mirror of
git://holbrook.no/erc20-demurrage-token
synced 2026-05-20 19:04:33 +02:00
Improve documentation, add mark constants, add removeMinter method
This commit is contained in:
nolash
@@ -11,6 +11,6 @@ test: all
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python ../python/tests/test_redistribution.py
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install: all
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cp -v RedistributedDemurrageToken.{json,bin} ../python/eth_address_declarator/data/
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cp -v RedistributedDemurrageToken.{json,bin} ../python/sarafu_token/data/
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.PHONY: test install
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@@ -2,51 +2,121 @@ pragma solidity > 0.6.11;
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// SPDX-License-Identifier: GPL-3.0-or-later
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// TODO: assign bitmask values to contants
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contract RedistributedDemurrageToken {
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// Redistribution bit field, with associated shifts and masks
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// (Uses sub-byte boundaries)
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bytes32[] public redistributions; // uint1(isFractional) | uint95(unused) | uint20(demurrageModifier) | uint36(participants) | uint72(value) | uint32(period)
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uint8 constant shiftRedistributionPeriod = 0;
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uint256 constant maskRedistributionPeriod = 0x00000000000000000000000000000000000000000000000000000000ffffffff; // (1 << 32) - 1
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uint8 constant shiftRedistributionValue = 32;
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uint256 constant maskRedistributionValue = 0x00000000000000000000000000000000000000ffffffffffffffffff00000000; // ((1 << 72) - 1) << 32
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uint8 constant shiftRedistributionParticipants = 104;
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uint256 constant maskRedistributionParticipants = 0x00000000000000000000000000000fffffffff00000000000000000000000000; // ((1 << 36) - 1) << 104
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uint8 constant shiftRedistributionDemurrage = 140;
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uint256 constant maskRedistributionDemurrage = 0x000000000000000000000000fffff00000000000000000000000000000000000; // ((1 << 20) - 1) << 140
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uint8 constant shiftRedistributionIsFractional = 255;
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uint256 constant maskRedistributionIsFractional = 0x8000000000000000000000000000000000000000000000000000000000000000; // 1 << 255
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// Account bit field, with associated shifts and masks
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// Mirrors structure of redistributions for consistency
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mapping (address => bytes32) account; // uint152(unused) | uint32(period) | uint72(value)
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uint8 constant shiftAccountValue = 0;
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uint256 constant maskAccountValue = 0x0000000000000000000000000000000000000000000000ffffffffffffffffff; // (1 << 72) - 1
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uint8 constant shiftAccountPeriod = 72;
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uint256 constant maskAccountPeriod = 0x00000000000000000000000000000000000000ffffffff000000000000000000; // ((1 << 32) - 1) << 72
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// TODO: use 2 x uint128 instead
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// Demurrage cache bit field, with associated shifts and masks
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uint256 public demurrageModifier; // PPM uint128(block) | uint128(periodppm)
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uint8 constant shiftDemurrageValue = 0;
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uint256 constant maskDemurrageValue = 0x00000000000000000000000000000000ffffffffffffffffffffffffffffffff;
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uint8 constant shiftDemurragePeriod = 128;
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uint256 constant maskDemurragePeriod = 0xffffffffffffffffffffffffffffffff00000000000000000000000000000000;
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// Implements EIP172
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address public owner;
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// Implements ERC20
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string public name;
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// Implements ERC20
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string public symbol;
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// Implements ERC20
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uint256 public decimals;
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// Implements ERC20
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uint256 public totalSupply;
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// Minimum amount of (demurraged) tokens an account must spend to participate in redistribution for a particular period
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uint256 public minimumParticipantSpend;
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// 128 bit resolution of the demurrage divisor
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// (this constant x 1000000 is contained within 128 bits)
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uint256 constant ppmDivider = 100000000000000000000000000000000;
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uint256 public immutable periodStart; // timestamp
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uint256 public immutable periodDuration; // duration in SECONDS
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uint256 public immutable taxLevel; // PPM per MINUTE
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uint256 public demurrageModifier; // PPM uint128(block) | uint128(ppm)
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// Timestamp of start of periods (time which contract constructor was called)
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uint256 public immutable periodStart;
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bytes32[] public redistributions; // uint1(isFractional) | uint95(unused) | uint20(demurrageModifier) | uint36(participants) | uint72(value) | uint32(period)
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mapping (address => bytes32) account; // uint152(unused) | uint32(period) | uint72(value)
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// Duration of a single redistribution period in seconds
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uint256 public immutable periodDuration;
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// Demurrage in ppm per minute
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uint256 public immutable taxLevel;
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// Addresses allowed to mint new tokens
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mapping (address => bool) minter;
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// Storage for ERC20 approve/transferFrom methods
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mapping (address => mapping (address => uint256 ) ) allowance; // holder -> spender -> amount (amount is subject to demurrage)
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address sinkAddress; // receives redistribuion remainders
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// Address to send unallocated redistribution tokens
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address sinkAddress;
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// Implements ERC20
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event Transfer(address indexed _from, address indexed _to, uint256 _value);
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// Implements ERC20
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event Approval(address indexed _owner, address indexed _spender, uint256 _value);
