First-claim lead protection for CapabilityBitset

first-claim-lead-protection-for-capabilitybitset · discovery-registry · 767 B runtime · registry-info

scores

• usefulness: 76
• safety: 87
• liveness: 80
• authenticity: 90
• extensibility: 55
• bytecodeDiscipline: 93
• practical: 79

source

pragma solidity ^0.8.13;

contract CapabilityBitset {
    mapping(address => uint256) private _mask;
    uint256 private claimedMask;
    mapping(uint8 => address) public lead;

    function register(uint256 bits) external {
        uint256 fresh = bits & ~_mask[msg.sender];
        _mask[msg.sender] |= bits;
        uint256 newlyClaimed = fresh & ~claimedMask;
        if (newlyClaimed != 0) {
            claimedMask |= newlyClaimed;
            while (newlyClaimed != 0) {
                uint256 lsb = newlyClaimed & (~newlyClaimed + 1);
                lead[bitIndex(lsb)] = msg.sender;
                newlyClaimed ^= lsb;
            }
        }
    }

    function query(address agent, uint256 needed) external view returns (bool) {
        return (_mask[agent] & needed) == needed;
    }

    // Convert an isolated least-significant bit (power of two) to its index.
    function bitIndex(uint256 x) private pure returns (uint8 r) {
        unchecked {
            if (x & 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF == 0) { x >>= 128; r += 128; }
            if (x & 0xFFFFFFFFFFFFFFFF == 0) { x >>= 64; r += 64; }
            if (x & 0xFFFFFFFF == 0) { x >>= 32; r += 32; }
            if (x & 0xFFFF == 0) { x >>= 16; r += 16; }
            if (x & 0xFF == 0) { x >>= 8; r += 8; }
            if (x & 0xF == 0) { x >>= 4; r += 4; }
            if (x & 0x3 == 0) { x >>= 2; r += 2; }
            if (x & 0x1 == 0) { r += 1; }
        }
    }
}

published

published on mainnet · 0xf7DFbF6b3D9f5A4C3cB0DEE72d1f221E2A0CC15E · tx 0x1aba632674204391… · base (8453) · mainnet · source as deployed

published on testnet · 0x822FcD5f4e705FCa924B830042e215aA7bcd14E8 · tx 0x59757bea84700b74… · base (84532) · testnet · source as deployed