library ABDKMath64x64 {
    /*
     * Minimum value signed 64.64-bit fixed point number may have.
     */
    int128 private constant MIN_64x64 = -0x80000000000000000000000000000000;

    /*
     * Maximum value signed 64.64-bit fixed point number may have.
     */
    int128 private constant MAX_64x64 = 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF;

    /**
     * Convert signed 256-bit integer number into signed 64.64-bit fixed point
     * number.  Revert on overflow.
     *
     * @param x signed 256-bit integer number
     * @return signed 64.64-bit fixed point number
     */
    function fromInt(int256 x) internal pure returns (int128) {
        unchecked {
            require(x >= -0x8000000000000000 && x <= 0x7FFFFFFFFFFFFFFF);
            return int128(x << 64);
        }
    }

    /**
     * Convert signed 64.64 fixed point number into signed 64-bit integer number
     * rounding down.
     *
     * @param x signed 64.64-bit fixed point number
     * @return signed 64-bit integer number
     */
    function toInt(int128 x) internal pure returns (int64) {
        unchecked {
            return int64(x >> 64);
        }
    }

    /**
     * Convert unsigned 256-bit integer number into signed 64.64-bit fixed point
     * number.  Revert on overflow.
     *
     * @param x unsigned 256-bit integer number
     * @return signed 64.64-bit fixed point number
     */
    function fromUInt(uint256 x) internal pure returns (int128) {
        unchecked {
            require(x <= 0x7FFFFFFFFFFFFFFF);
            return int128(int256(x << 64));
        }
    }

    /**
     * Convert signed 64.64 fixed point number into unsigned 64-bit integer
     * number rounding down.  Revert on underflow.
     *
     * @param x signed 64.64-bit fixed point number
     * @return unsigned 64-bit integer number
     */
    function toUInt(int128 x) internal pure returns (uint64) {
        unchecked {
            require(x >= 0);
            return uint64(uint128(x >> 64));
        }
    }

    /**
     * Convert signed 128.128 fixed point number into signed 64.64-bit fixed point
     * number rounding down.  Revert on overflow.
     *
     * @param x signed 128.128-bin fixed point number
     * @return signed 64.64-bit fixed point number
     */
    function from128x128(int256 x) internal pure returns (int128) {
        unchecked {
            int256 result = x >> 64;
            require(result >= MIN_64x64 && result <= MAX_64x64);
            return int128(result);
        }
    }

    /**
     * Convert signed 64.64 fixed point number into signed 128.128 fixed point
     * number.
     *
     * @param x signed 64.64-bit fixed point number
     * @return signed 128.128 fixed point number
     */
    function to128x128(int128 x) internal pure returns (int256) {
        unchecked {
            return int256(x) << 64;
        }
    }

    /**
     * Calculate x + y.  Revert on overflow.
     *
     * @param x signed 64.64-bit fixed point number
     * @param y signed 64.64-bit fixed point number
     * @return signed 64.64-bit fixed point number
     */
    function add(int128 x, int128 y) internal pure returns (int128) {
        unchecked {
            int256 result = int256(x) + y;
            require(result >= MIN_64x64 && result <= MAX_64x64);
            return int128(result);
        }
    }

    /**
     * Calculate x - y.  Revert on overflow.
     *
     * @param x signed 64.64-bit fixed point number
     * @param y signed 64.64-bit fixed point number
     * @return signed 64.64-bit fixed point number
     */
    function sub(int128 x, int128 y) internal pure returns (int128) {
        unchecked {
            int256 result = int256(x) - y;
            require(result >= MIN_64x64 && result <= MAX_64x64);
            return int128(result);
        }
    }

    /**
     * Calculate x * y rounding down.  Revert on overflow.
     *
     * @param x signed 64.64-bit fixed point number
     * @param y signed 64.64-bit fixed point number
     * @return signed 64.64-bit fixed point number
     */
    function mul(int128 x, int128 y) internal pure returns (int128) {
        unchecked {
            int256 result = (int256(x) * y) >> 64;
            require(result >= MIN_64x64 && result <= MAX_64x64);
            return int128(result);
        }
    }

