CRC32🔗ℹ

jrtxio

(require crc32)

package: crc32

This package provides CRC32 (IEEE 802.3 standard) checksum computation functions.

CRC32 is commonly used for error detection in network transmissions and file integrity checks.

1 API Reference🔗ℹ

procedure
(crc32-bytes bs) → exact-nonnegative-integer?
bs : bytes?

Computes the CRC32 checksum of the given byte string.

Examples:

> (require crc32)
> (crc32-bytes #"abc")
891568578
> (number->string (crc32-bytes #"abc") 16)
"352441c2"

procedure
(crc32-string/utf8 str) → exact-nonnegative-integer?
str : string?

Computes the CRC32 checksum of the UTF-8 encoding of the given string.

Examples:

> (require crc32)
> (crc32-string/utf8 "hello")
907060870
> (number->string (crc32-string/utf8 "hello") 16)
"3610a686"

procedure
(crc32-string/latin-1 str) → exact-nonnegative-integer?
str : string?

Computes the CRC32 checksum of the Latin-1 encoding of the given string.

procedure
(crc32-string/locale str) → exact-nonnegative-integer?
str : string?

Computes the CRC32 checksum of the locale encoding of the given string.

procedure
(crc32-input-port [in]) → exact-nonnegative-integer?
in : input-port? = (current-input-port)

Computes the CRC32 checksum of all bytes read from the input port.

Examples:

> (require crc32)
> (crc32-input-port (open-input-bytes #"test data"))
3540561586

2 Low-level API🔗ℹ

For incremental computation or when you need more control over the process:

value
crc32-initial-value : exact-nonnegative-integer?

The initial value for CRC32 computation (4294967295).

procedure
(crc32-update acc byte) → exact-nonnegative-integer?
acc : exact-nonnegative-integer?
byte : exact-nonnegative-integer?

Updates the CRC32 accumulator with a single byte.

procedure
(crc32-finalize acc) → exact-nonnegative-integer?
acc : exact-nonnegative-integer?

Finalizes the CRC32 computation by applying the final XOR.

3 Examples🔗ℹ

Examples:

> (require crc32)
> (crc32-bytes #"hello world")
222957957
> (define acc crc32-initial-value)
> (set! acc (crc32-update acc 104))
> (set! acc (crc32-update acc 101))
> (set! acc (crc32-update acc 108))
> (set! acc (crc32-update acc 108))
> (set! acc (crc32-update acc 111))
> (crc32-finalize acc)
907060870
> (crc32-bytes #"hello")
907060870