extentions: none
single cycle execution,
comparator a mix of these designs:
https://circuitverse.org/users/49594/projects/compare-a8bfbb20-bc4c-447e-8300-5e0bd31a5282
shift units stolen from this design
https://circuitverse.org/users/233415/projects/risc-v-32-bit-computer-rv-32i-user-mode
