/*
 * --------------------------------------------------------------------------------------
 * Company              : 江苏中信博新能源科技股份有限公司上海子公司 2020-2021 版权所有
 * --------------------------------------------------------------------------------------
 * file Name            : crc16.c 
 * Description			    : crc-lib
 * --------------------------------------------------------------------------------------
 * Tool Versions        : uVision V5.29.0.0
 * Target Device        : STM32F103|GD32F103
 * --------------------------------------------------------------------------------------
 * Engineer				      : tangtao
 * Revision				      : V0.0
 * Created Date			    : 2021.09.18
 * --------------------------------------------------------------------------------------
 * Engineer				      : 
 * Revision				      : 
 * Modified Date		    : 
 * Additional Comments	: 
 * --------------------------------------------------------------------------------------
 */

/*************************************************
  Function              : CRC16_HalfWord()
  Description           : CRC16_HalfWord 
  Input                 : *buf, number       
  Output                : crc16        
  Return                : unsigned short
  Engineer				      : tangtao
  Revision				      : V0.0
  Modified Date			    : 2021.09.18
  Additional Comments	  : 
*************************************************/
unsigned short CRC16_HalfWord(unsigned short *buf, unsigned short num_of_bytes)
{
    unsigned short i     = 0;
    unsigned char  j     = 0;
    unsigned short w_crc = 0xFFFF;
    unsigned char  temp  = 0;
    
    for(i = 0; i < num_of_bytes; i++)
    {
        temp  =  buf[i]>>8;
        w_crc ^= temp;
        for(j = 0; j < 8; j++)
        {
            if(w_crc & 1)
            {
                w_crc >>= 1;
                w_crc ^=  0xA001;
            }
            else
            {
                w_crc >>= 1;
            }
        }

        temp  =  (buf[i]&0xff);
        w_crc ^= temp;
        for(j = 0; j < 8; j++)
        {
            if(w_crc & 1)
            {
                w_crc >>= 1;
                w_crc ^=  0xA001;
            }
            else
            {
                w_crc >>= 1;
            }
        }      
    }   
    return w_crc;
}

/*************************************************
  Function              : CRC16_Byte()
  Description           : CRC16_Byte 
  Input                 : *buf, number       
  Output                : crc16        
  Return                : unsigned short
  Engineer				      : tangtao
  Revision				      : V0.0
  Modified Date			    : 2021.09.18
  Additional Comments	  : 
*************************************************/
unsigned short CRC16_Byte(unsigned char *buf, unsigned short num_of_bytes)
{
    unsigned short i     = 0;
    unsigned char  j     = 0;
    unsigned short w_crc = 0xFFFF;
    
    for(i = 0; i < num_of_bytes; i++)
    {
        w_crc ^= buf[i];
        for(j = 0; j < 8; j++)
        {
            if(w_crc & 1)
            {
                w_crc >>= 1;
                w_crc ^= 0xA001;
            }
            else
            {
                w_crc >>= 1;
            }
        }
    }
    return w_crc;
}