library PamPamMath {
    function byteToUint(byte b) internal pure returns(uint8) {
        return uint8(b) - 48;
    }

    function isDigit(byte b) internal pure returns(bool) {
        return b >= 48 && b <= 57;
    }

    function isDot(byte b) internal pure returns(bool) {
        return b == 46;
    }

    function isE(byte b) internal pure returns(bool) {
        return b == 69 || b == 101;
    }

    function isPlus(byte b) internal pure returns(bool) {
        return b == 43;
    }

    function isMinus(byte b) internal pure returns(bool) {
        return b == 45;
    }

    enum Part { Int, Fraq, Exp }

    function parseCoinMarketCurrency(string num) internal pure returns (uint256) {
        bytes memory buf = bytes(num);
        uint256 result = 0;
        Part part = Part.Int;
        uint8 fraqLength = 0;
        uint8 exp = 0;
        bool negExp = false;

        for(uint i = 0; i < buf.length; i++) {
            byte b = buf[i];
            if (isDigit(b)) {
                if (part == Part.Int || part == Part.Fraq) {
                    result *= 10;
                    result += byteToUint(b);
                    if (part == Part.Fraq) {
                        fraqLength++;
                    }
                } else {
                    exp *= 10;
                    exp += byteToUint(b);
                }
            } else if (isDot(b)) {
                part = Part.Fraq;
            } else if (isE(b)) {
                part = Part.Exp;
            } else if (isMinus(b) && part == Part.Exp) {
                negExp = true;
            }
        }

        uint256 pow = 0;
        if (negExp) {
            pow = 18 - fraqLength - exp;
        } else {
            pow = 18 - fraqLength + exp;
        }

        return result * (10 ** pow);
    }
}