/
Lib_RLPWriter.sol
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/
Lib_RLPWriter.sol
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// SPDX-License-Identifier: MIT
pragma solidity ^0.8.9;
/**
* @title Lib_RLPWriter
* @author Bakaoh (with modifications)
*/
library Lib_RLPWriter {
/**********************
* Internal Functions *
**********************/
/**
* RLP encodes a byte string.
* @param _in The byte string to encode.
* @return The RLP encoded string in bytes.
*/
function writeBytes(
bytes memory _in
)
internal
pure
returns (
bytes memory
)
{
bytes memory encoded;
if (_in.length == 1 && uint8(_in[0]) < 128) {
encoded = _in;
} else {
encoded = abi.encodePacked(_writeLength(_in.length, 128), _in);
}
return encoded;
}
/**
* RLP encodes a list of RLP encoded byte byte strings.
* @param _in The list of RLP encoded byte strings.
* @return The RLP encoded list of items in bytes.
*/
function writeList(
bytes[] memory _in
)
internal
pure
returns (
bytes memory
)
{
bytes memory list = _flatten(_in);
return abi.encodePacked(_writeLength(list.length, 192), list);
}
/**
* RLP encodes a string.
* @param _in The string to encode.
* @return The RLP encoded string in bytes.
*/
function writeString(
string memory _in
)
internal
pure
returns (
bytes memory
)
{
return writeBytes(bytes(_in));
}
/**
* RLP encodes an address.
* @param _in The address to encode.
* @return The RLP encoded address in bytes.
*/
function writeAddress(
address _in
)
internal
pure
returns (
bytes memory
)
{
return writeBytes(abi.encodePacked(_in));
}
/**
* RLP encodes a uint.
* @param _in The uint256 to encode.
* @return The RLP encoded uint256 in bytes.
*/
function writeUint(
uint256 _in
)
internal
pure
returns (
bytes memory
)
{
return writeBytes(_toBinary(_in));
}
/**
* RLP encodes a bool.
* @param _in The bool to encode.
* @return The RLP encoded bool in bytes.
*/
function writeBool(
bool _in
)
internal
pure
returns (
bytes memory
)
{
bytes memory encoded = new bytes(1);
encoded[0] = (_in ? bytes1(0x01) : bytes1(0x80));
return encoded;
}
/*********************
* Private Functions *
*********************/
/**
* Encode the first byte, followed by the `len` in binary form if `length` is more than 55.
* @param _len The length of the string or the payload.
* @param _offset 128 if item is string, 192 if item is list.
* @return RLP encoded bytes.
*/
function _writeLength(
uint256 _len,
uint256 _offset
)
private
pure
returns (
bytes memory
)
{
bytes memory encoded;
if (_len < 56) {
encoded = new bytes(1);
encoded[0] = bytes1(uint8(_len) + uint8(_offset));
} else {
uint256 lenLen;
uint256 i = 1;
while (_len / i != 0) {
lenLen++;
i *= 256;
}
encoded = new bytes(lenLen + 1);
encoded[0] = bytes1(uint8(lenLen) + uint8(_offset) + 55);
for(i = 1; i <= lenLen; i++) {
encoded[i] = bytes1(uint8((_len / (256**(lenLen-i))) % 256));
}
}
return encoded;
}
/**
* Encode integer in big endian binary form with no leading zeroes.
* @notice TODO: This should be optimized with assembly to save gas costs.
* @param _x The integer to encode.
* @return RLP encoded bytes.
*/
function _toBinary(
uint256 _x
)
private
pure
returns (
bytes memory
)
{
bytes memory b = abi.encodePacked(_x);
uint256 i = 0;
for (; i < 32; i++) {
if (b[i] != 0) {
break;
}
}
bytes memory res = new bytes(32 - i);
for (uint256 j = 0; j < res.length; j++) {
res[j] = b[i++];
}
return res;
}
/**
* Copies a piece of memory to another location.
* @notice From: https://github.com/Arachnid/solidity-stringutils/blob/master/src/strings.sol.
* @param _dest Destination location.
* @param _src Source location.
* @param _len Length of memory to copy.
*/
function _memcpy(
uint256 _dest,
uint256 _src,
uint256 _len
)
private
pure
{
uint256 dest = _dest;
uint256 src = _src;
uint256 len = _len;
for(; len >= 32; len -= 32) {
assembly {
mstore(dest, mload(src))
}
dest += 32;
src += 32;
}
uint256 mask;
unchecked {
mask = 256 ** (32 - len) - 1;
}
assembly {
let srcpart := and(mload(src), not(mask))
let destpart := and(mload(dest), mask)
mstore(dest, or(destpart, srcpart))
}
}
/**
* Flattens a list of byte strings into one byte string.
* @notice From: https://github.com/sammayo/solidity-rlp-encoder/blob/master/RLPEncode.sol.
* @param _list List of byte strings to flatten.
* @return The flattened byte string.
*/
function _flatten(
bytes[] memory _list
)
private
pure
returns (
bytes memory
)
{
if (_list.length == 0) {
return new bytes(0);
}
uint256 len;
uint256 i = 0;
for (; i < _list.length; i++) {
len += _list[i].length;
}
bytes memory flattened = new bytes(len);
uint256 flattenedPtr;
assembly { flattenedPtr := add(flattened, 0x20) }
for(i = 0; i < _list.length; i++) {
bytes memory item = _list[i];
uint256 listPtr;
assembly { listPtr := add(item, 0x20)}
_memcpy(flattenedPtr, listPtr, item.length);
flattenedPtr += _list[i].length;
}
return flattened;
}
}