Boost CRC 和 linux/lib/crc-ccitt.c 的区别
Difference in Boost CRC and linux/lib/crc-ccitt.c
我有两个来源来计算看似相同的crc值。
我不明白为什么 'boost/crc.hpp' 实现与 'linux/lib/crc-ccitt.c' 实现不同。
这是一个说明问题的例子。
由于我的计算机上没有 Linux 内核源代码，所以它稍长一些。
如果你 link 提升它，它会编译。
问题是 Linux 和 boost 在 crc 值上不一致。
Linux 消息来源指出：
- 多项式... 0x8408。
- 加上隐含的 x^16，你就有了标准的 CRC-CCITT。
我不知道如何应用 x^16 但我死于编辑这个问题以反映偏离的多项式。
#include <stdio.h>
#include <boost\crc.hpp>
typedef unsigned short u16;
typedef unsigned char u8;
/*
* linux/lib/crc-ccitt.c
*
* This source code is licensed under the GNU General Public License,
* Version 2. See the file COPYING for more details.
*/
/*modified for minimal example on Whosebug*/
/*original source from http://mirrors.neusoft.edu.cn/rpi-kernel/lib/crc-ccitt.c */
u16 const crc_ccitt_table[256] = {
0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf,
0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7,
0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e,
0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876,
0x2102, 0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd,
0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5,
0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c,
0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974,
0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb,
0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3,
0x5285, 0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a,
0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72,
0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9,
0xef4e, 0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1,
0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738,
0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70,
0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7,
0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff,
0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036,
0x18c1, 0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e,
0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5,
0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd,
0xb58b, 0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134,
0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c,
0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3,
0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb,
0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232,
0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a,
0xe70e, 0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1,
0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9,
0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330,
0x7bc7, 0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78
};
//from crc-ccitt.h
static inline u16 crc_ccitt_byte(u16 crc, const u8 c)
{
return (crc >> 8) ^ crc_ccitt_table[(crc ^ c) & 0xff];
}
u16 crc_ccitt(u16 crc, u8 const *buffer, size_t len)
{
while (len--)
crc = crc_ccitt_byte(crc, *buffer++);
return crc;
}
#define check(X, Y) \
if (X != Y) { \
printf("%s != %s\n", #X, #Y); \
} else { \
printf("%s == %s !!! celebrate\n", #X, #Y); \
}
void runTestSet(unsigned char * data, unsigned size)
{
u16 linux = crc_ccitt(0xFFFF, data, size);
boost::crc_ccitt_type boost_crc_ccitt_type;
boost::crc_16_type boost_crc_16_type;
boost::crc_32_type boost_crc_32_type;
boost::crc_xmodem_type boost_crc_xmodem_type;
boost::crc_optimal<16, 0x8408, 0xFFFF, 0, false, false> boost_crc_optimal_16_8408_FFFF_0_0_0;
