // overspend guard
|
|
newBalance = oldBalance - _delta;
|
|
account[_account] &= bytes32(0xffffffffffffffffffffffff0000000000000000000000000000000000000000);
|
|
account[_account] |= bytes32(newBalance & 0x00ffffffffffffffffffffffffffffffffffffffff);
|
|
return true;
|
|
}
|
|
|
|
// Creates new tokens out of thin air, and allocates them to the given address
|
|
// Triggers tax
|
|
function mintTo(address _beneficiary, uint256 _amount) external returns (bool) {
|
|
require(minter[msg.sender]);
|
|
|
|
applyDemurrage();
|
|
changePeriod();
|
|
totalSupply += _amount;
|
|
increaseBaseBalance(_beneficiary, _amount);
|
|
emit Mint(msg.sender, _beneficiary, _amount);
|
|
saveRedistributionSupply();
|
|
return true;
|
|
}
|
|
|
|
// Deserializes the redistribution word
|
|
function toRedistribution(uint256 _participants, uint256 _value, uint256 _period) private pure returns(bytes32) {
|
|
bytes32 redistribution;
|
|
|
|
redistribution |= bytes32((_participants & 0x7fffffffff) << 216);
|
|
redistribution |= bytes32((_value & 0xffffffffffffffffffffffff) << 56);
|
|
redistribution |= bytes32(_period & 0xffffffffffffff);
|
|
return redistribution;
|
|
}
|
|
|
|
// Serializes the demurrage period part of the redistribution word
|
|
function toRedistributionPeriod(bytes32 redistribution) public pure returns (uint256) {
|
|
return uint256(redistribution & 0x00000000000000000000000000000000000000000000000000ffffffffffffff);
|
|
}
|
|
|
|
// Serializes the supply part of the redistribution word
|
|
function toRedistributionSupply(bytes32 redistribution) public pure returns (uint256) {
|
|
return uint256(redistribution & 0x0000000000ffffffffffffffffffffffffffffffffffffffff00000000000000) >> 56;
|
|
}
|
|
|
|
// Serializes the number of participants part of the redistribution word
|
|
function toRedistributionParticipants(bytes32 redistribution) public pure returns (uint256) {
|
|
return uint256(redistribution & 0x7fffffffff000000000000000000000000000000000000000000000000000000) >> 216;
|
|
}
|
|
|
|
// Client accessor to the redistributions array length
|
|
function redistributionCount() public view returns (uint256) {
|
|
return redistributions.length;
|
|
}
|
|
|
|
// Add number of participants for the current redistribution period by one
|
|
function incrementRedistributionParticipants() private returns (bool) {
|
|
uint256 currentRedistribution;
|
|
uint256 participants;
|
|
|
|
currentRedistribution = uint256(redistributions[redistributions.length-1]);
|
|
participants = ((currentRedistribution & 0x7fffffffff000000000000000000000000000000000000000000000000000000) >> 216) + 1;
|
|
currentRedistribution &= 0x8000000000ffffffffffffffffffffffffffffffffffffffffffffffffffffff;
|
|
currentRedistribution |= participants << 216;
|
|
|
|
//emit Debug(participants);
|
|
redistributions[redistributions.length-1] = bytes32(currentRedistribution);
|
|
}
|
|
|
|
// Save the current total supply amount to the current redistribution period
|
|
function saveRedistributionSupply() private returns (bool) {
|
|
uint256 currentRedistribution;
|
|
|
|
currentRedistribution = uint256(redistributions[redistributions.length-1]);
|
|
currentRedistribution &= 0xffffffffff0000000000000000000000000000000000000000ffffffffffffff;
|
|
currentRedistribution |= totalSupply << 56;
|
|
|
|
redistributions[redistributions.length-1] = bytes32(currentRedistribution);
|
|
}
