6

我希望有人能够解释为什么我的 CRC-16 实现似乎无法在 Visual Studio 上正确运行？我从特定设备的手册中获得了算法，并自己编写了 int main()。当我尝试将参数传递给函数时总是出现“类型”错误，所以我怀疑格式有问题？这是代码附带的信息：

  • CRC名称：CRC-16
  • 宽度：16 位
  • 使用的多项式：1189（十六进制）
  • 种子值：FFFF（十六进制）
  • 反射输入/输出：否
  • 异或输出：否

  • 测试字符串“123456789”的CRC：5502（十六进制）

    #include <stdio.h>

unsigned int crctable[256] =
{
0x0000, 0x1189, 0x2312, 0x329B, 0x4624, 0x57AD, 0x6536, 0x74BF,
0x8C48, 0x9DC1, 0xAF5A, 0xBED3, 0xCA6C, 0xDBE5, 0xE97E, 0xF8F7,
0x0919, 0x1890, 0x2A0B, 0x3B82, 0x4F3D, 0x5EB4, 0x6C2F, 0x7DA6,
0x8551, 0x94D8, 0xA643, 0xB7CA, 0xC375, 0xD2FC, 0xE067, 0xF1EE,
0x1232, 0x03BB, 0x3120, 0x20A9, 0x5416, 0x459F, 0x7704, 0x668D,
0x9E7A, 0x8FF3, 0xBD68, 0xACE1, 0xD85E, 0xC9D7, 0xFB4C, 0xEAC5,
0x1B2B, 0x0AA2, 0x3839, 0x29B0, 0x5D0F, 0x4C86, 0x7E1D, 0x6F94,
0x9763, 0x86EA, 0xB471, 0xA5F8, 0xD147, 0xC0CE, 0xF255, 0xE3DC,
0x2464, 0x35ED, 0x0776, 0x16FF, 0x6240, 0x73C9, 0x4152, 0x50DB,
0xA82C, 0xB9A5, 0x8B3E, 0x9AB7, 0xEE08, 0xFF81, 0xCD1A, 0xDC93,
0x2D7D, 0x3CF4, 0x0E6F, 0x1FE6, 0x6B59, 0x7AD0, 0x484B, 0x59C2,
0xA135, 0xB0BC, 0x8227, 0x93AE, 0xE711, 0xF698, 0xC403, 0xD58A,
0x3656, 0x27DF, 0x1544, 0x04CD, 0x7072, 0x61FB, 0x5360, 0x42E9,
0xBA1E, 0xAB97, 0x990C, 0x8885, 0xFC3A, 0xEDB3, 0xDF28, 0xCEA1,
0x3F4F, 0x2EC6, 0x1C5D, 0x0DD4, 0x796B, 0x68E2, 0x5A79, 0x4BF0,
0xB307, 0xA28E, 0x9015, 0x819C, 0xF523, 0xE4AA, 0xD631, 0xC7B8,
0x48C8, 0x5941, 0x6BDA, 0x7A53, 0x0EEC, 0x1F65, 0x2DFE, 0x3C77,
0xC480, 0xD509, 0xE792, 0xF61B, 0x82A4, 0x932D, 0xA1B6, 0xB03F,
0x41D1, 0x5058, 0x62C3, 0x734A, 0x07F5, 0x167C, 0x24E7, 0x356E,
0xCD99, 0xDC10, 0xEE8B, 0xFF02, 0x8BBD, 0x9A34, 0xA8AF, 0xB926,
0x5AFA, 0x4B73, 0x79E8, 0x6861, 0x1CDE, 0x0D57, 0x3FCC, 0x2E45,
0xD6B2, 0xC73B, 0xF5A0, 0xE429, 0x9096, 0x811F, 0xB384, 0xA20D,
0x53E3, 0x426A, 0x70F1, 0x6178, 0x15C7, 0x044E, 0x36D5, 0x275C,
0xDFAB, 0xCE22, 0xFCB9, 0xED30, 0x998F, 0x8806, 0xBA9D, 0xAB14,
0x6CAC, 0x7D25, 0x4FBE, 0x5E37, 0x2A88, 0x3B01, 0x099A, 0x1813,
0xE0E4, 0xF16D, 0xC3F6, 0xD27F, 0xA6C0, 0xB749, 0x85D2, 0x945B,
0x65B5, 0x743C, 0x46A7, 0x572E, 0x2391, 0x3218, 0x0083, 0x110A,
0xE9FD, 0xF874, 0xCAEF, 0xDB66, 0xAFD9, 0xBE50, 0x8CCB, 0x9D42,
0x7E9E, 0x6F17, 0x5D8C, 0x4C05, 0x38BA, 0x2933, 0x1BA8, 0x0A21,
0xF2D6, 0xE35F, 0xD1C4, 0xC04D, 0xB4F2, 0xA57B, 0x97E0, 0x8669,
0x7787, 0x660E, 0x5495, 0x451C, 0x31A3, 0x202A, 0x12B1, 0x0338,
0xFBCF, 0xEA46, 0xD8DD, 0xC954, 0xBDEB, 0xAC62, 0x9EF9, 0x8F70
};
unsigned int // Returns Calculated CRC value
CalculateCRC16(
unsigned int crc_seed, // Seed for CRC calculation
void *c_ptr, // Pointer to byte array to perform CRC on
unsigned int len) // Number of bytes to CRC
{
unsigned char *c = c_ptr;
unsigned int crc = crc_seed;
while (len--){
crc = (crc << 8) ^ crctable[((crc >> 8) ^ *c++)];
printf("%d", crc);
}
return (crc);
}