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// New tokens minted
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event Mint(address indexed _minter, address indexed _beneficiary, uint256 _value);
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event Debug(bytes32 _foo);
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// New demurrage cache milestone calculated
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event Decayed(uint256 indexed _period, uint256 indexed _periodCount, uint256 indexed _oldAmount, uint256 _newAmount);
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// When a new period threshold has been crossed
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event Period(uint256 _period);
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// Redistribution applied on a single eligible account
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event Redistribution(address indexed _account, uint256 indexed _period, uint256 _value);
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// Temporary event used in development, will be removed on prod
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event Debug(bytes32 _foo);
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constructor(string memory _name, string memory _symbol, uint8 _decimals, uint256 _taxLevelMinute, uint256 _periodMinutes, address _defaultSinkAddress) public {
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// ACL setup
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owner = msg.sender;
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minter[owner] = true;
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periodStart = block.timestamp;
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periodDuration = _periodMinutes * 60;
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// ERC20 setup
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name = _name;
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symbol = _symbol;
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decimals = _decimals;
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// Demurrage setup
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periodStart = block.timestamp;
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periodDuration = _periodMinutes * 60;
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demurrageModifier = ppmDivider * 1000000; // Represents 38 decimal places
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demurrageModifier |= (1 << 128);
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taxLevel = _taxLevelMinute; // Represents 38 decimal places
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sinkAddress = _defaultSinkAddress;
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bytes32 initialRedistribution = toRedistribution(0, 1000000, 0, 1);
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redistributions.push(initialRedistribution);
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// Misc settings
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sinkAddress = _defaultSinkAddress;
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minimumParticipantSpend = 10 ** uint256(_decimals);
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}
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@@ -57,7 +127,14 @@ contract RedistributedDemurrageToken {
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return true;
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}
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/// ERC20
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// Given address will no longer be allowed to call the mintTo() function
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function removeMinter(address _minter) public returns (bool) {
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require(msg.sender == owner || _minter == msg.sender);
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minter[_minter] = false;
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return true;
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}
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/// Implements ERC20
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function balanceOf(address _account) public view returns (uint256) {
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uint256 baseBalance;
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uint256 anchorDemurrageAmount;
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@@ -78,7 +155,7 @@ contract RedistributedDemurrageToken {
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/// Balance unmodified by demurrage
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function baseBalanceOf(address _account) public view returns (uint256) {
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return uint256(account[_account]) & 0xffffffffffffffffff;
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return uint256(account[_account]) & maskAccountValue;
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}
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/// Increases base balance for a single account
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@@ -96,8 +173,8 @@ contract RedistributedDemurrageToken {
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oldBalance = baseBalanceOf(_account);
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newBalance = oldBalance + _delta;
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require(uint160(newBalance) > uint160(oldBalance), 'ERR_WOULDWRAP'); // revert if increase would result in a wrapped value
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workAccount &= 0xfffffffffffffffffffffffffffffffffffffffffffff000000000000000000;
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workAccount |= newBalance & 0xffffffffffffffffff;
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workAccount &= (~maskAccountValue);
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workAccount |= (newBalance & maskAccountValue);
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account[_account] = bytes32(workAccount);
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return true;
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}
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@@ -117,8 +194,8 @@ contract RedistributedDemurrageToken {
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oldBalance = baseBalanceOf(_account);
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require(oldBalance >= _delta, 'ERR_OVERSPEND'); // overspend guard
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newBalance = oldBalance - _delta;
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workAccount &= 0xfffffffffffffffffffffffffffffffffffffffffffff000000000000000000;
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workAccount |= newBalance & 0xffffffffffffffffff;
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workAccount &= (~maskAccountValue);
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workAccount |= (newBalance & maskAccountValue);
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account[_account] = bytes32(workAccount);
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return true;
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}
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@@ -144,31 +221,31 @@ contract RedistributedDemurrageToken {
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function toRedistribution(uint256 _participants, uint256 _demurrageModifierPpm, uint256 _value, uint256 _period) private pure returns(bytes32) {
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bytes32 redistribution;
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redistribution |= bytes32((_demurrageModifierPpm & 0x0fffff) << 140);
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redistribution |= bytes32((_participants & 0x0fffffffff) << 104);
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redistribution |= bytes32((_value & 0xffffffffffffffffff) << 32);
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redistribution |= bytes32(_period & 0xffffffff);
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redistribution |= bytes32((_demurrageModifierPpm << shiftRedistributionDemurrage) & maskRedistributionDemurrage);
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redistribution |= bytes32((_participants << shiftRedistributionParticipants) & maskRedistributionParticipants);
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redistribution |= bytes32((_value << shiftRedistributionValue) & maskRedistributionValue);
