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Base64.sol
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// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;
/// @notice Library to encode strings in Base64.
/// @author Solady (https://github.com/vectorized/solady/blob/main/src/utils/Base64.sol)
/// @author Modified from Solmate (https://github.com/transmissions11/solmate/blob/main/src/utils/Base64.sol)
/// @author Modified from (https://github.com/Brechtpd/base64/blob/main/base64.sol) by Brecht Devos - <[email protected]>.
library Base64 {
/// @dev Encodes `data` using the base64 encoding described in RFC 4648.
/// See: https://datatracker.ietf.org/doc/html/rfc4648
/// @param fileSafe Whether to replace '+' with '-' and '/' with '_'.
/// @param noPadding Whether to strip away the padding.
function encode(bytes memory data, bool fileSafe, bool noPadding)
internal
pure
returns (string memory result)
{
/// @solidity memory-safe-assembly
assembly {
let dataLength := mload(data)
if dataLength {
// Multiply by 4/3 rounded up.
// The `shl(2, ...)` is equivalent to multiplying by 4.
let encodedLength := shl(2, div(add(dataLength, 2), 3))
// Set `result` to point to the start of the free memory.
result := mload(0x40)
// Store the table into the scratch space.
// Offsetted by -1 byte so that the `mload` will load the character.
// We will rewrite the free memory pointer at `0x40` later with
// the allocated size.
// The magic constant 0x0670 will turn "-_" into "+/".
mstore(0x1f, "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdef")
mstore(0x3f, xor("ghijklmnopqrstuvwxyz0123456789-_", mul(iszero(fileSafe), 0x0670)))
// Skip the first slot, which stores the length.
let ptr := add(result, 0x20)
let end := add(ptr, encodedLength)
let dataEnd := add(add(0x20, data), dataLength)
let dataEndValue := mload(dataEnd) // Cache the value at the `dataEnd` slot.
mstore(dataEnd, 0x00) // Zeroize the `dataEnd` slot to clear dirty bits.
// Run over the input, 3 bytes at a time.
for {} 1 {} {
data := add(data, 3) // Advance 3 bytes.
let input := mload(data)
// Write 4 bytes. Optimized for fewer stack operations.
mstore8(0, mload(and(shr(18, input), 0x3F)))
mstore8(1, mload(and(shr(12, input), 0x3F)))
mstore8(2, mload(and(shr(6, input), 0x3F)))
mstore8(3, mload(and(input, 0x3F)))
mstore(ptr, mload(0x00))
ptr := add(ptr, 4) // Advance 4 bytes.
if iszero(lt(ptr, end)) { break }
}
mstore(dataEnd, dataEndValue) // Restore the cached value at `dataEnd`.
mstore(0x40, add(end, 0x20)) // Allocate the memory.
// Equivalent to `o = [0, 2, 1][dataLength % 3]`.
let o := div(2, mod(dataLength, 3))
// Offset `ptr` and pad with '='. We can simply write over the end.
mstore(sub(ptr, o), shl(240, 0x3d3d))
// Set `o` to zero if there is padding.
o := mul(iszero(iszero(noPadding)), o)
mstore(sub(ptr, o), 0) // Zeroize the slot after the string.
mstore(result, sub(encodedLength, o)) // Store the length.
}
}
}
/// @dev Encodes `data` using the base64 encoding described in RFC 4648.
/// Equivalent to `encode(data, false, false)`.
function encode(bytes memory data) internal pure returns (string memory result) {
result = encode(data, false, false);
}
/// @dev Encodes `data` using the base64 encoding described in RFC 4648.
/// Equivalent to `encode(data, fileSafe, false)`.
function encode(bytes memory data, bool fileSafe)
internal
pure
returns (string memory result)
{
result = encode(data, fileSafe, false);
}
/// @dev Decodes base64 encoded `data`.
///
/// Supports:
/// - RFC 4648 (both standard and file-safe mode).
/// - RFC 3501 (63: ',').
///
/// Does not support:
/// - Line breaks.
///
/// Note: For performance reasons,
/// this function will NOT revert on invalid `data` inputs.
/// Outputs for invalid inputs will simply be undefined behaviour.
/// It is the user's responsibility to ensure that the `data`
/// is a valid base64 encoded string.
function decode(string memory data) internal pure returns (bytes memory result) {
/// @solidity memory-safe-assembly
assembly {
let dataLength := mload(data)
if dataLength {
let decodedLength := mul(shr(2, dataLength), 3)
for {} 1 {} {
// If padded.
if iszero(and(dataLength, 3)) {
let t := xor(mload(add(data, dataLength)), 0x3d3d)
// forgefmt: disable-next-item
decodedLength := sub(
decodedLength,
add(iszero(byte(30, t)), iszero(byte(31, t)))
)
break
}
// If non-padded.
decodedLength := add(decodedLength, sub(and(dataLength, 3), 1))
break
}
result := mload(0x40)
// Write the length of the bytes.
mstore(result, decodedLength)
// Skip the first slot, which stores the length.
let ptr := add(result, 0x20)
let end := add(ptr, decodedLength)
// Load the table into the scratch space.
// Constants are optimized for smaller bytecode with zero gas overhead.
// `m` also doubles as the mask of the upper 6 bits.
let m := 0xfc000000fc00686c7074787c8084888c9094989ca0a4a8acb0b4b8bcc0c4c8cc
mstore(0x5b, m)
mstore(0x3b, 0x04080c1014181c2024282c3034383c4044484c5054585c6064)
mstore(0x1a, 0xf8fcf800fcd0d4d8dce0e4e8ecf0f4)
for {} 1 {} {
// Read 4 bytes.
data := add(data, 4)
let input := mload(data)
// Write 3 bytes.
// forgefmt: disable-next-item
mstore(ptr, or(
and(m, mload(byte(28, input))),
shr(6, or(
and(m, mload(byte(29, input))),
shr(6, or(
and(m, mload(byte(30, input))),
shr(6, mload(byte(31, input)))
))
))
))
ptr := add(ptr, 3)
if iszero(lt(ptr, end)) { break }
}
mstore(0x40, add(end, 0x20)) // Allocate the memory.
mstore(end, 0) // Zeroize the slot after the bytes.
mstore(0x60, 0) // Restore the zero slot.
}
}
}
}