    /**
     * Calculate x * y rounding towards zero, where x is signed 64.64 fixed point
     * number and y is signed 256-bit integer number.  Revert on overflow.
     *
     * @param x signed 64.64 fixed point number
     * @param y signed 256-bit integer number
     * @return signed 256-bit integer number
     */
    function muli(int128 x, int256 y) internal pure returns (int256) {
        unchecked {
            if (x == MIN_64x64) {
                require(
                    y >= -0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF &&
                        y <= 0x1000000000000000000000000000000000000000000000000
                );
                return -y << 63;
            } else {
                bool negativeResult = false;
                if (x < 0) {
                    x = -x;
                    negativeResult = true;
                }
                if (y < 0) {
                    y = -y; // We rely on overflow behavior here
                    negativeResult = !negativeResult;
                }
                uint256 absoluteResult = mulu(x, uint256(y));
                if (negativeResult) {
                    require(
                        absoluteResult <=
                            0x8000000000000000000000000000000000000000000000000000000000000000
                    );
                    return -int256(absoluteResult); // We rely on overflow behavior here
                } else {
                    require(
                        absoluteResult <=
                            0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
                    );
                    return int256(absoluteResult);
                }
            }
        }
    }

    /**
     * Calculate x * y rounding down, where x is signed 64.64 fixed point number
     * and y is unsigned 256-bit integer number.  Revert on overflow.
     *
     * @param x signed 64.64 fixed point number
     * @param y unsigned 256-bit integer number
     * @return unsigned 256-bit integer number
     */
    function mulu(int128 x, uint256 y) internal pure returns (uint256) {
        unchecked {
            if (y == 0) return 0;

            require(x >= 0);

            uint256 lo = (uint256(int256(x)) *
                (y & 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF)) >> 64;
            uint256 hi = uint256(int256(x)) * (y >> 128);

            require(hi <= 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF);
            hi <<= 64;

            require(
                hi <=
                    0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF -
                        lo
            );
            return hi + lo;
        }
    }

    /**
     * Calculate x / y rounding towards zero.  Revert on overflow or when y is
     * zero.
     *
     * @param x signed 64.64-bit fixed point number
     * @param y signed 64.64-bit fixed point number
     * @return signed 64.64-bit fixed point number
     */
    function div(int128 x, int128 y) internal pure returns (int128) {
        unchecked {
            require(y != 0);
            int256 result = (int256(x) << 64) / y;
            require(result >= MIN_64x64 && result <= MAX_64x64);
            return int128(result);
        }
    }

    /**
     * Calculate x / y rounding towards zero, where x and y are signed 256-bit
     * integer numbers.  Revert on overflow or when y is zero.
     *
     * @param x signed 256-bit integer number
     * @param y signed 256-bit integer number
     * @return signed 64.64-bit fixed point number
     */
    function divi(int256 x, int256 y) internal pure returns (int128) {
        unchecked {
            require(y != 0);

            bool negativeResult = false;
            if (x < 0) {
                x = -x; // We rely on overflow behavior here
                negativeResult = true;
            }
            if (y < 0) {
                y = -y; // We rely on overflow behavior here
                negativeResult = !negativeResult;
            }
            uint128 absoluteResult = divuu(uint256(x), uint256(y));
            if (negativeResult) {
                require(absoluteResult <= 0x80000000000000000000000000000000);
                return -int128(absoluteResult); // We rely on overflow behavior here
            } else {
                require(absoluteResult <= 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF);
                return int128(absoluteResult); // We rely on overflow behavior here
            }
        }
    }

    /**
     * Calculate x / y rounding towards zero, where x and y are unsigned 256-bit
     * integer numbers.  Revert on overflow or when y is zero.
     *
     * @param x unsigned 256-bit integer number
     * @param y unsigned 256-bit integer number
     * @return signed 64.64-bit fixed point number
     */
    function divu(uint256 x, uint256 y) internal pure returns (int128) {
        unchecked {
            require(y != 0);
            uint128 result = divuu(x, y);
            require(result <= uint128(MAX_64x64));
            return int128(result);
        }
    }

    /**
     * Calculate -x.  Revert on overflow.
     *
     * @param x signed 64.64-bit fixed point number
     * @return signed 64.64-bit fixed point number
     */
    function neg(int128 x) internal pure returns (int128) {
        unchecked {
            require(x != MIN_64x64);
            return -x;
        }
    }