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redistribution |= bytes32(_period & maskRedistributionPeriod);
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return redistribution;
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}
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// Serializes the demurrage period part of the redistribution word
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function toRedistributionPeriod(bytes32 redistribution) public pure returns (uint256) {
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return uint256(redistribution) & 0xffffffff;
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return uint256(redistribution) & maskRedistributionPeriod;
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}
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// Serializes the supply part of the redistribution word
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function toRedistributionSupply(bytes32 redistribution) public pure returns (uint256) {
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return uint256(redistribution & 0x00000000000000000000000000000000000000ffffffffffffffffff00000000) >> 32;
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return (uint256(redistribution) & maskRedistributionValue) >> shiftRedistributionValue;
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}
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// Serializes the number of participants part of the redistribution word
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function toRedistributionParticipants(bytes32 redistribution) public pure returns (uint256) {
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return uint256(redistribution & 0x00000000000000000000000000000fffffffff00000000000000000000000000) >> 104;
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return (uint256(redistribution) & maskRedistributionParticipants) >> shiftRedistributionParticipants;
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}
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// Serializes the number of participants part of the redistribution word
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function toRedistributionDemurrageModifier(bytes32 redistribution) public pure returns (uint256) {
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return uint256(redistribution & 0x000000000000000000000000fffff00000000000000000000000000000000000) >> 140;
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return (uint256(redistribution) & maskRedistributionDemurrage) >> shiftRedistributionDemurrage;
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}
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// Client accessor to the redistributions array length
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@@ -185,8 +262,8 @@ contract RedistributedDemurrageToken {
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currentRedistribution = redistributions[redistributions.length-1];
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participants = toRedistributionParticipants(currentRedistribution) + 1;
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tmpRedistribution = uint256(currentRedistribution);
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tmpRedistribution &= 0xfffffffffffffffffffffffffffff000000000ffffffffffffffffffffffffff;
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tmpRedistribution |= (participants & 0x0fffffffff) << 104;
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tmpRedistribution &= (~maskRedistributionParticipants);
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tmpRedistribution |= ((participants << shiftRedistributionParticipants) & maskRedistributionParticipants);
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redistributions[redistributions.length-1] = bytes32(tmpRedistribution);
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@@ -198,8 +275,8 @@ contract RedistributedDemurrageToken {
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uint256 currentRedistribution;
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currentRedistribution = uint256(redistributions[redistributions.length-1]);
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currentRedistribution &= 0xffffffffffffffffffffffffffffffffffffff000000000000000000ffffffff;
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currentRedistribution |= totalSupply << 32;
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currentRedistribution &= (~maskRedistributionValue);
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currentRedistribution |= (totalSupply << shiftRedistributionValue);
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redistributions[redistributions.length-1] = bytes32(currentRedistribution);
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return true;
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@@ -225,13 +302,13 @@ contract RedistributedDemurrageToken {
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// Deserialize the pemurrage period for the given account is participating in
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function accountPeriod(address _account) public view returns (uint256) {
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return (uint256(account[_account]) & 0x00000000000000000000000000000000000000ffffffff000000000000000000) >> 72;
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return (uint256(account[_account]) & maskAccountPeriod) >> shiftAccountPeriod;
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}
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// Save the given demurrage period as the currently participation period for the given address
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function registerAccountPeriod(address _account, uint256 _period) private returns (bool) {
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account[_account] &= 0xffffffffffffffffffffffffffffffffffffff00000000ffffffffffffffffff;
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account[_account] |= bytes32(_period << 72);
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account[_account] &= bytes32(~maskAccountPeriod);
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account[_account] |= bytes32((_period << shiftAccountPeriod) & maskAccountPeriod);
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incrementRedistributionParticipants();
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return true;
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}
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@@ -268,11 +345,11 @@ contract RedistributedDemurrageToken {
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if (truncatedResult < redistributionSupply) {
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redistributionPeriod = toRedistributionPeriod(_redistribution); // since we reuse period here, can possibly be optimized by passing period instead
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redistributions[redistributionPeriod-1] &= 0xfffffffffffffffffffffffffffff000000000ffffffffffffffffffffffffff; // just to be safe, zero out all participant count data, in this case there will be only one
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redistributions[redistributionPeriod-1] |= 0x8000000000000000000000000000000000000100000000000000000000000000;
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redistributions[redistributionPeriod-1] &= bytes32(~maskRedistributionParticipants); // just to be safe, zero out all participant count data, in this case there will be only one
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redistributions[redistributionPeriod-1] |= bytes32(maskRedistributionIsFractional | (1 << shiftRedistributionParticipants));
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}
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increaseBaseBalance(sinkAddress, unit / ppmDivider); //truncatedResult);
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increaseBaseBalance(sinkAddress, unit / ppmDivider);
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return unit;
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}
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@@ -285,8 +362,8 @@ contract RedistributedDemurrageToken {
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return false;
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}
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// is this needed?
