[J-core] [Possible bug] It seems only decode_table_reverse.vhd works out of the decode implementations

Robert Ou rqou at robertou.com
Mon Jul 18 15:11:27 EDT 2016

Actually, this seems to work after selecting the correct CPU
configuration and ensuring that the CPU and the decode logic are all
reset properly. Sorry for the noise.

On Mon, Jul 18, 2016 at 2:44 AM, Robert Ou <rqou at robertou.com> wrote:
> Hi,
> It seems to me that only the decode_table_reverse.vhd implementation
> actually works correctly. If you take my MyHDL demonstration sent to
> the list earlier and change the ghdl command line to use one of the
> other decode implementations, you will get:
> with decode_table_rom.vhd:
> The CPU continuously fetches instructions sequentially. It never seems
> to actually execute them. Some poking around seems to show that the
> line signal never changes.
> with decode_table_simple.vhd:
> Nothing ever happens externally. I didn't investigate what happens
> inside the core.
> Of course, these issues could very well be with my particular
> demonstration setup. Can someone confirm that these other decode
> implementations are/are not working with the normal J-core build
> system? I am using the 20160418 source dump, md5
> f6876049560136ab0a6b21914a939b95.
> Robert

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