# crc16

##### how to calculate ANSI CRC16 polynomial (0x8005) in python3?

Question I tried to calculate ANSI CRC16 polynomial (0x8005) using this code import crcmod crc16 = crcmod.mkCrcFun(0x8005, 0xffff, True) but I got this error message ValueError: The degree of the polynomial must be 8, 16, 24, 32 or 64 Answer1 There is an implied 1 at the beginning of 0x8005 crcmod expects you to provide the 1 explicitly import crcmod crc16 = crcmod.mkCrcFun(0x18005, 0xffff, True)

2021-09-13 21:07:54 分类:技术分享 python python-3.x crc crc16

##### Calculation of CCITT standard CRC with polynomial x^16 + x^12 + x^5 + 1 in Java

Question I need help with calculating of CCITT standard CRC with polynomial x^16 + x^12 + x^5 + 1 (0x1081) in Java. I have tried many examples on the internet but every one of them returns other values than the ones in the example. For example for this array [0xFC] [05] [11] the result needs to be [27] [56]. Using this code: public static void main(String[] args) { byte[] array = new byte[3]; array[0] = (byte) 0xFC; array[1] = (byte) 0x05; array[2] = (byte) 0x11; // array[3] = (byte) 0x00; // array[4] = (byte) 0x00; System.out.println(Integer.toHexString(crc16(array))); } private static final

2021-09-01 02:13:46 分类:技术分享 java calculator polynomial-math crc16

##### CCITT CRC 16 Bit Start Value 0xffff

Question I need to calculate a CCITT 16 bit checksum value for data passed as a parameter together with the length. If I fill my array TempStr with the test data "123456789", use the polynomial 0x8408 with the length excluding the null termination character, I get the result string 6E90(Hex). Together with the null termination char I get 907A. When I swap out the polynomial to 0x1201 then I get results 29E2(Hex) and EFE8(Hex) with and without termination character. My questions are: Do I need to calculate the CRC with or without the null termination character to obtain the correct value? Do I

##### CRC-CCITT to CRC16 Modbus implementation

Question I am having a lot of trouble on generating a modbus CRC16 code using PHP. I have found a lot of different codes over the internet but i have tried them and for some reason i didnt get right results. I have found a PHP code for generating CRC16-CCITT. I have chenge the look up table to the modbus CRC corresponding table but the result is still not the right one. The code is bellow. What do i need to do more in order to transform a CRC16-CCITT code into CRC16-MODBUS code. <?php /************************************************************************* * phpCrc16 v1.1 -- CRC16/CCITT

##### CRC-ITU calculation in c#

Question I'm new to C#. I need to calculate CRC-ITU for the packet recieved from GPS devices. There is C code provided in the documentation but i don't know how to port it to C#, anyone could help me? here is CRC-ITU algorithm in C : static const U16 crctab16[] = { 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

##### Convert C to PHP for CRC16 Function

Question I need help in converting C code into PHP. The following is the C Code: static const U16 crctab16[] = { 0x0000, 0x1189, ... }; U16 GetCrc16(const U8* pData, int nLength) { U16 fcs = 0xffff; while(nLength > 0) { fcs = (fcs >> 8) ^ crctab16[fcs ^ *pData) & 0xff]; nLength--; pData++; } return ~fcs; } I have the following PHP code that I have managed to convert thus far: $crctab16 = array(0x0000, 0x1189, ... ); function getCrc16($pData) { $hexdata = pack('H*',$pData); $nLength = strlen($hexdata); $fcs = 0xFFFF; $pos = 0; while($nLength > 0) { $fcs = ($fcs >> 8) ^ $crctab16[($fcs ^

##### How to calculate CRC16 CCITT in PHP HEX?

Question I'm trying to use a PHP CRC16 CCITT function to calculate the checksum. A device sends me a PACKET with Checksum included: 10 00 00 00 00 00 00 00 12 51 09 08 00 18 00 04 02 14 00 0c 00 0c 02 1c 00 02 00 00 00 00 00 00 a0 77 The checksum is at the end: a0 77 I've tried using How to calculate crc16 in php Convert C to PHP for CRC16 Function With no success, the CRC 16 Calculations return: E6 F4 instead of a0 77 I get the correct Hex information returned, when I lookup: 100000000000000012510908001800040214000c000c021c0002000000000000 on the website http://www.lammertbies.nl/comm/info

##### Calculating CRC initial value instead of appending the CRC to payload

Question Most of the CRCs I've implemented were appending the calculated CRC value to the message (payload) and checking for a zero result at the receiver after all bytes incl. CRC value were fed through the CRC register. Obviously this is a quite standard approach. Now I would like to use a different approach: Calculate a value from the payload. Use that value as initial value for the CRC register before the message bytes (payload) are fed through the CRC register such that the result after the last byte of the payload was fed through will be zero. What is the best approach to do this? Does

##### CRC16 algorithm two: java implementation of CRC16-CCITT-XMODEM algorithm

CRC16 algorithm series articles:One of CRC16 algorithm: java implementation of CRC16-CCITT-FALSE algorithmCRC16 algorithm two: java implementation of CRC16-CCITT-XMODEM algorithmCRC16 algorithm three: java implementation of CRC16-CCITT-MODBUS algorithm PrefaceThere are many CRC16 algorithms. This article will introduce the CRC16-CCITT-XMODEM algorithm. FeaturesImplement CRC16-CCITT-XMODEM algorithmSupport int, short typeSupport selection of array area calculationachievepackage cc.eguid.crc16; /** * crc16多项式算法 * @author eguid * */ public class CRC16 { /** * CRC16-XMODEM算法（四字节） * @param bytes *

##### One of CRC16 algorithm: java implementation of CRC16-CCITT-FALSE algorithm

CRC16 algorithm series articles: One of CRC16 algorithms: java implementation of CRC16-CCITT-FALSE algorithmCRC16 algorithm two: java implementation of CRC16-CCITT-XMODEM algorithmCRC16 algorithm three: java implementation of CRC16-CCITT-MODBUS algorithm Preface The JDK contains the CRC32 algorithm, but there is no CRC16. I searched a bunch of online but did not find what I wanted. I simply realized it myselfNote : There are many types of CRC16 algorithms. In this article, only one of them will be discussed : CRC16-CCITT-FALSE algorithmOne of the CRC16 algorithm series: the java implementation

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