In Django Design Patterns, the author recommends using zlib.crc32 to mask primary keys in URLs. After some quick testing, I noticed that crc32 produces negative integers about half the time, which seems undesirable for use in a URL. zlib.adler32 does not appear to produce negatives, but is described as "weaker" than CRC. Is this method...
I need to communicate with a RS232 device, I have no specs or information available. I send a 16 byte command and get a 16 byte result back. The last byte looks like some kind of crc or checksum, I have tried using this http://miscel.dk/MiscEl/miscelCRCandChecksum.html with no luck. Anyone can reverse engineer the crc/checksum algorit...
I wish to use common CRC logic in a VB.NET or C# application as well as on a C/Linux application. I have one C/Linux application that interacts with a webservice (written in C#) and also a web application (written in VB.NET). For some data, I want to add a CRC to the data itself (say a file) from the .NET side and check for the integrity...
I am working on a function that will give me a Kermit CRC value from a HEX string. I have a piece of code in DELPHI. I am a .NET developer and need the code in C#. function CRC_16(cadena : string):word; var valuehex : word; i: integer; CRC : word; Begin CRC := 0; for i := 1 to length(cadena) do begin valuehex :=...
Hello I'm working in a big java project, with about 400 classes. Suddenly I got this error sun.awt.image.PNGImageDecoder$PNGException: crc corruption at sun.awt.image.PNGImageDecoder.getChunk(PNGImageDecoder.java:699) at sun.awt.image.PNGImageDecoder.getData(PNGImageDecoder.java:707) at sun.awt.image.PNGImageDecoder.produce...
I have a sensing device that transmits a 6-byte message along with an 1-byte counter and supposedly a checksum. The data looks something like this: ------DATA----------- -Counter- --Checksum?-- 55 FF 00 00 EC FF ---- 60---------- 1F The last four bits in the counter are always set 0, i.e those bits are probably not used. The last ...
[root@blanee local_cache]# gem install dm-core-0.9.11.gem ERROR: While executing gem ... (Zlib::GzipFile::CRCError) invalid compressed data -- crc error [root@blanee local_cache]# gem install ParseTree-3.0.5.gem ERROR: While executing gem ... (Zlib::GzipFile::CRCError) invalid compressed data -- crc error I have a lot gem p...
Hi guys, I need to implement the CRC error detection in my system. I wonder how to determine the maximal number of detectable error (and undetectable as well) having the generation polynomial? Assume that I have got, say, the following g(x) = x^4 + x^3 + 1. There are 2^15 possible transmissions - the 11-bit words might be protected by...
Hi guys, How to find the Hamming distance of a code generated by a certain CRC? Assume that I have a generating polynomial of order, say, 4 and 11 bits of data. How to compute the HD basing only on these information? Cheers. ...
If I have a certain number of bytes to transfer serially, how do I determine which CRC (CRC8, CRC16, etc., basically a how many bit CRC?) to use and still have error detection percentage be high? Is there a formula for this? ...
Hi, i'm trying to implement a CRC-CCITT (XModem) check in javascript without success. I need it in order to send socket string into a controller via RS232. does anyone know how to do it? or perhaps is there a sample code somewhere?? I would appreciate any kind of help :) ...
I need to compute the CRC-16 for arbitrary strings in a mixed java/groovy application. Specifically, I need the CRC-16-ANSI aka CRC-16-IBM variant (see http://en.wikipedia.org/wiki/Cyclic_redundancy_check for details; this is the modbus / USB version.) I could implement my own, but I'd much rather find a library out there that someone ...
On application startup I build a cache of icons (24x24 32bbp pre-multiplied argb bitmaps). this cache contains roughly a thousand items. I don't want to store the same image multiple times in this cache, for both memory and performance reasons. I figured the best way would be to create some sort of crc from each bitmap as it goes into th...
The situation is this: My system (Win XP Pro) is unable to copy a huge video file (around 6 gigs) from a DVD disk, which might be defective, scratched or whatever but which can be played back with mplayer with a few frames full of mosaic though. When the copying process lasted for a certain length of time, the system would abort the effo...
Hi, I am developing an application in flex in which I need to calculate checksum of different files. I would like to know if there is a direct method in actionscript to calculate that or do I have to go for any external libraries? Thanks in advance :) ...
Can someone please code me the CRC64 Reverse Algorithm in C#? I am unable to code it, can't understand anything. Thanks, I have copied the CRC64 Checksum code from C++ and converted it into C# .NET. The entire code is displayed below: using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace CRC64...
I am learning, trying to get thoughts behind CRC. I can't find CRC128 and CRC256 code anywhere. If anyone of you have the C++ or C# Code for them, please share them with me. Also provide online links to the websites. I am a newbie and can't code it by myself at all, neither can convert theories and mathematics to the coding. So I ask for...
How can I verify two CRC implementations will generate the same checksums? I'm looking for an exhaustive implementation evaluating methodology specific to CRC. ...
Hi So I have a CRC polynomial x3 + x1 + 1 on a letter 'P' I need to divide the binary code of 'P' by the polynomial But I'm stuck at this point.. 0 1 0 1 0 0 0 0 000 | 1 0 1 1 1 0 1 1 | --------- | 1 1 1 0 0 ? 1 0 1 1 I don't understand what to do with the 1 in front? Does someone know an answer here? ...
Given a file on the local filesystem: FileInfo file = new FileInfo(localFilename); How can I get a CRC-value (or some kind of checksum) for that file? ...