CRC32 is a checksum first proposed in 1961, and now used in a wide variety of performance sensitive contexts, from file formats (zip, png, gzip) to filesystems (ext4, btrfs) and protocols (like ethernet and SATA). So, naturally, a lot of effort has gone into optimising it over the years. However, I discovered a simple update to a widely used technique that makes it possible to run twice as fast as