文件 1 的 1：MetaStonezNFT.sol
pragma solidity ^0.8.0;
abstract contract Context {
function _msgSender() internal view virtual returns (address) {
return msg.sender;
}
function _msgData() internal view virtual returns (bytes calldata) {
return msg.data;
}
}
abstract contract Ownable is Context {
address private _owner;
event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
constructor() {
_transferOwnership(_msgSender());
}
function owner() public view virtual returns (address) {
return _owner;
}
modifier onlyOwner() {
require(owner() == _msgSender(), "Ownable: caller is not the owner");
_;
}
function renounceOwnership() public virtual onlyOwner {
_transferOwnership(address(0));
}
function transferOwnership(address newOwner) public virtual onlyOwner {
require(newOwner != address(0), "Ownable: new owner is the zero address");
_transferOwnership(newOwner);
}
function _transferOwnership(address newOwner) internal virtual {
address oldOwner = _owner;
_owner = newOwner;
emit OwnershipTransferred(oldOwner, newOwner);
}
}
library Strings {
bytes16 private constant _HEX_SYMBOLS = "0123456789abcdef";
function toString(uint256 value) internal pure returns (string memory) {
if (value == 0) {
return "0";
}
uint256 temp = value;
uint256 digits;
while (temp != 0) {
digits++;
temp /= 10;
}
bytes memory buffer = new bytes(digits);
while (value != 0) {
digits -= 1;
buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
value /= 10;
}
return string(buffer);
}
function toHexString(uint256 value) internal pure returns (string memory) {
if (value == 0) {
return "0x00";
}
uint256 temp = value;
uint256 length = 0;
while (temp != 0) {
length++;
temp >>= 8;
}
return toHexString(value, length);
}
function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
bytes memory buffer = new bytes(2 * length + 2);
buffer[0] = "0";
buffer[1] = "x";
for (uint256 i = 2 * length + 1; i > 1; --i) {
buffer[i] = _HEX_SYMBOLS[value & 0xf];
value >>= 4;
}
require(value == 0, "Strings: hex length insufficient");
return string(buffer);
}
}
interface LinkTokenInterface {
function allowance(address owner, address spender) external view returns (uint256 remaining);
function approve(address spender, uint256 value) external returns (bool success);
function balanceOf(address owner) external view returns (uint256 balance);
function decimals() external view returns (uint8 decimalPlaces);
function decreaseApproval(address spender, uint256 addedValue) external returns (bool success);
function increaseApproval(address spender, uint256 subtractedValue) external;
function name() external view returns (string memory tokenName);
function symbol() external view returns (string memory tokenSymbol);
function totalSupply() external view returns (uint256 totalTokensIssued);
function transfer(address to, uint256 value) external returns (bool success);
function transferAndCall(
address to,
uint256 value,
bytes calldata data
) external returns (bool success);
function transferFrom(
address from,
address to,
uint256 value
) external returns (bool success);
}
contract VRFRequestIDBase {
function makeVRFInputSeed(
bytes32 _keyHash,
uint256 _userSeed,
address _requester,
uint256 _nonce
) internal pure returns (uint256) {
return uint256(keccak256(abi.encode(_keyHash, _userSeed, _requester, _nonce)));
}
function makeRequestId(bytes32 _keyHash, uint256 _vRFInputSeed) internal pure returns (bytes32) {
return keccak256(abi.encodePacked(_keyHash, _vRFInputSeed));
}
}
abstract contract VRFConsumerBase is VRFRequestIDBase {
function fulfillRandomness(bytes32 requestId, uint256 randomness) internal virtual;
uint256 private constant USER_SEED_PLACEHOLDER = 0;
function requestRandomness(bytes32 _keyHash, uint256 _fee) internal returns (bytes32 requestId) {
LINK.transferAndCall(vrfCoordinator, _fee, abi.encode(_keyHash, USER_SEED_PLACEHOLDER));
uint256 vRFSeed = makeVRFInputSeed(_keyHash, USER_SEED_PLACEHOLDER, address(this), nonces[_keyHash]);
nonces[_keyHash] = nonces[_keyHash] + 1;
return makeRequestId(_keyHash, vRFSeed);
}
LinkTokenInterface internal immutable LINK;
address private immutable vrfCoordinator;
mapping(bytes32 => uint256)
private nonces;
constructor(address _vrfCoordinator, address _link) {
vrfCoordinator = _vrfCoordinator;
LINK = LinkTokenInterface(_link);
}
function rawFulfillRandomness(bytes32 requestId, uint256 randomness) external {
require(msg.sender == vrfCoordinator, "Only VRFCoordinator can fulfill");
