Fixed6.sol

// SPDX-License-Identifier: Apache-2.0
pragma solidity ^0.8.13;

import "@openzeppelin/contracts/utils/math/SignedMath.sol";
import "../NumberMath.sol";
import "./Fixed18.sol";
import "./UFixed6.sol";

/// @dev Fixed6 type
type Fixed6 is int256;
using Fixed6Lib for Fixed6 global;
type Fixed6Storage is bytes32;
using Fixed6StorageLib for Fixed6Storage global;

/**
 * @title Fixed6Lib
 * @notice Library for the signed fixed-decimal type.
 */
library Fixed6Lib {
    error Fixed6OverflowError(uint256 value);

    int256 private constant BASE = 1e6;
    Fixed6 public constant ZERO = Fixed6.wrap(0);
    Fixed6 public constant ONE = Fixed6.wrap(BASE);
    Fixed6 public constant NEG_ONE = Fixed6.wrap(-1 * BASE);
    Fixed6 public constant MAX = Fixed6.wrap(type(int256).max);
    Fixed6 public constant MIN = Fixed6.wrap(type(int256).min);

    /**
     * @notice Creates a signed fixed-decimal from an unsigned fixed-decimal
     * @param a Unsigned fixed-decimal
     * @return New signed fixed-decimal
     */
    function from(UFixed6 a) internal pure returns (Fixed6) {
        uint256 value = UFixed6.unwrap(a);
        if (value > uint256(type(int256).max)) revert Fixed6OverflowError(value);
        return Fixed6.wrap(int256(value));
    }

    /**
     * @notice Creates a signed fixed-decimal from a sign and an unsigned fixed-decimal
     * @param s Sign
     * @param m Unsigned fixed-decimal magnitude
     * @return New signed fixed-decimal
     */
    function from(int256 s, UFixed6 m) internal pure returns (Fixed6) {
        if (s > 0) return from(m);
        if (s < 0) {
            // Since from(m) multiplies m by BASE, from(m) cannot be type(int256).min
            // which is the only value that would overflow when negated. Therefore,
            // we can safely negate from(m) without checking for overflow.
            unchecked { return Fixed6.wrap(-1 * Fixed6.unwrap(from(m))); }
        }
        return ZERO;
    }

    /**
     * @notice Creates a signed fixed-decimal from a signed integer
     * @param a Signed number
     * @return New signed fixed-decimal
     */
    function from(int256 a) internal pure returns (Fixed6) {
        return Fixed6.wrap(a * BASE);
    }

    /**
     * @notice Creates a signed fixed-decimal from a base-18 signed fixed-decimal
     * @param a Base-18 signed fixed-decimal
     * @return New signed fixed-decimal
     */
    function from(Fixed18 a) internal pure returns (Fixed6) {
        return Fixed6.wrap(Fixed18.unwrap(a) / 1e12);
    }

    /**
     * @notice Creates a signed fixed-decimal from a base-18 signed fixed-decimal
     * @param a Base-18 signed fixed-decimal
     * @param roundOut Whether to round the result away from zero if there is a remainder
     * @return New signed fixed-decimal
     */
    function from(Fixed18 a, bool roundOut) internal pure returns (Fixed6) {
        return roundOut ? Fixed6.wrap(NumberMath.divOut(Fixed18.unwrap(a), 1e12)): from(a);
    }

    /**
     * @notice Returns whether the signed fixed-decimal is equal to zero.
     * @param a Signed fixed-decimal
     * @return Whether the signed fixed-decimal is zero.
     */
    function isZero(Fixed6 a) internal pure returns (bool) {
        return Fixed6.unwrap(a) == 0;
    }

    /**
     * @notice Adds two signed fixed-decimals `a` and `b` together
     * @param a First signed fixed-decimal
     * @param b Second signed fixed-decimal
     * @return Resulting summed signed fixed-decimal
     */
    function add(Fixed6 a, Fixed6 b) internal pure returns (Fixed6) {
        return Fixed6.wrap(Fixed6.unwrap(a) + Fixed6.unwrap(b));
    }

    /**
     * @notice Subtracts signed fixed-decimal `b` from `a`
     * @param a Signed fixed-decimal to subtract from
     * @param b Signed fixed-decimal to subtract
     * @return Resulting subtracted signed fixed-decimal
     */
    function sub(Fixed6 a, Fixed6 b) internal pure returns (Fixed6) {
        return Fixed6.wrap(Fixed6.unwrap(a) - Fixed6.unwrap(b));
    }

    /**
     * @notice Multiplies two signed fixed-decimals `a` and `b` together
     * @param a First signed fixed-decimal
     * @param b Second signed fixed-decimal
     * @return Resulting multiplied signed fixed-decimal
     */
    function mul(Fixed6 a, Fixed6 b) internal pure returns (Fixed6) {
        return Fixed6.wrap(Fixed6.unwrap(a) * Fixed6.unwrap(b) / BASE);
    }

