nosahama · May 31, 2022 22:57 · Jan 23, 2022 · Jan 23, 2022
diff --git a/Base64.sol b/Base64.sol
@@ -0,0 +1,73 @@
+pragma solidity >=0.8.0 <0.9.0;
+
+// SPDX-License-Identifier: MIT
+/// [MIT License]
+/// @title Base64
+/// @notice Provides a function for encoding some bytes in base64
+/// @author Brecht Devos <[email protected]>
+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);
+    }
+}