    /**
     * Calculate |x|.  Revert on overflow.
     *
     * @param x signed 64.64-bit fixed point number
     * @return signed 64.64-bit fixed point number
     */
    function abs(int128 x) internal pure returns (int128) {
        unchecked {
            require(x != MIN_64x64);
            return x < 0 ? -x : x;
        }
    }

    /**
     * Calculate 1 / x rounding towards zero.  Revert on overflow or when x is
     * zero.
     *
     * @param x signed 64.64-bit fixed point number
     * @return signed 64.64-bit fixed point number
     */
    function inv(int128 x) internal pure returns (int128) {
        unchecked {
            require(x != 0);
            int256 result = int256(0x100000000000000000000000000000000) / x;
            require(result >= MIN_64x64 && result <= MAX_64x64);
            return int128(result);
        }
    }

    /**
     * Calculate arithmetics average of x and y, i.e. (x + y) / 2 rounding down.
     *
     * @param x signed 64.64-bit fixed point number
     * @param y signed 64.64-bit fixed point number
     * @return signed 64.64-bit fixed point number
     */
    function avg(int128 x, int128 y) internal pure returns (int128) {
        unchecked {
            return int128((int256(x) + int256(y)) >> 1);
        }
    }

    /**
     * Calculate geometric average of x and y, i.e. sqrt (x * y) rounding down.
     * Revert on overflow or in case x * y is negative.
     *
     * @param x signed 64.64-bit fixed point number
     * @param y signed 64.64-bit fixed point number
     * @return signed 64.64-bit fixed point number
     */
    function gavg(int128 x, int128 y) internal pure returns (int128) {
        unchecked {
            int256 m = int256(x) * int256(y);
            require(m >= 0);
            require(
                m <
                    0x4000000000000000000000000000000000000000000000000000000000000000
            );
            return int128(sqrtu(uint256(m)));
        }
    }

    /**
     * Calculate x^y assuming 0^0 is 1, where x is signed 64.64 fixed point number
     * and y is unsigned 256-bit integer number.  Revert on overflow.
     *
     * @param x signed 64.64-bit fixed point number
     * @param y uint256 value
     * @return signed 64.64-bit fixed point number
     */
    function pow(int128 x, uint256 y) internal pure returns (int128) {
        unchecked {
            bool negative = x < 0 && y & 1 == 1;

            uint256 absX = uint128(x < 0 ? -x : x);
            uint256 absResult;
            absResult = 0x100000000000000000000000000000000;

            if (absX <= 0x10000000000000000) {
                absX <<= 63;
                while (y != 0) {
                    if (y & 0x1 != 0) {
                        absResult = (absResult * absX) >> 127;
                    }
                    absX = (absX * absX) >> 127;

                    if (y & 0x2 != 0) {
                        absResult = (absResult * absX) >> 127;
                    }
                    absX = (absX * absX) >> 127;

                    if (y & 0x4 != 0) {
                        absResult = (absResult * absX) >> 127;
                    }
                    absX = (absX * absX) >> 127;

                    if (y & 0x8 != 0) {
                        absResult = (absResult * absX) >> 127;
                    }
                    absX = (absX * absX) >> 127;

                    y >>= 4;
                }

                absResult >>= 64;
            } else {
                uint256 absXShift = 63;
                if (absX < 0x1000000000000000000000000) {
                    absX <<= 32;
                    absXShift -= 32;
                }
                if (absX < 0x10000000000000000000000000000) {
                    absX <<= 16;
                    absXShift -= 16;
                }
                if (absX < 0x1000000000000000000000000000000) {
                    absX <<= 8;
                    absXShift -= 8;
                }
                if (absX < 0x10000000000000000000000000000000) {
                    absX <<= 4;
                    absXShift -= 4;
                }
                if (absX < 0x40000000000000000000000000000000) {
                    absX <<= 2;
                    absXShift -= 2;
                }
                if (absX < 0x80000000000000000000000000000000) {
                    absX <<= 1;
                    absXShift -= 1;
                }

                uint256 resultShift = 0;
                while (y != 0) {
                    require(absXShift < 64);

