如题
我手头做一个上位机程序，需要发送命令集，其中就有一个 CRC16效验码的发送。
初涉CRC16 不太懂。时间紧迫。
网上找到的都不能直接用。
感谢各位帮帮忙
C版本的
#define PRESET_VALUE 0xFFFF
#define POLYNOMIAL 0x8408
unsigned int uiCrc16Cal(unsigned char const * pucY, unsigned char ucX)
{
unsigned char ucI,ucJ;
unsigned short int uiCrcValue = PRESET_VALUE;
for(ucI = 0; ucI < ucX; ucI++)
{
uiCrcValue = uiCrcValue ^ *(pucY + ucI);
for(ucJ = 0; ucJ < 8; ucJ++)
{
if(uiCrcValue & 0x0001)
{
uiCrcValue = (uiCrcValue >> 1) ^ POLYNOMIAL;
}
else
{
uiCrcValue = (uiCrcValue >> 1);
}
}
}
return uiCrcValue;
}
C#版本的
public class Crc16
{
private const ushort polynomial = 0x8408;
private ushort[] table = new ushort[256];
public ushort ComputeChecksum(byte[] bytes)
{
ushort crc = 0xffff;
for (int i = 0; i < bytes.Length; ++i)
{
byte index = (byte)(crc ^ bytes[i]);
crc = (ushort)((crc >> 8) ^ table[index]);
}
return crc;
}
public Crc16()
{
ushort value;
ushort temp;
for (ushort i = 0; i < table.Length; ++i)
{
value = 0;
temp = i;
for (byte j = 0; j < 8; ++j)
{
if (((value ^ temp) & 0x0001) != 0)
{
value = (ushort)((value >> 1) ^ polynomial);
}
else
{
value >>= 1;
}
temp >>= 1;
}
table[i] = value;
}
}
}
可以用 04 00 01 验证。 计算出的CRC16低字节为 DB 高字节为 4B
也可以用 0B 00 01 01 01 04 EE 35 45 45 验证。 结果为 3A 3E 前低为 后高位
感谢
------解决方案--------------------
- Java code
public class Crc16 { private final int polynomial = 0x8408; private int[] table = new int[256]; public int ComputeChecksum(int[] bytes) { int crc = 0xffff; for (int i = 0; i < bytes.length; ++i) { int index = (crc ^ bytes[i]) % 256; crc = (crc >> 8) ^ table[index]; } return crc; } public Crc16() { int value; int temp; for (int i = 0; i < table.length; ++i) { value = 0; temp = i; for (byte j = 0; j < 8; ++j) { if (((value ^ temp) & 0x0001) != 0) { value = (value >> 1) ^ polynomial; } else { value >>= 1; } temp >>= 1; } table[i] = value; } } public static void main(String[] args) { Crc16 c = new Crc16(); int[] arr = new int[]{0x4, 0x0, 0x1}; System.out.println(Integer.toString(c.ComputeChecksum(arr), 16)); arr = new int[]{0xB, 0x0, 0x1, 0x1, 0x1, 0x4, 0xEE, 0x35, 0x45, 0x45 }; System.out.println(Integer.toString(c.ComputeChecksum(arr), 16)); }}