Compiler Explorer

Source code

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

/// @title Math library for computing sqrt prices from ticks and vice versa
/// @notice Computes sqrt price for ticks of size 1.0001, i.e. sqrt(1.0001^tick) as fixed point Q64.96 numbers. Supports
/// prices between 2**-128 and 2**128
contract TickMath {
    /// @dev The minimum tick that may be passed to #getSqrtPriceAtTick computed from log base 1.0001 of 2**-128
    /// @dev If ever MIN_TICK and MAX_TICK are not centered around 0, the absTick logic in getSqrtPriceAtTick cannot be used
    int24 internal constant MIN_TICK = -887272;
    /// @dev The maximum tick that may be passed to #getSqrtPriceAtTick computed from log base 1.0001 of 2**128
    /// @dev If ever MIN_TICK and MAX_TICK are not centered around 0, the absTick logic in getSqrtPriceAtTick cannot be used
    int24 internal constant MAX_TICK = 887272;

/// @dev The minimum tick spacing value drawn from the range of type int16 that is greater than 0, i.e. min from the range [1, 32767]
    int24 internal constant MIN_TICK_SPACING = 1;
    /// @dev The maximum tick spacing value drawn from the range of type int16, i.e. max from the range [1, 32767]
    int24 internal constant MAX_TICK_SPACING = type(int16).max;

/// @dev The minimum value that can be returned from #getSqrtPriceAtTick. Equivalent to getSqrtPriceAtTick(MIN_TICK)
    uint160 internal constant MIN_SQRT_PRICE = 4295128739;
    /// @dev The maximum value that can be returned from #getSqrtPriceAtTick. Equivalent to getSqrtPriceAtTick(MAX_TICK)
    uint160 internal constant MAX_SQRT_PRICE = 1461446703485210103287273052203988822378723970342;
    /// @dev A threshold used for optimized bounds check, equals `MAX_SQRT_PRICE - MIN_SQRT_PRICE - 1`
    uint160 internal constant MAX_SQRT_PRICE_MINUS_MIN_SQRT_PRICE_MINUS_ONE =
        1461446703485210103287273052203988822378723970342 - 4295128739 - 1;

/// @notice Given a tickSpacing, compute the maximum usable tick
    function maxUsableTick(int24 tickSpacing) internal pure returns (int24) {
        unchecked {
            return (MAX_TICK / tickSpacing) * tickSpacing;
        }
    }

/// @notice Given a tickSpacing, compute the minimum usable tick
    function minUsableTick(int24 tickSpacing) internal pure returns (int24) {
        unchecked {
            return (MIN_TICK / tickSpacing) * tickSpacing;
        }
    }

/// @notice Calculates sqrt(1.0001^tick) * 2^96
    /// @dev Throws if |tick| > max tick
    /// @param tick The input tick for the above formula
    /// @return sqrtPriceX96 A Fixed point Q64.96 number representing the sqrt of the price of the two assets (currency1/currency0)
    /// at the given tick
    function getSqrtPriceAtTick(int24 tick) public pure returns (uint160 sqrtPriceX96) {
        unchecked {
            uint256 absTick;
            assembly ("memory-safe") {
                tick := signextend(2, tick)
                // mask = 0 if tick >= 0 else -1 (all 1s)
                let mask := sar(255, tick)
                // if tick >= 0, |tick| = tick = 0 ^ tick
                // if tick < 0, |tick| = ~~|tick| = ~(-|tick| - 1) = ~(tick - 1) = (-1) ^ (tick - 1)
                // either way, |tick| = mask ^ (tick + mask)
                absTick := xor(mask, add(mask, tick))
            }

//if (absTick > uint256(int256(MAX_TICK))) InvalidTick.selector.revertWith(tick);
            require (absTick <= uint256(int256(MAX_TICK)), 'T');

// The tick is decomposed into bits, and for each bit with index i that is set, the product of 1/sqrt(1.0001^(2^i))
            // is calculated (using Q128.128). The constants used for this calculation are rounded to the nearest integer

// Equivalent to:
            //     price = absTick & 0x1 != 0 ? 0xfffcb933bd6fad37aa2d162d1a594001 : 0x100000000000000000000000000000000;
            //     or price = int(2**128 / sqrt(1.0001)) if (absTick & 0x1) else 1 << 128
            uint256 price;
            assembly ("memory-safe") {
                price := xor(shl(128, 1), mul(xor(shl(128, 1), 0xfffcb933bd6fad37aa2d162d1a594001), and(absTick, 0x1)))
            }

if (absTick & 0x2 != 0) price = (price * 0xfff97272373d413259a46990580e213a) >> 128;
            if (absTick & 0x4 != 0) price = (price * 0xfff2e50f5f656932ef12357cf3c7fdcc) >> 128;
            if (absTick & 0x8 != 0) price = (price * 0xffe5caca7e10e4e61c3624eaa0941cd0) >> 128;
            if (absTick & 0x10 != 0) price = (price * 0xffcb9843d60f6159c9db58835c926644) >> 128;
            if (absTick & 0x20 != 0) price = (price * 0xff973b41fa98c081472e6896dfb254c0) >> 128;
            if (absTick & 0x40 != 0) price = (price * 0xff2ea16466c96a3843ec78b326b52861) >> 128;
            if (absTick & 0x80 != 0) price = (price * 0xfe5dee046a99a2a811c461f1969c3053) >> 128;
            if (absTick & 0x100 != 0) price = (price * 0xfcbe86c7900a88aedcffc83b479aa3a4) >> 128;
            if (absTick & 0x200 != 0) price = (price * 0xf987a7253ac413176f2b074cf7815e54) >> 128;
            if (absTick & 0x400 != 0) price = (price * 0xf3392b0822b70005940c7a398e4b70f3) >> 128;
            if (absTick & 0x800 != 0) price = (price * 0xe7159475a2c29b7443b29c7fa6e889d9) >> 128;
            if (absTick & 0x1000 != 0) price = (price * 0xd097f3bdfd2022b8845ad8f792aa5825) >> 128;
            if (absTick & 0x2000 != 0) price = (price * 0xa9f746462d870fdf8a65dc1f90e061e5) >> 128;
            if (absTick & 0x4000 != 0) price = (price * 0x70d869a156d2a1b890bb3df62baf32f7) >> 128;
            if (absTick & 0x8000 != 0) price = (price * 0x31be135f97d08fd981231505542fcfa6) >> 128;
            if (absTick & 0x10000 != 0) price = (price * 0x9aa508b5b7a84e1c677de54f3e99bc9) >> 128;
            if (absTick & 0x20000 != 0) price = (price * 0x5d6af8dedb81196699c329225ee604) >> 128;
            if (absTick & 0x40000 != 0) price = (price * 0x2216e584f5fa1ea926041bedfe98) >> 128;
            if (absTick & 0x80000 != 0) price = (price * 0x48a170391f7dc42444e8fa2) >> 128;

assembly ("memory-safe") {
                // if (tick > 0) price = type(uint256).max / price;
                if sgt(tick, 0) { price := div(not(0), price) }

// this divides by 1<<32 rounding up to go from a Q128.128 to a Q128.96.
                // we then downcast because we know the result always fits within 160 bits due to our tick input constraint
                // we round up in the division so getTickAtSqrtPrice of the output price is always consistent
                // `sub(shl(32, 1), 1)` is `type(uint32).max`
                // `price + type(uint32).max` will not overflow because `price` fits in 192 bits
                sqrtPriceX96 := shr(32, add(price, sub(shl(32, 1), 1)))
            }
        }
    }
}