Pack fractional bytes (uint4, uint6, uint7) into bytes.
$ go test -bench=. -benchmem .
goos: darwin
goarch: arm64
pkg: github.com/nikolaydubina/go-bit-packing
Benchmark_2x4b/pack-16 1000000000 0.8389 ns/op 2.220 GB/s 0 B/op 0 allocs/op
Benchmark_2x4b/unpack-16 1000000000 0.6956 ns/op 1.339 GB/s 0 B/op 0 allocs/op
Benchmark_4x6b/pack-16 1000000000 1.047 ns/op 3.559 GB/s 0 B/op 0 allocs/op
Benchmark_4x6b/unpack-16 453752890 2.563 ns/op 1.090 GB/s 0 B/op 0 allocs/op
Benchmark_8x7b/pack-16 399813974 2.951 ns/op 2.525 GB/s 0 B/op 0 allocs/op
Benchmark_8x7b/unpack-16 251525857 4.805 ns/op 1.357 GB/s 0 B/op 0 allocs/op