boost::crc_optimal<16, 0x8408, 0xFFFF, 0, true, true> boost_crc_optimal_16_8408_FFFF_0_1_1;
boost::crc_optimal<16, 0xA001, 0xFFFF, 0, true, true> boost_crc_optimal_16_A001_FFFF_0_1_1;
boost::crc_optimal<16, 0x8408, 0xFFFF, 0, true, false> boost_crc_optimal_16_8408_FFFF_0_1_0;
boost::crc_optimal<16, 0x856F, 0xFFFF, 0, true, true> boost_crc_optimal_16_856F_FFFF_0_1_1;
boost::crc_optimal<16, 0x856F, 0xFFFF, 0, true, false> boost_crc_optimal_16_856F_FFFF_0_1_0;
boost_crc_ccitt_type.process_bytes(data, size);
boost_crc_16_type.process_bytes(data, size);
boost_crc_32_type.process_bytes(data, size);
boost_crc_xmodem_type.process_bytes(data, size);
boost_crc_optimal_16_8408_FFFF_0_0_0.process_bytes(data, size);
boost_crc_optimal_16_8408_FFFF_0_1_1.process_bytes(data, size);
boost_crc_optimal_16_A001_FFFF_0_1_1.process_bytes(data, size);
boost_crc_optimal_16_8408_FFFF_0_1_0.process_bytes(data, size);
boost_crc_optimal_16_856F_FFFF_0_1_1.process_bytes(data, size);
boost_crc_optimal_16_856F_FFFF_0_1_0.process_bytes(data, size);
printf("Testing with sequence: '");
for (unsigned n = 0; n < size; ++n)
{
if (n > 0) printf(" ");
printf("0x%02X", data[n]);
}
printf("'\n");
check(boost_crc_ccitt_type.checksum(), linux);
check(boost_crc_16_type.checksum(), linux);
check(boost_crc_32_type.checksum(), linux);
check(boost_crc_xmodem_type.checksum(), linux);
check(boost_crc_optimal_16_8408_FFFF_0_0_0.checksum(), linux);
check(boost_crc_optimal_16_8408_FFFF_0_1_1.checksum(), linux);
check(boost_crc_optimal_16_A001_FFFF_0_1_1.checksum(), linux);
check(boost_crc_optimal_16_8408_FFFF_0_1_0.checksum(), linux);
check(boost_crc_optimal_16_856F_FFFF_0_1_1.checksum(), linux);
check(boost_crc_optimal_16_856F_FFFF_0_1_0.checksum(), linux);
printf("End Of Testrun\n\n");
}
int main()
{
unsigned char simple[] = {0x80};
unsigned char sequence[] = "123456789";
runTestSet(simple, sizeof(simple));
runTestSet(sequence, sizeof(sequence));
return 0;
}
我看到我没有为此说明我的用例。
我有系统依赖性，需要使用不正确的 (?) Linux crc。
我想 trim 以一种允许我使用 boost 来执行此操作的方式实现 boost。
我机器上的输出是：
鉴于 lib/crc-ccitt.c 不使用 CRC-CCITT 所需的 0x1021 多项式。所以，我认为提升版本是正确的，因为 crc_ccitt_type 是一个 typedef:
typedef crc_optimal<16, 0x1021, 0xFFFF, 0, false, false> crc_ccitt_type;
P.S。警告：您的行 size = sizeof(data) / sizeof(data[0]) 不正确，但它给出了正确的数字。这计算元素的数量，而不是字节数（但由于 sizeof(char)==1 它计算正确的大小）。
更新 - 基于这些网站的 crc 计算器
（选择ccitt（0xffff））
http://www.lammertbies.nl/comm/info/crc-calculation.html
（选择crc ccitt）
http://www.zorc.breitbandkatze.de/crc.html
第三个站点将此版本称为 crc-16-ccitt-false，并且还列出了其他也称为 ccitt 的变体。
http://reveng.sourceforge.net/crc-catalogue/16.htm#crc.cat.crc-16-ccitt-false
在这种情况下，位不会反转。此外，9 字节字符串“123456789”似乎是一个常见的测试。然而，其他网站提到某些版本的 ccitt 确实会像 linux 示例中那样反转位。我的猜测是使用哪一个将是特定于协议/设备的。如果您需要切换，至少现在您同时拥有反向（linux）和非反向（此答案中的代码）。
添加了示例代码：
CRC 是将一串位除以 n 位多项式后的余数，产生 n-1 位余数。在软盘的情况下，17 位多项式 0x11021 用于产生 16 位余数。每个位的逻辑是这样的：
crc << = 1;
if(crc & 0x10000)crc ^= 0x11021;
这个也可以实现s:
if(crc & 0x8000){crc = ((crc<<1) & 0xffff) & 0x1021;}
else {crc = ((crc<<1) & 0xffff);}
示例代码。这应该与提升代码匹配。
typedef unsigned short u16;
typedef unsigned char u8;
u16 crctbl[256] = {
0x0000,0x1021,0x2042,0x3063,0x4084,0x50a5,0x60c6,0x70e7,
0x8108,0x9129,0xa14a,0xb16b,0xc18c,0xd1ad,0xe1ce,0xf1ef,
0x1231,0x0210,0x3273,0x2252,0x52b5,0x4294,0x72f7,0x62d6,
0x9339,0x8318,0xb37b,0xa35a,0xd3bd,0xc39c,0xf3ff,0xe3de,
0x2462,0x3443,0x0420,0x1401,0x64e6,0x74c7,0x44a4,0x5485,
