CRC.jl

A Julia module (and command line tool) for calculating Cyclic Redundancy Checksums (CRCs)
Popularity
11 Stars
Updated Last
11 Months Ago
Started In
March 2014

Build Status Coverage Status

CRC

This is a Julia module for calculating Cyclic Redundancy Checksums (CRCs).

  • All the algorithms in the RevEng Catalogue are supported.

  • New algorithms can be easily added.

  • Calculation can be direct or via cached tables.

  • Speed is comparable to optimized C (checked against CRC32 in libz).

  • Only arrays of bytes are accepted as data (it's certainly possible to handle arbitrary sized sequences; previous versions did this, but it complicated the code for little practical gain so I removed it - please contact me if you want me to add it back).

Examples

Calculate a CRC-32 Sum

julia> using CRC

julia> crc32 = crc(CRC_32)
(anonymous function)

julia> crc32("123456789")
0xcbf43926

The function crc() constructs a lookup table, which is cached in the returned function (here, crc32()). Re-using crc32() to calculate a series of CRCs is therefore more efficient than starting with crc() each time.

The returned function can also be called with a file handle, so calling open(crc32, file) will return the checksum of file.

Within Your Program

The same example as above, but inside your program, would look like this:

using CRC
...
crc32 = crc(CRC_32)  # create our own crc function, just once
...
function some_func(...)
    ...
    x = crc32(data)  # use the crc function created above, many times
    ...
end
...

Force Direct (Tableless) Calculation

julia> crc(CRC_32, tables=NoTables)("123456789")
0xcbf43926

Define an Algorithm

For example, CRC-7, catalogued as width=7 poly=0x09 init=0x00 refin=false refout=false xorout=0x00 check=0x75 name="CRC-7"

julia> myCRC7 = spec(7, 0x09, 0x00, false, false, 0x00, 0x75)
CRC.Spec{UInt8}(7, 0x09, 0x00, false, false, 0x00, 0x75)

julia> @assert crc(myCRC7)(CHECK) == myCRC7.check

Of course, this is already defined:

julia> CRC_7
CRC.Spec{UInt8}(7, 0x09, 0x00, false, false, 0x00, 0x75)

Installation

Julia can be downloaded here. Once Julia is working you can install this package using:

julia> Pkg.add("CRC")

Versions

  • 4.0.0 - 2020-11-27 Remove command line functionality.

  • 3.1.0 - 2020-11-07 Update ArgParse dependency and add Project.toml.

  • 3.0.0 - 2018-02-28 Update for Julia 1.0

  • 1.2.0 - 2016-09-28 Drop Julia 0.3 support and switch to Libz.

  • 1.1.0 - 2015-06-09 Small fixes for Julia 0.4, Travis + Coverage.

  • 1.0.0 - 2014-06-31 Changed handler method so that a String is converted to bytes (instead of being treated as a file path). This will break existing code that uses the current handler (sorry!), but I hope I don't have many users (particularly users that are calling that method)!

  • 0.2.0 - Initial release(s).