// SPDX-License-Identifier: MIT
pragma solidity >=0.8.0;
/// @notice Efficient library for creating string representations of integers.
/// @author Solmate (https://github.com/transmissions11/solmate/blob/main/src/utils/LibString.sol)
/// @author Modified from Solady (https://github.com/Vectorized/solady/blob/main/src/utils/LibString.sol)
library LibString {
function toString(uint256 value) internal pure returns (string memory str) {
assembly {
// The maximum value of a uint256 contains 78 digits (1 byte per digit), but we allocate 160 bytes
// to keep the free memory pointer word aligned. We'll need 1 word for the length, 1 word for the
// trailing zeros padding, and 3 other words for a max of 78 digits. In total: 5 * 32 = 160 bytes.
let newFreeMemoryPointer := add(mload(0x40), 160)
// Update the free memory pointer to avoid overriding our string.
mstore(0x40, newFreeMemoryPointer)
// Assign str to the end of the zone of newly allocated memory.
str := sub(newFreeMemoryPointer, 32)
// Clean the last word of memory it may not be overwritten.
mstore(str, 0)
// Cache the end of the memory to calculate the length later.
let end := str
// We write the string from rightmost digit to leftmost digit.
// The following is essentially a do-while loop that also handles the zero case.
// prettier-ignore
for { let temp := value } 1 {} {
// Move the pointer 1 byte to the left.
str := sub(str, 1)
// Write the character to the pointer.
// The ASCII index of the '0' character is 48.
mstore8(str, add(48, mod(temp, 10)))
// Keep dividing temp until zero.
temp := div(temp, 10)
// prettier-ignore
if iszero(temp) { break }
}
// Compute and cache the final total length of the string.
let length := sub(end, str)
// Move the pointer 32 bytes leftwards to make room for the length.
str := sub(str, 32)
// Store the string's length at the start of memory allocated for our string.
mstore(str, length)
}
}
}