checksum

问题 i am trying to implement the 8-bit fletcher algorithm. I wrote a piece of code that does that but i am not sure if i understood the algorithm correctly. this is my piece of code: public class TestFletcher { public static void main(String[] argv) { String bin = "10010010101111101110101101110011"; char[] cA = bin.toCharArray(); int ckA = 0, ckB = 0; for (int i = 0; i < cA.length; i++){ ckA += Integer.valueOf(cA[i])/49; ckB += ckA; } System.out.println(ckA); System.out.println(ckB); } the

问题 i am trying to implement the 8-bit fletcher algorithm. I wrote a piece of code that does that but i am not sure if i understood the algorithm correctly. this is my piece of code: public class TestFletcher { public static void main(String[] argv) { String bin = "10010010101111101110101101110011"; char[] cA = bin.toCharArray(); int ckA = 0, ckB = 0; for (int i = 0; i < cA.length; i++){ ckA += Integer.valueOf(cA[i])/49; ckB += ckA; } System.out.println(ckA); System.out.println(ckB); } the

问题 Interestingly, I can find implementations for the Internet Checksum in almost every language except C#. Does anyone have an implementation to share? Remember, the internet protocol specifies that: "The checksum field is the 16 bit one's complement of the one's complement sum of all 16 bit words in the header. For purposes of computing the checksum, the value of the checksum field is zero." More explanation can be found from Dr. Math. There are some efficiency pointers available, but that's

问题 I need a C# .NET function to evaluate whether a typed or scanned barcode is a valid Global Trade Item Number (UPC or EAN). The last digit of a bar code number is a computer Check Digit which makes sure the bar code is correctly composed. GTIN Check Digit Calculator 回答1: public static bool IsValidGtin(string code) { if (code != (new Regex("[^0-9]")).Replace(code, "")) { // is not numeric return false; } // pad with zeros to lengthen to 14 digits switch (code.Length) { case 8: code = "000000" +

问题 I'm trying to communicate with a serial port as defined in a specification. ser = serial.Serial("/dev/ttyUSB0", baudrate="115200") frame = bytearray([ 0x00, 0x00, #frame control (2 bytes) 0x00, 0x00, #machine id (2 bytes) 0x07, # number of bytes in data field 0x01, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, #data field itself 0x00, 0x0A #checksum ]) ser.write(frame) ser.close() The code executes without error, and I am monitoring the same port in a separate script/process. The device is supposed to

问题 I have seen many different implementations of the same basic CRC-32 algorithm shown below: int remain; int sbox[SIZESBOX]; int dividend; int bit; for(dividend = 0; dividend < SIZESBOX; dividend++) { remain = dividend << 24; for(bit = 0; bit < 8; bit++) { if(remain & TOPBIT) { remain = (remain << 1) ^ POLYNOMIAL; } else { remain = (remain << 1); } } sbox[dividend] = remain; } Some of them XOR the dividend before going into the sbox. Others XOR before going into the bit loop, and others use

问题 Is there any existing tool which checks the SHA-1 checksums of the artifacts in a local Maven repository? I'd like to check the whole repository with one command. 来源： https://stackoverflow.com/questions/7949068/checking-local-maven-repository-checksums

问题 I have to do a lookup in a table, and I have a string identifier and the CRC32 of the string. If there is a miss, I have to decrement the size and lookup for a prefix of the identifier. Therefore, I would need to calculate the checksum of the prefix and repeat the process for each prefix. My C code of this algorithm is something like this: find_prefix(char* string, uint16_t size, uint32_t crc, hash_table_t *hash_table){ do{ if(perform_lookup(string, size, crc, hash_table)==HIT){ return size;

问题 This is from IEEE Std 802.11-2012 Clause 8.2.4.8 FCS field: I cannot understand the last two paragraphs: What's the meaning by "the initial remainder of the division is preset to all ones", and why we need to do that? What's the meaning by "... the serial incoming bits of the calculation fields and FCS..." ? 回答1: Initializing the CRC to all ones avoids the problem of a string of zeros of any length giving a zero CRC. Read Ross Williams CRC tutorial. 来源： https://stackoverflow.com/questions

问题 I'm currently looking for on how to determine the CRC produced from the machine to PC (and vice-versa). The devices are communicating using serial communication or RS232 cable. I do only have data to be able for us to create a program to be used for both devices. The data given was from my boss and the program was corrupted. So we are trying for it to work out. I hope everyone can help. Thanks :) 回答1: The sequence to use for the CRC calculation in your protocol is the ASCII string starting