关于 CRC16 计算

1万 · 2019-1-8 14:09

unsigned short CRC16_USB(unsigned char *puchMsg, unsigned int usDataLen)
{
  unsigned short wCRCin = 0xFFFF;
  unsigned short wCPoly = 0x8005;
  unsigned char wChar = 0;

  while (usDataLen--)
  {
      wChar = *(puchMsg++);
      InvertUint8(&wChar,&wChar);
      wCRCin ^= (wChar << 8);
      for(int i = 0;i < 8;i++)
      {
      if(wCRCin & 0x8000)
         wCRCin = (wCRCin << 1) ^ wCPoly;
      else
         wCRCin = wCRCin << 1;
      }
  }
  InvertUint16(&wCRCin,&wCRCin);
  return (wCRCin^0xFFFF) ;
}
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1万 · 2019-1-8 14:09

void InvertUint8(unsigned char *dBuf,unsigned char *srcBuf)
{
int i;
unsigned char tmp[4];
tmp[0] = 0;
for(i=0;i< 8;i++)
{
if(srcBuf[0]& (1 << i))
tmp[0]|=1<<(7-i);
}
dBuf[0] = tmp[0];

}
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1万 · 2019-1-8 14:09

void InvertUint16(unsigned short *dBuf,unsigned short *srcBuf)
{
int i;
unsigned short tmp[4];
tmp[0] = 0;
for(i=0;i< 16;i++)
{
if(srcBuf[0]& (1 << i))
tmp[0]|=1<<(15 - i);
}
dBuf[0] = tmp[0];
}
---------------------

1万 · 2019-1-8 14:12

void InvertUint32(unsigned int *dBuf,unsigned int *srcBuf)
{
int i;
unsigned int tmp[4];

tmp[0] = 0;

for(i=0;i< 32;i++)
{
if(srcBuf[0]& (1 << i))
tmp[0]|=1<<(15 - i);
}
dBuf[0] = tmp[0];
}
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1万 · 2019-1-8 14:13

//CRC32算法：
unsigned int CRC32(unsigned char *puchMsg, unsigned int usDataLen)
{
  int i;
  unsigned int wCRCin = 0xFFFFFFFF;
  unsigned int wCPoly = 0x04C11DB7;
  unsigned int wChar = 0;
  while (usDataLen--)
  {
      wChar = *(puchMsg++);
      InvertUint8((unsigned char *)&wChar,(unsigned char *)&wChar);
      wCRCin ^= (wChar << 24);
      for(i = 0;i < 8;i++)
      {
      if(wCRCin & 0x80000000)
         wCRCin = (wCRCin << 1) ^ wCPoly;
      else
         wCRCin = wCRCin << 1;
      }
  }
  InvertUint32(&wCRCin,&wCRCin);
  return (wCRCin ^ 0xFFFFFFFF) ;
}
---------------------

1万 · 2019-2-1 11:26

写的好详细啊