Checksums

Crc32 and Adler32: the checksums gzip and zlib streams carry, for checking data as it is read or written.

Source: runtime/compress/checksum.pep

Crc32

struct Crc32

The CRC-32 checksum (IEEE 802.3, the polynomial gzip, zip and PNG use), computed over data given in one or more pieces.

Example

import compress;

var crc = compress.Crc32();
crc.update("hello ".bytes());
crc.update("world".bytes());
assert(crc.value == compress.Crc32.of("hello world".bytes()), "same in pieces");
assert(compress.Crc32.of("123456789".bytes()) == 0xCBF43926, "the check value");

Properties

value

var value: uint { get; }

The checksum of everything given to update so far.

Constructor

Crc32()

construct()

Makes a checksum of no data yet (value is 0).

Static methods

of

static of(data: u8[]): uint

Returns the CRC-32 of data.

Parameters

• data — the bytes to check

Returns

• the checksum

Methods

update

update(data: u8[])

Adds data to the checksum.

Parameters

• data — the next bytes of the data

reset

reset()

Starts over, as if no data had been given.

Adler32

struct Adler32

The Adler-32 checksum (RFC 1950, the one zlib streams carry), computed over data given in one or more pieces.

Example

import compress;

assert(compress.Adler32.of("Wikipedia".bytes()) == 0x11E60398, "the example");

Properties

value

var value: uint { get; }

The checksum of everything given to update so far.

Constructor

Adler32()

construct()

Makes a checksum of no data yet (value is 1).

Static methods

of

static of(data: u8[]): uint

Returns the Adler-32 of data.

Parameters

• data — the bytes to check

Returns

• the checksum

Methods

update

update(data: u8[])

Adds data to the checksum.

Parameters

• data — the next bytes of the data

reset

reset()

Starts over, as if no data had been given.