Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.arch.embedded > #29866

Re: Need Help with CRC16

Show all headers | View raw

On 28/07/2020 03:57, Miguel Angel Palos M wrote:
> El lunes, 27 de julio de 2020 a las 20:45:25 UTC-5, Rick C escribió:
>> On Monday, July 27, 2020 at 3:55:00 PM UTC-4, Miguel Angel Palos M
>> wrote:
>>> Hi good day; I want to see the possibility that if someone can
>>> help me generate 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?
>> 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 details?
>> 
>> --
>> 
>> Rick C.
>> 
>> - Get 1,000 miles of free Supercharging - Tesla referral code -
>> https://ts.la/richard11209
> 
> 
> 
> 
> 
> 
> Sure, the File is attached; I have a program that checks the value of
> the crc 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.
> 
> I do not know if I explained well?
> 
> 

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.

<https://en.wikipedia.org/wiki/Cyclic_redundancy_check>

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.

Back to comp.arch.embedded | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Need Help with CRC16 Miguel Angel Palos M <miguel.palos@gmail.com> - 2020-07-27 12:54 -0700
  Re: Need Help with CRC16 Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-27 18:45 -0700
    Re: Need Help with CRC16 Miguel Angel Palos M <miguel.palos@gmail.com> - 2020-07-27 18:57 -0700
      Re: Need Help with CRC16 David Brown <david.brown@hesbynett.no> - 2020-07-28 09:09 +0200
  Re: Need Help with CRC16 Don Y <blockedofcourse@foo.invalid> - 2020-07-28 01:00 -0700
    Re: Need Help with CRC16 Miguel Angel Palos M <miguel.palos@gmail.com> - 2020-07-29 16:46 -0700
      Re: Need Help with CRC16 Rick C <gnuarm.deletethisbit@gmail.com> - 2020-07-29 17:38 -0700
      Re: Need Help with CRC16 Don Y <blockedofcourse@foo.invalid> - 2020-07-29 22:27 -0700
      Re: Need Help with CRC16 Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2020-07-30 11:15 +0300
      Re: Need Help with CRC16 Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2020-07-30 11:15 +0300
        Re: Need Help with CRC16 Don Y <blockedofcourse@foo.invalid> - 2020-07-30 02:41 -0700
          Re: Need Help with CRC16 Miguel Angel Palos M <miguel.palos@gmail.com> - 2020-07-30 06:46 -0700
            Re: Need Help with CRC16 Don Y <blockedofcourse@foo.invalid> - 2020-07-30 07:00 -0700
        Re: Need Help with CRC16 Miguel Angel Palos M <miguel.palos@gmail.com> - 2020-07-30 06:40 -0700
          Re: Need Help with CRC16 Miguel Angel Palos M <miguel.palos@gmail.com> - 2020-07-30 06:48 -0700
  Re: Need Help with CRC16 jgh@mdfs.net - 2020-07-31 17:24 -0700

csiph-web