Individual Pin Inversion

[anuejn]

This PR implements individual pin inversion as discussed in RFC #510. I was unsure about changing the internal representation of invert from a single bool to a tuple of bool. Is that a breaking change and should methods in vendor still support being passed a single bool?

[codecov[bot]]

Codecov Report

Merging #514 into master will increase coverage by 0.04%. The diff coverage is 89.47%.

@@            Coverage Diff             @@
##           master     #514      +/-   ##
==========================================
+ Coverage   81.34%   81.38%   +0.04%     
==========================================
  Files          49       49              
  Lines        6412     6426      +14     
  Branches     1279     1286       +7     
==========================================
+ Hits         5216     5230      +14     
  Misses       1007     1007              
  Partials      189      189              

Impacted Files	Coverage Δ
nmigen/build/plat.py	26.56% <0.00%> (ø)
nmigen/build/dsl.py	96.57% <100.00%> (+0.29%)	:arrow_up:
nmigen/build/res.py	82.65% <100.00%> (ø)

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[whitequark]

I would strongly prefer it if there was only a single invert property, containing a tuple of booleans or perhaps more nicely a single int that can be XOR'd in the vendor code.

[anuejn]

I would strongly prefer it if there was only a single invert property

In the DSL? That would introduce a bunch of breaking changes (for example the repr of the Pins and DiffPairs objects), Moreover, the invert property of those DSL object would not be implementable as is (or am I wrong?). However, I am fine with that as well.

[whitequark]

In the DSL?

Internally. Let me review your changes more carefully first, though.

[anuejn]

Okay :+1:

[whitequark]

@anuejn This PR is pretty old at this point. Are you still interested in pursuing it?

[anuejn]

Oh sorry, I completely forgot about this PR. I still really want this functionality, and I am willing to continue. It would be sad if the work that already went into this was lost.

That said, I am on holiday for the following two weeks but would continue afterward if it is okay for you. Otherwise also feel free to close this PR for now, and I'll reopen another when I get back to it.

[whitequark]

No problem if you want to continue pursuing it. I think the existing RFC, despite not being written quite to the same high standard that we now require, seems to be good enough to pick up working on this feature. (Among my reasons are that it's not a core language feature and the platform system is likely to get a major reshape before 1.0.)

[anuejn]

closing this and maybe re-implementing it on top of rfc-55 once it lands