    /**
     * @notice Multiplies two signed fixed-decimals `a` and `b` together, rounding the result away from zero if there is a remainder
     * @param a First signed fixed-decimal
     * @param b Second signed fixed-decimal
     * @return Resulting multiplied signed fixed-decimal
     */
    function mulOut(Fixed6 a, Fixed6 b) internal pure returns (Fixed6) {
        return Fixed6.wrap(NumberMath.divOut(Fixed6.unwrap(a) * Fixed6.unwrap(b), BASE));
    }

    /**
     * @notice Divides signed fixed-decimal `a` by `b`
     * @param a Signed fixed-decimal to divide
     * @param b Signed fixed-decimal to divide by
     * @return Resulting divided signed fixed-decimal
     */
    function div(Fixed6 a, Fixed6 b) internal pure returns (Fixed6) {
        return Fixed6.wrap(Fixed6.unwrap(a) * BASE / Fixed6.unwrap(b));
    }

    /**
     * @notice Divides signed fixed-decimal `a` by `b`, rounding the result away from zero if there is a remainder
     * @param a Signed fixed-decimal to divide
     * @param b Signed fixed-decimal to divide by
     * @return Resulting divided signed fixed-decimal
     */
    function divOut(Fixed6 a, Fixed6 b) internal pure returns (Fixed6) {
        return Fixed6Lib.from(sign(a) * sign(b), a.abs().divOut(b.abs()));
    }

    /**
     * @notice Divides unsigned fixed-decimal `a` by `b`
     * @dev Does not revert on divide-by-0, instead returns `ONE` for `0/0`, `MAX` for `n/0`, and `MIN` for `-n/0`.
     * @param a Unsigned fixed-decimal to divide
     * @param b Unsigned fixed-decimal to divide by
     * @return Resulting divided unsigned fixed-decimal
     */
    function unsafeDiv(Fixed6 a, Fixed6 b) internal pure returns (Fixed6) {
        if (isZero(b)) {
            if (gt(a, ZERO)) return MAX;
            if (lt(a, ZERO)) return MIN;
            return ONE;
        } else {
            return div(a, b);
        }
    }

    /**
     * @notice Divides unsigned fixed-decimal `a` by `b`, rounding the result away from zero if there is a remainder
     * @dev Does not revert on divide-by-0, instead returns `ONE` for `0/0`, `MAX` for `n/0`, and `MIN` for `-n/0`.
     * @param a Unsigned fixed-decimal to divide
     * @param b Unsigned fixed-decimal to divide by
     * @return Resulting divided unsigned fixed-decimal
     */
    function unsafeDivOut(Fixed6 a, Fixed6 b) internal pure returns (Fixed6) {
        if (isZero(b)) {
            if (gt(a, ZERO)) return MAX;
            if (lt(a, ZERO)) return MIN;
            return ONE;
        } else {
            return divOut(a, b);
        }
    }

    /**
     * @notice Computes a * b / c without loss of precision due to BASE conversion
     * @param a First signed fixed-decimal
     * @param b Signed number to multiply by
     * @param c Signed number to divide by
     * @return Resulting computation
     */
    function muldiv(Fixed6 a, int256 b, int256 c) internal pure returns (Fixed6) {
        return muldiv(a, Fixed6.wrap(b), Fixed6.wrap(c));
    }

    /**
     * @notice Computes a * b / c without loss of precision due to BASE conversion, rounding the result up to the next integer if there is a remainder
     * @param a First signed fixed-decimal
     * @param b Signed number to multiply by
     * @param c Signed number to divide by
     * @return Resulting computation
     */
    function muldivOut(Fixed6 a, int256 b, int256 c) internal pure returns (Fixed6) {
        return muldivOut(a, Fixed6.wrap(b), Fixed6.wrap(c));
    }

    /**
     * @notice Computes a * b / c without loss of precision due to BASE conversion
     * @param a First signed fixed-decimal
     * @param b Signed fixed-decimal to multiply by
     * @param c Signed fixed-decimal to divide by
     * @return Resulting computation
     */
    function muldiv(Fixed6 a, Fixed6 b, Fixed6 c) internal pure returns (Fixed6) {
        return Fixed6.wrap(Fixed6.unwrap(a) * Fixed6.unwrap(b) / Fixed6.unwrap(c));
    }

    /**
     * @notice Computes a * b / c without loss of precision due to BASE conversion, rounding the result up to the next integer if there is a remainder
     * @param a First signed fixed-decimal
     * @param b Signed fixed-decimal to multiply by
     * @param c Signed fixed-decimal to divide by
     * @return Resulting computation
     */
    function muldivOut(Fixed6 a, Fixed6 b, Fixed6 c) internal pure returns (Fixed6) {
        return Fixed6.wrap(NumberMath.divOut(Fixed6.unwrap(a) * Fixed6.unwrap(b), Fixed6.unwrap(c)));
    }

