如何将这个crc16 C实现转换为java

Question

嗨，我有这个C crc16实现：

const unsigned short CRCtbl[ 256 ] =
{
    0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241,
    0xC601, 0x06C0, 0x0780, 0xC741, 0x0500, 0xC5C1, 0xC481, 0x0440,
    0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40,
    0x0A00, 0xCAC1, 0xCB81, 0x0B40, 0xC901, 0x09C0, 0x0880, 0xC841,
    0xD801, 0x18C0, 0x1980, 0xD941, 0x1B00, 0xDBC1, 0xDA81, 0x1A40,
    0x1E00, 0xDEC1, 0xDF81, 0x1F40, 0xDD01, 0x1DC0, 0x1C80, 0xDC41,
    0x1400, 0xD4C1, 0xD581, 0x1540, 0xD701, 0x17C0, 0x1680, 0xD641,
    0xD201, 0x12C0, 0x1380, 0xD341, 0x1100, 0xD1C1, 0xD081, 0x1040,
    0xF001, 0x30C0, 0x3180, 0xF141, 0x3300, 0xF3C1, 0xF281, 0x3240,
    0x3600, 0xF6C1, 0xF781, 0x3740, 0xF501, 0x35C0, 0x3480, 0xF441,
    0x3C00, 0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0, 0x3E80, 0xFE41,
    0xFA01, 0x3AC0, 0x3B80, 0xFB41, 0x3900, 0xF9C1, 0xF881, 0x3840,
    0x2800, 0xE8C1, 0xE981, 0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41,
    0xEE01, 0x2EC0, 0x2F80, 0xEF41, 0x2D00, 0xEDC1, 0xEC81, 0x2C40,
    0xE401, 0x24C0, 0x2580, 0xE541, 0x2700, 0xE7C1, 0xE681, 0x2640,
    0x2200, 0xE2C1, 0xE381, 0x2340, 0xE101, 0x21C0, 0x2080, 0xE041,
    0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281, 0x6240,
    0x6600, 0xA6C1, 0xA781, 0x6740, 0xA501, 0x65C0, 0x6480, 0xA441,
    0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80, 0xAE41,
    0xAA01, 0x6AC0, 0x6B80, 0xAB41, 0x6900, 0xA9C1, 0xA881, 0x6840,
    0x7800, 0xB8C1, 0xB981, 0x7940, 0xBB01, 0x7BC0, 0x7A80, 0xBA41,
    0xBE01, 0x7EC0, 0x7F80, 0xBF41, 0x7D00, 0xBDC1, 0xBC81, 0x7C40,
    0xB401, 0x74C0, 0x7580, 0xB541, 0x7700, 0xB7C1, 0xB681, 0x7640,
    0x7200, 0xB2C1, 0xB381, 0x7340, 0xB101, 0x71C0, 0x7080, 0xB041,
    0x5000, 0x90C1, 0x9181, 0x5140, 0x9301, 0x53C0, 0x5280, 0x9241,
    0x9601, 0x56C0, 0x5780, 0x9741, 0x5500, 0x95C1, 0x9481, 0x5440,
    0x9C01, 0x5CC0, 0x5D80, 0x9D41, 0x5F00, 0x9FC1, 0x9E81, 0x5E40,
    0x5A00, 0x9AC1, 0x9B81, 0x5B40, 0x9901, 0x59C0, 0x5880, 0x9841,
    0x8801, 0x48C0, 0x4980, 0x8941, 0x4B00, 0x8BC1, 0x8A81, 0x4A40,
    0x4E00, 0x8EC1, 0x8F81, 0x4F40, 0x8D01, 0x4DC0, 0x4C80, 0x8C41,
    0x4400, 0x84C1, 0x8581, 0x4540, 0x8701, 0x47C0, 0x4680, 0x8641,
    0x8201, 0x42C0, 0x4380, 0x8341, 0x4100, 0x81C1, 0x8081,
    0x4040
};
unsigned short Crc_16(unsigned char *str, int n)
{
    unsigned short crc = 0xFFFF;
    do
    {
        crc = ( crc >> 8 ) ^ CRCtbl[ ( crc & 0xFF ) ^ *str ];
        str++;
    }
    while(--n);
    return(crc);
}

我需要将其转换为java。我的问题是，由于 java 不提供无符号的 int 类型，因此在某些情况下实现会失败（当将其视为无符号时，某些 info[] 字节为>127）。

