ThomasTJdev / crunchy

SIMD-optimized hashing, checksums and CRCs.

Crunchy

nimble install crunchy

API reference

About

Crunchy provides pure Nim implementations of common hashes and data integrity checks (cyclic redundancy checks and checksums). These implementations are intended to be high-performance, including amd64 and arm64 SIMD implementations or using instruction set intrinsics.

Function	Scalar	SIMD:	amd64	arm64
SHA-1	✅		⛔	⛔
SHA-256	✅		✅	⛔
CRC-32	✅		✅	✅
CRC-32C	⛔		✅	⛔
Adler-32	✅		✅	✅

Crunchy is a new repo so keep an eye on releases for more functions and SIMD optimization.

Examples

Runnable examples using Crunchy can be found in the examples/ folder.

Here is a basic example that prints the hex-encoded SHA-256 of a string:

import crunchy

let data = "The quick brown fox jumps over the lazy dog"
echo sha256(data).toHex()

Or calculating the CRC-32 of a string:

import crunchy

let data = "The quick brown fox jumps over the lazy dog"
echo crc32(data)

Now, lets say you want to compute the CRC-32 of a file. Many approaches are possible, but lets look at these two:

First, the easy way. Just read the file into memory and compute:

import crunchy

let data = readFile("tests/data/zlib.rfc")
echo crc32(data)

Alternatively, to avoid copying the file, memory-map the file and compute instead:

import crunchy, std/memfiles

var memFile = memfiles.open("tests/data/zlib.rfc")
echo crc32(memFile.mem, memFile.size)
memFile.close()

Memory-mapping the file is great if the file is very large or you want to avoid copying a large file's contents. This uses Crunchy's pointer + len API.

Testing

nimble test