0xa56a,0xb54b,0x8528,0x9509,0xe5ee,0xf5cf,0xc5ac,0xd58d,
0x3653,0x2672,0x1611,0x0630,0x76d7,0x66f6,0x5695,0x46b4,
0xb75b,0xa77a,0x9719,0x8738,0xf7df,0xe7fe,0xd79d,0xc7bc,
0x48c4,0x58e5,0x6886,0x78a7,0x0840,0x1861,0x2802,0x3823,
0xc9cc,0xd9ed,0xe98e,0xf9af,0x8948,0x9969,0xa90a,0xb92b,
0x5af5,0x4ad4,0x7ab7,0x6a96,0x1a71,0x0a50,0x3a33,0x2a12,
0xdbfd,0xcbdc,0xfbbf,0xeb9e,0x9b79,0x8b58,0xbb3b,0xab1a,
0x6ca6,0x7c87,0x4ce4,0x5cc5,0x2c22,0x3c03,0x0c60,0x1c41,
0xedae,0xfd8f,0xcdec,0xddcd,0xad2a,0xbd0b,0x8d68,0x9d49,
0x7e97,0x6eb6,0x5ed5,0x4ef4,0x3e13,0x2e32,0x1e51,0x0e70,
0xff9f,0xefbe,0xdfdd,0xcffc,0xbf1b,0xaf3a,0x9f59,0x8f78,
0x9188,0x81a9,0xb1ca,0xa1eb,0xd10c,0xc12d,0xf14e,0xe16f,
0x1080,0x00a1,0x30c2,0x20e3,0x5004,0x4025,0x7046,0x6067,
0x83b9,0x9398,0xa3fb,0xb3da,0xc33d,0xd31c,0xe37f,0xf35e,
0x02b1,0x1290,0x22f3,0x32d2,0x4235,0x5214,0x6277,0x7256,
0xb5ea,0xa5cb,0x95a8,0x8589,0xf56e,0xe54f,0xd52c,0xc50d,
0x34e2,0x24c3,0x14a0,0x0481,0x7466,0x6447,0x5424,0x4405,
0xa7db,0xb7fa,0x8799,0x97b8,0xe75f,0xf77e,0xc71d,0xd73c,
0x26d3,0x36f2,0x0691,0x16b0,0x6657,0x7676,0x4615,0x5634,
0xd94c,0xc96d,0xf90e,0xe92f,0x99c8,0x89e9,0xb98a,0xa9ab,
0x5844,0x4865,0x7806,0x6827,0x18c0,0x08e1,0x3882,0x28a3,
0xcb7d,0xdb5c,0xeb3f,0xfb1e,0x8bf9,0x9bd8,0xabbb,0xbb9a,
0x4a75,0x5a54,0x6a37,0x7a16,0x0af1,0x1ad0,0x2ab3,0x3a92,
0xfd2e,0xed0f,0xdd6c,0xcd4d,0xbdaa,0xad8b,0x9de8,0x8dc9,
0x7c26,0x6c07,0x5c64,0x4c45,0x3ca2,0x2c83,0x1ce0,0x0cc1,
0xef1f,0xff3e,0xcf5d,0xdf7c,0xaf9b,0xbfba,0x8fd9,0x9ff8,
0x6e17,0x7e36,0x4e55,0x5e74,0x2e93,0x3eb2,0x0ed1,0x1ef0};
u16 gencrc(u8 *bfr, size_t len)
{
u16 crc = 0xffff;
while(len--)
crc = (crc << 8) ^ crctbl[(crc >> 8)^*bfr++];
return(crc);
}
int main()
{
u16 crc;
u8 a[4] = {0x80, 0, 0, 0};
u8 b[10] = {"123456789"};
crc = gencrc(a, 1); // returns 0x7078
crc = gencrc(b, 9); // returns 0x29b1
return(0);
}
问题中的 table 确实使用了多项式 0x1021。这可以通过使用这个短程序生成 table 来检查：
#include <iostream>
unsigned long SwapBits(unsigned long swap, int bits)
{
unsigned long r = 0;
for(int i = 0; i < bits; i++) {
if(swap & 1) r |= 1 << (bits - i - 1);
swap >>= 1;
}
return r;
}
int main()
{
const unsigned short poly = 0x1021;
unsigned short CRCTab[256];
for(int i = 0; i < 256; i++) {
CRCTab[i] = SwapBits(i, 8) << 8;
for(int j = 0; j < 8; j++) CRCTab[i] = (CRCTab[i] << 1) ^ ((CRCTab[i] & 0x8000) ? poly : 0);
CRCTab[i] = SwapBits(CRCTab[i], 16);
}
for(int i = 0; i < 256; ) {
char str[10];
for(int j = 0; j < 8; j++, i++) {
sprintf(str, "0x%04x, ", CRCTab[i]);
std::cout << str;
}
std::cout << "\n";
}
return 0;
}
通过反复试验，我找到了一个似乎能产生正确匹配的解决方案。
谢谢大家的提示。
这种类型boost::crc_optimal<16, 0x1021, 0xFFFF, 0, true, true>似乎是正确的。
我不知道为什么，这让我有点担心。
#include <stdio.h>
#include <boost\crc.hpp>
typedef unsigned short u16;
typedef unsigned char u8;
/*
* linux/lib/crc-ccitt.c
*
* This source code is licensed under the GNU General Public License,
* Version 2. See the file COPYING for more details.
*/
/*modified for minimal example on Whosebug*/
/*original source from http://mirrors.neusoft.edu.cn/rpi-kernel/lib/crc-ccitt.c */
u16 const crc_ccitt_table[256] = {
0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf,
0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7,
0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e,
0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876,
0x2102, 0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd,
