Copy
60bytes32 hashStruct;
61uint256 nonce = _nonces[owner].current();
62
63assembly {
64    // Load free memory pointer
65    let memPtr := mload(64)
66
67    // keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)")
68    mstore(memPtr, 0x6e71edae12b1b97f4d1f60370fef10105fa2faae0126114a169c64845d6126c9)
69    mstore(add(memPtr, 32), owner)
70    mstore(add(memPtr, 64), spender)
71    mstore(add(memPtr, 96), amount)
72    mstore(add(memPtr, 128), nonce)
73    mstore(add(memPtr, 160), deadline)
74
75    hashStruct := keccak256(memPtr, 192)
76}
77
78bytes32 eip712DomainHash = _domainSeparator();
79
80// Assembly for more efficient computing:
81// bytes32 hash = keccak256(
82//     abi.encodePacked(uint16(0x1901), eip712DomainHash, hashStruct)
83// );
84
85bytes32 hash;
86
87assembly {
88    // Load free memory pointer
89    let memPtr := mload(64)
90
91    mstore(memPtr, 0x1901000000000000000000000000000000000000000000000000000000000000)  // EIP191 header
92    mstore(add(memPtr, 2), eip712DomainHash)                                            // EIP712 domain hash
93    mstore(add(memPtr, 34), hashStruct)                                                 // Hash of struct
94
95    hash := keccak256(memPtr, 66)
96}
97
98address signer = _recover(hash, v, r, s);
99
100require(signer == owner, "ERC20Permit: invalid signature");
101
102_nonces[owner].increment();
103_approve(owner, spender, amount);