# crc8-icode-fast
SIMD implementation of CRC-8/I-CODE, with table and loop fallbacks.
This crate was generated by
[crc-fast-rs](https://github.com/TobiasBengtsson/crc-fast-rs).
## Principle of operation
TL;DR: uses SIMD if available, otherwise falls back seamlessly to a lookup table
algorithm.
- If using `hash`, will use SIMD if the CPU is capable
- x86-64 CPU:s with the following CPU flags are supported (runtime detection):
- `pclmulqdq`
- `sse4.1`
- aarch64 CPU:s with the following CPU flags are supported:
- `nano`
- `aes`
- **IMPORTANT**: To use runtime CPU feature detection on aarch64, the `std`
feature is required. Otherwise it has to be built with a compatible
target-cpu to use SIMD, unlike x86-64.
- If using `hash` with an incompatible CPU the fallback algorithm will be
invoked. If the `table-fallback` feature is active the fallback is based on
a lookup table, otherwise a simple loop (slowest option). Deactivating
`table-fallback` (default enabled) can be useful when memory is very scarce,
as the lookup table requires a small amount of extra RAM.
- If `table-fallback` feature is enabled, it can be manually invoked by
`hash_table` (not recommended in the typical case).
- Similarly, `hash_simple` can be used to force the loop algorithm (also not
recommended in the typical case).
## Usage
```
let res: u32 = crc8_icode_fast::hash(&my_binary_slice);
```
There is no "update"-like functionality yet, since doing this with arbitrarily
lengths can be tricky with SIMD and destroy performance.