0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5,
0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c,
0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974,
0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb,
0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3,
0x5285, 0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a,
0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72,
0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9,
0xef4e, 0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1,
0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738,
0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70,
0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7,
0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff,
0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036,
0x18c1, 0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e,
0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5,
0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd,
0xb58b, 0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134,
0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c,
0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3,
0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb,
0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232,
0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a,
0xe70e, 0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1,
0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9,
0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330,
0x7bc7, 0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78
};
//from crc-ccitt.h
static inline u16 crc_ccitt_byte(u16 crc, const u8 c)
{
return (crc >> 8) ^ crc_ccitt_table[(crc ^ c) & 0xff];
}
u16 crc_ccitt(u16 crc, u8 const *buffer, size_t len)
{
while (len--)
crc = crc_ccitt_byte(crc, *buffer++);
return crc;
}
#define check(X, Y) \
if (X != Y) { \
printf("%s (0x%08X) != %s (0x%08X)\n", #X, X, #Y, Y); \
} else { \
printf("%s (0x%08X) == %s (0x%08X)!!! celebrate\n", #X, X, #Y, Y); \
}
void runTestSet(unsigned char * data, unsigned size)
{
u16 linux = crc_ccitt(0xFFFF, data, size);
boost::crc_optimal<16, 0x1021, 0xFFFF, 0, true, true> boost_crc_optimal_16_1021_FFFF_0_1_1;
boost_crc_optimal_16_1021_FFFF_0_1_1.process_bytes(data, size);
printf("Testing with sequence: '");
for (unsigned n = 0; n < size; ++n)
{
if (n > 0) printf(" ");
printf("0x%02X", data[n]);
}
printf("'\n");
check(boost_crc_optimal_16_1021_FFFF_0_1_1.checksum(), linux);
printf("End Of Testrun\n\n");
}
int main()
{
unsigned char zero_Length[] = {0x00};
unsigned char simple[] = {0x80};
unsigned char sequence[] = "123456789";
unsigned char LotsOfAs[] = "AAAAAAAAAAAAAAAAAAAAAAAAA";
runTestSet(zero_Length, 0);
runTestSet(simple, sizeof(simple));
runTestSet(sequence, sizeof(sequence)-1);
runTestSet(LotsOfAs, sizeof(LotsOfAs)-1);
return 0;
}
我有两个来源来计算看似相同的crc值。 我不明白为什么 'boost/crc.hpp' 实现与 'linux/lib/crc-ccitt.c' 实现不同。
这是一个说明问题的例子。 由于我的计算机上没有 Linux 内核源代码，所以它稍长一些。 如果你 link 提升它，它会编译。
问题是 Linux 和 boost 在 crc 值上不一致。 Linux 消息来源指出：
- 多项式... 0x8408。
- 加上隐含的 x^16，你就有了标准的 CRC-CCITT。
我不知道如何应用 x^16 但我死于编辑这个问题以反映偏离的多项式。
#include <stdio.h>
#include <boost\crc.hpp>
typedef unsigned short u16;
typedef unsigned char u8;
/*
* linux/lib/crc-ccitt.c
*
* This source code is licensed under the GNU General Public License,
* Version 2. See the file COPYING for more details.