|
|
|
|
// Get the demurrage period of the current block number
|
|
function actualPeriod() public view returns (uint256) {
|
|
return (block.timestamp - periodStart) / periodDuration + 1;
|
|
}
|
|
|
|
// Add an entered demurrage period to the redistribution array
|
|
function checkPeriod() private view returns (bytes32) {
|
|
bytes32 lastRedistribution;
|
|
uint256 currentPeriod;
|
|
|
|
lastRedistribution = redistributions[redistributions.length-1];
|
|
currentPeriod = this.actualPeriod();
|
|
if (currentPeriod <= toRedistributionPeriod(lastRedistribution)) {
|
|
return bytes32(0x00);
|
|
}
|
|
return lastRedistribution;
|
|
}
|
|
|
|
// Deserialize the pemurrage period for the given account is participating in
|
|
function accountPeriod(address _account) public view returns (uint256) {
|
|
return (uint256(account[_account]) & 0xffffffffffffffffffffffff0000000000000000000000000000000000000000) >> 160;
|
|
}
|
|
|
|
// Save the given demurrage period as the currently participation period for the given address
|
|
function registerAccountPeriod(address _account, uint256 _period) private returns (bool) {
|
|
account[_account] &= 0x000000000000000000000000ffffffffffffffffffffffffffffffffffffffff;
|
|
account[_account] |= bytes32(_period << 160);
|
|
incrementRedistributionParticipants();
|
|
}
|
|
|
|
// Determine whether the unit number is rounded down, rounded up or evenly divides.
|
|
// Returns 0 if evenly distributed, or the remainder as a positive number
|
|
// A _numParts value 0 will be interpreted as the value 1
|
|
function remainder(uint256 _numParts, uint256 _sumWhole) public pure returns (uint256) {
|
|
uint256 unit;
|
|
uint256 truncatedResult;
|
|
|
|
if (_numParts == 0) { // no division by zero please
|
|
revert('ERR_NUMPARTS_ZERO');
|
|
}
|
|
require(_numParts < _sumWhole); // At least you are never LESS than the sum of your parts. Think about that.
|
|
|
|
unit = _sumWhole / _numParts;
|
|
truncatedResult = unit * _numParts;
|
|
return _sumWhole - truncatedResult;
|
|
}
|
|
|
|
// Called in the edge case where participant number is 0. It will override the participant count to 1.
|
|
// Returns the remainder sent to the sink address
|
|
function applyDefaultRedistribution(bytes32 _redistribution) private returns (uint256) {
|
|
uint256 redistributionSupply;
|
|
uint256 redistributionPeriod;
|
|
uint256 unit;
|
|
uint256 truncatedResult;
|
|
|
|
redistributionSupply = toRedistributionSupply(_redistribution);
|
|
|
|
unit = (redistributionSupply * taxLevel) / 1000000;
|
|
truncatedResult = (unit * 1000000) / taxLevel;
|
|
|
|
if (truncatedResult < redistributionSupply) {
|
|
redistributionPeriod = toRedistributionPeriod(_redistribution); // since we reuse period here, can possibly be optimized by passing period instead
|
|
redistributions[redistributionPeriod-1] &= 0x0000000000ffffffffffffffffffffffffffffffffffffffffffffffffffffff; // just to be safe, zero out all participant count data, in this case there will be only one
|
|
redistributions[redistributionPeriod-1] |= 0x8000000001000000000000000000000000000000000000000000000000000000;
|
|
}
|
|
|
|
increaseBaseBalance(sinkAddress, unit / ppmDivider); //truncatedResult);
|
|
return unit;
|
|
}
|
|
|
|
// sets the remainder bit for the given period and books the remainder to the sink address balance
|
|
// returns false if no change was made
|
|
