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Re: Simulator: base_insn and insn in decode.c


I forgot to address your other question which was about the difficulty of setting entire_insn before decoding. It's a bit of a chicken and egg situation isnt'y it? You can't set entire insn properly until you know something about the insn, but you can't call decode without setting entire_insn properly.

Your method of calling decode twice won't work because of this.

Most existing ports determine the insn length by looking at a few bits in base_insn and use this information to fill entire_insn.

I'm wondering if the decoder shouldn't be redesigned so that all it takes is base_insn, which should be all that is necessary to identify the insn. The extractors for each format would then read any additional bytes as needed. There is already support for this for ISAs with insns which are longer than an insn word.

Dave


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