*/
/*modified for minimal example on Whosebug*/
/*original source from http://mirrors.neusoft.edu.cn/rpi-kernel/lib/crc-ccitt.c */
u16 const crc_ccitt_table[256] = {
0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf,
0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7,
0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e,
0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876,
0x2102, 0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd,
0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5,
0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c,
0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974,
0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb,
0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3,
0x5285, 0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a,
0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72,
0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9,
0xef4e, 0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1,
0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738,
0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70,
0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7,
0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff,
0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036,
0x18c1, 0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e,
0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5,
0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd,
0xb58b, 0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134,
0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c,
0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3,
0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb,
0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232,
0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a,
0xe70e, 0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1,
0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9,
0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330,
0x7bc7, 0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78
};
//from crc-ccitt.h
static inline u16 crc_ccitt_byte(u16 crc, const u8 c)
{
return (crc >> 8) ^ crc_ccitt_table[(crc ^ c) & 0xff];
}
u16 crc_ccitt(u16 crc, u8 const *buffer, size_t len)
{
while (len--)
crc = crc_ccitt_byte(crc, *buffer++);
return crc;
}
#define check(X, Y) \
if (X != Y) { \
printf("%s != %s\n", #X, #Y); \
} else { \
printf("%s == %s !!! celebrate\n", #X, #Y); \
}
void runTestSet(unsigned char * data, unsigned size)
{
u16 linux = crc_ccitt(0xFFFF, data, size);
boost::crc_ccitt_type boost_crc_ccitt_type;
boost::crc_16_type boost_crc_16_type;
boost::crc_32_type boost_crc_32_type;
boost::crc_xmodem_type boost_crc_xmodem_type;
boost::crc_optimal<16, 0x8408, 0xFFFF, 0, false, false> boost_crc_optimal_16_8408_FFFF_0_0_0;
boost::crc_optimal<16, 0x8408, 0xFFFF, 0, true, true> boost_crc_optimal_16_8408_FFFF_0_1_1;
boost::crc_optimal<16, 0xA001, 0xFFFF, 0, true, true> boost_crc_optimal_16_A001_FFFF_0_1_1;
boost::crc_optimal<16, 0x8408, 0xFFFF, 0, true, false> boost_crc_optimal_16_8408_FFFF_0_1_0;