fulfillRandomness(requestId, randomness);
}
}
interface IDelegatedMintable {
function mint(address recipient, uint256 tokenId) external;
function mintMany(address recipient, uint256 tokenIdStart, uint256 count) external;
function totalSupply() external view returns(uint256);
}
interface IERC165 {
function supportsInterface(bytes4 interfaceId) external view returns (bool);
}
interface IERC721 is IERC165 {
event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);
event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);
event ApprovalForAll(address indexed owner, address indexed operator, bool approved);
function balanceOf(address owner) external view returns (uint256 balance);
function ownerOf(uint256 tokenId) external view returns (address owner);
function safeTransferFrom(
address from,
address to,
uint256 tokenId
) external;
function transferFrom(
address from,
address to,
uint256 tokenId
) external;
function approve(address to, uint256 tokenId) external;
function getApproved(uint256 tokenId) external view returns (address operator);
function setApprovalForAll(address operator, bool _approved) external;
function isApprovedForAll(address owner, address operator) external view returns (bool);
function safeTransferFrom(
address from,
address to,
uint256 tokenId,
bytes calldata data
) external;
}
interface IERC721Receiver {
function onERC721Received(
address operator,
address from,
uint256 tokenId,
bytes calldata data
) external returns (bytes4);
}
interface IERC721Metadata is IERC721 {
function name() external view returns (string memory);
function symbol() external view returns (string memory);
function tokenURI(uint256 tokenId) external view returns (string memory);
}
library Address {
function isContract(address account) internal view returns (bool) {
uint256 size;
assembly {
size := extcodesize(account)
}
return size > 0;
}
function sendValue(address payable recipient, uint256 amount) internal {
require(address(this).balance >= amount, "Address: insufficient balance");
(bool success, ) = recipient.call{value: amount}("");
require(success, "Address: unable to send value, recipient may have reverted");
}
function functionCall(address target, bytes memory data) internal returns (bytes memory) {
return functionCall(target, data, "Address: low-level call failed");
}
function functionCall(
address target,
bytes memory data,
string memory errorMessage
) internal returns (bytes memory) {
return functionCallWithValue(target, data, 0, errorMessage);
}
function functionCallWithValue(
address target,
bytes memory data,
uint256 value
) internal returns (bytes memory) {
return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
}
function functionCallWithValue(
address target,
bytes memory data,
uint256 value,
string memory errorMessage
) internal returns (bytes memory) {
require(address(this).balance >= value, "Address: insufficient balance for call");
require(isContract(target), "Address: call to non-contract");
(bool success, bytes memory returndata) = target.call{value: value}(data);
return verifyCallResult(success, returndata, errorMessage);
}
function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
return functionStaticCall(target, data, "Address: low-level static call failed");
}
function functionStaticCall(
address target,
bytes memory data,
string memory errorMessage
) internal view returns (bytes memory) {
require(isContract(target), "Address: static call to non-contract");
(bool success, bytes memory returndata) = target.staticcall(data);
return verifyCallResult(success, returndata, errorMessage);
}
function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
return functionDelegateCall(target, data, "Address: low-level delegate call failed");
}
function functionDelegateCall(
address target,
bytes memory data,
string memory errorMessage
) internal returns (bytes memory) {
require(isContract(target), "Address: delegate call to non-contract");
(bool success, bytes memory returndata) = target.delegatecall(data);
return verifyCallResult(success, returndata, errorMessage);
}
function verifyCallResult(
bool success,
bytes memory returndata,
string memory errorMessage
) internal pure returns (bytes memory) {
if (success) {
return returndata;
} else {
if (returndata.length > 0) {
assembly {
let returndata_size := mload(returndata)
revert(add(32, returndata), returndata_size)
