crcxx 0.3.0

The crate compute CRC-8/16/32/64/128 using various methods. Included catalog of CRC parameters simplify usage.
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# crcxx

[![Crate](https://img.shields.io/crates/v/crcxx.svg)](https://crates.io/crates/crcxx)
[![API](https://docs.rs/crcxx/badge.svg)](https://docs.rs/crcxx)
[![License](https://img.shields.io/badge/license-Apache--2.0-blue.svg)](LICENSE)
[![Windows Build Status](https://ci.appveyor.com/api/projects/status/loj512o2qo6q0rwg?svg=true)](https://ci.appveyor.com/project/khrs/crcxx)

The crate compute CRC-8/16/32/64/128 using various methods. Included catalog of CRC parameters simplify usage.
It is applicable from small embedded systems to modern desktops and servers. No unsafe or architecture specific code.

### Processing using no lookup table, single byte per step

The slowest method. No additional memory required.

```rust
use crcxx::crc32::{*, catalog::CRC_32_BZIP2};

const CRC: Crc<NoLookupTable> = Crc::<NoLookupTable>::new(&CRC_32_BZIP2);

fn main() {
    // singlepart data.
    let crc = CRC.compute(b"123456789");
    assert_eq!(crc, 0xFC89_1918);

    // Multipart data.
    let mut multipart = CRC.compute_multipart();
    multipart.update(b"1234");
    multipart.update(b"5678");
    multipart.update(b"9");

    let crc = multipart.value();
    assert_eq!(crc, 0xFC89_1918);
}
```

### Processing using a lookup table with 32 entries, single byte per step

Good compromise between speed and memory consumption for small embedded devices.
Depending on usage scenario usually 2-5 times faster than the previous method.

```rust
use crcxx::crc32::{*, catalog::CRC_32_BZIP2};

const CRC: Crc<LookupTable32> =
    Crc::<LookupTable32>::new(&CRC_32_BZIP2);

fn main() {
    // singlepart data.
    let crc = CRC.compute(b"123456789");
    assert_eq!(crc, 0xFC89_1918);

    // Multipart data.
    let mut multipart = CRC.compute_multipart();
    multipart.update(b"1234");
    multipart.update(b"5678");
    multipart.update(b"9");

    let crc = multipart.value();
    assert_eq!(crc, 0xFC89_1918);
}
```

### Processing using a lookup table with 256 entries, single byte per step

Depending on usage scenario usually no more than 2 times faster than the previous method.

```rust
use crcxx::crc32::{*, catalog::CRC_32_BZIP2};

const CRC: Crc<LookupTable256> =
    Crc::<LookupTable256>::new(&CRC_32_BZIP2);

fn main() {
    // singlepart data.
    let crc = CRC.compute(b"123456789");
    assert_eq!(crc, 0xFC89_1918);

    // Multipart data.
    let mut multipart = CRC.compute_multipart();
    multipart.update(b"1234");
    multipart.update(b"5678");
    multipart.update(b"9");

    let crc = multipart.value();
    assert_eq!(crc, 0xFC89_1918);
}
```

### Processing using a lookup table with 256 x SLICES entries, multiple bytes per step

Ultimate method for processing big amounts of data on modern desktops and servers.
Depending on usage scenario (prefer bigger chunks) usually 6 times faster than the previous method.
The recommended number of slices is 16. There is usually less than 10% improvement when going from 16 to 32.

```rust
use crcxx::crc32::{*, catalog::CRC_32_BZIP2};

const SLICES: usize = 16;
const CRC: Crc<LookupTable256xN<SLICES>> =
    Crc::<LookupTable256xN<SLICES>>::new(&CRC_32_BZIP2);

fn main() {
    // singlepart data.
    let crc = CRC.compute(b"123456789");
    assert_eq!(crc, 0xFC89_1918);

    // Multipart data.
    let mut multipart = CRC.compute_multipart();
    multipart.update(b"1234");
    multipart.update(b"5678");
    multipart.update(b"9");

    let crc = multipart.value();
    assert_eq!(crc, 0xFC89_1918);
}
```

## MSRV

Current MSRV is 1.59. Keep in mind the official crate policy is latest stable.

## License

This project is licensed under the [Apache 2.0 license](LICENSE)