int main(){

    printf("%d", CalculateCRC16(0xFFFF, "123456789", 2));

 return 0;  
}
4

6 回答 6

6

全部清理干净，准备出发：

#include <stdio.h>
#include <stdint.h>

static const uint16_t crctable[256] =
{
    0x0000, 0x1189, 0x2312, 0x329B, 0x4624, 0x57AD, 0x6536, 0x74BF,
    0x8C48, 0x9DC1, 0xAF5A, 0xBED3, 0xCA6C, 0xDBE5, 0xE97E, 0xF8F7,
    0x0919, 0x1890, 0x2A0B, 0x3B82, 0x4F3D, 0x5EB4, 0x6C2F, 0x7DA6,
    0x8551, 0x94D8, 0xA643, 0xB7CA, 0xC375, 0xD2FC, 0xE067, 0xF1EE,
    0x1232, 0x03BB, 0x3120, 0x20A9, 0x5416, 0x459F, 0x7704, 0x668D,
    0x9E7A, 0x8FF3, 0xBD68, 0xACE1, 0xD85E, 0xC9D7, 0xFB4C, 0xEAC5,
    0x1B2B, 0x0AA2, 0x3839, 0x29B0, 0x5D0F, 0x4C86, 0x7E1D, 0x6F94,
    0x9763, 0x86EA, 0xB471, 0xA5F8, 0xD147, 0xC0CE, 0xF255, 0xE3DC,
    0x2464, 0x35ED, 0x0776, 0x16FF, 0x6240, 0x73C9, 0x4152, 0x50DB,
    0xA82C, 0xB9A5, 0x8B3E, 0x9AB7, 0xEE08, 0xFF81, 0xCD1A, 0xDC93,
    0x2D7D, 0x3CF4, 0x0E6F, 0x1FE6, 0x6B59, 0x7AD0, 0x484B, 0x59C2,
    0xA135, 0xB0BC, 0x8227, 0x93AE, 0xE711, 0xF698, 0xC403, 0xD58A,
    0x3656, 0x27DF, 0x1544, 0x04CD, 0x7072, 0x61FB, 0x5360, 0x42E9,
    0xBA1E, 0xAB97, 0x990C, 0x8885, 0xFC3A, 0xEDB3, 0xDF28, 0xCEA1,
    0x3F4F, 0x2EC6, 0x1C5D, 0x0DD4, 0x796B, 0x68E2, 0x5A79, 0x4BF0,
    0xB307, 0xA28E, 0x9015, 0x819C, 0xF523, 0xE4AA, 0xD631, 0xC7B8,
    0x48C8, 0x5941, 0x6BDA, 0x7A53, 0x0EEC, 0x1F65, 0x2DFE, 0x3C77,
    0xC480, 0xD509, 0xE792, 0xF61B, 0x82A4, 0x932D, 0xA1B6, 0xB03F,
    0x41D1, 0x5058, 0x62C3, 0x734A, 0x07F5, 0x167C, 0x24E7, 0x356E,
    0xCD99, 0xDC10, 0xEE8B, 0xFF02, 0x8BBD, 0x9A34, 0xA8AF, 0xB926,
    0x5AFA, 0x4B73, 0x79E8, 0x6861, 0x1CDE, 0x0D57, 0x3FCC, 0x2E45,
    0xD6B2, 0xC73B, 0xF5A0, 0xE429, 0x9096, 0x811F, 0xB384, 0xA20D,
    0x53E3, 0x426A, 0x70F1, 0x6178, 0x15C7, 0x044E, 0x36D5, 0x275C,
    0xDFAB, 0xCE22, 0xFCB9, 0xED30, 0x998F, 0x8806, 0xBA9D, 0xAB14,
    0x6CAC, 0x7D25, 0x4FBE, 0x5E37, 0x2A88, 0x3B01, 0x099A, 0x1813,
    0xE0E4, 0xF16D, 0xC3F6, 0xD27F, 0xA6C0, 0xB749, 0x85D2, 0x945B,
    0x65B5, 0x743C, 0x46A7, 0x572E, 0x2391, 0x3218, 0x0083, 0x110A,
    0xE9FD, 0xF874, 0xCAEF, 0xDB66, 0xAFD9, 0xBE50, 0x8CCB, 0x9D42,
    0x7E9E, 0x6F17, 0x5D8C, 0x4C05, 0x38BA, 0x2933, 0x1BA8, 0x0A21,
    0xF2D6, 0xE35F, 0xD1C4, 0xC04D, 0xB4F2, 0xA57B, 0x97E0, 0x8669,
    0x7787, 0x660E, 0x5495, 0x451C, 0x31A3, 0x202A, 0x12B1, 0x0338,
    0xFBCF, 0xEA46, 0xD8DD, 0xC954, 0xBDEB, 0xAC62, 0x9EF9, 0x8F70
};

