42compress #142
42compress #142
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…nto 42compress
…nto 42compress
| /// The carry results [carry]. | ||
| Logic get carry => output('carry'); | ||
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| late final List<List<double>> _delays; |
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do you think it may be useful to expose a @protected API for setting these delays rather than private, so that if someone has a technology-specific delay they want to set, they could just extend one of the compressors and change the delay numbers? this also leads to another question: should there be an argument to generate compressors in ColumnCompressor (even the smaller ones) rather than just a flag on whether to use 4:2 or not?
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The bare minimum is to use 2:2 and 3:2 compressors (half and full-adders). But you have a point -- people have invented even wider compressors.
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do you want to include changes to support arbitrary delays and user-defined compressors in this PR? one consideration is this flag to "use 4:2 compressors" is an API that wouldn't really make sense if we later replace it with a list of compressor types that can be used, for example
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| /// Compute the first One find operation on LogicValue, returning its position | ||
| int? firstOne() { |
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you could still import that other non-public file to gain access to this, rather than copy-paste the function
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i still see it in both "evaluate_partial_product.dart" and "logicvalue_extension.dart"
| '${signedMultiplier ? 'SM_' : ''}' | ||
| '${selectSignedMultiplicand != null ? 'SSD_' : ''}' | ||
| '${selectSignedMultiplier != null ? 'SSM_' : ''}' | ||
| 'with${adderGen(a, b).definitionName}') { |
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this call to adderGen i think will actually construct an adder connected to those ports, which could lead to additional verilog generation (outside of the module, even) and also slow down simulation since it's simulating a whole additional adder. i think i remember seeing this pattern in a few other places as well and didnt think it through.
| /// The carry results [carry]. | ||
| Logic get carry => output('carry'); | ||
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| late final List<List<double>> _delays; |
There was a problem hiding this comment.
do you want to include changes to support arbitrary delays and user-defined compressors in this PR? one consideration is this flag to "use 4:2 compressors" is an API that wouldn't really make sense if we later replace it with a list of compressor types that can be used, for example
Description & Motivation
Adds 4:2 compressors option to ColumnCompressor as well as a better delay table for optimizing the compression tree.
Added a popCount as a LogicValue extension which may need to be migrated to ROHD itself (along with majority). Eventually we will need hardware versions of these.
Related Issue(s)
#120 #86
Testing
Modified tests to enable the 4:2 compression option.
Backwards-compatibility
compression trees will take on a different shape with different delay tables as the delay optimization gets more realistic.
Documentation
Yes. Code is updated. We could update the component generation to expose this option as well as we need to update the documentation of multipliers that use this option.