// SPDX-License-Identifier: MIT
pragma solidity 0.8.17;
library LibBytes {
// solhint-disable no-inline-assembly
// LibBytes specific errors
error SliceOverflow();
error SliceOutOfBounds();
error AddressOutOfBounds();
bytes16 private constant _SYMBOLS = "0123456789abcdef";
// -------------------------
function slice(
bytes memory _bytes,
uint256 _start,
uint256 _length
) internal pure returns (bytes memory) {
if (_length + 31 < _length) revert SliceOverflow();
if (_bytes.length < _start + _length) revert SliceOutOfBounds();
bytes memory tempBytes;
assembly {
switch iszero(_length)
case 0 {
// Get a location of some free memory and store it in tempBytes as
// Solidity does for memory variables.
tempBytes := mload(0x40)
// The first word of the slice result is potentially a partial
// word read from the original array. To read it, we calculate
// the length of that partial word and start copying that many
// bytes into the array. The first word we copy will start with
// data we don't care about, but the last `lengthmod` bytes will
// land at the beginning of the contents of the new array. When
// we're done copying, we overwrite the full first word with
// the actual length of the slice.
let lengthmod := and(_length, 31)
// The multiplication in the next line is necessary
// because when slicing multiples of 32 bytes (lengthmod == 0)
// the following copy loop was copying the origin's length
// and then ending prematurely not copying everything it should.
let mc := add(
add(tempBytes, lengthmod),
mul(0x20, iszero(lengthmod))
)
let end := add(mc, _length)
for {
// The multiplication in the next line has the same exact purpose
// as the one above.
let cc := add(
add(
add(_bytes, lengthmod),
mul(0x20, iszero(lengthmod))
),
_start
)
} lt(mc, end) {
mc := add(mc, 0x20)
cc := add(cc, 0x20)
} {
mstore(mc, mload(cc))
}
mstore(tempBytes, _length)
//update free-memory pointer
//allocating the array padded to 32 bytes like the compiler does now
mstore(0x40, and(add(mc, 31), not(31)))
}
//if we want a zero-length slice let's just return a zero-length array
default {
tempBytes := mload(0x40)
//zero out the 32 bytes slice we are about to return
//we need to do it because Solidity does not garbage collect
mstore(tempBytes, 0)
mstore(0x40, add(tempBytes, 0x20))
}
}
return tempBytes;
}
function toAddress(
bytes memory _bytes,
uint256 _start
) internal pure returns (address) {
if (_bytes.length < _start + 20) {
revert AddressOutOfBounds();
}
address tempAddress;
assembly {
tempAddress := div(
mload(add(add(_bytes, 0x20), _start)),
0x1000000000000000000000000
)
}
return tempAddress;
}
/// Copied from OpenZeppelin's `Strings.sol` utility library.
/// https://github.com/OpenZeppelin/openzeppelin-contracts/blob/8335676b0e99944eef6a742e16dcd9ff6e68e609/contracts/utils/Strings.sol
function toHexString(
uint256 value,
uint256 length
) internal pure returns (string memory) {
bytes memory buffer = new bytes(2 * length + 2);
buffer[0] = "0";
buffer[1] = "x";
for (uint256 i = 2 * length + 1; i > 1; --i) {
buffer[i] = _SYMBOLS[value & 0xf];
value >>= 4;
}
require(value == 0, "Strings: hex length insufficient");
return string(buffer);
}
}