boost::crc_optimal<16, 0x856F, 0xFFFF, 0, true, true> boost_crc_optimal_16_856F_FFFF_0_1_1;
boost::crc_optimal<16, 0x856F, 0xFFFF, 0, true, false> boost_crc_optimal_16_856F_FFFF_0_1_0;
boost_crc_ccitt_type.process_bytes(data, size);
boost_crc_16_type.process_bytes(data, size);
boost_crc_32_type.process_bytes(data, size);
boost_crc_xmodem_type.process_bytes(data, size);
boost_crc_optimal_16_8408_FFFF_0_0_0.process_bytes(data, size);
boost_crc_optimal_16_8408_FFFF_0_1_1.process_bytes(data, size);
boost_crc_optimal_16_A001_FFFF_0_1_1.process_bytes(data, size);
boost_crc_optimal_16_8408_FFFF_0_1_0.process_bytes(data, size);
boost_crc_optimal_16_856F_FFFF_0_1_1.process_bytes(data, size);
boost_crc_optimal_16_856F_FFFF_0_1_0.process_bytes(data, size);
printf("Testing with sequence: '");
for (unsigned n = 0; n < size; ++n)
{
if (n > 0) printf(" ");
printf("0x%02X", data[n]);
}
printf("'\n");
check(boost_crc_ccitt_type.checksum(), linux);
check(boost_crc_16_type.checksum(), linux);
check(boost_crc_32_type.checksum(), linux);
check(boost_crc_xmodem_type.checksum(), linux);
check(boost_crc_optimal_16_8408_FFFF_0_0_0.checksum(), linux);
check(boost_crc_optimal_16_8408_FFFF_0_1_1.checksum(), linux);
check(boost_crc_optimal_16_A001_FFFF_0_1_1.checksum(), linux);
check(boost_crc_optimal_16_8408_FFFF_0_1_0.checksum(), linux);
check(boost_crc_optimal_16_856F_FFFF_0_1_1.checksum(), linux);
check(boost_crc_optimal_16_856F_FFFF_0_1_0.checksum(), linux);
printf("End Of Testrun\n\n");
}
int main()
{
unsigned char simple[] = {0x80};
unsigned char sequence[] = "123456789";
runTestSet(simple, sizeof(simple));
runTestSet(sequence, sizeof(sequence));
return 0;
}
我看到我没有为此说明我的用例。 我有系统依赖性，需要使用不正确的 (?) Linux crc。 我想 trim 以一种允许我使用 boost 来执行此操作的方式实现 boost。
我机器上的输出是：
鉴于 lib/crc-ccitt.c 不使用 CRC-CCITT 所需的 0x1021 多项式。所以，我认为提升版本是正确的，因为 crc_ccitt_type 是一个 typedef:
typedef crc_optimal<16, 0x1021, 0xFFFF, 0, false, false> crc_ccitt_type;
P.S。警告：您的行 size = sizeof(data) / sizeof(data[0]) 不正确，但它给出了正确的数字。这计算元素的数量，而不是字节数（但由于 sizeof(char)==1 它计算正确的大小）。
更新 - 基于这些网站的 crc 计算器
（选择ccitt（0xffff）） http://www.lammertbies.nl/comm/info/crc-calculation.html
（选择crc ccitt） http://www.zorc.breitbandkatze.de/crc.html
第三个站点将此版本称为 crc-16-ccitt-false，并且还列出了其他也称为 ccitt 的变体。
http://reveng.sourceforge.net/crc-catalogue/16.htm#crc.cat.crc-16-ccitt-false
在这种情况下，位不会反转。此外，9 字节字符串“123456789”似乎是一个常见的测试。然而，其他网站提到某些版本的 ccitt 确实会像 linux 示例中那样反转位。我的猜测是使用哪一个将是特定于协议/设备的。如果您需要切换，至少现在您同时拥有反向（linux）和非反向（此答案中的代码）。
添加了示例代码：
CRC 是将一串位除以 n 位多项式后的余数，产生 n-1 位余数。在软盘的情况下，17 位多项式 0x11021 用于产生 16 位余数。每个位的逻辑是这样的：
crc << = 1;
if(crc & 0x10000)crc ^= 0x11021;
这个也可以实现s:
if(crc & 0x8000){crc = ((crc<<1) & 0xffff) & 0x1021;}
else {crc = ((crc<<1) & 0xffff);}
示例代码。这应该与提升代码匹配。
typedef unsigned short u16;
typedef unsigned char u8;
u16 crctbl[256] = {
0x0000,0x1021,0x2042,0x3063,0x4084,0x50a5,0x60c6,0x70e7,
0x8108,0x9129,0xa14a,0xb16b,0xc18c,0xd1ad,0xe1ce,0xf1ef,
0x1231,0x0210,0x3273,0x2252,0x52b5,0x4294,0x72f7,0x62d6,
0x9339,0x8318,0xb37b,0xa35a,0xd3bd,0xc39c,0xf3ff,0xe3de,
0x2462,0x3443,0x0420,0x1401,0x64e6,0x74c7,0x44a4,0x5485,
