C# 字节数组位操作_c#byte中位移动

public class BitBuffer
    {
        private byte[] m_data = null;
        private int m_dataLen = 0;
        private int m_pos = 0;
 
        public BitBuffer(byte[] data)
        {
            m_data = data;
            m_dataLen = data.Length;
        }
 
        public BitBuffer(byte[] data, int len)
        {
            m_data = data;
            m_dataLen = len;
        }
 
        public void Skip(int offset)
        {
            m_pos += offset;
 
            if (m_dataLen * 8 < m_pos)
            {
                throw new Exception("m_data.Length * 8 < m_offset");
            }
        }
 
        public int Read(int size, bool noseek = false)
        {
            int starBytePos = m_pos / 8;
            int starBitOffset = m_pos % 8;
            int starBitMask = 0;
            for (int i = 0; i < 8 - starBitOffset; ++i)
            {
                starBitMask <<= 1;
                starBitMask += 1;
            }
 
            int spanByte = (size + 7) / 8;
            if (4 < spanByte)
            {
                throw new Exception("4 < spanByte");
            }
 
            int value = 0;
            for (int i = 0; i < spanByte; ++i)
            {
                value <<= 8;
                value += m_data[starBytePos + i];
 
                if (0 == i)
                {
                    value &= starBitMask;
                }
            }
 
            int endBitOffset = (m_pos + size) % 8;
            if (0 < endBitOffset)
            {
                value >>= (8 - endBitOffset);
            }
 
            if (!noseek)
            {
                Skip(size);
            }
 
            return value;
        }
 
        public byte[] ReadBytes(int size, bool noseek = false)
        {
            if (size <= 0)
            {
                return null;
            }
 
            byte[] temp = new byte[size / 8];
 
            Array.Copy(m_data, m_pos / 8, temp, 0, size / 8);
 
            if (!noseek)
            {
                Skip(size);
            }
 
            return temp;
        }
    }