CRC32-C is specified as the CRC that uses the iSCSI polynomial (#x1edc6f41) in RFC 3720. The polynomial was introduced by G. Castagnoli, S. Braeuer and M. Herrmann.

1Basic Generation🔗 i

procedure
( crc32c-bytes bytes)→fixnum?
bytes:bytes?

Generates a checksum from a bytes? object.

Example:

> (crc32c-bytes #"Lorem ipsum dolor sit amet")

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procedure
( crc32c-string/utf8 string)→fixnum?
string:string?
( crc32c-string/latin-1 string)→fixnum?
string:string?
( crc32c-string/locale string)→fixnum?
string:string?

Generates a checksum from a string? object.

Example:

> (crc32c-string/utf8 "Lorem ipsum dolor sit amet")

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procedure
( crc32c-input-port [in])→fixnum?
in:input-port? =(current-input-port )

Generates a checksum reading bytes from an input-port? object.

Examples:

> (crc32c-input-port (open-input-bytes #"Lorem ipsum dolor sit amet"))

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> (crc32c-input-port (open-input-string "Lorem ipsum dolor sit amet"))

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2Incremental Generation🔗 i

The following procedures generate a checksum incrementally, one byte at a time.

value
crc32c-initial-value :fixnum? =4294967295

Initial value to use to start the generation of a checksum.

procedure
( crc32c-update accbyte)→fixnum?
acc:fixnum?
byte:byte?

Returns updated acc after using byte.

Example:

> (crc32c-update crc32c-initial-value 123)

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procedure
( crc32c-finalize acc)→fixnum?
acc:fixnum?

Finalizes the generation by applying the final XOR operation to acc.

Examples:

> (crc32c-finalize (crc32c-update crc32c-initial-value 123))

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> (for/fold ([acccrc32c-initial-value ]
#:result(crc32c-finalize acc))
([ch"Lorem ipsum dolor sit amet"])
(crc32c-update acc(char->integer ch)))

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