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techmap: add a Han-Carlson option for `$lcu` mapping

This commit is contained in:
Emil J. Tywoniak 2024-11-28 15:13:51 +01:00
parent 98b4affc4a
commit 6c78bd3637
2 changed files with 58 additions and 0 deletions
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1
techlibs/common/Makefile.inc
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@ -36,3 +36,4 @@ $(eval $(call add_share_file,share,techlibs/common/abc9_unmap.v))
$(eval $(call add_share_file,share,techlibs/common/cmp2lcu.v))
$(eval $(call add_share_file,share,techlibs/common/cmp2softlogic.v))
$(eval $(call add_share_file,share/choices,techlibs/common/choices/kogge-stone.v))
$(eval $(call add_share_file,share/choices,techlibs/common/choices/han-carlson.v))

57
techlibs/common/choices/han-carlson.v Normal file
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@ -0,0 +1,57 @@
(* techmap_celltype = "$lcu" *)
module _85_lcu_han_carlson (P, G, CI, CO);
parameter WIDTH = 2;
(* force_downto *)
input [WIDTH-1:0] P, G;
input CI;
(* force_downto *)
output [WIDTH-1:0] CO;
integer i, j;
(* force_downto *)
reg [WIDTH-1:0] p, g;
always @* begin
i = 0;
p = P;
g = G;
// in almost all cases CI will be constant zero
g[0] = g[0] | (p[0] & CI);
if (i < $clog2(WIDTH)) begin
// First layer: BK
for (j = WIDTH - 1; j >= 0; j = j - 1) begin
if (j % 2 == 1) begin
g[j] = g[j] | p[j] & g[j - 1];
p[j] = p[j] & p[j - 1];
end
end
// Inner (log(WIDTH) - 1) layers: KS
for (i = 1; i < $clog2(WIDTH); i = i + 1) begin
for (j = WIDTH - 1; j >= 2**i; j = j - 1) begin
if (j % 2 == 1) begin
g[j] = g[j] | p[j] & g[j - 2**i];
p[j] = p[j] & p[j - 2**i];
end
end
end
// Last layer: BK
if (i < ($clog2(WIDTH) + 1)) begin
for (j = WIDTH - 1; j >= 0; j = j - 1) begin
if ((j % 2 == 0) && (j > 0)) begin
g[j] = g[j] | p[j] & g[j - 1];
p[j] = p[j] & p[j - 1];
end
end
end
end
end
assign CO = g;
endmodule