function applyRemainderOnPeriod(uint256 _remainder, uint256 _period) private returns (bool) {
|
|
uint256 periodSupply;
|
|
|
|
if (_remainder == 0) {
|
|
return false;
|
|
}
|
|
|
|
redistributions[_period-1] |= 0x8000000000000000000000000000000000000000000000000000000000000000;
|
|
|
|
periodSupply = toRedistributionSupply(redistributions[_period-1]);
|
|
increaseBaseBalance(sinkAddress, periodSupply - _remainder);
|
|
return true;
|
|
}
|
|
|
|
|
|
function toDemurrageAmount(uint256 _demurrage) public pure returns (uint256) {
|
|
return _demurrage & 0x00000000000000000000000000000000ffffffffffffffffffffffffffffffff;
|
|
}
|
|
|
|
function toDemurragePeriod(uint256 _demurrage) public pure returns (uint256) {
|
|
return (_demurrage & 0xffffffffffffffffffffffffffffffff00000000000000000000000000000000) >> 128;
|
|
}
|
|
|
|
function applyDemurrage() public returns (bool) {
|
|
uint256 epochPeriodCount;
|
|
uint256 periodCount;
|
|
uint256 lastDemurrageAmount;
|
|
uint256 newDemurrageAmount;
|
|
|
|
epochPeriodCount = actualPeriod();
|
|
//epochPeriodCount = (block.timestamp - periodStart) / periodDuration; // toDemurrageTime(demurrageModifier);
|
|
periodCount = epochPeriodCount - toDemurragePeriod(demurrageModifier);
|
|
if (periodCount == 0) {
|
|
return false;
|
|
}
|
|
lastDemurrageAmount = toDemurrageAmount(demurrageModifier);
|
|
newDemurrageAmount = toTaxPeriodAmount(lastDemurrageAmount, periodCount);
|
|
demurrageModifier = 0;
|
|
demurrageModifier |= (newDemurrageAmount & 0x00000000000000000000000000000000ffffffffffffffffffffffffffffffff);
|
|
demurrageModifier |= (epochPeriodCount << 128);
|
|
emit Decayed(epochPeriodCount, periodCount, lastDemurrageAmount, newDemurrageAmount);
|
|
return true;
|
|
}
|
|
|
|
// Recalculate the demurrage modifier for the new period
|
|
// After this, all REPORTED balances will have been reduced by the corresponding ratio (but the effecive totalsupply stays the same)
|
|
//function applyTax() public returns (uint256) {
|
|
function changePeriod() public returns (uint256) {
|
|
bytes32 currentRedistribution;
|
|
bytes32 nextRedistribution;
|
|
uint256 currentPeriod;
|
|
uint256 currentParticipants;
|
|
uint256 currentRemainder;
|
|
|
|
currentRedistribution = checkPeriod();
|
|
if (currentRedistribution == bytes32(0x00)) {
|
|
return demurrageModifier;
|
|
}
|
|
//demurrageModifier -= (demurrageModifier * taxLevel) / 1000000;
|
|
currentPeriod = toRedistributionPeriod(currentRedistribution);
|
|
nextRedistribution = toRedistribution(0, totalSupply, currentPeriod + 1);
|
|
redistributions.push(nextRedistribution);
|
|
|
|
currentParticipants = toRedistributionParticipants(currentRedistribution);
|
|
if (currentParticipants == 0) {
|
|
currentRemainder = applyDefaultRedistribution(currentRedistribution);
|
|
} else {
|
|
currentRemainder = remainder(currentParticipants, totalSupply); // we can use totalSupply directly because it will always be the same as the recorded supply on the current redistribution
|
|
applyRemainderOnPeriod(currentRemainder, currentPeriod);
|
|
}
|
|
return demurrageModifier;
|
|
}
|
|
|
|
// Calculate a value reduced by demurrage by the given period
|
|
function toTaxPeriodAmount(uint256 _value, uint256 _period) public view returns (uint256) {
|
|
uint256 valueFactor;
|
|
uint256 truncatedTaxLevel;
|
|
|
|
// TODO: if can't get to work, reverse the iteration from current period.
