[libre-riscv-dev] using a stage chain in a stage

Luke Kenneth Casson Leighton lkcl at lkcl.net
Thu Jun 4 02:20:18 BST 2020

On Thursday, June 4, 2020, Jacob Lifshay <programmerjake at gmail.com> wrote:

> I'm trying to build the div pipe, however, the ispec and ospec need to
> be different than the currently existing code since that is FP
> specific, there needs to be additional io signals that are not
> included in all the FP*Data classes. Additionally, I don't want to
> just overwrite the existing FPDiv pipe code since I'm not planning on
> adding FP div support right away, and the code needs to be refactored
> somewhat since the FPdiv pipe code is currently generic over being
> 16/32/64-bit at compile-time and the new code will need to be able to
> dynamically switch between them at runtime, once FP is added again.

ah we're not doing dynamic partitioning.  we are doing 64 bit only,
standard POWER9 and will refactor later.

> Luke, or whoever's available, can you give me an example of a
> combinatorial stage chain that is used inside a single stage without
> being wired as the inputs and outputs, along with getting all the
> pipekls stuff connected properly?

i placed a cookie cut version here already:


ctx will automatically pick up the context, which contains op, which is the
operand data structure.  you should stick with CompALUSubset for now.

> Somewhat unrelated, I moved all the unused code out of the fpdiv
> folder and into the unused folder

ah good, ok.


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