                    if (y & 0x1 != 0) {
                        absResult = (absResult * absX) >> 127;
                        resultShift += absXShift;
                        if (absResult > 0x100000000000000000000000000000000) {
                            absResult >>= 1;
                            resultShift += 1;
                        }
                    }
                    absX = (absX * absX) >> 127;
                    absXShift <<= 1;
                    if (absX >= 0x100000000000000000000000000000000) {
                        absX >>= 1;
                        absXShift += 1;
                    }

                    y >>= 1;
                }

                require(resultShift < 64);
                absResult >>= 64 - resultShift;
            }
            int256 result = negative ? -int256(absResult) : int256(absResult);
            require(result >= MIN_64x64 && result <= MAX_64x64);
            return int128(result);
        }
    }

    /**
     * Calculate sqrt (x) rounding down.  Revert if x < 0.
     *
     * @param x signed 64.64-bit fixed point number
     * @return signed 64.64-bit fixed point number
     */
    function sqrt(int128 x) internal pure returns (int128) {
        unchecked {
            require(x >= 0);
            return int128(sqrtu(uint256(int256(x)) << 64));
        }
    }

    /**
     * Calculate binary logarithm of x.  Revert if x <= 0.
     *
     * @param x signed 64.64-bit fixed point number
     * @return signed 64.64-bit fixed point number
     */
    function log_2(int128 x) internal pure returns (int128) {
        unchecked {
            require(x > 0);

            int256 msb = 0;
            int256 xc = x;
            if (xc >= 0x10000000000000000) {
                xc >>= 64;
                msb += 64;
            }
            if (xc >= 0x100000000) {
                xc >>= 32;
                msb += 32;
            }
            if (xc >= 0x10000) {
                xc >>= 16;
                msb += 16;
            }
            if (xc >= 0x100) {
                xc >>= 8;
                msb += 8;
            }
            if (xc >= 0x10) {
                xc >>= 4;
                msb += 4;
            }
            if (xc >= 0x4) {
                xc >>= 2;
                msb += 2;
            }
            if (xc >= 0x2) msb += 1; // No need to shift xc anymore

            int256 result = (msb - 64) << 64;
            uint256 ux = uint256(int256(x)) << uint256(127 - msb);
            for (int256 bit = 0x8000000000000000; bit > 0; bit >>= 1) {
                ux *= ux;
                uint256 b = ux >> 255;
                ux >>= 127 + b;
                result += bit * int256(b);
            }

            return int128(result);
        }
    }

    /**
     * Calculate natural logarithm of x.  Revert if x <= 0.
     *
     * @param x signed 64.64-bit fixed point number
     * @return signed 64.64-bit fixed point number
     */
    function ln(int128 x) internal pure returns (int128) {
        unchecked {
            require(x > 0);

            return
                int128(
                    int256(
                        (uint256(int256(log_2(x))) *
                            0xB17217F7D1CF79ABC9E3B39803F2F6AF) >> 128
                    )
                );
        }
    }

    /**
     * Calculate binary exponent of x.  Revert on overflow.
     *
     * @param x signed 64.64-bit fixed point number
     * @return signed 64.64-bit fixed point number
     */
    function exp_2(int128 x) internal pure returns (int128) {
        unchecked {
            require(x < 0x400000000000000000); // Overflow

            if (x < -0x400000000000000000) return 0; // Underflow

            uint256 result = 0x80000000000000000000000000000000;