}
} else {
revert(errorMessage);
}
}
}
}
abstract contract ERC165 is IERC165 {
function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
return interfaceId == type(IERC165).interfaceId;
}
}
contract ERC721 is Context, ERC165, IERC721, IERC721Metadata {
using Address for address;
using Strings for uint256;
string private _name;
string private _symbol;
mapping(uint256 => address) private _owners;
mapping(address => uint256) private _balances;
mapping(uint256 => address) private _tokenApprovals;
mapping(address => mapping(address => bool)) private _operatorApprovals;
constructor(string memory name_, string memory symbol_) {
_name = name_;
_symbol = symbol_;
}
function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {
return
interfaceId == type(IERC721).interfaceId ||
interfaceId == type(IERC721Metadata).interfaceId ||
super.supportsInterface(interfaceId);
}
function balanceOf(address owner) public view virtual override returns (uint256) {
require(owner != address(0), "ERC721: balance query for the zero address");
return _balances[owner];
}
function ownerOf(uint256 tokenId) public view virtual override returns (address) {
address owner = _owners[tokenId];
require(owner != address(0), "ERC721: owner query for nonexistent token");
return owner;
}
function name() public view virtual override returns (string memory) {
return _name;
}
function symbol() public view virtual override returns (string memory) {
return _symbol;
}
function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
require(_exists(tokenId), "ERC721Metadata: URI query for nonexistent token");
string memory baseURI = _baseURI();
return bytes(baseURI).length > 0 ? string(abi.encodePacked(baseURI, tokenId.toString())) : "";
}
function _baseURI() internal view virtual returns (string memory) {
return "";
}
function approve(address to, uint256 tokenId) public virtual override {
address owner = ERC721.ownerOf(tokenId);
require(to != owner, "ERC721: approval to current owner");
require(
_msgSender() == owner || isApprovedForAll(owner, _msgSender()),
"ERC721: approve caller is not owner nor approved for all"
);
_approve(to, tokenId);
}
function getApproved(uint256 tokenId) public view virtual override returns (address) {
require(_exists(tokenId), "ERC721: approved query for nonexistent token");
return _tokenApprovals[tokenId];
}
function setApprovalForAll(address operator, bool approved) public virtual override {
_setApprovalForAll(_msgSender(), operator, approved);
}
function isApprovedForAll(address owner, address operator) public view virtual override returns (bool) {
return _operatorApprovals[owner][operator];
}
function transferFrom(
address from,
address to,
uint256 tokenId
) public virtual override {
require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");
_transfer(from, to, tokenId);
}
function safeTransferFrom(
address from,
address to,
uint256 tokenId
) public virtual override {
safeTransferFrom(from, to, tokenId, "");
}
function safeTransferFrom(
address from,
address to,
uint256 tokenId,
bytes memory _data
) public virtual override {
require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");
_safeTransfer(from, to, tokenId, _data);
}
function _safeTransfer(
address from,
address to,
uint256 tokenId,
bytes memory _data
) internal virtual {
_transfer(from, to, tokenId);
require(_checkOnERC721Received(from, to, tokenId, _data), "ERC721: transfer to non ERC721Receiver implementer");
}
function _exists(uint256 tokenId) internal view virtual returns (bool) {
return _owners[tokenId] != address(0);
}
function _isApprovedOrOwner(address spender, uint256 tokenId) internal view virtual returns (bool) {
require(_exists(tokenId), "ERC721: operator query for nonexistent token");
address owner = ERC721.ownerOf(tokenId);
return (spender == owner || getApproved(tokenId) == spender || isApprovedForAll(owner, spender));
}
function _safeMint(address to, uint256 tokenId) internal virtual {
_safeMint(to, tokenId, "");
}
function _safeMint(
address to,
uint256 tokenId,
bytes memory _data
) internal virtual {
_mint(to, tokenId);
require(
_checkOnERC721Received(address(0), to, tokenId, _data),
"ERC721: transfer to non ERC721Receiver implementer"
);
}
function _mint(address to, uint256 tokenId) internal virtual {
require(to != address(0), "ERC721: mint to the zero address");
require(!_exists(tokenId), "ERC721: token already minted");
