Hi good day; I want to see the possibility that if someone can help me gene rate a crc calculator from txt files, I have a text file, and the result of the crc by which it must be submitted I already have, but I don't know how to get to He actually has several files to do the test, but I couldn't get to those results; Can someone help me?
nerate a crc calculator from txt files, I have a text file, and the result of the crc by which it must be submitted I already have, but I don't know h ow to get to He actually has several files to do the test, but I couldn't g et to those results; Can someone help me?
What is in the text file, the data you need to calculate the CRC16 on?
Are you coding this in some particular language? Can you give us some deta ils?
- Get 1,000 miles of free Supercharging
generate a crc calculator from txt files, I have a text file, and the resul t of the crc by which it must be submitted I already have, but I don't know how to get to He actually has several files to do the test, but I couldn't get to those results; Can someone help me?
Sure, the File is attached; I have a program that checks the value of the c rc that is in the first line against the crc that gives the checksum of the file; so my purpose is to figure out how to modify the file and obviously put the new crc on the first line.
Do you have any documentation or information about the file format or the way the CRC is calculated?
As I see it, there are two key challenges. First, there are a large number of variations as to what "CRC16" could mean. The Wikipedia article can give you some idea - there are lots of suitable polynomials for 16-bit CRC's, you can have any starting value, there can be bit reversals, byte reversals, and other variations.
The biggest question, I think, is knowing what part of the file the CRC is run over, and in what way. Obviously the first line is not part of the checksummed data, since it contains the CRC. Which other parts are omitted? Are the numbers used directly as 16-bit values? Are ASCII characters used as the data? Is white space skipped or included? Line endings?
No one here can tell you (unless someone happens to recognize the file format). Trying to figure out the variation used by guesswork and trial and error is going to be a lot of effort.
In the Internet RFC 1662 part C, there is a pretty general example of calculating CRCs. The PPP polynomial is different from the IBM CRC-16, but the algorithm is valid for it, too, if the polynomial is adjusted in a suitable way.
At least, you need the initial value of the generator and which way the bits are processed, most significant end first or least significant end first.
If you have many examples, the initial value can be deduced, but it would be better to know it. Often all ones (0xffff) are used, to prevent initial null bytes of the message being ignored. Sometimes the final value is inverted.
The example text file cannot be reliably used to check, as its whitespace can be transformed during transfers through the NNTP protocol.
of ??how to obtain the other data that I lack to calculate the data of the crc?
Mr Tauno Voipio
I have many examples of +10 files with the crc in the header which is what it should give and all in TXT format, the detail is that I have not even fo und what you are commenting on and it makes itself look so easy.