modbuscr.c

DS12C887在MSP430上读写操作程序

typedef unsigned short word;
typedef unsigned char  byte;
const word genpoly = 0xa001;

static word code _crc16_16_table[16] = {
    0x0000, 0xCC01, 0xD801, 0x1400, 0xF001, 0x3C00, 0x2800, 0xE401,
    0xA001, 0x6C00, 0x7800, 0xB401, 0x5000, 0x9C01, 0x8801, 0x4400
};

word data crc;
word make_crc_rbank_1(void idata *pMem, byte size) using 1
{
  byte idata *pData = (byte idata*)pMem;
  crc = 0xFFFF;

  while (size-- > 0) {
    crc ^= *pData ++;
    crc = (crc >> 4) ^ _crc16_16_table[crc & 15];
    crc = (crc >> 4) ^ _crc16_16_table[crc & 15];
  }

  return crc;
}

word make_crc_rbank_0(void idata *pMem, byte size)
{
  byte idata *pData = (byte idata*)pMem;
  crc = 0xFFFF;

  while (size-- > 0) {
    crc ^= *pData ++;
    crc = (crc >> 4) ^ _crc16_16_table[crc & 15];
    crc = (crc >> 4) ^ _crc16_16_table[crc & 15];
  }

  return crc;
}