            if (x & 0x8000000000000000 > 0)
                result = (result * 0x16A09E667F3BCC908B2FB1366EA957D3E) >> 128;
            if (x & 0x4000000000000000 > 0)
                result = (result * 0x1306FE0A31B7152DE8D5A46305C85EDEC) >> 128;
            if (x & 0x2000000000000000 > 0)
                result = (result * 0x1172B83C7D517ADCDF7C8C50EB14A791F) >> 128;
            if (x & 0x1000000000000000 > 0)
                result = (result * 0x10B5586CF9890F6298B92B71842A98363) >> 128;
            if (x & 0x800000000000000 > 0)
                result = (result * 0x1059B0D31585743AE7C548EB68CA417FD) >> 128;
            if (x & 0x400000000000000 > 0)
                result = (result * 0x102C9A3E778060EE6F7CACA4F7A29BDE8) >> 128;
            if (x & 0x200000000000000 > 0)
                result = (result * 0x10163DA9FB33356D84A66AE336DCDFA3F) >> 128;
            if (x & 0x100000000000000 > 0)
                result = (result * 0x100B1AFA5ABCBED6129AB13EC11DC9543) >> 128;
            if (x & 0x80000000000000 > 0)
                result = (result * 0x10058C86DA1C09EA1FF19D294CF2F679B) >> 128;
            if (x & 0x40000000000000 > 0)
                result = (result * 0x1002C605E2E8CEC506D21BFC89A23A00F) >> 128;
            if (x & 0x20000000000000 > 0)
                result = (result * 0x100162F3904051FA128BCA9C55C31E5DF) >> 128;
            if (x & 0x10000000000000 > 0)
                result = (result * 0x1000B175EFFDC76BA38E31671CA939725) >> 128;
            if (x & 0x8000000000000 > 0)
                result = (result * 0x100058BA01FB9F96D6CACD4B180917C3D) >> 128;
            if (x & 0x4000000000000 > 0)
                result = (result * 0x10002C5CC37DA9491D0985C348C68E7B3) >> 128;
            if (x & 0x2000000000000 > 0)
                result = (result * 0x1000162E525EE054754457D5995292026) >> 128;
            if (x & 0x1000000000000 > 0)
                result = (result * 0x10000B17255775C040618BF4A4ADE83FC) >> 128;
            if (x & 0x800000000000 > 0)
                result = (result * 0x1000058B91B5BC9AE2EED81E9B7D4CFAB) >> 128;
            if (x & 0x400000000000 > 0)
                result = (result * 0x100002C5C89D5EC6CA4D7C8ACC017B7C9) >> 128;
            if (x & 0x200000000000 > 0)
                result = (result * 0x10000162E43F4F831060E02D839A9D16D) >> 128;
            if (x & 0x100000000000 > 0)
                result = (result * 0x100000B1721BCFC99D9F890EA06911763) >> 128;
            if (x & 0x80000000000 > 0)
                result = (result * 0x10000058B90CF1E6D97F9CA14DBCC1628) >> 128;
            if (x & 0x40000000000 > 0)
                result = (result * 0x1000002C5C863B73F016468F6BAC5CA2B) >> 128;
            if (x & 0x20000000000 > 0)
                result = (result * 0x100000162E430E5A18F6119E3C02282A5) >> 128;
            if (x & 0x10000000000 > 0)
                result = (result * 0x1000000B1721835514B86E6D96EFD1BFE) >> 128;
            if (x & 0x8000000000 > 0)
                result = (result * 0x100000058B90C0B48C6BE5DF846C5B2EF) >> 128;
            if (x & 0x4000000000 > 0)
                result = (result * 0x10000002C5C8601CC6B9E94213C72737A) >> 128;
            if (x & 0x2000000000 > 0)
                result = (result * 0x1000000162E42FFF037DF38AA2B219F06) >> 128;
            if (x & 0x1000000000 > 0)
                result = (result * 0x10000000B17217FBA9C739AA5819F44F9) >> 128;
            if (x & 0x800000000 > 0)
                result = (result * 0x1000000058B90BFCDEE5ACD3C1CEDC823) >> 128;
            if (x & 0x400000000 > 0)
                result = (result * 0x100000002C5C85FE31F35A6A30DA1BE50) >> 128;
            if (x & 0x200000000 > 0)
                result = (result * 0x10000000162E42FF0999CE3541B9FFFCF) >> 128;
