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Merge pull request #2467 from YosysHQ/dave/nexus-carry-fix

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nexus: More efficient CO mapping
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David Shah 2020-12-02 22:07:25 +00:00 committed by GitHub
parent 2945e27020 264e924abb
commit c3eb346e1e
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1 changed files with 2 additions and 2 deletions
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techlibs/nexus/arith_map.v
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@ -88,9 +88,9 @@ module _80_nexus_alu (A, B, CI, BI, X, Y, CO);
.COUT(FCO[i+2])
);
assign CO[i] = (AA[i] && BB[i]) || (((i == 0) ? CI : CO[i-1]) && (AA[i] || BB[i]));
assign CO[i] = (AA[i] && BB[i]) || ((Y[i] ^ AA[i] ^ BB[i]) && (AA[i] || BB[i]));
if (i+1 < Y_WIDTH) begin
assign CO[i+1] = (AA[i+1] && BB[i+1]) || (CO[i] && (AA[i+1] || BB[i+1]));
assign CO[i + 1] = (AA[i] && BB[i]) || ((Y[i] ^ AA[i] ^ BB[i]) && (AA[i] || BB[i]));
assign Y[i+1] = Y1[i];
end
end endgenerate