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

79 lines
4.0 KiB
Solidity

// SPDX-License-Identifier: BUSL-1.1
pragma solidity >=0.5.0;
import './BitMath.sol';
/// @title Packed tick initialized state library
/// @notice Stores a packed mapping of tick index to its initialized state
/// @dev The mapping uses int16 for keys since ticks are represented as int24 and there are 256 (2^8) values per word.
library TickBitmap {
/// @notice Computes the position in the mapping where the initialized bit for a tick lives
/// @param tick The tick for which to compute the position
/// @return wordPos The key in the mapping containing the word in which the bit is stored
/// @return bitPos The bit position in the word where the flag is stored
function position(int24 tick) private pure returns (int16 wordPos, uint8 bitPos) {
wordPos = int16(tick >> 8);
bitPos = uint8(tick % 256);
}
/// @notice Flips the initialized state for a given tick from false to true, or vice versa
/// @param self The mapping in which to flip the tick
/// @param tick The tick to flip
/// @param tickSpacing The spacing between usable ticks
function flipTick(
mapping(int16 => uint256) storage self,
int24 tick,
int24 tickSpacing
) internal {
require(tick % tickSpacing == 0); // ensure that the tick is spaced
(int16 wordPos, uint8 bitPos) = position(tick / tickSpacing);
uint256 mask = 1 << bitPos;
self[wordPos] ^= mask;
}
/// @notice Returns the next initialized tick contained in the same word (or adjacent word) as the tick that is either
/// to the left (less than or equal to) or right (greater than) of the given tick
/// @param self The mapping in which to compute the next initialized tick
/// @param tick The starting tick
/// @param tickSpacing The spacing between usable ticks
/// @param lte Whether to search for the next initialized tick to the left (less than or equal to the starting tick)
/// @return next The next initialized or uninitialized tick up to 256 ticks away from the current tick
/// @return initialized Whether the next tick is initialized, as the function only searches within up to 256 ticks
function nextInitializedTickWithinOneWord(
mapping(int16 => uint256) storage self,
int24 tick,
int24 tickSpacing,
bool lte
) internal view returns (int24 next, bool initialized) {
int24 compressed = tick / tickSpacing;
if (tick < 0 && tick % tickSpacing != 0) compressed--; // round towards negative infinity
if (lte) {
(int16 wordPos, uint8 bitPos) = position(compressed);
// all the 1s at or to the right of the current bitPos
uint256 mask = (1 << bitPos) - 1 + (1 << bitPos);
uint256 masked = self[wordPos] & mask;
// if there are no initialized ticks to the right of or at the current tick, return rightmost in the word
initialized = masked != 0;
// overflow/underflow is possible, but prevented externally by limiting both tickSpacing and tick
next = initialized
? (compressed - int24(bitPos - BitMath.mostSignificantBit(masked))) * tickSpacing
: (compressed - int24(bitPos)) * tickSpacing;
} else {
// start from the word of the next tick, since the current tick state doesn't matter
(int16 wordPos, uint8 bitPos) = position(compressed + 1);
// all the 1s at or to the left of the bitPos
uint256 mask = ~((1 << bitPos) - 1);
uint256 masked = self[wordPos] & mask;
// if there are no initialized ticks to the left of the current tick, return leftmost in the word
initialized = masked != 0;
// overflow/underflow is possible, but prevented externally by limiting both tickSpacing and tick
next = initialized
? (compressed + 1 + int24(BitMath.leastSignificantBit(masked) - bitPos)) * tickSpacing
: (compressed + 1 + int24(type(uint8).max - bitPos)) * tickSpacing;
}
}
}