            if (x & 0x100000000 > 0)
                result = (result * 0x100000000B17217F80F4EF5AADDA45554) >> 128;
            if (x & 0x80000000 > 0)
                result = (result * 0x10000000058B90BFBF8479BD5A81B51AD) >> 128;
            if (x & 0x40000000 > 0)
                result = (result * 0x1000000002C5C85FDF84BD62AE30A74CC) >> 128;
            if (x & 0x20000000 > 0)
                result = (result * 0x100000000162E42FEFB2FED257559BDAA) >> 128;
            if (x & 0x10000000 > 0)
                result = (result * 0x1000000000B17217F7D5A7716BBA4A9AE) >> 128;
            if (x & 0x8000000 > 0)
                result = (result * 0x100000000058B90BFBE9DDBAC5E109CCE) >> 128;
            if (x & 0x4000000 > 0)
                result = (result * 0x10000000002C5C85FDF4B15DE6F17EB0D) >> 128;
            if (x & 0x2000000 > 0)
                result = (result * 0x1000000000162E42FEFA494F1478FDE05) >> 128;
            if (x & 0x1000000 > 0)
                result = (result * 0x10000000000B17217F7D20CF927C8E94C) >> 128;
            if (x & 0x800000 > 0)
                result = (result * 0x1000000000058B90BFBE8F71CB4E4B33D) >> 128;
            if (x & 0x400000 > 0)
                result = (result * 0x100000000002C5C85FDF477B662B26945) >> 128;
            if (x & 0x200000 > 0)
                result = (result * 0x10000000000162E42FEFA3AE53369388C) >> 128;
            if (x & 0x100000 > 0)
                result = (result * 0x100000000000B17217F7D1D351A389D40) >> 128;
            if (x & 0x80000 > 0)
                result = (result * 0x10000000000058B90BFBE8E8B2D3D4EDE) >> 128;
            if (x & 0x40000 > 0)
                result = (result * 0x1000000000002C5C85FDF4741BEA6E77E) >> 128;
            if (x & 0x20000 > 0)
                result = (result * 0x100000000000162E42FEFA39FE95583C2) >> 128;
            if (x & 0x10000 > 0)
                result = (result * 0x1000000000000B17217F7D1CFB72B45E1) >> 128;
            if (x & 0x8000 > 0)
                result = (result * 0x100000000000058B90BFBE8E7CC35C3F0) >> 128;
            if (x & 0x4000 > 0)
                result = (result * 0x10000000000002C5C85FDF473E242EA38) >> 128;
            if (x & 0x2000 > 0)
                result = (result * 0x1000000000000162E42FEFA39F02B772C) >> 128;
            if (x & 0x1000 > 0)
                result = (result * 0x10000000000000B17217F7D1CF7D83C1A) >> 128;
            if (x & 0x800 > 0)
                result = (result * 0x1000000000000058B90BFBE8E7BDCBE2E) >> 128;
            if (x & 0x400 > 0)
                result = (result * 0x100000000000002C5C85FDF473DEA871F) >> 128;
            if (x & 0x200 > 0)
                result = (result * 0x10000000000000162E42FEFA39EF44D91) >> 128;
            if (x & 0x100 > 0)
                result = (result * 0x100000000000000B17217F7D1CF79E949) >> 128;
            if (x & 0x80 > 0)
                result = (result * 0x10000000000000058B90BFBE8E7BCE544) >> 128;
            if (x & 0x40 > 0)
                result = (result * 0x1000000000000002C5C85FDF473DE6ECA) >> 128;
            if (x & 0x20 > 0)
                result = (result * 0x100000000000000162E42FEFA39EF366F) >> 128;
            if (x & 0x10 > 0)
                result = (result * 0x1000000000000000B17217F7D1CF79AFA) >> 128;
            if (x & 0x8 > 0)
                result = (result * 0x100000000000000058B90BFBE8E7BCD6D) >> 128;
            if (x & 0x4 > 0)
                result = (result * 0x10000000000000002C5C85FDF473DE6B2) >> 128;
            if (x & 0x2 > 0)
                result = (result * 0x1000000000000000162E42FEFA39EF358) >> 128;
            if (x & 0x1 > 0)
                result = (result * 0x10000000000000000B17217F7D1CF79AB) >> 128;

