各位大佬，这段C代码小弟实在看不懂，在线求助谢谢

char crcCACheck(char *p, char len) 
{     
    short t_short =0;     
    for(int i=0; i<len; i++)    
    {         
        t_short +=*p++; 
        t_short += t_short >>8;         
        t_short &=0xFF;     
    }          
    return 0xFF - t_short; 
}    

校验的数据如下：

 Len  PhyId  prim     appId  L/H   D1  D2  D3   D4 CRC    
08    8e     00        00    2f   18   ff  e3   1b  df

Len byte the value is the number of bytes in the frame, Len/CRC bytes are not included CRC byte this byte is summed after Len field to the byte in front of CRC with carry should be 0xFF. Every frame has a CRC byte, this byte is calculated with an add-with-carry method, bytes in frame are added from Len field, together with the carry value.
**Every frame has a Len byte, which calculate the frame bytes, does not include Len/CRC byte **
这是一段C代码（应该是C吧），写的是对crc校验，我想改写成python，一时无能为力，向各位大佬求助，十分感谢。

a = 'Hello'
b = 0
for x in a:
  b += ord(x)
    b += b>>8
    b = b & 0xff
c = 0xff - b
print(c)