    /**
     * @notice Returns whether signed fixed-decimal `a` is equal to `b`
     * @param a First signed fixed-decimal
     * @param b Second signed fixed-decimal
     * @return Whether `a` is equal to `b`
     */
    function eq(Fixed6 a, Fixed6 b) internal pure returns (bool) {
        return compare(a, b) == 1;
    }

    /**
     * @notice Returns whether signed fixed-decimal `a` is greater than `b`
     * @param a First signed fixed-decimal
     * @param b Second signed fixed-decimal
     * @return Whether `a` is greater than `b`
     */
    function gt(Fixed6 a, Fixed6 b) internal pure returns (bool) {
        return compare(a, b) == 2;
    }

    /**
     * @notice Returns whether signed fixed-decimal `a` is less than `b`
     * @param a First signed fixed-decimal
     * @param b Second signed fixed-decimal
     * @return Whether `a` is less than `b`
     */
    function lt(Fixed6 a, Fixed6 b) internal pure returns (bool) {
        return compare(a, b) == 0;
    }

    /**
     * @notice Returns whether signed fixed-decimal `a` is greater than or equal to `b`
     * @param a First signed fixed-decimal
     * @param b Second signed fixed-decimal
     * @return Whether `a` is greater than or equal to `b`
     */
    function gte(Fixed6 a, Fixed6 b) internal pure returns (bool) {
        return gt(a, b) || eq(a, b);
    }

    /**
     * @notice Returns whether signed fixed-decimal `a` is less than or equal to `b`
     * @param a First signed fixed-decimal
     * @param b Second signed fixed-decimal
     * @return Whether `a` is less than or equal to `b`
     */
    function lte(Fixed6 a, Fixed6 b) internal pure returns (bool) {
        return lt(a, b) || eq(a, b);
    }

    /**
     * @notice Compares the signed fixed-decimals `a` and `b`
     * @dev Returns: 2 for greater than
     *               1 for equal to
     *               0 for less than
     * @param a First signed fixed-decimal
     * @param b Second signed fixed-decimal
     * @return Compare result of `a` and `b`
     */
    function compare(Fixed6 a, Fixed6 b) internal pure returns (uint256) {
        (int256 au, int256 bu) = (Fixed6.unwrap(a), Fixed6.unwrap(b));
        if (au > bu) return 2;
        if (au < bu) return 0;
        return 1;
    }

    /**
     * @notice Returns a signed fixed-decimal representing the ratio of `a` over `b`
     * @param a First signed number
     * @param b Second signed number
     * @return Ratio of `a` over `b`
     */
    function ratio(int256 a, int256 b) internal pure returns (Fixed6) {
        return Fixed6.wrap(a * BASE / b);
    }

    /**
     * @notice Returns the minimum of signed fixed-decimals `a` and `b`
     * @param a First signed fixed-decimal
     * @param b Second signed fixed-decimal
     * @return Minimum of `a` and `b`
     */
    function min(Fixed6 a, Fixed6 b) internal pure returns (Fixed6) {
        return Fixed6.wrap(SignedMath.min(Fixed6.unwrap(a), Fixed6.unwrap(b)));
    }

    /**
     * @notice Returns the maximum of signed fixed-decimals `a` and `b`
     * @param a First signed fixed-decimal
     * @param b Second signed fixed-decimal
     * @return Maximum of `a` and `b`
     */
    function max(Fixed6 a, Fixed6 b) internal pure returns (Fixed6) {
        return Fixed6.wrap(SignedMath.max(Fixed6.unwrap(a), Fixed6.unwrap(b)));
    }

    /**
     * @notice Converts the signed fixed-decimal into an integer, truncating any decimal portion
     * @param a Signed fixed-decimal
     * @return Truncated signed number
     */
    function truncate(Fixed6 a) internal pure returns (int256) {
        return Fixed6.unwrap(a) / BASE;
    }

    /**
     * @notice Returns the sign of the signed fixed-decimal
     * @dev Returns: -1 for negative
     *                0 for zero
     *                1 for positive
     * @param a Signed fixed-decimal
     * @return Sign of the signed fixed-decimal
     */
    function sign(Fixed6 a) internal pure returns (int256) {
        if (Fixed6.unwrap(a) > 0) return 1;
        if (Fixed6.unwrap(a) < 0) return -1;
        return 0;
    }

    /**
     * @notice Returns the absolute value of the signed fixed-decimal
     * @param a Signed fixed-decimal
     * @return Absolute value of the signed fixed-decimal
     */
    function abs(Fixed6 a) internal pure returns (UFixed6) {
        return UFixed6.wrap(SignedMath.abs(Fixed6.unwrap(a)));
    }
}

library Fixed6StorageLib {
    function read(Fixed6Storage self) internal view returns (Fixed6 value) {
        assembly ("memory-safe") {
            value := sload(self)
        }
    }

    function store(Fixed6Storage self, Fixed6 value) internal {
        assembly ("memory-safe") {
            sstore(self, value)
        }
    }
}