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redistributions[_period-1] |= 0x8000000000000000000000000000000000000000000000000000000000000000;
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// TODO: is this needed?
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redistributions[_period-1] |= bytes32(maskRedistributionIsFractional);
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periodSupply = toRedistributionSupply(redistributions[_period-1]);
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increaseBaseBalance(sinkAddress, periodSupply - _remainder);
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@@ -294,14 +371,17 @@ contract RedistributedDemurrageToken {
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}
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// Deserialize demurrage amount from demurrage bitfield
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function toDemurrageAmount(uint256 _demurrage) public pure returns (uint256) {
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return _demurrage & 0x00000000000000000000000000000000ffffffffffffffffffffffffffffffff;
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return _demurrage & maskDemurrageValue;
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}
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// Deserialize demurrage period from demurrage bitfield
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function toDemurragePeriod(uint256 _demurrage) public pure returns (uint256) {
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return (_demurrage & 0xffffffffffffffffffffffffffffffff00000000000000000000000000000000) >> 128;
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return (_demurrage & maskDemurragePeriod) >> shiftDemurragePeriod;
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}
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// Calculate and cache the demurrage value corresponding to the (period of the) time of the method call
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function applyDemurrage() public returns (bool) {
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uint256 epochPeriodCount;
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uint256 periodCount;
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@@ -316,8 +396,8 @@ contract RedistributedDemurrageToken {
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lastDemurrageAmount = toDemurrageAmount(demurrageModifier);
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newDemurrageAmount = decayBy(lastDemurrageAmount, periodCount);
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demurrageModifier = 0;
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demurrageModifier |= (newDemurrageAmount & 0x00000000000000000000000000000000ffffffffffffffffffffffffffffffff);
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demurrageModifier |= (epochPeriodCount << 128);
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demurrageModifier |= (newDemurrageAmount & maskDemurrageValue);
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demurrageModifier |= ((epochPeriodCount << shiftDemurragePeriod) & maskDemurragePeriod);
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emit Decayed(epochPeriodCount, periodCount, lastDemurrageAmount, newDemurrageAmount);
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return true;
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}
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@@ -334,7 +414,6 @@ contract RedistributedDemurrageToken {
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// Recalculate the demurrage modifier for the new period
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// After this, all REPORTED balances will have been reduced by the corresponding ratio (but the effecive totalsupply stays the same)
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//function applyTax() public returns (uint256) {
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function changePeriod() public returns (bool) {
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bytes32 currentRedistribution;
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bytes32 nextRedistribution;
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@@ -380,11 +459,11 @@ contract RedistributedDemurrageToken {
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return true;
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}
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// Reverse a value reduced by demurrage by the given period to its original value
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function growBy(uint256 _value, uint256 _period) public view returns (uint256) {
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uint256 valueFactor;
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uint256 truncatedTaxLevel;
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// TODO: if can't get to work, reverse the iteration from current period.
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valueFactor = 1000000;
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truncatedTaxLevel = taxLevel / ppmDivider;
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@@ -395,12 +474,11 @@ contract RedistributedDemurrageToken {
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}
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// Calculate a value reduced by demurrage by the given period
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// TODO: higher precision
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// TODO: higher precision if possible
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function decayBy(uint256 _value, uint256 _period) public view returns (uint256) {
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uint256 valueFactor;
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uint256 truncatedTaxLevel;
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// TODO: if can't get to work, reverse the iteration from current period.
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valueFactor = 1000000;
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truncatedTaxLevel = taxLevel / ppmDivider;
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@@ -436,7 +514,8 @@ contract RedistributedDemurrageToken {
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baseValue = ((supply / participants) * (taxLevel / 1000000)) / ppmDivider;
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value = (baseValue * demurrage) / 1000000;
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account[_account] &= bytes32(0xffffffffffffffffffffffffffffffffffffff00000000ffffffffffffffffff);
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// zero out period for the account
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account[_account] &= bytes32(~maskAccountPeriod);
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increaseBaseBalance(_account, value);
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emit Redistribution(_account, period, value);
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@@ -469,7 +548,6 @@ contract RedistributedDemurrageToken {
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changePeriod();
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applyRedistributionOnAccount(msg.sender);
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// TODO: Prefer to truncate the result, instead it seems to round to nearest :/
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baseValue = toBaseAmount(_value);
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result = transferBase(msg.sender, _to, baseValue);
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emit Transfer(msg.sender, _to, _value);
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