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Questions tagged [crc]

Cyclic redundancy check. An error checking mechanism used for verifying data integrity in serial protocols.

1120 questions
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Algorithm for hash/crc of unordered multiset

Let's say I would like to create a unordered set of unordered multisets of unsigned int. For this, I need to create a hash function to calculate a hash of the unordered multiset. In fact, it has to be good for CRC as well. One obvious solution is to…
gsf
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Best way to test CRC logic?

How can I verify two CRC implementations will generate the same checksums? I'm looking for an exhaustive implementation evaluating methodology specific to CRC.
Joseph Weissman
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Python gzip CRC check failed

I have a folder with huge text files. Each one is gzipped and weighs several Giga byte. I wrote a piece of code to split the content of each gzip file: each gzip file is open with gzip, then every specified chunk of line is read and written to a new…
kaligne
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How to recalculate a CRC32 on a large byte array when replacing a small number of bytes

I have a problem where as input I have a large byte array (typically >1K length) which has a computed CRC32. I need to replace a small chunk of the array with different values, and recalculate the CRC. Is there an efficient way to do this without…
R. Vreeland
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How to Determine Which CRC to Use?

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?
djpark121
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How could I guess a checksum algorithm?

How can I figure out the CRC algorithm if a given code + CRC string is given? I have got several strings consisting of code + matching CRCs but don't know how to calculate the CRC in question so that I could produce more code strings. Here are some…
Tom
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ios - How to calculate CRC-8-Dallas/Maxim of NSData?

I need to calculate exactly CRC-8-Dallas/Maxim. Can someone provide an algorithm? Any help is appreciated!
stsmkrv
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_mm_crc32_u8 gives different result than reference code

I've been struggling with the intrinsics. In particular I don't get the same results using the standard CRC calculation and the supposedly equivalent intel intrinsics. I'd like to move to using _mm_crc32_u16, and _mm_crc32_u32 but if I can't get the…
David Larson
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Find out CRC or CHECKSUM of RS232 data

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…
Carlos Alloatti
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Prove the linearity for CRC

I know that CRC is a linear function which means CRC(x xor y) = CRC(x) xor CRC(y), but I don't know how to prove this property for CRC. Does anyone have any idea? Thanks a lot!
user1995098
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CCITT CRC 16 Bit Start Value 0xffff

I need to calculate a CCITT 16 bit checksum value for data passed as a parameter together with the length. If I fill my array TempStr with the test data "123456789", use the polynomial 0x8408 with the length excluding the null termination character,…
Ruaan Volschenk
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CRC test vectors for CRC16 (CCITT)

Does anyone know of some CRC test vectors for CRC16-CCITT? I do not have a CRC implementation I can trust and either need to test someone's implementation or my own. (For CRC32, I use the PNG code as the gold standard, as it's a reputable reference…
Jason S
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CRC16 ISO 13239 Implementation

i'm trying to implement Crc16 in C#. I already tried many different implementations, but most of them gives me different values. Here are some of the codes that i already used. private static int POLYNOMIAL = 0x8408; private static int…
Fabio Reis
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Eliminating sequences in a message

I have an odd communications channel, and I need to detect errors as well as eliminate certain sequences in the channel. Each message is 12 bits long, split into 3 nibbles (of 4 bits each). I need to extract at least 450 different codes out of this,…
Adam Davis
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different between CRC8 , CRC16 and CRC32?

I would like to know the difference and how to choose the polynomial generator for different crc ? And in some C code they have look up table to compute crc and some of them do it by xor truth table. but in both the cases it is 1byte data array.…
Vino
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