0xa56a,0xb54b,0x8528,0x9509,0xe5ee,0xf5cf,0xc5ac,0xd58d,
0x3653,0x2672,0x1611,0x0630,0x76d7,0x66f6,0x5695,0x46b4,
0xb75b,0xa77a,0x9719,0x8738,0xf7df,0xe7fe,0xd79d,0xc7bc,
0x48c4,0x58e5,0x6886,0x78a7,0x0840,0x1861,0x2802,0x3823,
0xc9cc,0xd9ed,0xe98e,0xf9af,0x8948,0x9969,0xa90a,0xb92b,
0x5af5,0x4ad4,0x7ab7,0x6a96,0x1a71,0x0a50,0x3a33,0x2a12,
0xdbfd,0xcbdc,0xfbbf,0xeb9e,0x9b79,0x8b58,0xbb3b,0xab1a,
0x6ca6,0x7c87,0x4ce4,0x5cc5,0x2c22,0x3c03,0x0c60,0x1c41,
0xedae,0xfd8f,0xcdec,0xddcd,0xad2a,0xbd0b,0x8d68,0x9d49,
0x7e97,0x6eb6,0x5ed5,0x4ef4,0x3e13,0x2e32,0x1e51,0x0e70,
0xff9f,0xefbe,0xdfdd,0xcffc,0xbf1b,0xaf3a,0x9f59,0x8f78,
0x9188,0x81a9,0xb1ca,0xa1eb,0xd10c,0xc12d,0xf14e,0xe16f,
0x1080,0x00a1,0x30c2,0x20e3,0x5004,0x4025,0x7046,0x6067,
0x83b9,0x9398,0xa3fb,0xb3da,0xc33d,0xd31c,0xe37f,0xf35e,
0x02b1,0x1290,0x22f3,0x32d2,0x4235,0x5214,0x6277,0x7256,
0xb5ea,0xa5cb,0x95a8,0x8589,0xf56e,0xe54f,0xd52c,0xc50d,
0x34e2,0x24c3,0x14a0,0x0481,0x7466,0x6447,0x5424,0x4405,
0xa7db,0xb7fa,0x8799,0x97b8,0xe75f,0xf77e,0xc71d,0xd73c,
0x26d3,0x36f2,0x0691,0x16b0,0x6657,0x7676,0x4615,0x5634,
0xd94c,0xc96d,0xf90e,0xe92f,0x99c8,0x89e9,0xb98a,0xa9ab,
0x5844,0x4865,0x7806,0x6827,0x18c0,0x08e1,0x3882,0x28a3,
0xcb7d,0xdb5c,0xeb3f,0xfb1e,0x8bf9,0x9bd8,0xabbb,0xbb9a,
0x4a75,0x5a54,0x6a37,0x7a16,0x0af1,0x1ad0,0x2ab3,0x3a92,
0xfd2e,0xed0f,0xdd6c,0xcd4d,0xbdaa,0xad8b,0x9de8,0x8dc9,
0x7c26,0x6c07,0x5c64,0x4c45,0x3ca2,0x2c83,0x1ce0,0x0cc1,
0xef1f,0xff3e,0xcf5d,0xdf7c,0xaf9b,0xbfba,0x8fd9,0x9ff8,
0x6e17,0x7e36,0x4e55,0x5e74,0x2e93,0x3eb2,0x0ed1,0x1ef0};
u16 gencrc(u8 *bfr, size_t len)
{
u16 crc = 0xffff;
while(len--)
crc = (crc << 8) ^ crctbl[(crc >> 8)^*bfr++];
return(crc);
}
int main()
{
u16 crc;
u8 a[4] = {0x80, 0, 0, 0};
u8 b[10] = {"123456789"};
crc = gencrc(a, 1); // returns 0x7078
crc = gencrc(b, 9); // returns 0x29b1
return(0);
}
问题中的 table 确实使用了多项式 0x1021。这可以通过使用这个短程序生成 table 来检查：
#include <iostream>
unsigned long SwapBits(unsigned long swap, int bits)
{
unsigned long r = 0;
for(int i = 0; i < bits; i++) {
if(swap & 1) r |= 1 << (bits - i - 1);
swap >>= 1;
}
return r;
}
int main()
{
const unsigned short poly = 0x1021;
unsigned short CRCTab[256];
for(int i = 0; i < 256; i++) {
CRCTab[i] = SwapBits(i, 8) << 8;
for(int j = 0; j < 8; j++) CRCTab[i] = (CRCTab[i] << 1) ^ ((CRCTab[i] & 0x8000) ? poly : 0);
CRCTab[i] = SwapBits(CRCTab[i], 16);
}
for(int i = 0; i < 256; ) {
char str[10];
for(int j = 0; j < 8; j++, i++) {
sprintf(str, "0x%04x, ", CRCTab[i]);
std::cout << str;
}
std::cout << "\n";
}
return 0;
}
通过反复试验，我找到了一个似乎能产生正确匹配的解决方案。
谢谢大家的提示。
这种类型boost::crc_optimal<16, 0x1021, 0xFFFF, 0, true, true>似乎是正确的。
我不知道为什么，这让我有点担心。
#include <stdio.h>
#include <boost\crc.hpp>
typedef unsigned short u16;
typedef unsigned char u8;
/*
* linux/lib/crc-ccitt.c
*
* This source code is licensed under the GNU General Public License,
* Version 2. See the file COPYING for more details.
*/
/*modified for minimal example on Whosebug*/
/*original source from http://mirrors.neusoft.edu.cn/rpi-kernel/lib/crc-ccitt.c */
u16 const crc_ccitt_table[256] = {
0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf,