private int crc_xor(byte[] info) {
    int[] table = {
            0x0000 ,0xC0C1 ,0xC181 ,0x0140 ,0xC301 ,0x03C0 ,0x0280 ,0xC241,
            0xC601 ,0x06C0 ,0x0780 ,0xC741 ,0x0500 ,0xC5C1 ,0xC481 ,0x0440,
            0xCC01 ,0x0CC0 ,0x0D80 ,0xCD41 ,0x0F00 ,0xCFC1 ,0xCE81 ,0x0E40,
            0x0A00 ,0xCAC1 ,0xCB81 ,0x0B40 ,0xC901 ,0x09C0 ,0x0880 ,0xC841,
            0xD801 ,0x18C0 ,0x1980 ,0xD941 ,0x1B00 ,0xDBC1 ,0xDA81 ,0x1A40,
            0x1E00 ,0xDEC1 ,0xDF81 ,0x1F40 ,0xDD01 ,0x1DC0 ,0x1C80 ,0xDC41,
            0x1400 ,0xD4C1 ,0xD581 ,0x1540 ,0xD701 ,0x17C0 ,0x1680 ,0xD641,
            0xD201 ,0x12C0 ,0x1380 ,0xD341 ,0x1100 ,0xD1C1 ,0xD081 ,0x1040,
            0xF001 ,0x30C0 ,0x3180 ,0xF141 ,0x3300 ,0xF3C1 ,0xF281 ,0x3240,
            0x3600 ,0xF6C1 ,0xF781 ,0x3740 ,0xF501 ,0x35C0 ,0x3480 ,0xF441,
            0x3C00 ,0xFCC1 ,0xFD81 ,0x3D40 ,0xFF01 ,0x3FC0 ,0x3E80 ,0xFE41,
            0xFA01 ,0x3AC0 ,0x3B80 ,0xFB41 ,0x3900 ,0xF9C1 ,0xF881 ,0x3840,
            0x2800 ,0xE8C1 ,0xE981 ,0x2940 ,0xEB01 ,0x2BC0 ,0x2A80 ,0xEA41,
            0xEE01 ,0x2EC0 ,0x2F80 ,0xEF41 ,0x2D00 ,0xEDC1 ,0xEC81 ,0x2C40,
            0xE401 ,0x24C0 ,0x2580 ,0xE541 ,0x2700 ,0xE7C1 ,0xE681 ,0x2640,
            0x2200 ,0xE2C1 ,0xE381 ,0x2340 ,0xE101 ,0x21C0 ,0x2080 ,0xE041,
            0xA001 ,0x60C0 ,0x6180 ,0xA141 ,0x6300 ,0xA3C1 ,0xA281 ,0x6240,
            0x6600 ,0xA6C1 ,0xA781 ,0x6740 ,0xA501 ,0x65C0 ,0x6480 ,0xA441,
            0x6C00 ,0xACC1 ,0xAD81 ,0x6D40 ,0xAF01 ,0x6FC0 ,0x6E80 ,0xAE41,
            0xAA01 ,0x6AC0 ,0x6B80 ,0xAB41 ,0x6900 ,0xA9C1 ,0xA881 ,0x6840,
            0x7800 ,0xB8C1 ,0xB981 ,0x7940 ,0xBB01 ,0x7BC0 ,0x7A80 ,0xBA41,
            0xBE01 ,0x7EC0 ,0x7F80 ,0xBF41 ,0x7D00 ,0xBDC1 ,0xBC81 ,0x7C40,
            0xB401 ,0x74C0 ,0x7580 ,0xB541 ,0x7700 ,0xB7C1 ,0xB681 ,0x7640,
            0x7200 ,0xB2C1 ,0xB381 ,0x7340 ,0xB101 ,0x71C0 ,0x7080 ,0xB041,
            0x5000 ,0x90C1 ,0x9181 ,0x5140 ,0x9301 ,0x53C0 ,0x5280 ,0x9241,
            0x9601 ,0x56C0 ,0x5780 ,0x9741 ,0x5500 ,0x95C1 ,0x9481 ,0x5440,
            0x9C01 ,0x5CC0 ,0x5D80 ,0x9D41 ,0x5F00 ,0x9FC1 ,0x9E81 ,0x5E40,
            0x5A00 ,0x9AC1 ,0x9B81 ,0x5B40 ,0x9901 ,0x59C0 ,0x5880 ,0x9841,
            0x8801 ,0x48C0 ,0x4980 ,0x8941 ,0x4B00 ,0x8BC1 ,0x8A81 ,0x4A40,
            0x4E00 ,0x8EC1 ,0x8F81 ,0x4F40 ,0x8D01 ,0x4DC0 ,0x4C80 ,0x8C41,
            0x4400 ,0x84C1 ,0x8581 ,0x4540 ,0x8701 ,0x47C0 ,0x4680 ,0x8641,
            0x8201 ,0x42C0 ,0x4380 ,0x8341 ,0x4100 ,0x81C1 ,0x8081 ,0x4040};
            int crc16=0;
            int pos=0;
            int lungh=info.length;
            lungh-=1;
            while(lungh>=0)
            {
                crc16 = ((crc16 >> 8) ^ table[(crc16&0xFF) ^ info[pos]]) & 0xFFFF;
                pos+=1;
                lungh-=1;
            }
            return crc16;
}

有许多Java crc16实现，但没有这个（在SIA标准中使用）。你可以帮我吗？谢谢

Answer 1

尝试将(crc16&0xFF) ^ info[pos]更改为 (crc16 ^ info[pos])&0xFF 。