Crate internet_checksum

RFC 1071 "internet checksum" computation.

This crate implements the "internet checksum" defined in RFC 1071 and updated in RFC 1141 and RFC 1624, which is used by many different protocols' packet formats. The checksum operates by computing the 1s complement of the 1s complement sum of successive 16-bit words of the input.

SIMD acceleration is used on some platforms (currently, x86_64 with the avx2 extensions).

Benchmarks

The following microbenchmarks were performed on a 2018 Google Pixelbook. Each benchmark constructs a Checksum object, calls Checksum::add_bytes with an input of the given number of bytes, and then calls Checksum::checksum to finalize. Benchmarks were performed with SIMD both enabled and disabled. Average values were calculated over 3 trials.

Bytes	Time w/o SIMD	Rate w/o SIMD	Time w/ SIMD	Rate w/ SIMD	Ratio (time w / time w/o)
31	3,657 ns	8.48 MB/s	3,692 ns	8.40 MB/s	1.01
32	3,735 ns	8.57 MB/s	3,767 ns	8.50 MB/s	1.01
64	7,092 ns	9.02 MB/s	6,580 ns	9.73 MB/s	0.93
128	13,790 ns	9.28 MB/s	7,428 ns	17.2 MB/s	0.54
256	27,169 ns	9.42 MB/s	9,224 ns	27.8 MB/s	0.34
1024	107,609 ns	9.52 MB/s	20,071 ns	51.0 MB/s	0.19

Structs

Checksum

RFC 1071 "internet checksum" computation.

Functions

checksum	Compute the checksum of "bytes".
update	Updates bytes in an existing checksum.