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Re^5: How to use perl digest module to calculate CRC?

by BrowserUk (Pope)
on Mar 21, 2013 at 13:07 UTC ( #1024749=note: print w/ replies, xml ) Need Help??


in reply to Re^4: How to use perl digest module to calculate CRC?
in thread How to use perl digest module to calculate CRC?

I need to calculate the CRC

You still aren't answering the question of why you need this?

That is, the normal reason for calculating a crc is to detect transmission errors; but to do that, you need the crc as calculated prior to transmission to compare against. (Or if you are the transmitter; then a full description of the CRC algorithm expected by the receiver.

I'll be more specific: is the CRC algorithm you wish to use 'Rocksoft Model CRC Algorithm'?

If so, the full parameter set for teh algorithm should read something like:

Name : "CRC-32C" Width : 32 Poly : 1EDC6F41 (note that the leading "1" is implied) Init : FFFFFFFF RefIn : True RefOut : True XorOut : FFFFFFFF Check : E3069283
By the way, as far as I understand, the digest::CRC consider the data as an ASCII string. Meaning it takes each char, gets it ascii value, and then convert it to BIN. This is not what I need.

Then you'll need to pre-pack the data before giving it to Digest::CRC.

To do that, you'll need to know whether the CRC should be calculated for the data bytes alone; or should the preceding addresses be included some how?

What format is the data file in? Ie. Where does it come from? What produces it?


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