1、概述

CRC16循环冗余校验常用在MODBUS协议中，用于校验报文的完整性。CRC16校验值为uint16_t 无符号整形2字节，在MODBUS协议中，低检验字节在前，高校验字节在后，比如校验结果crc16=0x1788，则MODBUS中的校验顺序为 ...0x88 0x17。

以下为自己写的linux C 代码，可以直接用。

2、C程序

/*******************************************************************************
_____ ___ ____  ___   _____    _             _   _             
| ____|_ _|  _ \|_ _| |_   _|__(_)_ __   __ _| | | |_   _  __ _ 
|  _|  | || |_) || |    | |/ __| | '_ \ / _` | |_| | | | |/ _` |
| |___ | ||  _ < | |    | |\__ \ | | | | (_| |  _  | |_| | (_| |
|_____|___|_| \_\___|   |_||___/_|_| |_|\__, |_| |_|\__,_|\__,_|* File Name          : main.c* Description        : This file provides code for crc16 caculation in linuxc.* Author             : jackwang by jiawang16@foxmail.com* Date               : 2018-07-15
*******************************************************************************/
/*! -------------------------------------------------------------------------- */
/*! Include headers */
#include <stdio.h>
#include <string.h>
#include <stdbool.h>/*! -------------------------------------------------------------------------- */
/*! Private function declarations */
static unsigned char Char2Int(char chr,bool *isOK);/*! convert char to int type*/
static unsigned char HexStr2Int(char *str, bool *isOK);/*!convert hexstr to int*/
/*! caculate crc16 of buff-input:arr_buff and length: len */
static unsigned short GenerateCRC16(unsigned char *arr_buff, unsigned short len);/*! -------------------------------------------------------------------------- */
/*! main function defination */
int main(int argc, char* argv[])
{/*! variable define */int ret = 0;int numByte = argc; unsigned char bccVal = 0x00;char inPutbuff[10];unsigned char databuff[1000];unsigned short buffsize = 0;unsigned short crcVal;bool isOK;int Nibb;if(argc == 1){printf("[note]  no params to caculate, please input hex string,splite by space!\r\n");}else{printf("[note]  input %d byte: ",numByte-1);for(int i = 1; i < numByte; i++){printf("%s ",argv[i]);}printf("\r\n");for(int i = 1; i < numByte; i++){memcpy(inPutbuff,argv[i],2);Nibb = HexStr2Int(inPutbuff,&isOK);if(isOK){databuff[i-1] = Nibb;buffsize++;}}crcVal = GenerateCRC16(databuff,buffsize);printf("[note]  crc16 value: 0x%04X\r\n",crcVal);}return 0;
}/*! -------------------------------------------------------------------------- */
/*! Private function definations */
/*! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */
static unsigned char Char2Int(char chr,bool *isOK)
{unsigned char nibb1;if(chr >= '0' && chr <= '9'){ nibb1 = chr - '0'; *isOK = true;}else if(chr >= 'a' && chr <= 'f'){ nibb1 = chr - 'a' + 10; *isOK = true;}else if(chr >= 'A' && chr <= 'F'){ nibb1 = chr -'A' + 10; *isOK = true; }else{  printf("[error]  invalid hex str input: %c \r\n",chr); *isOK = false; }return nibb1;
}/*! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */
static unsigned char HexStr2Int(char *str, bool *isOK)
{unsigned char nibb1,nibb2;bool isOK1,isOK2;nibb1 = Char2Int(*str, &isOK1);nibb2 = Char2Int(*(str+1),&isOK2);if(isOK1 && isOK2){*isOK = true;return nibb1*16 + nibb2;}else{*isOK = false;return 0;}
} /*! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */
static unsigned short GenerateCRC16(unsigned char *arr_buff, unsigned short len)
{unsigned short crc=0xFFFF;unsigned char i, j;for ( j=0; j < len;j++){crc=crc ^*arr_buff++;for ( i=0; i<8; i++) {if( ( crc&0x0001) >0){crc=crc>>1;crc=crc^ 0xa001;}else{ crc=crc>>1;}}}return crc;
}

3、编译

~$ gcc main.c -o getcrc16

4、使用

 
~$ ./getcrc16 01 03 00 04 00 04
~$ [note]  input 6 byte: 01 03 00 04 00 04
~$ [note]  crc16 value: 0xC805