Created
November 28, 2021 08:12
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library Base64 { | |
bytes internal constant TABLE = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; | |
/// @notice Encodes some bytes to the base64 representation | |
function encode(bytes memory data) internal pure returns (string memory) { | |
uint256 len = data.length; | |
if (len == 0) return ""; | |
// multiply by 4/3 rounded up | |
uint256 encodedLen = 4 * ((len + 2) / 3); | |
// Add some extra buffer at the end | |
bytes memory result = new bytes(encodedLen + 32); | |
bytes memory table = TABLE; | |
assembly { | |
let tablePtr := add(table, 1) | |
let resultPtr := add(result, 32) | |
for { | |
let i := 0 | |
} lt(i, len) { | |
} { | |
i := add(i, 3) | |
let input := and(mload(add(data, i)), 0xffffff) | |
let out := mload(add(tablePtr, and(shr(18, input), 0x3F))) | |
out := shl(8, out) | |
out := add(out, and(mload(add(tablePtr, and(shr(12, input), 0x3F))), 0xFF)) | |
out := shl(8, out) | |
out := add(out, and(mload(add(tablePtr, and(shr(6, input), 0x3F))), 0xFF)) | |
out := shl(8, out) | |
out := add(out, and(mload(add(tablePtr, and(input, 0x3F))), 0xFF)) | |
out := shl(224, out) | |
mstore(resultPtr, out) | |
resultPtr := add(resultPtr, 4) | |
} | |
switch mod(len, 3) | |
case 1 { | |
mstore(sub(resultPtr, 2), shl(240, 0x3d3d)) | |
} | |
case 2 { | |
mstore(sub(resultPtr, 1), shl(248, 0x3d)) | |
} | |
mstore(result, encodedLen) | |
} | |
return string(result); | |
} | |
} |
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