我正在查看一个 32 字节的序列，我认为 chksum 是第一个两个字节或最后一个 2 个字节（我倾向于最后 2 个字节）。我认为它是一个直接的 16 位异或，但我找不到与之抗衡的紧缩数字。也可能是 crc 或 citt，我不能肯定。
这里有 3 个数据包可以使用，任何帮助将不胜感激。
55 00 53 4D 34 34 51 49 00 00 00 00 00 00 4F 1F DF F1 00 00 00 00 00 00 00 00 00 00 00 00 C7 CC
16 02 53 4D 31 30 30 54 51 47 00 00 00 00 C8 7F A8 F4 00 00 00 00 00 00 00 00 00 00 00 00 41 F5
11 00 53 4D 34 38 44 00 00 00 00 00 00 00 69 DC 9C F3 00 00 00 00 00 00 00 00 00 00 00 00 F3 48
unsigned int seed=0x3412;
unsigned int len=15;
unsigned int vec1[] = {
0x5500,0x534D,0x3434,0x5149,0x0000,0x0000,0x0000,0x4F1F,0xDFF1,0x0000,0x0000,0x0000,0x0000,0x0000,0x0000
// 0xC7CC
};
unsigned int vec2[] = {
0x1602,0x534D,0x3130,0x3054,0x5147,0x0000,0x0000,0xC87F,0xA8F4,0x0000,0x0000,0x0000,0x0000,0x0000,0x0000
// 0x41F5
};
unsigned int vec3[] = {
0x1100,0x534D,0x3438,0x4400,0x0000,0x0000,0x0000,0x69DC,0x9CF3,0x0000,0x0000,0x0000,0x0000,0x0000,0x0000
// 0xF348
};
// poly = 0xffff
unsigned int fcalc(int len, unsigned int s, unsigned int *v)
{
unsigned int ret, i;
ret = s;
for (i=0; i<len; i++)
ret ^= *v++;
return ret;
}
main()
{
unsigned int c;
c = fcalc(len, seed, vec1);
printf("c = %04x\n", c);
c = fcalc(len, seed, vec2);
printf("c = %04x\n", c);
c = fcalc(len, seed, vec3);
printf("c = %04x\n", c);
}