uint16_t // Returns Calculated CRC value
CalculateCRC16(
    uint16_t crc,      // Seed for CRC calculation
    const void *c_ptr, // Pointer to byte array to perform CRC on
    size_t len)        // Number of bytes to CRC
{
    const uint8_t *c = c_ptr;

    while (len--)
        crc = (crc << 8) ^ crctable[((crc >> 8) ^ *c++)];

    return crc;
}

int main()
{
    printf("%04x\n", CalculateCRC16(0xFFFF, "123456789", 9));

    return 0;
}
于 2014-03-16T02:15:09.423 回答
1

在这条线上

crc = (crc << 8) ^ crctable[((crc >> 8) ^ *c++)];

的结果((crc >> 8) ^ *c++)可以变为 > 255，并导致访问冲突。只需通过将索引屏蔽为 crctable 来确保结果始终为 0.255

crc = (crc << 8) ^ crctable[((crc >> 8) ^ *c++) & 0x00FF];
// but you will need to clean up the result as its upper 16 bits
// are not guaranteed to be all 0
return crc & 0xffff;

或者更好，生成的 crc 值，因为它确保 crc 永远不会包含 > 0x0000ffff 的值

crc = ( (crc << 8) ^ crctable[((crc >> 8) ^ *c++)] ) & 0xffff;

你会准备好的。问题的根源在于原始代码似乎是 16 位代码（其中int是 16 位），而您使用的是 32 位编译器。

于 2014-03-16T02:11:13.647 回答
1

现在我附近没有电脑。试一试：

crc = (crc << 8) ^ crctable[(unsigned char)(crc >> 8) ^ *c++];

于 2014-03-16T02:12:03.763 回答
0

我使用了相同的 CRC 检查，在您的代码中，您只需更改以下行： crc = (crc >> 8) ^ crctable[(crc^(*c++))&0xFF];

于 2018-11-26T07:23:11.947 回答
0

您正在使用的表似乎生成不正确。前十六个条目是正确的，但之后就出现了分歧。我认为用它解码 CCITT CRC-16 不会有太多运气。

有关正确生成的表的示例，请参阅跨平台应用程序的 CRC 。

于 2017-02-08T10:05:14.987 回答
0

该表列出了多项式的幂，以避免表中的错误在计算过程中计算幂，并使多项式成为初始值。使用 Dartpad 模拟它：https ://dartpad.dev/?null_safety=true

void main() {
  final int polynomial = 0x1189;
  final int initialValue = 0xFFFF;
  String crc16(String expression, int polynomial, int initialValue) {
    int checkSum = initialValue;
    for (int i = 0; i < expression.length; i++) {
      checkSum ^= (expression.codeUnitAt(i) << 8);
      for (int j = 0; j < 8; j++) {
        if (((checkSum <<= 1) & 0x10000) == 0x10000) checkSum ^= polynomial;
        checkSum &= 0xFFFF;
      }
    }
    return checkSum.toRadixString(16).toUpperCase();
  }
  print(crc16('123456789', polynomial, initialValue));
}

要符合 CRC16 CCITT，您应该使用多项式 = 0x1021 和初始值 = 0xFFFF。

https://www.gatevidyalay.com/cyclic-redundancy-check-crc-error-detection/ 对 CRC 有很好的解释。

于 2021-04-15T00:28:54.717 回答