_beforeTokenTransfer(address(0), to, tokenId);
_balances[to] += 1;
_owners[tokenId] = to;
emit Transfer(address(0), to, tokenId);
_afterTokenTransfer(address(0), to, tokenId);
}
function _burn(uint256 tokenId) internal virtual {
address owner = ERC721.ownerOf(tokenId);
_beforeTokenTransfer(owner, address(0), tokenId);
_approve(address(0), tokenId);
_balances[owner] -= 1;
delete _owners[tokenId];
emit Transfer(owner, address(0), tokenId);
_afterTokenTransfer(owner, address(0), tokenId);
}
function _transfer(
address from,
address to,
uint256 tokenId
) internal virtual {
require(ERC721.ownerOf(tokenId) == from, "ERC721: transfer from incorrect owner");
require(to != address(0), "ERC721: transfer to the zero address");
_beforeTokenTransfer(from, to, tokenId);
_approve(address(0), tokenId);
_balances[from] -= 1;
_balances[to] += 1;
_owners[tokenId] = to;
emit Transfer(from, to, tokenId);
_afterTokenTransfer(from, to, tokenId);
}
function _approve(address to, uint256 tokenId) internal virtual {
_tokenApprovals[tokenId] = to;
emit Approval(ERC721.ownerOf(tokenId), to, tokenId);
}
function _setApprovalForAll(
address owner,
address operator,
bool approved
) internal virtual {
require(owner != operator, "ERC721: approve to caller");
_operatorApprovals[owner][operator] = approved;
emit ApprovalForAll(owner, operator, approved);
}
function _checkOnERC721Received(
address from,
address to,
uint256 tokenId,
bytes memory _data
) private returns (bool) {
if (to.isContract()) {
try IERC721Receiver(to).onERC721Received(_msgSender(), from, tokenId, _data) returns (bytes4 retval) {
return retval == IERC721Receiver.onERC721Received.selector;
} catch (bytes memory reason) {
if (reason.length == 0) {
revert("ERC721: transfer to non ERC721Receiver implementer");
} else {
assembly {
revert(add(32, reason), mload(reason))
}
}
}
} else {
return true;
}
}
function _beforeTokenTransfer(
address from,
address to,
uint256 tokenId
) internal virtual {}
function _afterTokenTransfer(
address from,
address to,
uint256 tokenId
) internal virtual {}
}
abstract contract ERC721Checkpointable is ERC721 {
uint8 public constant decimals = 0;
mapping(address => address) private _delegates;
struct Checkpoint {
uint32 fromBlock;
uint96 votes;
}
mapping(address => mapping(uint32 => Checkpoint)) public checkpoints;
mapping(address => uint32) public numCheckpoints;
bytes32 public constant DOMAIN_TYPEHASH =
keccak256("EIP712Domain(string name,uint256 chainId,address verifyingContract)");
bytes32 public constant DELEGATION_TYPEHASH =
keccak256("Delegation(address delegatee,uint256 nonce,uint256 expiry)");
mapping(address => uint256) public nonces;
event DelegateChanged(address indexed delegator, address indexed fromDelegate, address indexed toDelegate);
event DelegateVotesChanged(address indexed delegate, uint256 previousBalance, uint256 newBalance);
function votesToDelegate(address delegator) public view returns (uint96) {
return safe96(balanceOf(delegator), "ERC721Checkpointable::votesToDelegate: amount exceeds 96 bits");
}
function delegates(address delegator) public view returns (address) {
address current = _delegates[delegator];
return current == address(0) ? delegator : current;
}
function _beforeTokenTransfer(
address from,
address to,
uint256 tokenId
) internal override {
super._beforeTokenTransfer(from, to, tokenId);
_moveDelegates(delegates(from), delegates(to), 1);
}
function delegate(address delegatee) public {
if (delegatee == address(0)) delegatee = msg.sender;
return _delegate(msg.sender, delegatee);
}
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), "ERC721Checkpointable::delegateBySig: invalid signature");
require(nonce == nonces[signatory]++, "ERC721Checkpointable::delegateBySig: invalid nonce");
require(block.timestamp <= expiry, "ERC721Checkpointable::delegateBySig: signature expired");
return _delegate(signatory, delegatee);
}
function getCurrentVotes(address account) external view returns (uint96) {
uint32 nCheckpoints = numCheckpoints[account];
return nCheckpoints > 0 ? checkpoints[account][nCheckpoints - 1].votes : 0;
}
function getPriorVotes(address account, uint256 blockNumber) public view returns (uint96) {
require(blockNumber < block.number, "ERC721Checkpointable::getPriorVotes: not yet determined");
uint32 nCheckpoints = numCheckpoints[account];
if (nCheckpoints == 0) {
return 0;
}
if (checkpoints[account][nCheckpoints - 1].fromBlock <= blockNumber) {
