A very unusual CRC32 function (the most common variant used in PKZIP), it does not use tables and reads data in 32-bit aligned chunks (it can handle unaligned pointer and size not multiple of 4) and also processes 32 bits at a time.
Also the code is self-describing, see those big CRC letters? But maybe I misunderstand this term.
- Little-endian code, big-endian CPUs need byte swapping.