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techmap: Add a Kogge-Stone option for $lcu mapping

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Martin Povišer 2024-03-25 14:56:17 +01:00
parent d73f71e813
commit c38201e15d
1 changed files with 9 additions and 0 deletions
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9
techlibs/common/techmap.v
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@ -230,6 +230,7 @@ module _90_lcu (P, G, CI, CO);
// in almost all cases CI will be constant zero
g[0] = g[0] | (p[0] & CI);
`ifndef KOGGE_STONE
// [[CITE]] Brent Kung Adder
// R. P. Brent and H. T. Kung, "A Regular Layout for Parallel Adders",
// IEEE Transaction on Computers, Vol. C-31, No. 3, p. 260-264, March, 1982
@ -249,6 +250,14 @@ module _90_lcu (P, G, CI, CO);
p[j] = p[j] & p[j - 2**(i-1)];
end
end
`else
for (i = 0; i < $clog2(WIDTH); i = i + 1) begin
for (j = 2**i; j < WIDTH; j = j + 1) begin
g[j] = g[j] | p[j] & g[j - 2**i];
p[j] = p[j] & p[j - 2**i];
end
end
`endif
end
assign CO = g;