0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7,
0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e,
0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876,
0x2102, 0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd,
0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5,
0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c,
0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974,
0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb,
0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3,
0x5285, 0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a,
0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72,
0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9,
0xef4e, 0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1,
0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738,
0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70,
0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7,
0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff,
0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036,
0x18c1, 0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e,
0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5,
0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd,
0xb58b, 0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134,
0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c,
0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3,
0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb,
0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232,
0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a,
0xe70e, 0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1,
0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9,
0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330,
0x7bc7, 0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78
};
//from crc-ccitt.h
static inline u16 crc_ccitt_byte(u16 crc, const u8 c)
{
return (crc >> 8) ^ crc_ccitt_table[(crc ^ c) & 0xff];
}
u16 crc_ccitt(u16 crc, u8 const *buffer, size_t len)
{
while (len--)
crc = crc_ccitt_byte(crc, *buffer++);
return crc;
}
#define check(X, Y) \
if (X != Y) { \
printf("%s (0x%08X) != %s (0x%08X)\n", #X, X, #Y, Y); \
} else { \
printf("%s (0x%08X) == %s (0x%08X)!!! celebrate\n", #X, X, #Y, Y); \
}
void runTestSet(unsigned char * data, unsigned size)
{
u16 linux = crc_ccitt(0xFFFF, data, size);
boost::crc_optimal<16, 0x1021, 0xFFFF, 0, true, true> boost_crc_optimal_16_1021_FFFF_0_1_1;
boost_crc_optimal_16_1021_FFFF_0_1_1.process_bytes(data, size);
printf("Testing with sequence: '");
for (unsigned n = 0; n < size; ++n)
{
if (n > 0) printf(" ");
printf("0x%02X", data[n]);
}
printf("'\n");
check(boost_crc_optimal_16_1021_FFFF_0_1_1.checksum(), linux);
printf("End Of Testrun\n\n");
}
int main()
{
unsigned char zero_Length[] = {0x00};
unsigned char simple[] = {0x80};
unsigned char sequence[] = "123456789";
unsigned char LotsOfAs[] = "AAAAAAAAAAAAAAAAAAAAAAAAA";
runTestSet(zero_Length, 0);
runTestSet(simple, sizeof(simple));
runTestSet(sequence, sizeof(sequence)-1);
runTestSet(LotsOfAs, sizeof(LotsOfAs)-1);
return 0;
}