            result >>= uint256(int256(63 - (x >> 64)));
            require(result <= uint256(int256(MAX_64x64)));

            return int128(int256(result));
        }
    }

    /**
     * Calculate natural exponent of x.  Revert on overflow.
     *
     * @param x signed 64.64-bit fixed point number
     * @return signed 64.64-bit fixed point number
     */
    function exp(int128 x) internal pure returns (int128) {
        unchecked {
            require(x < 0x400000000000000000); // Overflow

            if (x < -0x400000000000000000) return 0; // Underflow

            return
                exp_2(
                    int128(
                        (int256(x) * 0x171547652B82FE1777D0FFDA0D23A7D12) >> 128
                    )
                );
        }
    }

    /**
     * Calculate x / y rounding towards zero, where x and y are unsigned 256-bit
     * integer numbers.  Revert on overflow or when y is zero.
     *
     * @param x unsigned 256-bit integer number
     * @param y unsigned 256-bit integer number
     * @return unsigned 64.64-bit fixed point number
     */
    function divuu(uint256 x, uint256 y) private pure returns (uint128) {
        unchecked {
            require(y != 0);

            uint256 result;

            if (x <= 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF)
                result = (x << 64) / y;
            else {
                uint256 msb = 192;
                uint256 xc = x >> 192;
                if (xc >= 0x100000000) {
                    xc >>= 32;
                    msb += 32;
                }
                if (xc >= 0x10000) {
                    xc >>= 16;
                    msb += 16;
                }
                if (xc >= 0x100) {
                    xc >>= 8;
                    msb += 8;
                }
                if (xc >= 0x10) {
                    xc >>= 4;
                    msb += 4;
                }
                if (xc >= 0x4) {
                    xc >>= 2;
                    msb += 2;
                }
                if (xc >= 0x2) msb += 1; // No need to shift xc anymore

                result = (x << (255 - msb)) / (((y - 1) >> (msb - 191)) + 1);
                require(result <= 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF);

                uint256 hi = result * (y >> 128);
                uint256 lo = result * (y & 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF);

                uint256 xh = x >> 192;
                uint256 xl = x << 64;

                if (xl < lo) xh -= 1;
                xl -= lo; // We rely on overflow behavior here
                lo = hi << 128;
                if (xl < lo) xh -= 1;
                xl -= lo; // We rely on overflow behavior here

                assert(xh == hi >> 128);

                result += xl / y;
            }

            require(result <= 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF);
            return uint128(result);
        }
    }

    /**
     * Calculate sqrt (x) rounding down, where x is unsigned 256-bit integer
     * number.
     *
     * @param x unsigned 256-bit integer number
     * @return unsigned 128-bit integer number
     */
    function sqrtu(uint256 x) private pure returns (uint128) {
        unchecked {
            if (x == 0) return 0;
            else {
                uint256 xx = x;
                uint256 r = 1;
                if (xx >= 0x100000000000000000000000000000000) {
                    xx >>= 128;
                    r <<= 64;
                }
                if (xx >= 0x10000000000000000) {
                    xx >>= 64;
                    r <<= 32;
                }
                if (xx >= 0x100000000) {
                    xx >>= 32;
                    r <<= 16;
                }
                if (xx >= 0x10000) {
                    xx >>= 16;
                    r <<= 8;
                }
                if (xx >= 0x100) {
                    xx >>= 8;
                    r <<= 4;
                }
                if (xx >= 0x10) {
                    xx >>= 4;
                    r <<= 2;
                }
                if (xx >= 0x8) {
                    r <<= 1;
                }
                r = (r + x / r) >> 1;
                r = (r + x / r) >> 1;
                r = (r + x / r) >> 1;
                r = (r + x / r) >> 1;
                r = (r + x / r) >> 1;
                r = (r + x / r) >> 1;
                r = (r + x / r) >> 1; // Seven iterations should be enough
                uint256 r1 = x / r;
                return uint128(r < r1 ? r : r1);
            }
        }
    }
}
/**
 * Smart contract library of mathematical functions operating with signed
 * 64.64-bit fixed point numbers.  Signed 64.64-bit fixed point number is
 * basically a simple fraction whose numerator is signed 128-bit integer and
 * denominator is 2^64.  As long as denominator is always the same, there is no
 * need to store it, thus in Solidity signed 64.64-bit fixed point numbers are
 * represented by int128 type holding only the numerator.
 */
function fromInt(int256 x) internal pure returns (int128) {
    unchecked {
        require(x >= -0x8000000000000000 && x <= 0x7FFFFFFFFFFFFFFF);
        return int128(x << 64);
    }
}

/**
 * Convert signed 256-bit integer number into signed 64.64-bit fixed point
 * number.  Revert on overflow.
 *
 * @param x signed 256-bit integer number
 * @return signed 64.64-bit fixed point number
 */