🔧 Refactor CRC-16 Configuration Naming and Expand Variants

[Nicoretti]

Summary

The current Crc16.CCITT implementation in our library aligns with CRC-16/XMODEM, which isn't listed among the alternative names/"Aliases" for "CCITT". One of the common names this configuration is known by is KERMIT (see here). We need to ensure CCITT provides the correct configuration or is replaced by at least one of the valid known alternative names/aliases.

Details

• Rename Crc16.CCITT to Crc16.XMODEM to accurately represent its configuration.
• Introduce Crc16.CCITT with the appropriate configuration.
• Bump major version.
• Introduce additional predefined CRC-16 configuration aliases, such as Crc16.KERMIT (optional).

References

• 🐞Predefined Crc16.CCITT is confusing #145

Expected Outcome:
The library will accurately represent various CRC-16 configurations, reducing confusion and increasing usability.

[IsaacDynamo]

Hi,

The proposed changes would be a nice improvement. I was surprised by the Crc16.CCITT behavior as well (#145).

Do you by any change have a source for Considering that "CCITT" refers to a group of related configurations rather than a single, specific one.? I'm trying to make sense of the CRC behavior in some other system and this sounds like an interesting reference.

[Nicoretti]

@IsaacDynamo sry, apparently the first section in this issue was formulated badly and is misleading.
I will update it.

[Nicoretti]

@IsaacDynamo this comment, may be interesting for you too.

[cmcqueen]

A tangential note about CCITT: There is further confusion about what algorithm is the "real CCITT CRC", to do with its initial value — whether the initial value is 0xFFFF or the "augmented" value of 0x1D0F (0xFFFF passed through the 16-bit shift register).

It's yet another reason to be cautious about providing a predefined definition for CCITT.

See

• CRC-CCITT -- 16-bit
• CCITT CRC 16 Bit Start Value 0xffff - Stack Overflow
• CRC-16/AUG-CCITT
• CRC-16/CCITT-FALSE