|
|
valueFactor = 1000000;
|
|
truncatedTaxLevel = taxLevel / ppmDivider;
|
|
|
|
for (uint256 i = 0; i < _period; i++) {
|
|
valueFactor = valueFactor - ((valueFactor * truncatedTaxLevel) / 1000000);
|
|
}
|
|
return (valueFactor * _value) / 1000000;
|
|
}
|
|
|
|
// If the given account is participating in a period and that period has been crossed
|
|
// THEN increase the base value of the account with its share of the value reduction of the period
|
|
function applyRedistributionOnAccount(address _account) public returns (bool) {
|
|
bytes32 periodRedistribution;
|
|
uint256 supply;
|
|
uint256 participants;
|
|
uint256 baseValue;
|
|
uint256 value;
|
|
uint256 period;
|
|
|
|
period = accountPeriod(_account);
|
|
if (period == 0 || period >= actualPeriod()) {
|
|
return false;
|
|
}
|
|
periodRedistribution = redistributions[period-1];
|
|
participants = toRedistributionParticipants(periodRedistribution);
|
|
if (participants == 0) {
|
|
return false;
|
|
}
|
|
|
|
supply = toRedistributionSupply(periodRedistribution);
|
|
baseValue = ((supply / participants) * (taxLevel / 1000000)) / ppmDivider;
|
|
value = toTaxPeriodAmount(baseValue, period - 1);
|
|
|
|
account[_account] &= bytes32(0x000000000000000000000000ffffffffffffffffffffffffffffffffffffffff);
|
|
increaseBaseBalance(_account, value);
|
|
|
|
emit Redistribution(_account, period, value);
|
|
return true;
|
|
}
|
|
|
|
// Inflates the given amount according to the current demurrage modifier
|
|
function toBaseAmount(uint256 _value) public view returns (uint256) {
|
|
return (_value * ppmDivider * 1000000) / toDemurrageAmount(demurrageModifier);
|
|
}
|
|
|
|
// ERC20, triggers tax and/or redistribution
|
|
function approve(address _spender, uint256 _value) public returns (bool) {
|
|
uint256 baseValue;
|
|
|
|
applyDemurrage();
|
|
changePeriod();
|
|
applyRedistributionOnAccount(msg.sender);
|
|
|
|
baseValue = toBaseAmount(_value);
|
|
allowance[msg.sender][_spender] += baseValue;
|
|
emit Approval(msg.sender, _spender, _value);
|
|
return true;
|
|
}
|
|
|
|
// ERC20, triggers tax and/or redistribution
|
|
function transfer(address _to, uint256 _value) public returns (bool) {
|
|
uint256 baseValue;
|
|
bool result;
|
|
|
|
applyDemurrage();
|
|
changePeriod();
|
|
applyRedistributionOnAccount(msg.sender);
|
|
|
|
// TODO: Prefer to truncate the result, instead it seems to round to nearest :/
|
|
baseValue = toBaseAmount(_value);
|
|
result = transferBase(msg.sender, _to, baseValue);
|
|
|
|
return result;
|
|
}
|
|
|
|
|
|
// ERC20, triggers tax and/or redistribution
|
|
function transferFrom(address _from, address _to, uint256 _value) public returns (bool) {
|
|
uint256 baseValue;
|
|
bool result;
|
|
|
|
applyDemurrage();
|
|
changePeriod();
|
|
applyRedistributionOnAccount(msg.sender);
|
|
|
|
baseValue = toBaseAmount(_value);
|
|
require(allowance[_from][msg.sender] >= baseValue);
|
|
|
|
result = transferBase(_from, _to, baseValue);
|
|
return result;
|
|
}
|
|
|
|
// ERC20 transfer backend for transfer, transferFrom
|
|
function transferBase(address _from, address _to, uint256 _value) private returns (bool) {
|
|
uint256 period;
|
|
|
|
decreaseBaseBalance(_from, _value);
|
|
increaseBaseBalance(_to, _value);
|
|
|
|
period = actualPeriod();
|
|
if (_value >= minimumParticipantSpend && accountPeriod(_from) != period && _from != _to) {
|
|
registerAccountPeriod(_from, period);
|
|
}
|
|
return true;
|
|
}
|
|
}
|