1、概述

CRC16循環冗余校驗常用在MODBUS協議中，用于校驗報文的完整性。CRC16校驗值為uint16_t 無符號整形2字節，在MODBUS協議中，低檢驗字節在前，高校驗字節在后，比如校驗結果crc16=0x1788，則MODBUS中的校驗順序為 ...0x88 0x17。

以下為自己寫的linux C 代碼，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、編譯

~$ 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

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總結

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