return checkpoints[account][nCheckpoints - 1].votes;
}
if (checkpoints[account][0].fromBlock > blockNumber) {
return 0;
}
uint32 lower = 0;
uint32 upper = nCheckpoints - 1;
while (upper > lower) {
uint32 center = upper - (upper - lower) / 2;
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);
_delegates[delegator] = delegatee;
emit DelegateChanged(delegator, currentDelegate, delegatee);
uint96 amount = votesToDelegate(delegator);
_moveDelegates(currentDelegate, delegatee, 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, "ERC721Checkpointable::_moveDelegates: 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, "ERC721Checkpointable::_moveDelegates: amount overflows");
_writeCheckpoint(dstRep, dstRepNum, dstRepOld, dstRepNew);
}
}
}
function _writeCheckpoint(
address delegatee,
uint32 nCheckpoints,
uint96 oldVotes,
uint96 newVotes
) internal {
uint32 blockNumber = safe32(
block.number,
"ERC721Checkpointable::_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;
}
}
contract MetaStonezNFT is Ownable, ERC721Checkpointable, IDelegatedMintable, VRFConsumerBase {
using Strings for uint256;
error NotAuthorized();
error SupplyExhausted();
error Frozen();
error NonexistentToken();
error EntropyAlreadySet();
uint256 public totalSupply;
uint256 public maxSupply;
bool public frozen;
mapping(address => bool) public minters;
string public prerevealURI;
string public baseURI;
bytes32 public LINK_KEY_HASH;
uint256 public entropy;
constructor(
string memory _name,
string memory _symbol,
uint256 _maxSupply,
bytes32 _LINK_KEY_HASH,
address _LINK_ADDRESS,
address _LINK_VRF_COORDINATOR_ADDRESS
)
ERC721(_name, _symbol)
VRFConsumerBase(_LINK_VRF_COORDINATOR_ADDRESS, _LINK_ADDRESS)
{
maxSupply = _maxSupply;
LINK_KEY_HASH = _LINK_KEY_HASH;
}
function mint(address recipient, uint256 tokenId) external override {
if (!minters[msg.sender]) {
revert NotAuthorized();
}
totalSupply += 1;
if (totalSupply > maxSupply) {
revert SupplyExhausted();
}
_safeMint(recipient, tokenId);
}
function mintMany(address recipient, uint256 tokenIdStart, uint256 count) external override {
if (!minters[msg.sender]) {
revert NotAuthorized();
}
totalSupply += count;
if (totalSupply > maxSupply) {
revert SupplyExhausted();
}
for (uint256 i = 0; i < count; i++) {
_safeMint(recipient, tokenIdStart + i);
}
}
function approveMinter(address minter, bool approve) external onlyOwner {
minters[minter] = approve;
}
function setPrerevealURI(string calldata newPrerevealURI) external onlyOwner {
if (frozen) {
revert Frozen();
}
prerevealURI = newPrerevealURI;
}
function setBaseURI(string calldata newBaseURI) external onlyOwner {
if (frozen) {
revert Frozen();
}
baseURI = newBaseURI;
}
function shrinkMaxSupply() external onlyOwner {
if (frozen) {
revert Frozen();
}
maxSupply = totalSupply;
}
function freezeSupplyAndMetadata() external onlyOwner {
frozen = true;
}
function setEntropy(
uint256 _entropy
) external onlyOwner {
if (entropy != 0) {
revert EntropyAlreadySet();
}
entropy = _entropy;
}
function reveal(
string calldata newBaseURI,
uint256 linkFee
) external onlyOwner returns (bytes32 requestId) {
if (entropy != 0) {
revert EntropyAlreadySet();
}
baseURI = newBaseURI;
return requestRandomness(LINK_KEY_HASH, linkFee);
}
function fulfillRandomness(bytes32, uint256 _entropy) internal override {
entropy = _entropy;
}
function tokenURI(uint256 tokenId) public view override returns (string memory) {
if (!_exists(tokenId)) {
revert NonexistentToken();
}
if (entropy == 0 || bytes(baseURI).length == 0) {
return prerevealURI;
}
return string(
abi.encodePacked(
baseURI,
"/",
uint256(
computeShuffledIndex(
uint64(tokenId),
uint64(maxSupply),
keccak256(abi.encode(entropy))
)
).toString(),
".json"
)
);
}
function computeShuffledIndex(
uint64 index,
uint64 indexCount,
bytes32 seed
)
public
pure
returns (uint64)
{
require(index < indexCount, "SwapOrNot: INVALID_PARAMS");
for (
uint8 currentRound = 0;
currentRound < 24;
currentRound++
) {
uint64 pivot = uint64(uint(keccak256(abi.encodePacked(seed, currentRound)))) % indexCount;
uint64 flip = (pivot + indexCount - index) % indexCount;
uint64 position = index > flip ? index : flip;
bytes32 source = keccak256(
abi.encodePacked(seed, currentRound, position / 256)
);
uint8 byt = uint8(source[(position % 256) / 8]);
uint8 bit = (byt >> (position % 8)) % 2;
if (bit > 0) {
index = flip;
}
}
return index;
}
}
