Re: BUG: non-fixed-length ISAs are unsupported for now
Sergey Belyashov via Cgen <[email protected]> Tue, 11 Aug 2020 18:57:12 +0300
| Newsgroups | gmane.comp.tools.cgen.devel |
|---|---|
| Message-ID | <CAOe0RDw6QWgRBRpiJ1Yr7scXrVPi-0z-DAFT8s8a+9RABh+S-A@mail.gmail.com> |
Hi, Thank you for your response. > .... these sound like they could fit into a single isa. You could > have a family of ifields, one set for each of these prefix > combinations. (Many could have different names and bit offsets but be > otherwise the same.) Then for each instruction, you would have a set > of separate define-instruction's for each prefix combination (!), > using the corresponding ifields. Ideally, use a cgen macro to > generate the separate define-instructions, to factor out the > commonalities. I have already tried to stay within one ISA but my attempt fails. You may look here for full source of my try: https://github.com/b-s-a/binutils-gdb/blob/z80-cgen/cpu/z80.cpu (invalid decoder is generated for last 2 lines - "reti" (ED 4D) and "retn" (ED 45) instructions, I have tried many types of ifields with same result, but these are simpler to read). I cannot understand what I'm doing wrong. Best regards, Sergey Belyashov