dsa-connectors/contracts/arbitrum/connectors/uniswap-sell-beta/libraries/BitMath.sol
pradyuman-verma 69ce278335
update
2021-11-19 18:29:55 +05:30

95 lines
2.7 KiB
Solidity

// SPDX-License-Identifier: GPL-2.0-or-later
pragma solidity >=0.5.0;
/// @title BitMath
/// @dev This library provides functionality for computing bit properties of an unsigned integer
library BitMath {
/// @notice Returns the index of the most significant bit of the number,
/// where the least significant bit is at index 0 and the most significant bit is at index 255
/// @dev The function satisfies the property:
/// x >= 2**mostSignificantBit(x) and x < 2**(mostSignificantBit(x)+1)
/// @param x the value for which to compute the most significant bit, must be greater than 0
/// @return r the index of the most significant bit
function mostSignificantBit(uint256 x) internal pure returns (uint8 r) {
require(x > 0);
if (x >= 0x100000000000000000000000000000000) {
x >>= 128;
r += 128;
}
if (x >= 0x10000000000000000) {
x >>= 64;
r += 64;
}
if (x >= 0x100000000) {
x >>= 32;
r += 32;
}
if (x >= 0x10000) {
x >>= 16;
r += 16;
}
if (x >= 0x100) {
x >>= 8;
r += 8;
}
if (x >= 0x10) {
x >>= 4;
r += 4;
}
if (x >= 0x4) {
x >>= 2;
r += 2;
}
if (x >= 0x2) r += 1;
}
/// @notice Returns the index of the least significant bit of the number,
/// where the least significant bit is at index 0 and the most significant bit is at index 255
/// @dev The function satisfies the property:
/// (x & 2**leastSignificantBit(x)) != 0 and (x & (2**(leastSignificantBit(x)) - 1)) == 0)
/// @param x the value for which to compute the least significant bit, must be greater than 0
/// @return r the index of the least significant bit
function leastSignificantBit(uint256 x) internal pure returns (uint8 r) {
require(x > 0);
r = 255;
if (x & type(uint128).max > 0) {
r -= 128;
} else {
x >>= 128;
}
if (x & type(uint64).max > 0) {
r -= 64;
} else {
x >>= 64;
}
if (x & type(uint32).max > 0) {
r -= 32;
} else {
x >>= 32;
}
if (x & type(uint16).max > 0) {
r -= 16;
} else {
x >>= 16;
}
if (x & type(uint8).max > 0) {
r -= 8;
} else {
x >>= 8;
}
if (x & 0xf > 0) {
r -= 4;
} else {
x >>= 4;
}
if (x & 0x3 > 0) {
r -= 2;
} else {
x >>= 2;
}
if (x & 0x1 > 0) r -= 1;
}
}