C#按比特位设置当前位的比特值

public void Test() 
    {
        byte[] results = new byte[1];
        results[0] = 0xff;
        int temp = results[0];

        byte b = SetBit(results[0], 7, 0);
        Console.WriteLine(b);
    }

    /// <summary>
    /// 设置字节中的指定Bit的值
    /// </summary>
    /// <param name="this">字节</param>
    /// <param name="index">Bit的索引值(0-7)</param>
    /// <param name="bitvalue">Bit值(0,1)</param>
    /// <returns></returns>
    public  byte SetBit(byte testb, int index, int bitvalue)
    {
        var _byte = testb;
        if (bitvalue == 1)
        {
            switch (index)
            {
                case 0: { return _byte |= 0x01; }
                case 1: { return _byte |= 0x02; }
                case 2: { return _byte |= 0x04; }
                case 3: { return _byte |= 0x08; }
                case 4: { return _byte |= 0x10; }
                case 5: { return _byte |= 0x20; }
                case 6: { return _byte |= 0x40; }
                case 7: { return _byte |= 0x80; }
                default: { return _byte; }
            }
        }
        else
        {
            switch (index)
            {
                case 0: { return _byte &= 0xFE; }
                case 1: { return _byte &= 0xFD; }
                case 2: { return _byte &= 0xFB; }
                case 3: { return _byte &= 0xF7; }
                case 4: { return _byte &= 0xEF; }
                case 5: { return _byte &= 0xDF; }
                case 6: { return _byte &= 0xBF; }
                case 7: { return _byte &= 0x7F; }
                default: { return _byte; }
            }
        }
    }